@article{wu_chen_2024, title={Embodiment of Virtual Body and Extremities With Movement Control in Reaching Tasks Using Virtual Reality}, url={https://doi.org/10.1177/10711813241273495}, DOI={10.1177/10711813241273495}, abstractNote={The study explores embodiment in virtual reality (VR), investigating its effects on task performance across various body representations. Previous research highlighted the impact of embodiment on motor performance in VR, emphasizing the importance of body representation. While prior studies mainly focused on full-body avatars, this study aims to understand the perceived embodiment in hand and foot-reaching tasks using different body representations. Thirty-two participants engaged in reaching tasks within VR environments, employing a 4 × 3 within-subjects design. Results indicated significant differences in embodiment across body representation conditions, with notable effects on task performance. These findings underscore the importance of tailoring virtual environments to enhance embodiment and consider task-specific demands to optimize performance outcomes. Personalizing VR experiences based on body representations could effectively enhance user engagement and satisfaction, offering valuable insights for future VR applications in various domains.}, journal={Proceedings of the Human Factors and Ergonomics Society Annual Meeting}, author={Wu, Linfeng and Chen, Karen B.}, year={2024}, month={Aug} }
 @article{wu_chen_2024, title={Examining the Effects of Embodiment on Working Memory Performance in VR}, url={https://doi.org/10.1177/10711813241273515}, DOI={10.1177/10711813241273515}, abstractNote={This study investigates the impact of immersive virtual reality (VR) environments on working memory task performance and the role of embodiment in VR. Sixteen participants engaged in N-back tasks presented either on a computer screen or in VR. Participants were assigned to one of four conditions: non-VR, VR without mimicking, VR with mimicking, or VR with mimicking and virtual mirror. Statistical analyses revealed no significant differences in sense of embodiment or task performance among the VR conditions. Additionally, there were no significant changes in working memory performance across conditions. While the findings suggest that variations in VR setups may not affect embodiment or task performance, the study’s preliminary nature emphasizes the need for larger sample sizes for more conclusive results. Further research is warranted to validate these findings and explore the effects of VR interventions on cognitive outcomes.}, journal={Proceedings of the Human Factors and Ergonomics Society Annual Meeting}, author={Wu, Linfeng and Chen, Karen B.}, year={2024}, month={Aug} }
 @article{chen_harper-gampp_wu_delgado_peterson_2024, title={Learning Scale in Virtual Reality: Experiences and Perception of Immersive Technology at a Public Middle School}, url={https://doi.org/10.1177/10711813241265650}, DOI={10.1177/10711813241265650}, abstractNote={Students have misconceptions of size and scale cognition as they confuse molecules and cells. The team deployed a virtual reality (VR) learning tool, namely Scale Worlds, for K-12 students to use at school. The present work aimed to examine the experience and perception of immersive technology, and logistical challenges of integrating Scale Worlds into a science class. Ten students and three teachers were included in this study with informed consent. Scale Worlds was introduced as part of a science class and then semi-structured interview was conducted. Students’ experience with VR technology included physiological discomfort, psychological nervousness and uncertainty of technology, personal abilities and unfamiliarity, and hardware latency. However, students perceived Scale Worlds to be a useful tool that helped them visualize entities of different sizes, and allowed them to work collaboratively. Teachers expressed desire for more exciting content in Scale Worlds and further usability enhancement, as well as need for additional material preparation time. The team planned to return to the same middle school for another round of in-field study after addressing some of the reported challenges.}, journal={Proceedings of the Human Factors and Ergonomics Society Annual Meeting}, author={Chen, Karen B. and Harper-Gampp, Tyler and Wu, Linfeng and Delgado, Cesar and Peterson, Matthew}, year={2024}, month={Sep} }
 @article{fang_sivaramakrishnan_chen_2024, title={Negative Emotions From Virtual Reality Usage: A Preliminary Exploratory Study Using Online Forums}, url={https://doi.org/10.1177/10711813241275079}, DOI={10.1177/10711813241275079}, abstractNote={As the virtual reality (VR) industry continues to grow, it becomes important to understand how individuals interact with VR in their everyday settings. The physical effects of VR such as fatigue are well-known, but research on emotional effects is not as common. This study aimed to explore VR head-mounted display users’ negative emotions regarding at-home VR usage. Examining 140 forum posts (with 118 from Reddit), the emotions, activities, and suggestions were extracted from the posts. The emotions were classified based on Plutchik’s wheel of emotions. Thematic analysis was used in coding posters’ activities and suggestions. The results suggest fear is the most common category of negative emotion experienced by posters. This work could help generate research questions to further examine VR use in naturalistic settings. Future work can include studies with a larger scope, extracting posts from a longer timeline and with fewer inclusion criteria.}, journal={Proceedings of the Human Factors and Ergonomics Society Annual Meeting}, author={Fang, Emily and Sivaramakrishnan, Anand and Chen, Karen B.}, year={2024}, month={Aug} }
 @article{sanders_sener_chen_2024, title={Robot-related injuries in the workplace: An analysis of OSHA Severe Injury Reports}, volume={121}, ISSN={["1872-9126"]}, url={https://doi.org/10.1016/j.apergo.2024.104324}, DOI={10.1016/j.apergo.2024.104324}, abstractNote={Industrial robots are increasingly commonplace, but research on prototypical accidents and injuries has been sparse, hindering evidence-based safety strategies. Using Severe Injury Reports (SIRs) from the U.S. Occupational Safety and Health Administration (OSHA), we identified 77 robot-related accidents from 2015-2022. Of these, 54 involved stationary robots, resulting in 66 injuries, mainly finger amputations and fractures to the head and torso. Mobile robots caused 23 accidents, leading to 27 injuries, mainly fractures to the legs and feet. A two-stage deductive-inductive thematic analysis was performed using text data from the final narratives in the reports to discover patterns in tasks, precipitating mechanisms, and contributing factors. Findings highlight the need for guards and collision avoidance systems that detect individual extremities. Post-contact strategies should focus on mitigating finger amputations. More structured and detailed narratives in the SIRs are needed.}, journal={APPLIED ERGONOMICS}, author={Sanders, Nathan E. and Sener, Elif and Chen, Karen B.}, year={2024}, month={Nov} }
 @article{sanders_xie_chen_2023, title={A comparison of the psychological effects of robot motion in physical and virtual environments}, volume={112}, ISSN={["1872-9126"]}, url={https://doi.org/10.1016/j.apergo.2023.104039}, DOI={10.1016/j.apergo.2023.104039}, abstractNote={A mixed-methods approach was used to assess the fidelity of virtual environments as ergonomic assessment tools for human-robot interaction. Participants performed a visual search task in the physical environment while a nearby collaborative robot repeatedly extended its arm toward them. This scenario was reconstructed in two virtual environments with different levels of graphical detail. Measures of presence, task performance, workload, and anxiety were taken to determine the effect of robot motion in all three environments. Task performance decreased in response to robot motion in the physical environment, while workload and anxiety increased. This simple effect of motion was consistent across environments for measures of task performance and anxiety. However, people performed faster overall in virtual reality, and the effect of motion on workload was greatly reduced in virtual reality. Results in the virtual environments suggest that people were distracted by the sound of the robot, and that presence was affected by manipulations of immersion and coherence.}, journal={APPLIED ERGONOMICS}, author={Sanders, Nathan Edward and Xie, Ziyang and Chen, Karen B.}, year={2023}, month={Oct} }
 @article{sanders_sener_chen_2023, title={Eliciting Ergonