@article{huang_pugh_kim_nam_2024, title={Brain dynamics of mental workload in a multitasking context: Evidence from dynamic causal modeling}, volume={152}, ISSN={["1873-7692"]}, DOI={10.1016/j.chb.2023.108043}, abstractNote={Multitasking is a common element in complex human-computer interactions and is known to impose deleterious mental workload demands. High mental workload is known to involve bilateral hemisphere activation, but the patterns of effective connectivity (directed causal influence or communication) among brain regions in such a context remain unclear. This study investigated the effect of mental workload on the causal influence brain regions exert over each other under a multitasking scenario. The Dynamic Causal Modeling (DCM) method was implemented to infer the flow of information and allocation of attentional resources. Thirty participants performed four subtasks with varying levels of workload on a computer-based multitasking program, simulating a pilot cockpit. Using eight brain regions commonly identified to be activated in multitasking conditions, nine candidate models were developed. Bayesian model averaging was then used to quantify the connectivity strengths among the brain regions. Linear regression was conducted to study the relationships between connection strengths and subtask performances. The results showed that the causal connections shifted from the left to both sides of the brain with increased workload. Linear regression analysis showed that the subtask performance could be predicted by connectivity strengths. Thus, by studying the brain dynamics of mental workload, we may be able to develop a predictor that supplements subjective self-report measures.}, journal={COMPUTERS IN HUMAN BEHAVIOR}, author={Huang, Jiali and Pugh, Zachary H. and Kim, Sangyeon and Nam, Chang S.}, year={2024}, month={Mar} }
 @article{won_kim_gwon_ahn_nam_jun_2023, title={Can vibrotactile stimulation and tDCS help inefficient BCI users?}, volume={20}, ISSN={["1743-0003"]}, DOI={10.1186/s12984-023-01181-0}, abstractNote={Abstract}, number={1}, journal={JOURNAL OF NEUROENGINEERING AND REHABILITATION}, author={Won, Kyungho and Kim, Heegyu and Gwon, Daeun and Ahn, Minkyu and Nam, Chang S. and Jun, Sung Chan}, year={2023}, month={May} }
 @article{kim_choo_park_park_nam_jung_lee_2023, title={Designing an XAI interface for BCI experts: A contextual design for pragmatic explanation interface based on domain knowledge in a specific context}, volume={174}, ISSN={["1095-9300"]}, DOI={10.1016/j.ijhcs.2023.103009}, abstractNote={Domain experts utilize a decision-support system depending on an artificial intelligence (AI) algorithm. Likewise, researchers in brain-computer interface (BCI) have recently employed deep learning (DL) algorithms for decoding and analyzing neural signals. Despite its outstanding performance, the BCI technology with the DLs has pointed out that it has a potential problem of low transparency due to algorithmic complexity of the models. On this problem, explainable artificial intelligence (XAI) can be a solution to make an AI algorithm and its decisions more interpretable. However, the explanation from the XAI has been emphasized that it should be designed corresponding with the user's different expectations which are contextually variable. Thus, our study aims to propose an explanation interface for the BCI expert under Pragmatism structuralizing an explanation with scientific knowledge in a contrastive manner. For this work, we conduct a contextual design process with five BCI experts, specifically conducting a contextual inquiry and work modeling to extract design requirements from their expertise in their work environment; next, designing and evaluating an interactive prototype of the explanation interface. The results indicated that our prototype has the advantages of increasing contextual understanding and intuitive interface design. Yet, there were also challenges on the explanation for novice users without prior knowledge on the XAI and objective understanding of the AI model with enough interpretability. This study contributes to providing a theoretical framework based on Pragmatism and designing a user-centered XAI system for domain experts in a specific context.}, journal={INTERNATIONAL JOURNAL OF HUMAN-COMPUTER STUDIES}, author={Kim, Sangyeon and Choo, Sanghyun and Park, Donghyun and Park, Hoonseok and Nam, Chang S. and Jung, Jae-Yoon and Lee, Sangwon}, year={2023}, month={Jun} }
 @article{choo_park_kim_park_jung_lee_nam_2023, title={Effectiveness of multi-task deep learning framework for EEG-based emotion and context recognition}, volume={227}, ISSN={["1873-6793"]}, DOI={10.1016/j.eswa.2023.120348}, abstractNote={Studies have investigated electroencephalogram (EEG)-based emotion recognition using hand-crafted EEG features (e.g., differential entropy) or the annotated emotion categories without any additional emotion factors (e.g., context). The effectiveness of raw EEG-based emotion recognition remains for further investigation. In this study, we investigated the effectiveness of multi-task learning (MTL) for raw EEG-based convolutional neural networks (CNNs) in emotion recognition with auxiliary context information. Thirty subjects participated in this study, where their brain signals were collected when watching six types of emotion images (social/nonsocial-fear, social/nonsocial-sad, and social/nonsocial-neutral). For the MTL architecture, we utilized temporal and spatial filtering layers from raw EEG-based CNNs as shared and task-specific layers for emotion and context classification tasks. Subject-dependent classifications and five repeated five-fold cross-validation were performed to test the classification accuracy for all comparison models. Our results showed that (1) the MTL classifier had a significantly higher classification accuracy and improved the performance of the single-task learnings (STLs) for both emotion and context, and (2) the ShallowConvNet was the best network architecture among the considered CNNs for the MTL with statistically significant improvement to the raw EEG-based STLs. This shows that the MTL can be a promising method for emotion recognition in utilizing the raw EEG-based CNN classifiers and emphasizes the importance of considering context information.}, journal={EXPERT SYSTEMS WITH APPLICATIONS}, author={Choo, Sanghyun and Park, Hoonseok and Kim, Sangyeon and Park, Donghyun and Jung, Jae-Yoon and Lee, Sangwon and Nam, Chang S.}, year={2023}, month={Oct} }
 @article{ghasemi_bayro_macdonald_jeong_reynolds_nam_2023, title={Enhancing Culinary Training with Spatial Augmented Reality: A User Study Comparing sAR Kitchen and Video Tutorials}, DOI={10.1109/VRW58643.2023.00085}, abstractNote={This paper presents sAR Kitchen, a cooking assistant that aims to enhance culinary training through the use of spatial augmented reality (sAR). We conducted a user study with twenty-two participants to investigate the effects of instructions given by our proposed sAR system and a monitor display with video tutorials in a playdough-making task representing the cooking task. Our study measured participants' perceived workload, usability, and performance regarding task completion time, product quality, and cooking station messiness. The results showed that sAR significantly decreased the perceived workload and increased the system's usability compared to traditional video-based tutorials. Additionally, our open-ended questions revealed that participants found the sAR instructions more engaging and interactive. Overall, this study demonstrates the potential of sAR to provide more user-friendly learning methods in culinary training.}, journal={2023 IEEE CONFERENCE ON VIRTUAL REALITY AND 3D USER INTERFACES ABSTRACTS AND WORKSHOPS, VRW}, author={Ghasemi, Yalda and Bayro, Allison and MacDonald, Justin and Jeong, Heejin and Reynolds, Joel and Nam, Chang S.}, year={2023}, pages={390–392} }
 @misc{gwon_won_song_nam_jun_ahn_2023, title={Review of public motor imagery and execution datasets in brain-computer interfaces}, volume={17}, ISSN={["1662-5161"]}, DOI={10.3389/fnhum.2023.1134869}, abstractNote={The demand for public datasets has increased as data-driven methodologies have been introduced in the field of brain-computer interfaces (BCIs). Indeed, many BCI datasets are available in various platforms or repositories on the web, and the studies that have employed these datasets appear to be increasing. Motor imagery is one of the significant control paradigms in the BCI field, and many datasets related to motor tasks are open to the public already. However, to the best of our knowledge, these studies have yet to investigate and evaluate the datasets, although data quality is essential for reliable results and the design of subject− or system-independent BCIs. In this study, we conducted a thorough investigation of motor imagery/execution EEG datasets recorded from healthy participants published over the past 13 years. The 25 datasets were collected from six repositories and subjected to a meta-analysis. In particular, we reviewed the specifications of the recording settings and experimental design, and evaluated the data quality measured by classification accuracy from standard algorithms such as Common Spatial Pattern (CSP) and Linear Discriminant Analysis (LDA) for comparison and compatibility across the datasets. As a result, we found that various stimulation types, such as text, figure, or arrow, were used to instruct subjects what to imagine and the length of each trial also differed, ranging from 2.5 to 29 s with a mean of 9.8 s. Typically, each trial consisted of multiple sections: pre-rest (2.38 s), imagination ready (1.64 s), imagination (4.26 s, ranging from 1 to 10 s), the post-rest (3.38 s). In a meta-analysis of the total of 861 sessions from all datasets, the mean classification accuracy of the two-class (left-hand vs. right-hand motor imagery) problem was 66.53%, and the population of the BCI poor performers, those who are unable to reach proficiency in using a BCI system, was 36.27% according to the estimated accuracy distribution. Further, we analyzed the CSP features and found that each dataset forms a cluster, and some datasets overlap in the feature space, indicating a greater similarity among them. Finally, we checked the minimal essential information (continuous signals, event type/latency, and channel information) that should be included in the datasets for convenient use, and found that only 71% of the datasets met those criteria. Our attempts to evaluate and compare the public datasets are timely, and these results will contribute to understanding the dataset’s quality and recording settings as well as the use of using public datasets for future work on BCIs.}, journal={FRONTIERS IN HUMAN NEUROSCIENCE}, author={Gwon, Daeun and Won, Kyungho and Song, Minseok and Nam, Chang S. and Jun, Sung Chan and Ahn, Minkyu}, year={2023}, month={Mar} }
 @article{gwon_won_song_nam_jun_ahn_2023, title={Review of public motor imagery and execution datasets in brain-computer interfaces (vol 17, 1134869, 2023)}, volume={17}, ISSN={["1662-5161"]}, DOI={10.3389/fnhum.2023.1205419}, abstractNote={[This corrects the article DOI: 10.3389/fnhum.2023.1134869.].}, journal={FRONTIERS IN HUMAN NEUROSCIENCE}, author={Gwon, Daeun and Won, Kyungho and Song, Minseok and Nam, Chang S. and Jun, Sung Chan and Ahn, Minkyu}, year={2023}, month={May} }
 @article{pugh_huang_leshin_lindquist_nam_2022, title={Culture and gender modulate dlPFC integration in the emotional brain: evidence from dynamic causal modeling}, volume={5}, ISSN={["1871-4099"]}, DOI={10.1007/s11571-022-09805-2}, abstractNote={Past research has recognized culture and gender variation in the experience of emotion, yet this has not been examined on a level of effective connectivity. To determine culture and gender differences in effective connectivity during emotional experiences, we applied dynamic causal modeling (DCM) to electroencephalography (EEG) measures of brain activity obtained from Chinese and American participants while they watched emotion-evoking images. Relative to US participants, Chinese participants favored a model bearing a more integrated dorsolateral prefrontal cortex (dlPFC) during fear v. neutral experiences. Meanwhile, relative to males, females favored a model bearing a less integrated dlPFC during fear v. neutral experiences. A culture-gender interaction for winning models was also observed; only US participants showed an effect of gender, with US females favoring a model bearing a less integrated dlPFC compared to the other groups. These findings suggest that emotion and its neural correlates depend in part on the cultural background and gender of an individual. To our knowledge, this is also the first study to apply both DCM and EEG measures in examining culture-gender interaction and emotion.}, journal={COGNITIVE NEURODYNAMICS}, author={Pugh, Zachary H. and Huang, Jiali and Leshin, Joseph and Lindquist, Kristen A. and Nam, Chang S.}, year={2022}, month={May} }
 @article{choo_nam_2022, title={Detecting Human Trust Calibration in Automation: A Convolutional Neural Network Approach}, volume={1}, ISSN={["2168-2305"]}, url={https://doi.org/10.1109/THMS.2021.3137015}, DOI={10.1109/THMS.2021.3137015}, abstractNote={There is a general lack of studies that are aimed at monitoring and detecting an operator's trust calibration, even though detecting someone's adjusted trust towards automation is essential to prevent misuse and disuse of automation. The goal of this article is to propose a convolutional neural network (CNN) based framework to estimate operators’ trust levels and detect their trust calibration in automation using image features of electroencephalogram (EEG) signals preserving temporal, spectral, and spatial information. Thirteen participants performed a set of automated Air Force multiattribute task battery tasks that differed in reliability (High/Low) and credibility (High/Low) levels. The proposed framework was compared with three machine learning methods—naïve bayes, support vector machine, multilayer perceptron—in terms of accuracy, sensitivity, and specificity of trust estimation and detection of trust calibration. Results of this article showed that the proposed framework had the highest performance of both trust estimation and detection of trust calibration in automation compared to the other comparison methods. This indicates that the proposed framework using the CNN classifier with the image-based EEG features could be an applicable model for estimating multilevel trust and detecting trust calibration during human-automation interaction. Also, it can help to prevent disuse and misuse of automation by estimating operators’ trust levels and monitoring their trust calibration in automation.}, number={4}, journal={IEEE TRANSACTIONS ON HUMAN-MACHINE SYSTEMS}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Choo, Sanghyun and Nam, Chang}, year={2022}, month={Jan} }
 @article{barresi_nam_esfahani_balconi_2022, title={Editorial: Neuroergonomics in Human-Robot Interaction}, volume={16}, ISSN={["1662-5218"]}, DOI={10.3389/fnbot.2022.1006103}, abstractNote={COPYRIGHT © 2022 Barresi, Nam, Esfahani and Balconi. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. Editorial: Neuroergonomics in Human-Robot Interaction}, journal={FRONTIERS IN NEUROROBOTICS}, author={Barresi, Giacinto and Nam, Chang S. and Esfahani, Ehsan T. and Balconi, Michela}, year={2022}, month={Sep} }
 @article{pugh_choo_leshin_lindquist_nam_2022, title={Emotion depends on context, culture and their interaction: evidence from effective connectivity}, volume={17}, ISSN={["1749-5024"]}, DOI={10.1093/scan/nsab092}, abstractNote={Abstract}, number={2}, journal={SOCIAL COGNITIVE AND AFFECTIVE NEUROSCIENCE}, author={Pugh, Zachary H. and Choo, Sanghyun and Leshin, Joseph C. and Lindquist, Kristen A. and Nam, Chang S.}, year={2022}, month={Feb}, pages={206–217} }
 @article{huang_jung_nam_2022, title={Estimating effective connectivity in Alzheimer's disease progression: A dynamic causal modeling study}, volume={16}, ISSN={["1662-5161"]}, DOI={10.3389/fnhum.2022.1060936}, abstractNote={IntroductionAlzheimer's disease (AD) affects the whole brain from the cellular level to the entire brain network structure. The causal relationship among brain regions concerning the different AD stages is not yet investigated. This study used Dynamic Causal Modeling (DCM) method to assess effective connectivity (EC) and investigate the changes that accompany AD progression.}, journal={FRONTIERS IN HUMAN NEUROSCIENCE}, author={Huang, Jiali and Jung, Jae-Yoon and Nam, Chang S.}, year={2022}, month={Dec} }
 @article{huang_choo_pugh_nam_2022, title={Evaluating Effective Connectivity of Trust in Human-Automation Interaction: A Dynamic Causal Modeling (DCM) Study}, volume={64}, ISSN={["1547-8181"]}, url={https://doi.org/10.1177/0018720820987443}, DOI={10.1177/0018720820987443}, abstractNote={Objective Using dynamic causal modeling (DCM), we examined how credibility and reliability affected the way brain regions exert causal influence over each other—effective connectivity (EC)—in the context of trust in automation. }, number={6}, journal={HUMAN FACTORS}, publisher={SAGE Publications}, author={Huang, Jiali and Choo, Sanghyun and Pugh, Zachary H. and Nam, Chang S.}, year={2022}, month={Sep}, pages={1051–1069} }
 @book{nam_jung_lee_2022, place={London}, title={Human-Centered Artificial Intelligence: Research and Applications}, ISBN={9780323856492}, publisher={Academic Press}, year={2022} }
 @article{chen_peng_wu_huang_kim_traylor_muller_chhatbar_nam_feng_et al._2022, title={Numerical and experimental evaluation of low-intensity transcranial focused ultrasound wave propagation using human skulls for brain neuromodulation}, volume={11}, ISSN={["2473-4209"]}, DOI={10.1002/mp.16090}, abstractNote={Abstract}, journal={MEDICAL PHYSICS}, author={Chen, Mengyue and Peng, Chang and Wu, Huaiyu and Huang, Chih-Chung and Kim, Taewon and Traylor, Zachary and Muller, Marie and Chhatbar, Pratik Y. and Nam, Chang S. and Feng, Wuwei and et al.}, year={2022}, month={Nov} }
 @article{hossaini_valeriani_nam_ferrante_mahmud_2021, title={A Functional BCI Model by the P2731 working group: Physiology}, volume={9}, ISSN={["2326-2621"]}, DOI={10.1080/2326263X.2021.1968665}, abstractNote={The development of Brain–Computer Interfaces (BCIs) requires specialists in various fields, including engineering, computer science, medicine and neuroscience. Each of these disciplines possesses a...}, journal={BRAIN-COMPUTER INTERFACES}, author={Hossaini, Ali and Valeriani, Davide and Nam, Chang S. and Ferrante, Raffaele and Mahmud, Mufti}, year={2021}, month={Sep} }
 @article{easttom_bianchi_valeriani_nam_hossaini_zapala_roman-gonzalez_singh_antonietti_sahonero-alvarez_et al._2021, title={A functional BCI model by the P2731 working group: control interface}, volume={8}, ISSN={["2326-2621"]}, DOI={10.1080/2326263X.2021.2002004}, abstractNote={In order to facilitate communication and collaboration between researchers, Brain–computer interfaces (BCI) require a generally applicable functional model as well as a common vocabulary. The IEEE P2731 working group is in the process of developing such a functional model and a lexicon of BCI terminology. Such a functional model has multiple aspects including the control interface, physiology, transducers, etc. This current paper focuses on the control interface aspects of that model. Having a generally applicable control interface model will facilitate interdisciplinar y research and communication. The control interface is a critical part of the functional model and is described in this current paper. The control interface presented intentionally is intentionally kept general in order to be widely applicable. Some details are specific to a particular application and are thus left to those applications. It does contain the encoder (which also contains a decoder), with a feedback submodule.}, number={4}, journal={BRAIN-COMPUTER INTERFACES}, author={Easttom, Chuck and Bianchi, Luigi and Valeriani, Davide and Nam, Chang S. and Hossaini, Ali and Zapala, Dariusz and Roman-Gonzalez, Avid and Singh, Avinash K. and Antonietti, Alberto and Sahonero-Alvarez, Guillermo and et al.}, year={2021}, month={Oct}, pages={154–160} }
 @misc{nam_traylor_chen_jiang_feng_chhatbar_2021, title={Direct Communication Between Brains: A Systematic PRISMA Review of Brain-To-Brain Interface}, volume={15}, ISSN={["1662-5218"]}, url={http://dx.doi.org/10.3389/fnbot.2021.656943}, DOI={10.3389/fnbot.2021.656943}, abstractNote={This paper aims to review the current state of brain-to-brain interface (B2BI) technology and its potential. B2BIs function via a brain-computer interface (BCI) to read a sender's brain activity and a computer-brain interface (CBI) to write a pattern to a receiving brain, transmitting information. We used the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) to systematically review current literature related to B2BI, resulting in 15 relevant publications. Experimental papers primarily used transcranial magnetic stimulation (tMS) for the CBI portion of their B2BI. Most targeted the visual cortex to produce phosphenes. In terms of study design, 73.3% (11) are unidirectional and 86.7% (13) use only a 1:1 collaboration model (subject to subject). Limitations are apparent, as the CBI method varied greatly between studies indicating no agreed upon neurostimulatory method for transmitting information. Furthermore, only 12.4% (2) studies are more complicated than a 1:1 model and few researchers studied direct bidirectional B2BI. These studies show B2BI can offer advances in human communication and collaboration, but more design and experiments are needed to prove potential. B2BIs may allow rehabilitation therapists to pass information mentally, activating a patient's brain to aid in stroke recovery and adding more complex bidirectionality may allow for increased behavioral synchronization between users. The field is very young, but applications of B2BI technology to neuroergonomics and human factors engineering clearly warrant more research.}, journal={FRONTIERS IN NEUROROBOTICS}, publisher={Frontiers Media SA}, author={Nam, Chang S. and Traylor, Zachary and Chen, Mengyue and Jiang, Xiaoning and Feng, Wuwei and Chhatbar, Pratik Yashvant}, year={2021}, month={May} }
 @article{kim_kim_kim_nam_2021, title={Dual Task Effects on Speed and Accuracy During Cognitive and Upper Limb Motor Tasks in Adults With Stroke Hemiparesis}, volume={15}, ISSN={["1662-5161"]}, DOI={10.3389/fnhum.2021.671541}, abstractNote={BackgroundAdults with stroke need to perform cognitive–motor dual tasks during their day-to-day activities. However, they face several challenges owing to their impaired motor and cognitive functions.}, journal={FRONTIERS IN HUMAN NEUROSCIENCE}, author={Kim, Hogene and Kim, Hyun-Ki and Kim, Nayoung and Nam, Chang S.}, year={2021}, month={Jun} }
 @misc{kim_park_chhatbar_feld_mac grory_nam_wang_chen_jiang_feng_2021, title={Effect of Low Intensity Transcranial Ultrasound Stimulation on Neuromodulation in Animals and Humans: An Updated Systematic Review}, volume={15}, ISSN={["1662-453X"]}, DOI={10.3389/fnins.2021.620863}, abstractNote={Background: Although low-intensity transcranial ultrasound stimulation (LI-TUS) has received more recognition for its neuromodulation potential, there remains a crucial knowledge gap regarding the neuromodulatory effects of LI-TUS and its potential for translation as a therapeutic tool in humans.}, journal={FRONTIERS IN NEUROSCIENCE}, author={Kim, Taewon and Park, Christine and Chhatbar, Pratik Y. and Feld, Jody and Mac Grory, Brian and Nam, Chang S. and Wang, Pu and Chen, Mengyue and Jiang, Xiaoning and Feng, Wuwei}, year={2021}, month={Apr} }
 @book{nam_lyons_2021, place={London}, title={Trust in human-robot interaction}, publisher={Elsevier Academic Press}, year={2021} }
 @article{lyons_vo_wynne_mahoney_nam_gallimore_2021, title={Trusting Autonomous Security Robots: The Role of Reliability and Stated Social Intent}, volume={63}, ISSN={["1547-8181"]}, DOI={10.1177/0018720820901629}, abstractNote={Objective This research examined the effects of reliability and stated social intent on trust, trustworthiness, and one’s willingness to endorse use of an autonomous security robot (ASR). }, number={4}, journal={HUMAN FACTORS}, author={Lyons, Joseph B. and Vo, Thy and Wynne, Kevin T. and Mahoney, Sean and Nam, Chang S. and Gallimore, Darci}, year={2021}, month={Jun}, pages={603–618} }
 @inbook{choi_kim_nam_2020, series={Cognitive Science and Technology Series}, title={A Sensorimotor Rhythm-Based Brain–Computer Interface Controlled Functional Electrical Stimulation for Handgrasp Rehabilitation}, ISBN={978-3-030-34783-3}, DOI={10.1007/978-3-030-34784-0_17}, abstractNote={Each year, 795,000 stroke patients suffer a new or recurrent stroke and 235,000 severe traumatic brain injuries (TBIs) occur in the US. These patients are susceptible to a combination of significant motor, sensory, and cognitive deficits, and it becomes difficult or impossible for them to perform activities of daily living due to residual functional impairments. Recently, sensorimotor rhythm (SMR)-based brain–computer interface (BCI)-controlled functional electrical stimulation (FES) has been studied for restoration and rehabilitation of motor deficits. To provide future neuroergonomists with the limitations of current BCI-controlled FES research, this chapter presents the state-of-the-art SMR-based BCI-controlled FES technologies, such as current motor imagery (MI) training procedures and guidelines, an EEG-channel montage used to decode MI features, and brain features evoked by MI.}, booktitle={Neuroergonomics: principles and practice}, publisher={Springer}, author={Choi, In and Kim, N. and Nam, C.S.}, editor={Nam, C.S.Editor}, year={2020}, pages={329–349}, collection={Cognitive Science and Technology Series} }
 @inbook{kim_nam_2020, place={Cham, Switzerland}, series={Cognitive Science and Technology}, title={Adaptive Control of Thought-Rational (ACT-R): Applying a Cognitive Architecture to Neuroergonomics}, ISBN={9783030347840 9783030347864 9783030347833}, DOI={10.1007/978-3-030-34784-0_6}, abstractNote={For neuroergonomists who wish to apply Adaptive Control of Thought-Rational (ACT-R)Adaptive Control of Thought-Rational (ACT-R) to investigate the human mind and its structure including learning, performance, and problem-solving skills, this chapter aims at providing an overview of ACT-R with an emphasis on its modules, buffers, and sub-symbolic levels. ACT-R is a high-level computational simulation of human cognitive processing and one of the cognition theories that seek to predict human performance in real-world settings. A group of previous studies on behavioral- and neural-based cognitive modelingCognitive modeling of human cognition using ACT-R will also be discussed. Finally, this chapter presents future directions of ACT-R for neuroergonomicsNeuroergonomics research.}, booktitle={Neuroergonomics: Principles and Practices}, publisher={Springer}, author={Kim, N. and Nam, C.S.}, editor={Nam, C.S.Editor}, year={2020}, pages={105–114}, collection={Cognitive Science and Technology} }
 @misc{nam_choo_huang_park_2020, title={Brain-to-Brain Neural Synchrony During Social Interactions: A Systematic Review on Hyperscanning Studies}, volume={10}, ISSN={["2076-3417"]}, url={https://www.mdpi.com/2076-3417/10/19/6669}, DOI={10.3390/app10196669}, abstractNote={The aim of this study was to conduct a comprehensive review on hyperscanning research (measuring brain activity simultaneously from more than two people interacting) using an explicit systematic method, the preferred reporting items for systematic reviews and meta-analyses (PRISMA). Data were searched from IEEE Xplore, PubMed, Engineering Village, Web of Science and Scopus databases. Inclusion criteria were journal articles written in English from 2000 to 19 June 2019. A total of 126 empirical studies were screened out to address three specific questions regarding the neuroimaging method, the application domain, and the experiment paradigm. Results showed that the most used neuroimaging method with hyperscanning was magnetoencephalography/electroencephalography (MEG/EEG; 47%), and the least used neuroimaging method was hyper-transcranial Alternating Current Stimulation (tACS) (1%). Applications in cognition accounted for almost half the studies (48%), while educational applications accounted for less than 5% of the studies. Applications in decision-making tasks were the second most common (26%), shortly followed by applications in motor synchronization (23%). The findings from this systematic review that were based on documented, transparent and reproducible searches should help build cumulative knowledge and guide future research regarding inter-brain neural synchrony during social interactions, that is, hyperscanning research.}, number={19}, journal={APPLIED SCIENCES-BASEL}, publisher={MDPI AG}, author={Nam, Chang S. and Choo, Sanghyun and Huang, Jiali and Park, Jiyoung}, year={2020}, month={Oct} }
 @inbook{merante_zhang_kumar_nam_2020, series={Cognitive Science and Technology}, title={Brain–Computer Interfaces for Spinal Cord Injury Rehabilitation}, ISBN={978-3-030-34783-3}, DOI={10.1007/978-3-030-34784-0_16}, abstractNote={Brain–computer interface (BCI) is an emerging tool that has a variety of practical applications, including rehabilitation. BCIs are systems that extract and classify features in neural data, and then produce an output when a specific feature is detected. Motor imagery-based BCIs (MI BCIs), a more specific form of BCI, detect features that indicate the user is imagining a specific motor action, such as moving their arm or leg. There have been several studies released discussing the potential for BCIs to be used in a clinical setting for applications like rehabilitation. Spinal cord injuries (SCIs) are a form of injury that damages the spinal cord and causes either partial or total paralyzation. Those with SCI typically undergo rehabilitation for many years after the injury, and BCIs have begun to be tested for their benefits when included in SCI rehabilitation sessions. There are several ways for BCI systems to be used in SCI rehabilitation, which include virtual reality, exoskeletons, and neuroprosthesis. When using these methods as an output for a BCI system, SCI patients experience numerous benefits, most notably being an increase in mobility in the paralyzed region of their body. While there are several advantages to using BCIs for SCI rehabilitation, there are also several challenges that need to be addressed. In this chapter, we will discuss the current potential of BCIs for SCI rehabilitation, as well as what areas of this field need to be improved in the future.}, booktitle={Neuroergonomics: Principles and Practices}, publisher={Springer}, author={Merante, A. and Zhang, Y. and Kumar, S. and Nam, C.S.}, editor={Nam, C.S.Editor}, year={2020}, pages={315–328}, collection={Cognitive Science and Technology} }
 @inbook{choo_nam_2020, place={Cham, Switzerland}, series={Cognitive Science and Technology}, title={Deep Learning Techniques in Neuroergonomics}, ISBN={9783030347840 9783030347864 9783030347833}, DOI={10.1007/978-3-030-34784-0_7}, abstractNote={There is increasing interest in using deep learning (DL) for neuroergonomics research that investigates the human brain in relation to behavioral performance in natural environments and everyday settings. But a better understanding of how to design and implement DL techniques is still needed for neuroergonomists. Written for novice neuroergonomists as well as experienced investigators, this chapter presents the history of advancements in DL, its concepts, and applications of DL in neuroergonomics research. In addition to artificial neural network (ANN) which is a basic model for DL, this chapter introduces popular DL models such as the multilayer perceptron (MLP), deep belief network (DBN), convolutional neural network (CNN), and recurrent neural networks (RNN). DL-based neuroergonomics research on four main research areas (i.e., mental workload, motor imagery, driving safety, and emotion recognition) will then be reviewed. Insights into how to model and apply DL techniques will be helpful for neuroergonomics researchers, in particular those who are not familiar with DL, but want to predict and classify brain states under various contexts.}, booktitle={Neuroergonomics: Principles and Practices}, publisher={Springer}, author={Choo, S. and Nam, C.S.}, editor={Nam, C.S.Editor}, year={2020}, pages={115–138}, collection={Cognitive Science and Technology} }
 @inbook{huang_nam_2020, place={Cham, Switzerland}, series={Cognitive Science and Technology}, title={Dynamic Causal Modeling (DCM) for EEG Approach to Neuroergonomics}, ISBN={9783030347840 9783030347864 9783030347833}, DOI={10.1007/978-3-030-34784-0_8}, abstractNote={To study the underlying neural mechanismsNeural mechanisms of human cognitive and physical activities, various neuroimaging techniques such as fMRI, fNIRS, and EEG have been used. Dynamic causal modeling (DCM) for EEG method has gained a considerable amount of attention in recent years for exploring the directional causal relationshipDirectional causal relationship between brain areas. Studies using the DCM for EEG method have investigated contemporary neuroergonomics research topics such as mechanisms behind the event-related potential (ERP) components, mismatch negativity (MMN), abnormal coupling of neural regions in neurologically disordered patients, and causal connections supporting motor tasks. This chapter is a good guide for both novice and experienced neuroergonomics researchers as it introduces the motivations behind DCM for EEG and its developmental timelines, as well as explains fundamentals of the DCM for EEG including the neural mass models, state and observer’s equation, and the model selection processes. This chapter also summarizes recent studies that used the DCM for EEG method in the past 10 years in terms of the tasks, preprocessing steps, model construction, and selection. Lastly, recommendations for the future DCM-based neuroergonomicsNeuroergonomics research are presented.}, booktitle={Neuroergonomics: Principles and Practices}, publisher={Springer}, author={Huang, J. and Nam, C.S.}, editor={Nam, C.S.Editor}, year={2020}, pages={139–158}, collection={Cognitive Science and Technology} }
 @article{kim_kim_lyons_nam_2020, title={Factors affecting trust in high-vulnerability human-robot interaction contexts: A structural equation modelling approach}, volume={85}, ISSN={["1872-9126"]}, DOI={10.1016/j.apergo.2020.103056}, abstractNote={The current research proposed and tested a structural equation model (SEM) that describes hypothesized relationships among factors affecting trust in human-robot interaction (HRI) such as trustworthiness, human-likeness, intelligence, perfect automation schema (PAS), and affect. A video stimulus depicting an autonomous guard robot interacting with humans was employed as a stimulus via Amazon's Mechanical Turk to recruit 233 participants. Human-related and robot-related metrics were found to affect trustworthiness that subsequently affected trust. In particular, ability (as a trustworthiness facet) was a dominant factor affecting trust in HRI. Integrity was found to mediate the relationships between robot- and human-related metrics and trustworthiness. This study also showed a correlation between intelligence and trustworthiness, as well as between PAS and trustworthiness. The findings of the present study have significant implications for both theory and practice on factors and levels that affect trust in HRI.}, journal={APPLIED ERGONOMICS}, author={Kim, Wonjoon and Kim, Nayoung and Lyons, Joseph B. and Nam, Chang S.}, year={2020}, month={May} }
 @article{choi_kwon_lee_nam_2020, title={Functional Electrical Stimulation Controlled by Motor Imagery Brain-Computer Interface for Rehabilitation}, volume={10}, ISSN={["2076-3425"]}, url={https://www.mdpi.com/2076-3425/10/8/512}, DOI={10.3390/brainsci10080512}, abstractNote={Sensorimotor rhythm (SMR)-based brain–computer interface (BCI) controlled Functional Electrical Stimulation (FES) has gained importance in recent years for the rehabilitation of motor deficits. However, there still remain many research questions to be addressed, such as unstructured Motor Imagery (MI) training procedures; a lack of methods to classify different MI tasks in a single hand, such as grasping and opening; and difficulty in decoding voluntary MI-evoked SMRs compared to FES-driven passive-movement-evoked SMRs. To address these issues, a study that is composed of two phases was conducted to develop and validate an SMR-based BCI-FES system with 2-class MI tasks in a single hand (Phase 1), and investigate the feasibility of the system with stroke and traumatic brain injury (TBI) patients (Phase 2). The results of Phase 1 showed that the accuracy of classifying 2-class MIs (approximately 71.25%) was significantly higher than the true chance level, while that of distinguishing voluntary and passive SMRs was not. In Phase 2, where the patients performed goal-oriented tasks in a semi-asynchronous mode, the effects of the FES existence type and adaptive learning on task performance were evaluated. The results showed that adaptive learning significantly increased the accuracy, and the accuracy after applying adaptive learning under the No-FES condition (61.9%) was significantly higher than the true chance level. The outcomes of the present research would provide insight into SMR-based BCI-controlled FES systems that can connect those with motor disabilities (e.g., stroke and TBI patients) to other people by greatly improving their quality of life. Recommendations for future work with a larger sample size and kinesthetic MI were also presented.}, number={8}, journal={BRAIN SCIENCES}, author={Choi, Inchul and Kwon, Gyu Hyun and Lee, Sangwon and Nam, Chang S.}, year={2020}, month={Aug} }
 @inbook{thomas_nam_2020, place={Cham, Switzerland}, title={Functional Near-infrared Spectroscopy (fNIRS) in Neuroergonomics}, ISBN={9783030347840 9783030347864 9783030347833}, DOI={10.1007/978-3-030-34784-0_4}, abstractNote={This chapter focuses on functional near-infrared spectroscopy (fNIRS)Functional near-infrared spectroscopy (fNIRS) and its applications in the field of neuroergonomics. Due to the small, portable, and flexible nature of fNIRS, it has been able to track the neurocognitive behavior of participants during complex and ambulatory activities. This chapter presents a comprehensive summary and review of fNIRS technology with respect to its design, implementation, and measurements. The three different types of fNIRS that exist—continuous wave, frequency domain, and time domain—are further explained through example studies of each tool in action. We also provide detailed technological information on numerous studies that focus on the four main topics that fNIRS has frequently been used for: driving, mental workload, motor function, and decision-making. It then concludes with the directions and potential applications that fNIRS can be used for in the future. The main purpose of this chapter is to show the necessity and value of fNIRS in research and how it is able to provide accurate information in situations that would have otherwise been inaccessible.}, booktitle={Neuroergonomics: Principles and Practices}, publisher={Springer International Publishing}, author={Thomas, L. and Nam, C.S.}, editor={Nam, C.S.Editor}, year={2020}, pages={53–76} }
 @inbook{eskander_sanders_nam_2020, place={Cham, Switzerland}, series={Cognitive Science and Technology}, title={Neural Correlates and Mechanisms of Trust}, ISBN={9783030347840 9783030347864 9783030347833}, DOI={10.1007/978-3-030-34784-0_22}, abstractNote={The decision to trust is the foundation for proper functioning in technology, work, and social environments. For this reason, it is of critical interest to understand and investigate the brain mechanisms involved in human trust for the neuroergonomics community. This chapter seeks to review the current understanding of the neurotransmitters and different neural correlates involved in the decision to trust compared to the decision not to trust. The neurotransmitters with these multifaceted behaviors are Oxytocin and Testosterone. While previously dubbed, the “love hormone” oxytocin is now believed to have an impact on the brain’s encoding of prediction error, and therefore its ability to modify preexisting beliefs. Testosterone, which was thought of as an inhibitor of trust, only shows decreases of trust only in men and a subgroup of women who displayed social naivety. The structural correlates involved in trust/distrust identified are the prefrontal cortex (PFC) (specifically the ventromedial PFC and orbitofrontal cortex), the insula, caudate, amygdala, and anterior paracingulate cortex (PCC). The caudate and anterior paracingulate cortex are currently thought to be involved with the positive decision to trust, whereas the prefrontal cortex, insula, and amygdala seem to have higher correlations with the negative decision to distrust. The academic literature used to determine these correlates methodology included lesion studies, intranasal administration, fMRI imaging of the trust game, and transcranial direct stimulation studies.}, booktitle={Neuroergonomics: Principles and Practices}, publisher={Springer}, author={Eskander, E. and Sanders, N. and Nam, C.S.}, editor={Nam, C.S.Editor}, year={2020}, pages={451–461}, collection={Cognitive Science and Technology} }
 @inbook{ware_feng_nam_2020, place={Cham, Switzerland}, series={Cognitive Science and Technology}, title={Neuroergonomics Behind the Wheel: Neural Correlates of Car Driving}, ISBN={9783030347840 9783030347864 9783030347833}, DOI={10.1007/978-3-030-34784-0_18}, abstractNote={Each year around the world, approximately 1.25 million lives are lost in fatal vehicle crashes. This statistic equates to 3,434 deaths per day. In addition, another 20–50 million people are injured or disabled in crashes (Association for Safe International Road Travel 2002). This chapter provides a review of studies that utilized neurocognitive methods to study how a driver’s brain functions to support various tasks while driving. These changes in brain activity can show how secondary tasks, distractions, and substances degrade driver performance and increase crash risks. The neural techniques analyzed in this chapter include electroencephalography (EEG), functional magnetic resonance imaging (fMRI), functional near-infrared spectroscopy (fNIRS), and magnetoencephalography (MEG). Most participants for these studies were in their mid-20s, except for a few in which the study’s purpose was to analyze driving performance between age groups. Given the difficulty in collecting neural activity data while a driver is on the road, most studies utilized driving simulation as opposed to on-road driving. Current findings suggest a critical role of frontal regions of the brain in driving. In addition, this chapter analyzes the effects that independent variables added to the driving task have on the organizational planning levels—strategical, tactical, and operational planning along with the brain activity that accompanies this planning. Lastly, the chapter provides a discussion of limitations of this literature and future directions.}, booktitle={Neuroergonomics: Principles and Practices}, publisher={Springer}, author={Ware, M. and Feng, J. and Nam, C.S.}, editor={Nam, C.S.Editor}, year={2020}, pages={353–388}, collection={Cognitive Science and Technology} }
 @book{nam_2020, place={Cham, Switzerland}, series={Cognitive Science and Technology}, title={Neuroergonomics: Principles and Practices.}, ISBN={9783030347840 9783030347864 9783030347833}, ISSN={2195-3988}, DOI={10.1007/978-3-030-34784-0}, publisher={Springer International Publishing}, year={2020}, month={Feb}, collection={Cognitive Science and Technology} }
 @inbook{sanders_choo_nam_2020, place={Cham, Switzerland}, series={Cognitive Science and Technology}, title={The EEG Cookbook: A Practical Guide to Neuroergonomics Research}, ISBN={9783030347840 9783030347864 9783030347833}, DOI={10.1007/978-3-030-34784-0_3}, abstractNote={Conducting an EEG-based neuroergonomics experiment can be a daunting task for novice researchers. This chapter provides an overview of three aspects of EEG research which we hope will help novice researchers efficiently produce meaningful and replicable results: power analysis, data preprocessing, and reporting. We explain why power analysis and sample size estimation are critical yet often overlooked aspects of experimental research and describe the most common measures of effect size likely to be encountered, Cohen’s d and eta-squared. We also provide a list of powerful (and free) power analysis tools to facilitate the actual calculations. We also provide step-by-step instructions for data preprocessing with EEGLAB which can be used in preparation for subsequent ERP or connectivity analyses. This includes filtering, artifact removal and correction, independent component analysis, and source localization. Finally, we condense EEG reporting guidelines into a checklist which can be used to ensure that your manuscript draft follows best practices.}, booktitle={Neuroergonomics: Principles and Practices}, publisher={Springer International Publishing}, author={Sanders, N. and Choo, S. and Nam, C.S.}, editor={Nam, C.S.Editor}, year={2020}, pages={33–51}, collection={Cognitive Science and Technology} }
 @book{green_jang_choi_jun_nam_2020, place={Cham, Switzerland}, series={Cognitive Science and Technology}, title={Transcranial Direct Current Stimulation (tDCS): A Beginner’s Guide for Neuroergonomists}, ISBN={9783030347840 9783030347864 9783030347833}, DOI={10.1007/978-3-030-34784-0_5}, abstractNote={This Beginner’s Guide is intended to provide the necessary information for neuroergonomists to be able to understand the effects and usages of Transcranial Direct Current Stimulation (tDCS) on the brain. A thorough timeline provides the transformation of tDCS with technological advancements as well as a representation of its benefits throughout human history. It was these benefits that propelled tDCS to still be a modern-day solution to neuroergonomical problems. A large part of this chapter is dedicated to the impacts of tDCS, specifically, its effects on motor and cognitive functions and how the configurations of a session can alter the intended results. By the end of this guide, the reader should have a comprehensive understanding of what tDCS is, how it works, how to accurately design and implement tDCS configurations as well as the impacts it has on cognitive and motor functions of the brain.}, journal={Neuroergonomics: Principles and Practices}, publisher={Springer}, author={Green, J. and Jang, S. and Choi, J. and Jun, S.C. and Nam, C.S.}, editor={Nam, C.S.Editor}, year={2020}, pages={77–101}, collection={Cognitive Science and Technology} }
 @inbook{ho_markosov_sanders_nam_2019, title={BCI-Based Expressive Arts: Moving Toward Mind-Body Alignment}, ISBN={9783030143220 9783030143237}, url={http://dx.doi.org/10.1007/978-3-030-14323-7_13}, DOI={10.1007/978-3-030-14323-7_13}, booktitle={Brain Art}, publisher={Springer International Publishing}, author={Ho, Rainbow Tin Hung and Markosov, Sunee H. and Sanders, Nathan and Nam, Chang S.}, year={2019}, pages={355–373} }
 @article{kim_jin_choo_nam_yun_2019, title={Designing of smart chair for monitoring of sitting posture using convolutional neural networks}, volume={53}, ISSN={["2514-9318"]}, DOI={10.1108/DTA-03-2018-0021}, abstractNote={
Purpose
Sitting in a chair is a typical act of modern people. Prolonged sitting and sitting with improper postures can lead to musculoskeletal disorders. Thus, there is a need for a sitting posture classification monitoring system that can predict a sitting posture. The purpose of this paper is to develop a system for classifying children’s sitting postures for the formation of correct postural habits.
}, number={2}, journal={DATA TECHNOLOGIES AND APPLICATIONS}, author={Kim, Wonjoon and Jin, Byungki and Choo, Sanghyun and Nam, Chang S. and Yun, Myung Hwan}, year={2019}, month={Apr}, pages={142–155} }
 @article{feng_sanchez_sall_lyons_nam_2019, title={Emotional expressions facilitate human-human trust when using automation in high-risk situations}, volume={31}, ISSN={["1532-7876"]}, DOI={10.1080/08995605.2019.1630227}, abstractNote={ABSTRACT This study investigated the utility of emotional expression for human decision aids, when human aids conflict with an automated decision support system (DSS). The increasing presence of automation in society has resulted in critical, and often life threatening, situations when information from human and automated sources disagree. It has been known that reliance on human aids decrease during high-risk situations, while reliance on automated aids increase. However, it is also possible that human decision aids gain credibility from users when they embody the charismatic and emotionally expressive gesticulations seen in successful organizational leaders. The present study tested how a human agent's expressiveness when providing information would influence participants' behavioral reliance. Using the program Convoy Leader, participants (n=56) engaged in three decision-making scenarios where risk was manipulated as a within-subject factor and emotional expression as a between-subject factor. Emotional susceptibility, perceived risk, and trust for human as well as automated aids were measured. Overall trust was higher for the automated tool than human decision aid, and that pattern was amplified in conditions without an emotionally expressive human aid. Reliance was greater for emotionally expressive human aids, than stoic human aids, particularly during high risk conditions. The findings suggest that emotional expression of a human aid significantly impacts both reliance and trust of a decision aid, especially at higher risk levels. Emotionally expressive human agents should be utilized in decision conflicts where the automated system has certainly failed.}, number={4}, journal={MILITARY PSYCHOLOGY}, author={Feng, Jing and Sanchez, Joseph and Sall, Robert and Lyons, Joseph B. and Nam, Chang S.}, year={2019}, pages={292–305} }
 @book{contreras-vidal_robleto_cruz-garza_azorín_nam_2019, title={Mobile Brain-Body Imaging and the Neuroscience of Art, Innovation and Creativity}, ISBN={9783030243258 9783030243265}, ISSN={2520-8535 2520-8543}, url={http://dx.doi.org/10.1007/978-3-030-24326-5}, DOI={10.1007/978-3-030-24326-5}, abstractNote={A book that details the state of the art in mobile brain–body imaging and its relevance for the burgeoning field of neuroaesthetics. It represents scholarly study of artistic expression and the nexus of engineering, science, medicine and the creative arts.}, journal={Springer Series on Bio- and Neurosystems}, publisher={Springer International Publishing}, year={2019} }
 @article{kim_house_yun_nam_2019, title={Neural Correlates of Workload Transition in Multitasking: An ACT-R Model of Hysteresis Effect}, volume={12}, ISSN={1662-5161}, url={http://dx.doi.org/10.3389/fnhum.2018.00535}, DOI={10.3389/fnhum.2018.00535}, abstractNote={This study investigated the effect of task demand transitions at multiple levels of analysis including behavioral performance, subjective rating, and brain effective connectivity, while comparing human data to Adaptive Control of Thought-Rational (ACT-R) simulated data. Three stages of task demand were designed and performed sequentially (Low-High-Low) during AF-MATB tasks, and the differences in neural connectivity during workload transition were identified. The NASA Task Load Index (NASA-TLX) and the Instantaneous Self-Assessment (ISA) were used to measure the subjective mental workload that accompanies the hysteresis effect in the task demand transitions. The results found significant hysteresis effects on performance and various brain network measures such as outflow of the prefrontal cortex and connectivity magnitude. These findings would assist in clarifying the direction and strength of the Granger Causality under demand transitions. As a result, these findings involving the neural mechanisms of hysteresis effects in multitasking environments may be utilized in applications of neuroergonomics research. The ability to compare data derived from human participants to data gathered by the ACT-R model allows researchers to better account for hysteresis effects in neuro-cognitive models in the future.}, journal={Frontiers in Human Neuroscience}, publisher={Frontiers Media SA}, author={Kim, Na Young and House, Russell and Yun, Myung H. and Nam, Chang S.}, year={2019}, month={Jan} }
 @article{zhang_nam_zhou_jin_wang_cichocki_2019, title={Temporally Constrained Sparse Group Spatial Patterns for Motor Imagery BCI}, volume={49}, ISSN={["2168-2275"]}, DOI={10.1109/TCYB.2018.2841847}, abstractNote={Common spatial pattern (CSP)-based spatial filtering has been most popularly applied to electroencephalogram (EEG) feature extraction for motor imagery (MI) classification in brain–computer interface (BCI) application. The effectiveness of CSP is highly affected by the frequency band and time window of EEG segments. Although numerous algorithms have been designed to optimize the spectral bands of CSP, most of them selected the time window in a heuristic way. This is likely to result in a suboptimal feature extraction since the time period when the brain responses to the mental tasks occurs may not be accurately detected. In this paper, we propose a novel algorithm, namely temporally constrained sparse group spatial pattern (TSGSP), for the simultaneous optimization of filter bands and time window within CSP to further boost classification accuracy of MI EEG. Specifically, spectrum-specific signals are first derived by bandpass filtering from raw EEG data at a set of overlapping filter bands. Each of the spectrum-specific signals is further segmented into multiple subseries using sliding window approach. We then devise a joint sparse optimization of filter bands and time windows with temporal smoothness constraint to extract robust CSP features under a multitask learning framework. A linear support vector machine classifier is trained on the optimized EEG features to accurately identify the MI tasks. An experimental study is implemented on three public EEG datasets (BCI Competition III dataset IIIa, BCI Competition IV datasets IIa, and BCI Competition IV dataset IIb) to validate the effectiveness of TSGSP in comparison to several other competing methods. Superior classification performance (averaged accuracies are 88.5%, 83.3%, and 84.3% for the three datasets, respectively) based on the experimental results confirms that the proposed algorithm is a promising candidate for performance improvement of MI-based BCIs.}, number={9}, journal={IEEE TRANSACTIONS ON CYBERNETICS}, author={Zhang, Yu and Nam, Chang S. and Zhou, Guoxu and Jin, Jing and Wang, Xingyu and Cichocki, Andrzej}, year={2019}, month={Sep}, pages={3322–3332} }
 @article{rhiu_bahn_nam_yun_2018, title={Affective experience of physical user interfaces: Similarities and differences among control types}, volume={28}, ISSN={["1520-6564"]}, DOI={10.1002/hfm.20722}, abstractNote={Abstract}, number={2}, journal={HUMAN FACTORS AND ERGONOMICS IN MANUFACTURING & SERVICE INDUSTRIES}, author={Rhiu, Ilsun and Bahn, Sangwoo and Nam, Chang S. and Yun, Myung Hwan}, year={2018}, month={Mar}, pages={56–68} }
 @book{nam_nijholt_lotte_2018, title={Brain-computer interfaces handbook: Technological and theoretical advances}, DOI={10.1201/9781351231954}, abstractNote={Thirty-eight chapters ago, we started this handbook with an introduction that began with brain-computer interface (BCI) technology trends and historical events that have broken ground for BCI research and development. We thought that the world is ready for a new handbook that comprehensively addresses the recent and rapid changes in the field of BCIs. However, this handbook was not intended to provide a single blueprint for BCIs. Rather, it highlighted a synopsis of key findings and technological and theoretical advances directly applicable to brain-computer interfacing technologies, readily understood and applied by individuals with no formal training in BCI research and development.}, publisher={Boca Raton, FL: CRC Press, Taylor & Francis Group}, author={nam and Nijholt, A. and Lotte, F.}, year={2018} }
 @article{rhiu_bahn_nam_yun_2018, title={Cover Image}, volume={28}, ISSN={1090-8471}, url={http://dx.doi.org/10.1002/HFM.20734}, DOI={10.1002/HFM.20734}, abstractNote={The cover image, by Ilsun Rhiu et al., is based on the Research Article Affective experience of physical user interfaces: Similarities and differences among control types, DOI 10.1002/hfm.20722.}, number={2}, journal={Human Factors and Ergonomics in Manufacturing & Service Industries}, publisher={Wiley}, author={Rhiu, Ilsun and Bahn, Sangwoo and Nam, Chang S. and Yun, Myung Hwan}, year={2018}, month={Feb}, pages={i-i} }
 @article{rose_nam_chen_2018, title={Immersion of virtual reality for rehabilitation - Review}, volume={69}, ISSN={0003-6870}, url={http://dx.doi.org/10.1016/j.apergo.2018.01.009}, DOI={10.1016/j.apergo.2018.01.009}, abstractNote={Virtual reality (VR) shows promise in the application of healthcare and because it presents patients an immersive, often entertaining, approach to accomplish the goal of improvement in performance. Eighteen studies were reviewed to understand human performance and health outcomes after utilizing VR rehabilitation systems. We aimed to understand: (1) the influence of immersion in VR performance and health outcomes; (2) the relationship between enjoyment and potential patient adherence to VR rehabilitation routine; and (3) the influence of haptic feedback on performance in VR. Performance measures including postural stability, navigation task performance, and joint mobility showed varying relations to immersion. Limited data did not allow a solid conclusion between enjoyment and adherence, but patient enjoyment and willingness to participate were reported in care plans that incorporates VR. Finally, different haptic devices such as gloves and controllers provided both strengths and weakness in areas such movement velocity, movement accuracy, and path efficiency.}, journal={Applied Ergonomics}, publisher={Elsevier BV}, author={Rose, Tyler and Nam, Chang S. and Chen, Karen B.}, year={2018}, month={May}, pages={153–161} }
 @article{liu_nam_2018, title={Quantitative modeling of user performance in multitasking environments}, volume={84}, ISSN={0747-5632}, url={http://dx.doi.org/10.1016/J.CHB.2018.02.035}, DOI={10.1016/J.CHB.2018.02.035}, abstractNote={Multitasking is one of the most important skills required for human operators to perform highly-complex and safety-critical jobs. This study proposed and validated a quantitative model for the study of user performance improvement in a multitasking environment. The Multi-Attribute Task Battery-II (MATB-II) was used in the experiments as a multitasking platform. The proposed model included quantification of stimuli from each MATB-II subtask as baud rate (bits per second), selection of task difficulty and task weight, as well as the rearrangement of task weights. This research followed a two-phase experimental approach. The first phase applied the proposed model and identified a performance baseline for each individual in a multitasking environment, MATB-II. The second phase validated the proposed model using a rearranged set of multitasks for each individual. Individual differences in working memory capacity (WMC) have been estimated as predictors of varying cognitive abilities. This study also investigated the relationship between WMC, task difficulty, and multitasking performance. Significant improvement of user performance was found after the rearrangement of tasks based on the proposed approach. This research provides a framework to quantitatively evaluate multitasking systems and improve human performance in order to understand the interaction between systems and human operators.}, journal={Computers in Human Behavior}, publisher={Elsevier BV}, author={Liu, Shijing and Nam, Chang S.}, year={2018}, month={Jul}, pages={130–140} }
 @article{liu_nam_fitts_2018, title={Quantitative modeling of user performance in multitasking environments}, volume={84}, journal={Computers in Human Behavior}, author={Liu, S. J. and Nam, C. S. and Fitts, E. P.}, year={2018}, pages={130–140} }
 @misc{hocraffer_nam_2017, title={A meta-analysis of human-system interfaces in unmanned aerial vehicle (UAV) swarm management}, volume={58}, ISSN={["1872-9126"]}, DOI={10.1016/j.apergo.2016.05.011}, abstractNote={A meta-analysis was conducted to systematically evaluate the current state of research on human-system interfaces for users controlling semi-autonomous swarms composed of groups of drones or unmanned aerial vehicles (UAVs). UAV swarms pose several human factors challenges, such as high cognitive demands, non-intuitive behavior, and serious consequences for errors. This article presents findings from a meta-analysis of 27 UAV swarm management papers focused on the human-system interface and human factors concerns, providing an overview of the advantages, challenges, and limitations of current UAV management interfaces, as well as information on how these interfaces are currently evaluated. In general allowing user and mission-specific customization to user interfaces and raising the swarm’s level of autonomy to reduce operator cognitive workload are beneficial and improve situation awareness (SA). It is clear more research is needed in this rapidly evolving field.}, journal={APPLIED ERGONOMICS}, author={Hocraffer, Amy and Nam, Chang S.}, year={2017}, month={Jan}, pages={66–80} }
 @misc{choi_rhiu_lee_yun_nam_2017, title={A systematic review of hybrid brain-computer interfaces: Taxonomy and usability perspectives}, volume={12}, ISSN={["1932-6203"]}, DOI={10.1371/journal.pone.0176674}, abstractNote={A new Brain-Computer Interface (BCI) technique, which is called a hybrid BCI, has recently been proposed to address the limitations of conventional single BCI system. Although some hybrid BCI studies have shown promising results, the field of hybrid BCI is still in its infancy and there is much to be done. Especially, since the hybrid BCI systems are so complicated and complex, it is difficult to understand the constituent and role of a hybrid BCI system at a glance. Also, the complicated and complex systems make it difficult to evaluate the usability of the systems. We systematically reviewed and analyzed the current state-of-the-art hybrid BCI studies, and proposed a systematic taxonomy for classifying the types of hybrid BCIs with multiple taxonomic criteria. After reviewing 74 journal articles, hybrid BCIs could be categorized with respect to 1) the source of brain signals, 2) the characteristics of the brain signal, and 3) the characteristics of operation in each system. In addition, we exhaustively reviewed recent literature on usability of BCIs. To identify the key evaluation dimensions of usability, we focused on task and measurement characteristics of BCI usability. We classified and summarized 31 BCI usability journal articles according to task characteristics (type and description of task) and measurement characteristics (subjective and objective measures). Afterwards, we proposed usability dimensions for BCI and hybrid BCI systems according to three core-constructs: Satisfaction, effectiveness, and efficiency with recommendations for further research. This paper can help BCI researchers, even those who are new to the field, can easily understand the complex structure of the hybrid systems at a glance. Recommendations for future research can also be helpful in establishing research directions and gaining insight in how to solve ergonomics and HCI design issues surrounding BCI and hybrid BCI systems by usability evaluation.}, number={4}, journal={PLOS ONE}, author={Choi, Inchul and Rhiu, Ilsun and Lee, Yushin and Yun, Myung Hwan and Nam, Chang S.}, year={2017}, month={Apr} }
 @article{kim_wittenberg_nam_2017, title={Behavioral and Neural Correlates of Executive Function: Interplay between Inhibition and Updating Processes}, volume={11}, ISSN={1662-453X}, url={http://dx.doi.org/10.3389/fnins.2017.00378}, DOI={10.3389/fnins.2017.00378}, abstractNote={This study investigated the interaction between two executive function processes, inhibition and updating, through analyses of behavioral, neurophysiological, and effective connectivity metrics. Although, many studies have focused on behavioral effects of executive function processes individually, few studies have examined the dynamic causal interactions between these two functions. A total of twenty participants from a local university performed a dual task combing flanker and n-back experimental paradigms, and completed the Operation Span Task designed to measure working memory capacity. We found that both behavioral (accuracy and reaction time) and neurophysiological (P300 amplitude and alpha band power) metrics on the inhibition task (i.e., flanker task) were influenced by the updating load (n-back level) and modulated by working memory capacity. Using independent component analysis, source localization (DIPFIT), and Granger Causality analysis of the EEG time-series data, the present study demonstrated that manipulation of cognitive demand in a dual executive function task influenced the causal neural network. We compared connectivity across three updating loads (n-back levels) and found that experimental manipulation of working memory load enhanced causal connectivity of a large-scale neurocognitive network. This network contains the prefrontal and parietal cortices, which are associated with inhibition and updating executive function processes. This study has potential applications in human performance modeling and assessment of mental workload, such as the design of training materials and interfaces for those performing complex multitasking under stress.}, journal={Frontiers in Neuroscience}, publisher={Frontiers Media SA}, author={Kim, Na Young and Wittenberg, Ellen and Nam, Chang S.}, year={2017}, month={Jun} }
 @article{lee_lindquist_nam_2017, title={Emotional Granularity Effects on Event-Related Brain Potentials during Affective Picture Processing}, volume={11}, ISSN={1662-5161}, url={http://dx.doi.org/10.3389/fnhum.2017.00133}, DOI={10.3389/fnhum.2017.00133}, abstractNote={There is debate about whether emotional granularity, the tendency to label emotions in a nuanced and specific manner, is merely a product of labeling abilities, or a systematic difference in the experience of emotion during emotionally evocative events. According to the Conceptual Act Theory of Emotion (CAT) (Barrett, 2006), emotional granularity is due to the latter and is a product of on-going temporal differences in how individuals categorize and thus make meaning of their affective states. To address this question, the present study investigated the effects of individual differences in emotional granularity on electroencephalography-based brain activity during the experience of emotion in response to affective images. Event-related potentials (ERP) and event-related desynchronization and synchronization (ERD/ERS) analysis techniques were used. We found that ERP responses during the very early (60–90 ms), middle (270–300 ms), and later (540–570 ms) moments of stimulus presentation were associated with individuals’ level of granularity. We also observed that highly granular individuals, compared to lowly granular individuals, exhibited relatively stable desynchronization of alpha power (8–12 Hz) and synchronization of gamma power (30–50 Hz) during the 3 s of stimulus presentation. Overall, our results suggest that emotional granularity is related to differences in neural processing throughout emotional experiences and that high granularity could be associated with access to executive control resources and a more habitual processing of affective stimuli, or a kind of “emotional complexity.” Implications for models of emotion are also discussed.}, journal={Frontiers in Human Neuroscience}, publisher={Frontiers Media SA}, author={Lee, Ja Y. and Lindquist, Kristen A. and Nam, Chang S.}, year={2017}, month={Mar}, pages={1–18} }
 @article{white_morejon_liu_lau_nam_kaber_2017, title={Muscle loading in exoskeletal orthotic use in an activity of daily living}, volume={58}, ISSN={["1872-9126"]}, DOI={10.1016/j.apergo.2016.06.010}, abstractNote={Strokes are the leading cause of major adult disability with up to 85% of U.S. survivors experiencing hemiparesis. Physical characteristics of upper-extremity exoskeletal orthotics, used in stroke rehabilitation, were evaluated in terms of performance of activities of daily living (ADL), perceived exertion, and muscle load. Simulated orthotic weight distributions, with total extremity loads of 0.81 kg, 1.25 kg and 2.27 kg, were evaluated along with a 0 kg control condition. Response measures included average shoulder/elbow muscle surface electromyography (sEMG) signal amplitude, quality of task completion and total rest time during performance, and Borg CR-10 scale ratings. Device weight distribution, or imposed shoulder moment, was found to have a significant effect on biceps brachii and anterior deltoid activation levels, percent task completion, total rest time, and perceived exertion ratings. Results suggest that heavier upper-extremity orthotics could cause undesirable effects in terms of muscle loading, performance and exertion; such adverse effects could potentially lead to lack of use during patient’s rehabilitation.}, journal={APPLIED ERGONOMICS}, author={White, Melissa M. and Morejon, Olivia N. and Liu, Shijing and Lau, Mei Y. and Nam, Chang S. and Kaber, David B.}, year={2017}, month={Jan}, pages={190–197} }
 @article{wittenberg_thompson_nam_franz_2017, title={Neuroimaging of Human Balance Control: A Systematic Review}, volume={11}, ISSN={1662-5161}, url={http://dx.doi.org/10.3389/fnhum.2017.00170}, DOI={10.3389/fnhum.2017.00170}, abstractNote={This review examined 83 articles using neuroimaging modalities to investigate the neural correlates underlying static and dynamic human balance control, with aims to support future mobile neuroimaging research in the balance control domain. Furthermore, this review analyzed the mobility of the neuroimaging hardware and research paradigms as well as the analytical methodology to identify and remove movement artifact in the acquired brain signal. We found that the majority of static balance control tasks utilized mechanical perturbations to invoke feet-in-place responses (27 out of 38 studies), while cognitive dual-task conditions were commonly used to challenge balance in dynamic balance control tasks (20 out of 32 studies). While frequency analysis and event related potential characteristics supported enhanced brain activation during static balance control, that in dynamic balance control studies was supported by spatial and frequency analysis. Twenty-three of the 50 studies utilizing EEG utilized independent component analysis to remove movement artifacts from the acquired brain signals. Lastly, only eight studies used truly mobile neuroimaging hardware systems. This review provides evidence to support an increase in brain activation in balance control tasks, regardless of mechanical, cognitive, or sensory challenges. Furthermore, the current body of literature demonstrates the use of advanced signal processing methodologies to analyze brain activity during movement. However, the static nature of neuroimaging hardware and conventional balance control paradigms prevent full mobility and limit our knowledge of neural mechanisms underlying balance control.}, journal={Frontiers in Human Neuroscience}, publisher={Frontiers Media SA}, author={Wittenberg, Ellen and Thompson, Jessica and Nam, Chang S. and Franz, Jason R.}, year={2017}, month={Apr} }
 @article{griffin_zhu_nam_2017, title={The Role of Haptic Feedback in Robotic-Assisted Retinal Microsurgery Systems: A Systematic Review}, volume={10}, ISSN={1939-1412}, url={http://dx.doi.org/10.1109/TOH.2016.2598341}, DOI={10.1109/toh.2016.2598341}, abstractNote={Retinal microsurgery is one of the most technically difficult surgeries since it is performed at the threshold of human capability. If certain retinal conditions are left untreated, they can lead to severe damage, including irreversible blindness. Thus, techniques for reliable retinal microsurgery operations are critical. Recent research shows promise for improving surgical safety by implementing various types of sensory input and output. Sensory information is used to inform the surgeon about the environment inside the eye in real time. This review examines literature that discusses human factors and ergonomics (HFE) of sensory inputs and outputs of retinal microsurgery instrumentation with a focus on force and haptic feedback. Thirty-four studies were reviewed on the following topics: (1) variation between different input sensory devices and their performance, (2) variation between alternative output sensory devices and their performance, and (3) variation between alternative output sensory devices and their user satisfaction. This review finds that the implementation of HFE is important for the consideration of retinal microsurgery devices, but it is largely missing from current research. The addition of direct comparisons between devices, measures of user acceptance, usability evaluations, and greater realism in testing would help advance the use of haptic sensory feedback for retinal microsurgery instruments.}, number={1}, journal={IEEE Transactions on Haptics}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Griffin, Julia A. and Zhu, Weihang and Nam, Chang S.}, year={2017}, month={Jan}, pages={94–105} }
 @article{pankok_zahabi_zhang_choi_liao_nam_kaber_2017, title={The effects of interruption similarity and complexity on performance in a simulated visual-manual assembly operation}, volume={59}, ISSN={["1872-9126"]}, DOI={10.1016/j.apergo.2016.08.022}, abstractNote={The objective of the study was to assess the effects of interruption task similarity and complexity on performance of a simulated industrial assembly operation. Eighteen participants performed a simulated industrial assembly operation, including one trial with no interruption and eight others presenting an interruption task. Interruption conditions comprised a full crossing of task similarity to the primary assembly operation (similar, dissimilar) and complexity (simple, complex) with replication for each participant. Order of condition presentation was randomized. Findings revealed greater time to return to primary visual-manual assembly performance after a similar task interruption. Results also indicated complex interruptions may promote cognitive arousal that increases productivity following assembly interruptions. The majority of results are explained in terms of the Activation-Based Memory for Goals model. Findings provide some guidance for interruption management protocol design for workers engaged in procedural visual-manual assembly operations.}, journal={APPLIED ERGONOMICS}, author={Pankok, Carl, Jr. and Zahabi, Maryam and Zhang, Wenjuan and Choi, Inchul and Liao, Yi-Fan and Nam, Chang S. and Kaber, David}, year={2017}, month={Mar}, pages={94–103} }
 @misc{orphanides_nam_2017, title={Touchscreen interfaces in context: A systematic review of research into touchscreens across settings, populations, and implementations}, volume={61}, ISSN={["1872-9126"]}, DOI={10.1016/j.apergo.2017.01.013}, abstractNote={Although many studies have been conducted on the human factors and ergonomics (HFE) of touchscreens, no comprehensive review has summarized the findings of these studies. Based on a schema (three dimensions of understanding critical for successful display selection) presented by Wickens et al. (2004), we identified three dimensions of analysis for touchscreen implementations: touchscreen technology, setting and environment of implementation, and user population. We conducted a systematic review based on the PRISMA protocol (Moher et al., 2009), searching five article databases for relevant quantitative literature on touchscreens. We found that all three dimensions of analysis have a significant effect on the HFE of touchscreens, and that a selection for or against touchscreens must take into consideration the specific context of system interaction in order to maximize safety, performance, and user satisfaction. Our report concludes with a set of specific recommendations for systems designers considering touchscreens as input/output devices, and suggestions for future study into the HFE of touchscreens.}, journal={APPLIED ERGONOMICS}, publisher={Elsevier}, author={Orphanides, Andreas K. and Nam, Chang S.}, year={2017}, month={May}, pages={116–143} }
 @inbook{guger_coyle_mattia_de lucia_hochberg_edlow_peters_eddy_nam_noirhomme_et al._2017, title={Trends in BCI Research I: Brain-Computer Interfaces for Assessment of Patients with Locked-in Syndrome or Disorders of Consciousness}, ISBN={9783319643724 9783319643731}, ISSN={2191-8112 2191-8120}, url={http://dx.doi.org/10.1007/978-3-319-64373-1_11}, DOI={10.1007/978-3-319-64373-1_11}, abstractNote={Patients diagnosed with complete locked in syndrome (CLIS) or a disorder of consciousness (DOC) have no reliable control of voluntary movements. Hence, assessing their cognitive functions and cognitive awareness can be challenging. The “gold standard” for such assessments relies on behavioral responses, and recent work using different neuroimaging methods has shown that behavioral diagnoses may underestimate patients’ capabilities. Thus, there is a pressing need for new methods that go beyond behavioral approaches and can help patients even if they are not able to produce any behavioral response. In one of the most prominent trends in brain-computer interface (BCI) research, many groups have been using BCI technology to provide a suite of approaches to assess cognition and consciousness using EEG-based tools. This paper presents results with P300, steady-state visual evoked potential (SSVEP) and motor imagery BCIs and other approaches with different target patients in several different real-world settings. Results confirm that EEG-based assessment can reveal details about patients’ remaining capabilities that can both change and extend diagnoses based on behavioral measures. The results can already be used in clinical practice to help physicians, patients, and families develop a more detailed and accurate assessments, and provide hope for further technical and methodological improvements through future research.}, booktitle={SpringerBriefs in Electrical and Computer Engineering}, publisher={Springer International Publishing}, author={Guger, Christoph and Coyle, Damien and Mattia, Donatella and De Lucia, Marzia and Hochberg, Leigh and Edlow, Brian L. and Peters, Betts and Eddy, Brandon and Nam, Chang S. and Noirhomme, Quentin and et al.}, year={2017}, pages={105–125} }
 @article{nam_nijholt_lotte_2016, title={Call For Book Chapters: Brain-Computer Interfaces Handbook: Technological and Theoretical Advances}, volume={3}, ISSN={2326-263X 2326-2621}, url={http://dx.doi.org/10.1080/2326263X.2016.1168204}, DOI={10.1080/2326263X.2016.1168204}, abstractNote={"Call For Book Chapters: Brain-Computer Interfaces Handbook: Technological and Theoretical Advances." Brain-Computer Interfaces, 3(2), pp. 121–122}, number={2}, journal={Brain-Computer Interfaces}, publisher={Informa UK Limited}, author={Nam, Chang and Nijholt, Anton and Lotte, Fabien}, year={2016}, month={Apr}, pages={121–122} }
 @article{li_nam_2016, title={Collaborative brain-computer interface for people with motor disabilities}, volume={11}, number={3}, journal={IEEE Computational Intelligence M-agazine}, author={Li, Y. Q. and Nam, C. S.}, year={2016}, pages={57–67} }
 @article{klein_nam_2016, title={Neuroethics and brain-computer interfaces (BCIs)}, volume={3}, ISSN={["2326-2621"]}, DOI={10.1080/2326263x.2016.1210989}, abstractNote={Advances in brain-computer interface (or brain-machine interface) technology raise interesting and important ethical questions. BCI researchers encounter some of these questions, such as informed c...}, number={3}, journal={BRAIN-COMPUTER INTERFACES}, author={Klein, Eran and Nam, C. S.}, year={2016}, pages={123–125} }
 @article{corbett_nam_yamaguchi_2016, title={The Effects of Haptic Feedback and Visual Distraction on Pointing Task Performance}, volume={32}, ISSN={["1532-7590"]}, DOI={10.1080/10447318.2015.1094914}, abstractNote={Previous research has not fully examined the effect of additional sensory feedback, particularly delivered through the haptic modality, in pointing task performance with visual distractions. This study examined the effect of haptic feedback and visual distraction on pointing task performance in a 3D virtual environment. Results indicate a strong positive effect of haptic feedback on performance in terms of task time and root mean square error of motion. Level of similarity between distractor objects and the target object significantly reduced performance, and subjective ratings indicated a sense of increased task difficulty as similarity increased. Participants produced the best performance in trials where distractor objects had a different color but the same shape as the target object and constant haptic assistive feedback was provided. Overall, this study provides insight toward the effect of object features and similarity and the effect of haptic feedback on pointing task performance.}, number={2}, journal={INTERNATIONAL JOURNAL OF HUMAN-COMPUTER INTERACTION}, author={Corbett, Brendan and Nam, Chang S. and Yamaguchi, Takehiko}, year={2016}, pages={89–102} }
 @article{bryant_wang_deardeuff_zoccoli_nam_2016, title={The Neural Correlates of Moral Thinking: A Meta-Analysis}, volume={3}, ISSN={2572-7389}, url={http://dx.doi.org/10.19070/2572-7389-160005}, DOI={10.19070/2572-7389-160005}, abstractNote={1 Department of Psychology, University of Oklahoma, Norman, OK, USA. 2 Department of Industrial Engineering, University of Arkansas, Fayetteville, AR, USA. 3 Department of Psychology, University of Oklahoma, Health Sciences Center, Oklahoma City, OK, USA. 4 Department of Psychology, University of Oklahoma, Norman, OK, USA. 5 Department of Industrial and Systems Engineering, North Carolina State University, Raleigh, NC, USA.}, number={2}, journal={International Journal of Computational & Neural Engineering}, publisher={SciDoc Publishers LLC}, author={Bryant, D. and Wang, F. and Deardeuff, K. and Zoccoli, E. and Nam, C.S.}, year={2016}, month={Jul}, pages={28–39} }
 @inbook{liu_wadeson_nam_2016, title={Toward Quantitative Modeling of User Performance in Multitasking Environments}, ISBN={9783319400297 9783319400303}, ISSN={0302-9743 1611-3349}, url={http://dx.doi.org/10.1007/978-3-319-40030-3_1}, DOI={10.1007/978-3-319-40030-3_1}, abstractNote={Multitasking performance requires the ability to perform multiple tasks in the same time period by switching between individual tasks. To quantify the performance, a quantitative model for user performance in a multitasking environment was proposed in this study. This model was based on Shannon’s information theory and quantified the information produced from each subtask in the multitasking environment. The Multi-Attribute Task Battery-II (MATB-II) was employed as a platform of multitasking. There were two phases of the experiment and ten participants completed the experiment. Results showed an overall improvement in user performance after reassigned task weights according to the proposed approach. Findings also indicated there was an effect of task difficulty on multitasking performance. The proposed model provided an approach to estimate and improve user performance in a multitasking environment.}, booktitle={Engineering Psychology and Cognitive Ergonomics}, publisher={Springer International Publishing}, author={Liu, Shijing and Wadeson, Amy and Nam, Chang S.}, year={2016}, pages={3–9} }
 @inproceedings{liu_wadeson_nam_2016, title={Toward quantitative modeling of user performance in multitasking environments}, volume={9736}, booktitle={Engineering psychology and cognitive ergonomics, (epce 2016)}, author={Liu, S. J. and Wadeson, A. and Nam, C. S.}, year={2016}, pages={3–9} }
 @article{wadeson_nijholt_nam_2015, title={Artistic brain-computer interfaces: state-of-the-art control mechanisms}, volume={2}, ISSN={2326-263X 2326-2621}, url={http://dx.doi.org/10.1080/2326263x.2015.1103155}, DOI={10.1080/2326263x.2015.1103155}, abstractNote={Artistic BCI applications offer a new modality for humans to express themselves creatively. In this survey we reviewed the available literature on artistic BCIs by classifying four types of user control afforded by the available applications: selective control, passive control, direct control and collaborative control. A brief overview of the history of artistic BCIs is presented, followed by examples of current artistic BCI applications in each defined sector of control. We questioned whether or not creative control affects the users’ sense of enjoyment or satisfaction. Finally, we made suggestions for the future of artistic BCI research to question the role that control plays in user satisfaction and entertainment.}, number={2-3}, journal={Brain-Computer Interfaces}, publisher={Informa UK Limited}, author={Wadeson, Amy and Nijholt, Anton and Nam, Chang S.}, year={2015}, month={Apr}, pages={70–75} }
 @article{nijholt_nam_2015, title={Arts and Brain-Computer Interfaces (BCIs)}, volume={2}, ISSN={2326-263X 2326-2621}, url={http://dx.doi.org/10.1080/2326263x.2015.1100514}, DOI={10.1080/2326263x.2015.1100514}, abstractNote={The primary goal of this special issue is to address contemporary challenges involved in designing BCI applications related to the creation and experience of art. This involves a low level artistic audification and visualization of brain activity patterns, a higher level musification and animation, and the control of instruments and tools. From 14 submissions initially received, eight articles were selected for publication after a rigorous two-step review process supported by experts in the areas of brain-computer interface, human-computer interaction, and human factors/ergonomics. The papers in the special issue present empirical and survey studies that explore contemporary research challenges involved in designing, developing and evaluating BCI applications related to the creation and experience of art.}, number={2-3}, journal={Brain-Computer Interfaces}, publisher={Informa UK Limited}, author={Nijholt, Anton and Nam, Chang S.}, year={2015}, month={Apr}, pages={57–59} }
 @article{nam_moore_choi_li_2015, title={Designing Better, Cost-Effective Brain–Computer Interfaces}, volume={23}, ISSN={1064-8046}, url={http://dx.doi.org/10.1177/1064804615572625}, DOI={10.1177/1064804615572625}, abstractNote={ Despite the increase in research interest in the brain–computer interface (BCI), there remains a general lack of understanding of, and even inattention to, human factors/ergonomics (HF/E) issues in BCI research and development. The goal of this article is to raise awareness of the importance of HF/E involvement in the emerging field of BCI technology by providing HF/E researchers with a brief guide on how to design and implement a cost-effective, steady-state visually evoked potential (SSVEP)–based BCI system. We also discuss how SSVEP BCI systems can be improved to accommodate users with special needs. }, number={4}, journal={Ergonomics in Design: The Quarterly of Human Factors Applications}, publisher={SAGE Publications}, author={Nam, Chang S. and Moore, Matthew and Choi, Inchul and Li, Yueqing}, year={2015}, month={Oct}, pages={13–19} }
 @article{mohammadzadeh_liu_bond_nam_2015, title={Feasibility of a Wearable, Sensor-based Motion Tracking System}, volume={3}, ISSN={2351-9789}, url={http://dx.doi.org/10.1016/j.promfg.2015.07.128}, DOI={10.1016/j.promfg.2015.07.128}, abstractNote={The objective of this study was to develop and evaluate the feasibility of a wearable, sensor-based motion tracking system that provides an economical and quantitative means of recording upper limb motion for physical rehabilitation. The tracking system is comprised of a wirelessly connected network of inertial measurement units (IMUs), each containing a gyroscope and an accelerometer. Two IMUs were rigidly attached to each subject's forearm and upper arm. A trajectorizing algorithm was developed to estimate the three dimensional upper limb motion based on the measurements of the IMUs. A major advantage of the algorithm is that it allows the IMUs to be attached with arbitrary orientation to each limb and no manual anthropomorphic measurements need to be performed. By recording specific, known motions, the sensors can be calibrated with respect to their orientation in space and with respect to their orientation relative to their respective body segments. During the experiment, healthy subjects performed elbow flexion-extension motions that were recorded using the IMUs. To validate the system including the accuracy of recorded data and the correctness of the trajectorizing algorithm, an optical motion capture system was also used to record the same motions. Results showed that the proposed motion tracking system measured the elbow joint angles of the flexion-extension motions with high consistency with the measurements obtained from the optical motion capture system. Statistical analysis showed that joint angles between two systems are highly correlated. The error of elbow joint angles measured by our system yielded small root mean square error (RMSE) and small median absolute deviation (MAD). These results suggest that an IMU-based (more specifically, a gyroscope-based) motion tracking system can be realistically used to accurately track a patient's motion without the need of numerous sensors or an overly complicated set-up.}, journal={Procedia Manufacturing}, publisher={Elsevier BV}, author={Mohammadzadeh, Farrokh F. and Liu, Shijing and Bond, Kyle A. and Nam, Chang S.}, year={2015}, pages={192–199} }
 @article{li_jeon_nam_2015, title={Navigation by vibration: Effects of vibrotactile feedback on a navigation task}, volume={46}, ISSN={["1872-8219"]}, DOI={10.1016/j.ergon.2014.12.008}, abstractNote={In the background of spatial orientation in a navigation task, this study investigated the effect of frequency, duration and amplitude of vibrotactile feedback when it provided primary information modality. Multiple levels of each parameter were designed for an experiment conducted with 18 participants. Their performance was evaluated via number of errors, task completion time, annoyance level, and user preference. Result showed that medium level of frequency and duration was more preferred and can produce better performance. However, optimal amplitude level varied by individuals and also interacted with frequency. The paper summarized a set of design guidelines, which could be used to the design of future user interface with vibrotactile feedback. The study should provide great empirical data and meaningful insight for the design of vibrotactile feedback for future applications. The paper evaluated the vibrotactile interfaces and summarized a set of design guidelines, which could help to speed up the commercialization and industrial application of vibrotactile user interface.}, journal={INTERNATIONAL JOURNAL OF INDUSTRIAL ERGONOMICS}, author={Li, Yueqing and Jeon, Woo Ram and Nam, Chang S.}, year={2015}, month={Mar}, pages={76–84} }
 @misc{powers_bieliaieva_wu_nam_2015, title={The Human Factors and Ergonomics of P300-Based Brain-Computer Interfaces}, volume={5}, ISSN={["2076-3425"]}, DOI={10.3390/brainsci5030318}, abstractNote={Individuals with severe neuromuscular impairments face many challenges in communication and manipulation of the environment. Brain-computer interfaces (BCIs) show promise in presenting real-world applications that can provide such individuals with the means to interact with the world using only brain waves. Although there has been a growing body of research in recent years, much relates only to technology, and not to technology in use—i.e., real-world assistive technology employed by users. This review examined the literature to highlight studies that implicate the human factors and ergonomics (HFE) of P300-based BCIs. We assessed 21 studies on three topics to speak directly to improving the HFE of these systems: (1) alternative signal evocation methods within the oddball paradigm; (2) environmental interventions to improve user performance and satisfaction within the constraints of current BCI systems; and (3) measures and methods of measuring user acceptance. We found that HFE is central to the performance of P300-based BCI systems, although researchers do not often make explicit this connection. Incorporation of measures of user acceptance and rigorous usability evaluations, increased engagement of disabled users as test participants, and greater realism in testing will help progress the advancement of P300-based BCI systems in assistive applications.}, number={3}, journal={BRAIN SCIENCES}, author={Powers, J. Clark and Bieliaieva, Kateryna and Wu, Shuohao and Nam, Chang S.}, year={2015}, month={Sep}, pages={318–354} }
 @article{nam_whang_liu_moore_2015, title={Wayfinding of Users With Visual Impairments in Haptically Enhanced Virtual Environments}, volume={31}, ISSN={["1532-7590"]}, DOI={10.1080/10447318.2015.1004151}, abstractNote={As a powerful interaction technology, haptically enhanced virtual environments (VEs) have found many useful applications. However, few studies have examined how wayfinding of users with visual impairments is affected by VE characteristics. An empirical experiment was conducted to investigate how different environmental characteristics (number of objects inside the environment, layout of the objects and density) affect task performance (completion time, completion ratio, and travel distance), perceived task difficulty, and behavior pattern (short and long pause) of users with visual impairments when they perform a wayfinding task in a desktop-based haptically enhanced VE. The present study found that the number of objects inside the environment and layout of the objects play a significant role in determining the completion time and distance traveled. Layout type also greatly affected the user’s behavioral pattern in terms of frequency of pauses. Finally, perceived task difficulty varied with different environmental characteristics. The study results should provide insight into the future research and development of haptically enhanced VEs for people with visual impairments.}, number={4}, journal={INTERNATIONAL JOURNAL OF HUMAN-COMPUTER INTERACTION}, author={Nam, Chang S. and Whang, Mincheol and Liu, Shijing and Moore, Matthew}, year={2015}, pages={295–306} }
 @article{nam_richard_yamaguchi_bahn_2014, title={Does Touch Matter?: The Effects of Haptic Visualization on Human Performance, Behavior and Perception}, volume={30}, ISSN={["1532-7590"]}, DOI={10.1080/10447318.2014.941270}, abstractNote={Chang S. Nam1, Paul Richard2, Takehiko Yamaguchi3, and Sangwoo Bahn4 1Edward P. Fitts Department of Industrial and Systems Engineering, North Carolina State University, Raleigh, North Carolina, USA 2Laboratoire Angevin de Recherche en Ingénierie des Systèmes (LARIS), Université d’Angers, Angers, France 3Department of Applied Electronics, Tokyo University of Science, Tokyo, Japan 4Department of Industrial and Management Engineering, Myongji University, Yongin, Korea}, number={11}, journal={INTERNATIONAL JOURNAL OF HUMAN-COMPUTER INTERACTION}, author={Nam, Chang S. and Richard, Paul and Yamaguchi, Takehiko and Bahn, Sangwoo}, year={2014}, month={Nov}, pages={839–841} }
 @article{nam_hill_2014, title={Editorial}, volume={1}, ISSN={2326-263X 2326-2621}, url={http://dx.doi.org/10.1080/2326263X.2014.882101}, DOI={10.1080/2326263X.2014.882101}, number={1}, journal={Brain-Computer Interfaces}, publisher={Informa UK Limited}, author={Nam, Chang S. and Hill, Jeremy}, year={2014}, month={Jan}, pages={1–1} }
 @article{li_bahn_nam_lee_2014, title={Effects of Luminosity Contrast and Stimulus Duration on User Performance and Preference in a P300-Based Brain-Computer Interface}, volume={30}, ISSN={["1532-7590"]}, DOI={10.1080/10447318.2013.839903}, abstractNote={Brain–computer interfaces (BCI) have potential to provide a new channel of communication and control for people with severe motor disabilities. Although many empirical studies exist, few have specifically evaluated the impact of contributing factors on user performance and perception in BCI applications, especially for users with motor disabilities. This article reports the effects of luminosity contrast and stimulus duration on user performance and usage preference in a P300-based BCI application, P300 Speller. Ten participants with neuromuscular disabilities (amyotrophic lateral sclerosis and cerebral palsy) and 10 able-bodied participants were asked to spell six 10-character phrases in the P300 Speller. The overall accuracy was 76.5% for the able-bodied participants and 26.8% for participants with motor disabilities. The results showed that luminosity contrast and stimulus duration have significant effects on user performance. In addition, participants preferred high luminosity contrast with middle or short stimulus duration. However, these effects on user performance and preference varied for participants with and without motor disabilities. The results also indicated that although most participants with motor disabilities can establish BCI control, BCI illiteracy does exist. These results of the study should provide insights into the future research of the BCI systems, especially the real-world applicability of the BCI applications as a nonmuscular communication and control system for people with severe motor disabilities.}, number={2}, journal={INTERNATIONAL JOURNAL OF HUMAN-COMPUTER INTERACTION}, author={Li, Yueqing and Bahn, Sangwoo and Nam, Chang S. and Lee, Jungnyun}, year={2014}, month={Feb}, pages={151–163} }
 @article{bahn_corbett_nam_2014, title={Scenario-Based Observation Approach for Eliciting User Requirements for Haptic User Interfaces}, volume={30}, ISSN={["1532-7590"]}, DOI={10.1080/10447318.2014.941271}, abstractNote={As tactual information processing of visually impaired users has not been investigated sufficiently and there are few guidelines on the development of haptic user interfaces, development of haptic assistive system can pose many challenges. Despite the breadth and variety of tools available for elicitation of user requirements, no single tool adequately provides the needed information to develop such a specialized system for a unique user population where the understanding of user behaviors is limited. This article explores the state-of-art of requirements engineering, discusses the challenges in developing a haptic assistive system, and proposes a methodology of combining a controlled observation in a naturalistic setting with scenario-based design for effective and efficient user requirements elicitation. A case study of developing a haptically enhanced, collaborative learning-by-feeling science education system for visually impaired students was conducted to show validity and effectiveness of the proposed methodology. The case study showed that the methodology has a variety of benefits including the reduced uncertainty and a better fit to the natural behaviors of the user population.}, number={11}, journal={INTERNATIONAL JOURNAL OF HUMAN-COMPUTER INTERACTION}, author={Bahn, Sangwoo and Corbett, Brendan and Nam, Chang S.}, year={2014}, month={Nov}, pages={842–854} }
 @article{lee_bahn_nam_2014, title={Use of Reference Frame and Movement Pattern in Haptically Enhanced 3D Virtual Environment}, volume={30}, ISSN={["1532-7590"]}, DOI={10.1080/10447318.2014.941275}, abstractNote={For the present article a haptically enhanced 3D virtual environment was created, and this study investigates how visually impaired users perceive and explain the virtual space when haptic is the only input modality. The study investigates what factors affect the use of reference frame when the users verbally express a haptically constructed mental map and how such preference corresponds to their haptic movement in the virtual environment. In the study, gravity was the most influential cue in determining a vertical axis of a frame. When the users were asked to explain the relationship between themselves and the target object, they had the tendency to use the frame they initially chose to use. It was also noted that totally blind users were more responsive to various frames than users with lower vision and were faster in determining a term to explain spatial relationship. Furthermore, people who preferred relative frame were more likely to keep the haptic cursor closer to their body. Limited range of exploration caused lack of understanding of the space, whereas longer exploration time made them use more frames.}, number={11}, journal={INTERNATIONAL JOURNAL OF HUMAN-COMPUTER INTERACTION}, author={Lee, Ja Young and Bahn, Sangwoo and Nam, Chang S.}, year={2014}, month={Nov}, pages={891–903} }
 @article{nam_bahn_lee_2013, title={Acceptance of Assistive Technology by Special Education Teachers: A Structural Equation Model Approach}, volume={29}, ISSN={["1532-7590"]}, DOI={10.1080/10447318.2012.711990}, abstractNote={To investigate the acceptance of assistive technology (AT) by special education teachers, the present study developed and tested hypothesized relationships among key determinants of AT acceptance such as the facilitating condition, perceived ease of use, computer self-efficacy, result demonstrability, perceived usefulness, and behavioral intention. Results from analysis of data collected from a number of special education teachers in schools for the visually and/or auditory impaired confirmed the effects hypothesized in our conceptual model of AT acceptance. In particular, perceived usefulness was a dominant factor affecting AT usage. Facilitating condition was strongly related to perceived ease of use, whereas perceived ease of use had a significant effect on computer self-efficacy. This study also found the importance of result demonstrability factor, which had significant effects on both computer self-efficacy and perceived usefulness. This study expanded and enriched a traditional technology acceptance model by further investigating determinants associated with the acceptance of AT by special education teachers for the blind and/or the deaf. In addition, the results of the present study should provide some insights into the understanding of AT acceptance and the decisions of AT utilization, as well as its distribution and training.}, number={5}, journal={INTERNATIONAL JOURNAL OF HUMAN-COMPUTER INTERACTION}, author={Nam, Chang S. and Bahn, Sangwoo and Lee, Raney}, year={2013}, month={Apr}, pages={365–377} }
 @inbook{jeon_li_bahn_nam_2013, title={Assessing the Effectiveness of Vibrotactile Feedback on a 2D Navigation Task}, ISBN={9783642393297 9783642393303}, ISSN={0302-9743 1611-3349}, url={http://dx.doi.org/10.1007/978-3-642-39330-3_64}, DOI={10.1007/978-3-642-39330-3_64}, abstractNote={The effect of vibrotactile parameters were investigated on a 2D navigation task. Participants performed a simple navigation task reproducing directional information presented by a series of vibrotactile stimuli consisting of different levels of amplitude and frequency. Task completion time and degree of annoyance were measured. The results demonstrated that both frequency and amplitude had a significant effect on the responses. In addition, interaction effects between the two parameters were found on the responses. It was concluded that user performance and comfort are significantly affected by frequency and amplitude. The results give some insight into designing navigating information presented by vibrotactile display for visually impaired people. More studies with people with visual impairment and manipulation of other vibrotactile parameters are recommended to be applicable to the potential research.}, booktitle={Human-Computer Interaction. Interaction Modalities and Techniques}, publisher={Springer Berlin Heidelberg}, author={Jeon, Wooram and Li, Yueqing and Bahn, Sangwoo and Nam, Chang S.}, year={2013}, pages={594–600} }
 @inbook{liu_bahn_choi_nam_2013, title={Behavioral Characteristics of Users with Visual Impairment in Haptically Enhanced Virtual Environments}, ISBN={9783642393297 9783642393303}, ISSN={0302-9743 1611-3349}, url={http://dx.doi.org/10.1007/978-3-642-39330-3_67}, DOI={10.1007/978-3-642-39330-3_67}, abstractNote={This study investigated behavioral characteristics of users with visual impairments and tested effect of factors regarding the layout of virtual environments (VEs). Various three-dimensional (3D) VEs were simulated with two different factors: number of objects and layout type (random, symmetric). Using a Novint Falcon haptic device, users with visual impairments were required to complete an object recognition task in 3D VEs with different levels of number of object and layout. The characteristics of their movements (speed, applied force, location, direction, etc.) were recorded, and participants evaluated perceived difficulty after they completed each trial. We analyzed their recorded movements and their rating on perceived difficulty. Results showed that 1) number of objects in 3D VE had significant impact on visually impaired users’ behavior; 2) different layout had not showed significant influence on their movement; 3) increased number of objects in 3D VE made the task more difficult; 4) visualized results implied that different users had significant different behavior preference in the same 3D VE. It is expected that the results of this study can improve behavioral understanding of users with visual impairments and guidance for assistive technology development for users with visual impairments.}, booktitle={Human-Computer Interaction. Interaction Modalities and Techniques}, publisher={Springer Berlin Heidelberg}, author={Liu, Shijing and Bahn, Sangwoo and Choi, Heesun and Nam, Chang S.}, year={2013}, pages={618–625} }
 @inproceedings{nam_lee_bahn_2013, title={Brain-computer interface supported collaborative work: Implications for rehabilitation}, DOI={10.1109/embc.2013.6609489}, abstractNote={Working together and collaborating in a group can provide greater benefits for people with severe motor disability. However, it is still not clear how collaboration should be supported by BCI systems. The present study explored BCI-supported collaborative work by investigating differences in performance and brain activity between when a pair of users performs a task jointly with each other and when they do alone only through means of their brain activity. We found differences in performance and brain activity between different work conditions. The results of this research should provide fundamental knowledge of BCI-supported cooperative work.}, booktitle={2013 35th annual international conference of the ieee engineering in medicine and biology society (embc)}, author={nam and Lee, J. and Bahn, S.}, year={2013}, pages={269–272} }
 @article{kim_smith-jackson_nam_2013, title={Elicitation of Haptic User Interface Needs of People with Low Vision}, volume={29}, ISSN={1044-7318 1532-7590}, url={http://dx.doi.org/10.1080/10447318.2012.722465}, DOI={10.1080/10447318.2012.722465}, abstractNote={Various assistive technologies such as haptic technology are used to help people with visual impairments comprehend complex information. Yet there is likely to be a misconception that users with the same disability category share the same user interface needs; furthermore, the majority of the literature has been oriented toward total blindness rather than low vision, possibly leading to dissatisfaction with assistive technologies and discontinuation of its use by those with low vision. The aim of this article is to advance the understanding of the needs of those with low vision especially in relation to haptic-incorporated multimodal user interfaces. A scenario-based, participatory design approach was used to explore their needs. A total of 19 user needs were systematically documented under three categories: audition (n = 5), touch (n = 11), and vision (n = 3). This article focuses on qualitatively exploring their needs and theoretically interpreting the needs in the light of previous studies.}, number={7}, journal={International Journal of Human-Computer Interaction}, publisher={Informa UK Limited}, author={Kim, Hyung Nam and Smith-Jackson, Tonya L. and Nam, Chang S.}, year={2013}, month={Jul}, pages={488–500} }
 @inbook{corbett_yamaguchi_liu_huang_bahn_nam_2013, title={Influence of Haptic Feedback on a Pointing Task in a Haptically Enhanced 3D Virtual Environment}, ISBN={9783642393297 9783642393303}, ISSN={0302-9743 1611-3349}, url={http://dx.doi.org/10.1007/978-3-642-39330-3_60}, DOI={10.1007/978-3-642-39330-3_60}, abstractNote={To gain a better view of the value of haptic feedback, human performance and preference in a pointing style task in a three-dimensional virtual environment was explored. Vibration and haptic attractive force were selected as two simple cases of feedback, each with two levels. These types of feedback were compared to a no-feedback condition to better understand how human performance changes under these conditions. The study included 8 undergraduate students. A Novint Falcon haptic controller was used in a simulated three-dimensional virtual environment. Analysis was conducted on how each type of feedback effects the movement time (MT) of users. The results showed that vibration was perceived negatively and had a slight negative impact on performance. The haptic attractive force significantly improved performance and was strongly preferred by subjects.}, booktitle={Human-Computer Interaction. Interaction Modalities and Techniques}, publisher={Springer Berlin Heidelberg}, author={Corbett, Brendan and Yamaguchi, Takehiko and Liu, Shijing and Huang, Lixiao and Bahn, Sangwoo and Nam, Chang S.}, year={2013}, pages={561–567} }
 @inbook{lee_bahn_nam_2013, title={Use of Reference Frame in Haptic Virtual Environments: Implications for Users with Visual Impairments}, ISBN={9783642393297 9783642393303}, ISSN={0302-9743 1611-3349}, url={http://dx.doi.org/10.1007/978-3-642-39330-3_66}, DOI={10.1007/978-3-642-39330-3_66}, abstractNote={Reference frame is key in explaining the relationship between two objects. This paper focused on the orientation parameter of a reference frame in use of projective spatial terms, and its use by visually impaired participants using a haptic device to explore a haptic virtual environment. A total of nine visually impaired participants between 12 and 17 years of age participated in this study. After exploring the 3D virtual environment with a haptic device, participants answered questions about the frame they had utilized. Overall results indicated that the participants used relative frame of reference slightly more than the intrinsic frame of reference. This inclination was especially clear when both the target object and the reference object were on the horizontal plane. Only when objects were on horizontal plane but intrinsically vertical to the reference object, the intrinsic frame of reference was preferred. We also found evidence that participants used a reflective subtype of the relative frame, and vertically aligned objects were easy to be perceived with the relative reference frame. We concluded that the virtual environment and haptic input had influence on the result by separating the user from the computer, only allowing one point of contact. Thus it would be possible to apply the result of this study to the development and assessment of assistive technology for people with visual impairment, especially in regard to how spatial information between the systems and the user is communicated.}, booktitle={Human-Computer Interaction. Interaction Modalities and Techniques}, publisher={Springer Berlin Heidelberg}, author={Lee, Ja Young and Bahn, Sangwoo and Nam, Chang S.}, year={2013}, pages={610–617} }
 @inbook{bahn_song_yun_nam_2012, place={Boca Raton, FL}, title={A Study on the Relationship between Pleasures and Design Attributes of Digital Appliances}, ISBN={9780429064890}, booktitle={Advances in Affective and Pleasurable Design}, publisher={CRC Press}, author={Bahn, S. and Song, J. and Yun, M.H. and Nam, C.S.}, editor={Ji, Y.G.Editor}, year={2012}, pages={222–230} }
 @article{nam_2012, title={Brain-computer interface (BCI) and ergonomics}, volume={55}, ISSN={["1366-5847"]}, DOI={10.1080/00140139.2012.676675}, abstractNote={Nearly two million people in the United States – and many more worldwide – suffer from severe motor disabilities brought on by neuromuscular impairments, such as amyotrophic lateral sclerosis (ALS)...}, number={5}, journal={ERGONOMICS}, author={Nam, Chang S.}, year={2012}, pages={513–515} }
 @article{nam_li_yamaguchi_smith-jackson_2012, title={Haptic User Interfaces for the Visually Impaired: Implications for Haptically Enhanced Science Learning Systems}, volume={28}, ISSN={["1532-7590"]}, DOI={10.1080/10447318.2012.661357}, abstractNote={The overall quality of haptic user interfaces designed to support visually impaired students' science learning through sensorial feedback was systematically studied to investigate task performance and user behavior. Fourteen 6th- to 11th-grade students with visual impairments recruited from a state-funded blind school were asked to perform three main tasks (i.e., menu selection, structure exploration, and force recognition) using haptic user interfaces and a haptic device. This study used several dependent measures that are categorized into three types of variables: (a) task performance including success rate, workload, and task completion time; (b) user behavior defined as cursor movements proportionately represented from the user's cursor positional data; and (c) user preference. Results showed that interface type has significant effects on task performance, user behavior, and user preference, with varying degree of impact to participants with severe visual impairments performing the tasks. The results of this study as well as a set of refined design guidelines and principles should provide insights to the future research of haptic user interfaces that can be used when developing haptically enhanced science learning systems for the visually impaired.}, number={12}, journal={INTERNATIONAL JOURNAL OF HUMAN-COMPUTER INTERACTION}, author={Nam, Chang S. and Li, Yueqing and Yamaguchi, Takehiko and Smith-Jackson, Tonya L.}, year={2012}, pages={784–798} }
 @article{nam_woo_bahn_2012, title={Severe motor disability affects functional cortical integration in the context of brain-computer interface (BCI) use}, volume={55}, ISSN={["0014-0139"]}, DOI={10.1080/00140139.2011.647095}, abstractNote={The purpose of this study was to investigate cortical interaction between brain regions in people with and without severe motor disability during brain–computer interface (BCI) operation through coherence analysis. Eighteen subjects, including six patients with cerebral palsy (CP) and three patients with amyotrophic lateral sclerosis (ALS), participated. The results showed (1) the existence of BCI performance difference caused by severe motor disability; (2) different coherence patterns between participants with and without severe motor disability during BCI operation and (3) effects of motor disability on cortical connections varying in the brain regions for the different frequency bands, indicating reduced cortical differentiation and specialisation. Participants with severe neuromuscular impairments, as compared with the able-bodied group, recruited more cortical regions to compensate for the difficulties caused by their motor disability, reflecting a less efficient operating strategy for the BCI task. This study demonstrated that coherence analysis can be applied to examine the ways cortical networks cooperate with each other during BCI tasks. Practitioner Summary: Few studies have investigated the electrophysiological underpinnings of differences in BCI performance. This study contributes by assessing neuronal synchrony among brain regions. Our findings revealed that severe motor disability causes more cortical areas to be recruited to perform the BCI task, indicating reduced cortical differentiation and specialisation.}, number={5}, journal={ERGONOMICS}, author={Nam, Chang S. and Woo, Jincheol and Bahn, Sangwoo}, year={2012}, pages={581–591} }
 @inbook{johnson_li_nam_yamaguchi_2011, title={Analyzing User Behavior within a Haptic System}, ISBN={9783642216046 9783642216053}, ISSN={0302-9743 1611-3349}, url={http://dx.doi.org/10.1007/978-3-642-21605-3_7}, DOI={10.1007/978-3-642-21605-3_7}, abstractNote={Haptic technology has the potential to enhance education, especially for those with severe visual impairments (those that are blind or who have low vision), by presenting abstract concepts through the sense of touch. Despite the advances in haptic research, little research has been conducted in the area of haptic user behavior toward the establishment of haptic interface development and design conventions. To advance haptic research closer to this goal, this study examines haptic user behavior data collected from 9 participants utilizing a haptic learning system, the Heat Temperature Module. ANOVA results showed that differences in the amount of haptic feedback result in significant differences in user behavior, indicating that higher levels of haptic friction feedback result in higher user interaction proportions of data. Results also suggested that minimal thresholds of friction haptic feedback can be established for a desired level of minimum user interaction data proportions, however; more research is needed to establish such thresholds.}, booktitle={Lecture Notes in Computer Science}, publisher={Springer Berlin Heidelberg}, author={Johnson, Steve and Li, Yueqing and Nam, Chang Soo and Yamaguchi, Takehiko}, year={2011}, pages={62–70} }
 @article{jeon_nam_kim_whang_2011, title={Event-related (De)synchronization (ERD/ERS) during motor imagery tasks: Implications for brain–computer interfaces}, volume={41}, ISSN={0169-8141}, url={http://dx.doi.org/10.1016/j.ergon.2011.03.005}, DOI={10.1016/j.ergon.2011.03.005}, abstractNote={The primary aims of this research were to examine (1) mu and beta event-related desynchronization/synchronization (ERD/ERS) during motor imagery tasks with varying movement duration and (2) the potential impacts of movement duration on ERD/ERS patterns. Motor imagery tasks included brief and continuous imagined hand movements. During an imagery task, participants imagined an indicated movement for 1 s (i.e., brief movement imagery) or 5 s (i.e., continuous movement imagery). The results of the study support (1) that mu and beta ERD/ERS patterns are elicited during imagined hand movements and (2) that movement duration affects ERS and does not affect ERD patterns, during motor movement imagery. Additionally, brief movement imagery had a greater impact on mu and beta ERD; continuous movement imagery had a greater impact on mu and beta ERS. This research will be useful for designing future brain–computer interfaces as it provides valuable insight into the dynamics of electroencephalographic (EEG) oscillatory changes during motor imagery tasks with varying movement duration. : Brain–computer interfaces (BCIs) have gained considerable interests by both research and industry communities who want to improve the quality of life for those who suffer from severe motor disabilities, such as amyotrophic lateral sclerosis (ALS), brainstem stroke, and cerebral palsy (CP). The results of this study should be applied to EEG-based BCI system design in order to enhance accuracy and classification performance for BCI system control.}, number={5}, journal={International Journal of Industrial Ergonomics}, publisher={Elsevier BV}, author={Jeon, Yongwoong and Nam, Chang S. and Kim, Young-Joo and Whang, Min Cheol}, year={2011}, month={Sep}, pages={428–436} }
 @inbook{li_johnson_nam_2011, title={Haptically Enhanced User Interface to Support Science Learning of Visually Impaired}, ISBN={9783642216183 9783642216190}, ISSN={0302-9743 1611-3349}, url={http://dx.doi.org/10.1007/978-3-642-21619-0_10}, DOI={10.1007/978-3-642-21619-0_10}, abstractNote={The primary purpose of this study is to evaluate the overall quality of haptic user interfaces designed to support various science learning activities in order to obtain usability and performance data. The result showed that haptic interface could significantly affect impaired students’ user performance. Audio & Tactile interface can produce significantly better user performance than the Tactile interface. Meanwhile, the learning effect could be greatly enhanced and students enjoyed the hands-on experience very much. This study should provide invaluable empirical data and some insight for the future research.}, booktitle={Lecture Notes in Computer Science}, publisher={Springer Berlin Heidelberg}, author={Li, Yueqing and Johnson, Steve and Nam, Chang}, year={2011}, pages={68–76} }
 @article{nam_jeon_kim_lee_park_2011, title={Movement imagery-related lateralization of event-related (de)synchronization (ERD/ERS): Motor-imagery duration effects}, volume={122}, ISSN={1388-2457}, url={http://dx.doi.org/10.1016/j.clinph.2010.08.002}, DOI={10.1016/j.clinph.2010.08.002}, abstractNote={To investigate movement imagery-related lateralization of event-related (de)synchronization (ERD/ERS) during two motor-imagery tasks with varying movement duration (brief versus continuous). Twelve subjects performed or kinesthetically imagined the indicated movement (left or right hand movement) for 1 s (brief) or 5 s (continuous) while electroencephalograms (EEGs) were recorded using 16 electrodes covering the sensorimotor cortex of the brain according to the modified 10–20 system. Significant hemispheric differences were found between contralateral and ipsilateral area in mu ERD, mu ERS and beta ERD during both brief and continuous conditions, showing contralateral dominance of mu and beta ERD and ipsilateral dominance of mu ERS. Beta ERS showed a significant ipsilateral dominance only in the brief condition. Movement imagery duration influenced the lateralization of mu ERD, beta ERD, and beta ERS, but not mu ERS. The results of this study will aid in clarifying movement-related lateralization in association with imagery tasks under varying movement duration. For designing an EEG-based brain–computer interface (BCI) for people with severe neuromuscular impairments, movement imagery-related lateralization can play a key role in utilizing motor-imagery tasks as a control or communication strategy.}, number={3}, journal={Clinical Neurophysiology}, publisher={Elsevier BV}, author={Nam, Chang S. and Jeon, Yongwoong and Kim, Young-Joo and Lee, Insuk and Park, Kyungkyu}, year={2011}, month={Mar}, pages={567–577} }
 @article{li_nam_shadden_johnson_2010, title={A P300-Based Brain–Computer Interface: Effects of Interface Type and Screen Size}, volume={27}, ISSN={1044-7318 1532-7590}, url={http://dx.doi.org/10.1080/10447318.2011.535753}, DOI={10.1080/10447318.2011.535753}, abstractNote={As a nonmuscular communication and control system for people with severe motor disabilities, brain–computer interface (BCI) has found several applications. Although a few empirical studies of BCI user performance do exist, little to no research has specifically evaluated the impact of contributing factors on user performance in the BCI applications. To that end, our within-subjects design compared the impact of two different types of interface (ABC interface vs. frequency-based interface) and three levels of screen size (computer monitor, global positioning system, and cell phone screen) of a P300-based BCI application, P300 Speller, on user performance (accuracy, information transfer rate, amplitude, and latency) and usage preference. Ten participants with neuromuscular disabilities such as amyotrophic lateral sclerosis and cerebral palsy and 10 nondisabled participants were asked to type six, 10-character phrases in the P300 Speller. The overall accuracy was 79.7% for the nondisabled participants and 28.7% for participants with motor disabilities. The results showed that interface type and screen size have significant effects on user performance and usage preference, with varying degree of impact to participants with and without motor disabilities. Specifically, participants typed significantly more accurately in frequency-based interface and computer monitor screen. The results of this study should provide invaluable insights to the future research of P300-based BCI applications.}, number={1}, journal={International Journal of Human-Computer Interaction}, publisher={Informa UK Limited}, author={Li, Yueqing and Nam, Chang S. and Shadden, Barbara B. and Johnson, Steven L.}, year={2010}, month={Dec}, pages={52–68} }
 @inbook{johnson_yamaguchi_li_kim_nam_2010, title={Analyzing the Behavior of Users with Visual Impairments in a Haptic Learning Application}, ISBN={9781439835012 9781439835029}, ISSN={2372-1944}, url={http://dx.doi.org/10.1201/ebk1439835012-c69}, DOI={10.1201/ebk1439835012-c69}, booktitle={Advances in Human Factors and Ergonomics Series}, publisher={CRC Press}, author={Johnson, Steve and Yamaguchi, Takehiko and Li, Yueqing and Kim, Hyung and Nam, Chang}, year={2010}, month={Jun}, pages={675–683} }
 @article{nam_schalk_jackson_2010, title={Current Trends in Brain–Computer Interface (BCI) Research and Development}, volume={27}, ISSN={1044-7318 1532-7590}, url={http://dx.doi.org/10.1080/10447318.2011.535748}, DOI={10.1080/10447318.2011.535748}, abstractNote={A brain–computer interface (BCI), sometimes called a direct neural interface or a brain–machine interface, detects and interprets brain signals and uses the results to communicate a user’s intent (Wolpaw, Birbaumer, McFarland, Pfurtscheller, & Vaughan, 2002). Because these systems directly translate brain activity into action, without depending on peripheral nerves and muscles, a major goal of BCI research has been to establish BCI technology as an assistive device to be used by people with severe motor disabilities. BCIs have shown encouraging possibilities in providing people, including those who cannot use their muscles but are cognitively intact, with alternative methods for interacting with the outside world (Nam, Lee, & Johnson, 2010; Schalk, McFarland, Hinterberger, Birbaumer, & Wolpaw, 2004). Despite long interest in the possibility to control devices directly using brain signals (e.g., Fetz & Finocchio, 1971; Vidal, 1973, 1977), it has only been in the past 20 years that sustained research has begun, and only in the past 10 years that a recognizable field of BCI research, populated by a rapidly growing number of research groups with increasing number of publications, has developed. Early BCI efforts have been developed from the field of clinical neurophysiology in humans (using mostly scalp-recorded electroencephalography [EEG]) and basic neuroscience investigations in animals (using mostly single-neuron recordings). Thus, initial efforts began with expertise in neuroscience, neurophysiology, and psychology. In parallel with the establishment of dedicated BCI research groups throughout the 1990s, these groups began to also seek specialists in signal processing, machine learning, and software engineering. This relatively narrow focus on the technical aspects of BCI research and development served the field well in its initial stages of method development. As the field has begun to mature, its scope has expanded to focus on application of BCI technology to the needs of people with disabilities—recent efforts are now}, number={1}, journal={International Journal of Human-Computer Interaction}, publisher={Informa UK Limited}, author={Nam, Chang S. and Schalk, Gerwin and Jackson, Melody M.}, year={2010}, month={Dec}, pages={1–4} }
 @article{nam_li_johnson_2010, title={Evaluation of P300-Based Brain-Computer Interface in Real-World Contexts}, volume={26}, ISSN={1044-7318 1532-7590}, url={http://dx.doi.org/10.1080/10447311003781326}, DOI={10.1080/10447311003781326}, abstractNote={Despite recent advances in brain-computer interface (BCI) development, system usability still remains a large oversight. The goal of this study was to investigate the usability of a P300-based BCI system, P300 Speller, by assessing how background noise and interface color contrast affect user performance and BCI usage preference. Fifteen able-bodied participants underwent a 2 (low and high interface color contrast) × 3 (low, medium, and high background noise level) within-subjects design experiment, in which participants were asked to type six 10-character phrases in the P300 Speller paradigm. The overall accuracy in the study was 80.2%. Participants showed higher accuracy, higher information transfer rate, bigger amplitude, and smaller latency in the high interface color contrast condition than in the low contrast condition. Participants had better performance in the noisy condition than in the quiet condition, but the background noise effects were not statistically significant in the present study. These results should give some insight to the real-world applicability of the current P300 Speller as a nonmuscular communication system, especially for individuals with severe neuromuscular disabilities.}, number={6}, journal={International Journal of Human-Computer Interaction}, publisher={Informa UK Limited}, author={Nam, Chang S. and Li, Yueqing and Johnson, Steve}, year={2010}, month={May}, pages={621–637} }
 @article{kim_lockhart_nam_2010, title={Leg strength comparison between younger and middle-age adults}, volume={40}, ISSN={0169-8141}, url={http://dx.doi.org/10.1016/j.ergon.2009.11.003}, DOI={10.1016/j.ergon.2009.11.003}, abstractNote={Although a risk of occupational musculoskeletal diseases has been identified with age-related strength degradation, strength measures from working group are somewhat sparse. This is especially true for the lower extremity strength measures in dynamic conditions (i.e., isokinetic). The objective of this study was to quantify the lower extremity muscle strength characteristics of three age groups (young, middle, and the elderly). Total of 42 subjects participated in the study: 14 subjects for each age group. A commercial dynamometer was used to evaluate isokinetic and isometric strength at ankle and knee joints. 2 × 2 (Age group (younger, middle-age, and older adult groups) × Gender (male and female)) between-subject design and Post-hoc analysis were performed to evaluate strength differences among three age groups. Post-hoc analysis indicated that, overall, middle-age workers' leg strengths (i.e. ankle and knee muscles) were significantly different from younger adults while middle-age workers' leg strengths were virtually identical to older adults' leg strengths. These results suggested that, overall, 14 middle-age workers in the present study could be at a higher risk of musculoskeletal injuries. Future studies looking at the likelihood of musculoskeletal injuries at different work places and from different working postures at various age levels should be required to validate the current findings. The future study would be a valuable asset in finding intervention strategies such that middle-age workers could stay healthier longer.}, number={3}, journal={International Journal of Industrial Ergonomics}, publisher={Elsevier BV}, author={Kim, Sukwon and Lockhart, Thurmon and Nam, Chang S.}, year={2010}, month={May}, pages={315–320} }
 @article{nam_johnson_li_seong_2009, title={Evaluation of human–agent user interfaces in multi-agent systems}, volume={39}, ISSN={0169-8141}, url={http://dx.doi.org/10.1016/j.ergon.2008.08.008}, DOI={10.1016/j.ergon.2008.08.008}, abstractNote={A multi-agent system (MAS) is a computational system in which two or more intelligent agents work together to perform a set of tasks. MAS's have had a significant impact in a wide range of applications. However, little attention has been paid to the design of human–agent user interfaces. Our research was conducted primarily to further explore interaction between humans and intelligent agents, as well as attempt to solidify foundational concepts for intelligent multi-agent system interface design. Based on the foundation of the commercialized PC game Unreal Tournament 2003, a framework was developed that utilized fundamental interface design principles as well as newly designed guidelines. Three user interfaces were designed for an experiment conducted with 25 participants. Their performances were evaluated via effectiveness, efficiency, satisfaction, and workload metrics. Through the testing of scenario tasks, an in-depth study was conducted on the collaboration between the human user and intelligent agents within a system. Finally, the paper summarized a set of design principles and guidelines developed through the study, which could easily be applicable to the design of future user interfaces for multi-agent systems. A deeper understanding of the manner by which the appropriate information is provided to the user interacting with multi-agent systems in the correct form at the right time should have a broad impact on the future development of intelligent multi-agent system interfaces.}, number={1}, journal={International Journal of Industrial Ergonomics}, publisher={Elsevier BV}, author={Nam, Chang S. and Johnson, Steve and Li, Yueqing and Seong, Younho}, year={2009}, month={Jan}, pages={192–201} }
 @inbook{yamaguchi_johnson_kim_li_nam_smith-jackson_2009, title={Haptic Science Learning System for Students with Visual Impairments: A Preliminary Study}, ISBN={9783642027123 9783642027130}, ISSN={0302-9743 1611-3349}, url={http://dx.doi.org/10.1007/978-3-642-02713-0_17}, DOI={10.1007/978-3-642-02713-0_17}, abstractNote={This paper assesses the usability of developed haptic interface features to support future development of haptically enhanced science learning applications for students with visual impairments. Of the features developed and evaluated, three features are described in this study: Haptic Boundary, Menu Selection, and Object Recognition. Two focus groups participated in an interview and usability session. Results from this study give insight to the needs of the visually impaired community in regard to haptic applications.}, booktitle={Lecture Notes in Computer Science}, publisher={Springer Berlin Heidelberg}, author={Yamaguchi, Takehiko and Johnson, Steve and Kim, Hyung Nam and Li, Yueqing and Nam, Chang S. and Smith-Jackson, Tonya L.}, year={2009}, pages={157–166} }
 @article{bahn_lee_nam_yun_2009, title={Incorporating affective customer needs for luxuriousness into product design attributes}, volume={19}, ISSN={1090-8471 1520-6564}, url={http://dx.doi.org/10.1002/hfm.20140}, DOI={10.1002/hfm.20140}, abstractNote={Abstract}, number={2}, journal={Human Factors and Ergonomics in Manufacturing}, publisher={Wiley}, author={Bahn, Sangwoo and Lee, Cheol and Nam, Chang S. and Yun, Myung Hwan}, year={2009}, month={Mar}, pages={105–127} }
 @article{konomi_nam_2009, title={Supporting Collaborative Privacy-Observant Information Sharing Using RFID-Tagged Objects}, volume={2009}, ISSN={1687-5893 1687-5907}, url={http://dx.doi.org/10.1155/2009/713516}, DOI={10.1155/2009/713516}, abstractNote={RFID technology provides an economically feasible means to embed computing and communication capabilities in numerous physical objects around us, thereby allowing anyone to effortlessly announce and expose varieties of information anywhere at any time. As the technology is increasingly used in everyday environments, there is a heightening tension in the design and shaping of social boundaries in the digitally enhanced real world. Our experiments of RFID-triggered information sharing have identified usability, deployment, and privacy issues of physically based information systems. We discuss awareness issues and cognitive costs in regulating RFID-triggered information flows and propose a framework for privacy-observant RFID applications. The proposed framework supports users' in situ privacy boundary control by allowing users to (1) see how their information is socially disclosed and viewed by others, (2) dynamically negotiate their privacy boundaries, and (3) automate certain information disclosure processes.}, journal={Advances in Human-Computer Interaction}, publisher={Hindawi Limited}, author={Konomi, Shin'ichi and Nam, Chang S.}, year={2009}, pages={1–13} }
 @article{nam_lyons_hwang_kim_2009, title={The process of team communication in multi-cultural contexts: An empirical study using Bales’ interaction process analysis (IPA)}, volume={39}, ISSN={0169-8141}, url={http://dx.doi.org/10.1016/j.ergon.2009.03.004}, DOI={10.1016/j.ergon.2009.03.004}, abstractNote={The main goal of the present study was to empirically investigate the manner in which cultural diversity and communication mode affect team communication process. Two independent variables were manipulated in the study: (1) cultural diversity (homogeneous versus heterogeneous); and (2) communication mode (face-to-face versus computer-mediated communication). Team members’ communication exchanges were measured by using Bales’ interaction process analysis (IPA) that divides the function (as opposed to the topical content) of communication during group discussion into either task-related or socio-emotional contributions at two-levels: communication profile and functional area. Results of this study indicated homogeneous teams used more showing agreement, giving opinions, and showing tension communication patterns compared to heterogeneous teams. Additionally, when considering the higher-level functional areas, teams using face-to-face (FTF) communication strategies were characterized by greater positive socio-emotional communication, more attempted answers, more questions, and more frequent negative socio-emotional communications. The results of the present study also suggested that the impact of communication mode on team communication varies by the level of diversity within the team. The outcomes of this research should have a broad impact on the management of a multi-cultural team, a task-oriented team consisting of people with different national cultures. Relevance to industry: Results of the present study should provide valuable insights into the ways in which cultural diversity and communication mode influence the communication mechanisms which take place among members during team interaction.}, number={5}, journal={International Journal of Industrial Ergonomics}, publisher={Elsevier BV}, author={Nam, Chang S. and Lyons, Joseph B. and Hwang, Ha-Sung and Kim, Sukwon}, year={2009}, month={Sep}, pages={771–782} }
 @article{nam_jeon_li_kim_yoon_2009, title={Usability of the P300 Speller: Towards a More Sustainable Brain-Computer Interface}, volume={1}, number={5}, journal={eMinds: International Journal on Human-Computer Interaction}, author={Nam, C.S. and Jeon, Y. and Li, Y. and Kim, Y.-J. and Yoon, H.}, year={2009}, pages={111–125} }
 @article{seong_nam_2008, title={Capturing judgment policy on customers’ creditworthiness: A lens model and SDT approach}, volume={38}, ISSN={0169-8141}, url={http://dx.doi.org/10.1016/j.ergon.2008.01.018}, DOI={10.1016/j.ergon.2008.01.018}, abstractNote={Designing an intervention program to train human operator's decision-making process and subsequently to improve their performance requires a thorough understanding of the relationships between the environment, the human operator, and cues on which decisions are based. Understanding these relationships provides opportunities to make better decisions when human operators encounter novel situations. This study investigated the operator's decision-making process from the lens model perspective and signal detection approach, in which operators make judgments on customers’ creditworthiness using three types of information such as (1) days that accounts were unpaid, (2) probability of the customers damaging the institution based on the customers’ credit histories, and (3) case-based reasoning (CBR) scores. Results showed that the operators were conservative, which resulted in extremely low performance while maintaining a good level of domain knowledge. Analyses of the relative cue weights also showed that the aggregated judgment strategy represented by the cue weights was similar to the validity of the cues to the ecology, reflected in the high level of policy matching (rm). Specifically, the probability and the days cues were more and equally emphasized over the CBR score. Capturing the human operator's judgment policy can be used to identify and develop customized training needs for individual operator to make better judgments on customers’ creditworthiness or the environment of interest in general.}, number={7-8}, journal={International Journal of Industrial Ergonomics}, publisher={Elsevier BV}, author={Seong, Younho and Nam, Chang S.}, year={2008}, month={Jul}, pages={593–600} }
 @article{nam_shu_chung_2008, title={The roles of sensory modalities in collaborative virtual environments (CVEs)}, volume={24}, ISSN={0747-5632}, url={http://dx.doi.org/10.1016/j.chb.2007.07.014}, DOI={10.1016/j.chb.2007.07.014}, abstractNote={This study was conducted to assess the effects of sensorial modalities on user performance, perception, and behavior in collaborative virtual environments (CVEs). Participants played a CVE game, air hockey, together with a remote partner under different sensory modality conditions, depending on the type of sensory feedback provided: visual-only (V), visual-haptic (V+H), and visual-haptic-audio feedback (V+H+A). Three types of measurements were used as dependent variables: (1) task performance measured as playing time, (2) user perception including the sense of presence, the sense of togetherness, and perceived collaboration, and (3) behavior measurement including the amount of force applied and the mallet deviation. Results of the study indicated that the task performance, perception, and user behavior in CVEs can be affected due to supported sensory modalities. Therefore, the multiple sensory information types that are required to perform the task at hand should be provided to effectively support collaboration between people in CVEs. The outcomes of this research should have a broad impact on multimodal user interaction, including research on physiological, psychophysical, and psychological mechanisms underlying human perception on multisensory feedback in CVEs.}, number={4}, journal={Computers in Human Behavior}, publisher={Elsevier BV}, author={Nam, Chang S. and Shu, Joseph and Chung, Donghun}, year={2008}, month={Jul}, pages={1404–1417} }
 @article{chung_nam_2007, title={An analysis of the variables predicting instant messenger use}, volume={9}, ISSN={1461-4448 1461-7315}, url={http://dx.doi.org/10.1177/1461444807072217}, DOI={10.1177/1461444807072217}, abstractNote={ This article focuses on which variables predict instant messenger (IM) use. A model was tested with a sample of 329 undergraduate participants. Results indicated a strong link between internet self-efficacy and perceived usefulness of IM. Subsequently, one's attitude toward using IM was impacted by the perceived usefulness of IM. Also, a peer groups' subjective norm about IM accurately predicted their intention to use IM. However, intention did not predict IM use for users, and attitude toward using IM did not predict intention to use IM for either group. Finally, the data were judged to be inconsistent with the model. }, number={2}, journal={New Media & Society}, publisher={SAGE Publications}, author={Chung, Donghun and Nam, Chang Soo}, year={2007}, month={Apr}, pages={212–234} }
 @inbook{söeffner_nam_2007, title={Co-presence in Shared Virtual Environments: Avatars Beyond the Opposition of Presence and Representation}, ISBN={9783540731047 9783540731054}, ISSN={0302-9743 1611-3349}, url={http://dx.doi.org/10.1007/978-3-540-73105-4_104}, DOI={10.1007/978-3-540-73105-4_104}, abstractNote={Avatars in shared virtual environments are usually described as representations of the users, but they can be much more than just an arbitrary icon ‘standing for‘ (re-presenting) somebody who is absent. In multi-user virtual reality avatars can be experienced by the users as presences or presentations of persons, as well as can be seen as re-presentations; and it is by this property that they allow for co-presence experience. This paper outlines a theory about the relation between persons and their avatars by focusing on both the experience of transmission (as opposed to simulation) and the experience of méthexis or participation (as opposed to representation).}, booktitle={Human-Computer Interaction. Interaction Design and Usability}, publisher={Springer Berlin Heidelberg}, author={Söeffner, Jan and Nam, Chang S.}, year={2007}, pages={949–958} }
 @inbook{arnim_piuzzi_nam_chung_2007, title={Guidelines for the Development and Improvement of Universal Access Systems for Blind Students}, ISBN={9783540732785}, url={http://dx.doi.org/10.1007/978-3-540-73279-2_67}, DOI={10.1007/978-3-540-73279-2_67}, abstractNote={This paper describes a study conducted to develop a set of interface design principles and guidelines that can be used to develop and improve universal access systems for the visually impaired, such as Haptic Audio Virtual Environments (HAVEs). Over the last few decades, user interface systems have advanced to allowing users to interact with computational systems physically, perceptively, and conceptually. However, this process has also left blind and partially blind users unable to access such new technologies. It is also true that there are currently only limited methods for presenting information non-visually and these do not provide an equivalent speed and ease of use to their graphical counterparts. Comprehensible design principles and guidelines addressing the needs of blind users should be helpful when developing universal access systems, such as haptic audio virtual environments that use multiple sensory modalities to present information.}, booktitle={Lecture Notes in Computer Science}, publisher={Springer Berlin Heidelberg}, author={Arnim, David and Piuzzi, Benito S. and Nam, Chang S. and Chung, Donghun}, year={2007}, month={Aug}, pages={603–612} }
 @inbook{chung_debuys_nam_2007, title={Influence of Avatar Creation on Attitude, Empathy, Presence, and Para-Social Interaction}, ISBN={9783540731047}, url={http://dx.doi.org/10.1007/978-3-540-73105-4_78}, DOI={10.1007/978-3-540-73105-4_78}, abstractNote={The present paper focuses on the influence of avatar creation in a video game. More specifically, this study investigates the effects of avatar creation on attitude towards avatar, empathy, presence, and para-social interaction of female non-game users. As a cyber-self, an avatar is a graphic character representing a user in cyberspace. Avatars are primarily used in the entertainment industry as high-tech novelties, controlled by game users, for high-end video games. Some games provide game characters by default that users cannot change, but other games provide various options gamers can choose. What if game users can create their own avatars? Do they have more psychological closeness with their avatars as their cyber-selves? This study tested the differences of attitude, empathy, presence, and para-social interaction of female non-game users between an avatar creation group and a non-avatar creation group and resulted in no difference.}, booktitle={Human-Computer Interaction. Interaction Design and Usability}, publisher={Springer Berlin Heidelberg}, author={Chung, Donghun and deBuys, Brahm Daniel and Nam, Chang S.}, year={2007}, month={Aug}, pages={711–720} }
 @article{s. nam_l. smith-jackson_2007, title={Web-Based Learning Environment: A Theory-Based Design Process for Development and Evaluation}, volume={6}, ISSN={1547-9714 1539-3585}, url={http://dx.doi.org/10.28945/200}, DOI={10.28945/200}, abstractNote={Web-based courses and programs have increasingly been developed by many academic institutions, organizations, and companies worldwide due to their benefits for both learners and educators.However, many of the developmental approaches lack two important considerations needed for implementing Web-based learning applications: (1) integration of the user interface design with instructional design and (2) development of the evaluation framework to improve the overall quality of Web-based learning support environments.This study addressed these two weaknesses while developing a user-centered, Web-based learning support environment for Global Positioning System (GPS) education: Web-based distance and distributed learning (WD 2 L) environment.The research goals of the study focused on the improvement of the design process and usability of the WD 2 L environment based on a theory-based Integrated Design Process (IDP) proposed in the study.Results indicated that the proposed IDP was effective in that the study showed (1) the WD 2 L environment's equivalence to traditional supplemental learning, especially as a Web-based supplemental learning program and (2) users' positive perceptions of WD 2 L environment resources.The study also confirmed that for an e-learning environment to be successful, various aspects of the learning environment should be considered such as application domain knowledge, conceptual learning theory, instructional design, user interface design, and evaluation about the overall quality of the learning environment.}, journal={Journal of Information Technology Education: Research}, publisher={Informing Science Institute}, author={S. Nam, Chang and L. Smith-Jackson, Tonya}, year={2007}, pages={023–043} }
 @article{nam_thomas_2006, title={Effects of Cultural Difference and Task Complexity on Team Interaction Process}, volume={25}, ISSN={1229-1684}, url={http://dx.doi.org/10.5143/jesk.2006.25.3.007}, DOI={10.5143/jesk.2006.25.3.007}, abstractNote={Although several theories and models have been proposed to explain the effects of cultural differences in team decision making, many aspects of team decision-making in multi-cultural contexts such as team performance, team communication, and team cognition still remain unclear. In particular, little attention has paid to the empirical studies on team processes multi-cultural team members use to interact with each other to accomplish the task in different task environments. To investigate the effects of culture and task characteristics on team decision making behavior in multi-cultural contexts, this study compared culturally homogenous and heterogeneous groups in the context of logistics decision making. Results of the study showed that cultural difference and task complexity may affect team performance as well as team interaction process to varying degree. Keyword: Culture ergonomics, Team}, number={3}, journal={Journal of the Ergonomics Society of Korea}, publisher={The Ergonomics Society of Korea}, author={Nam, C.S. and Thomas, Krystal}, year={2006}, month={Aug}, pages={7–16} }
 @article{nam_thomas_smith-jackson_2005, title={Effects of Individual Differences and Task Environments on Users’ Interactions with Web Resource Seeking}, volume={15}, number={2}, journal={Computers in Education Journal}, author={Nam, C.S. and Thomas, C. and Smith-Jackson, T.L.}, year={2005}, pages={79–92} }
 @misc{nam_2005, place={Mahwah, NJ}, title={Usability and Internationalization of Information Technology}, volume={42}, number={1}, journal={The HFES Potomac Chapter Newsletter}, publisher={Lawrence Erlbaum Associates}, author={Nam, C.S.}, year={2005}, pages={2} }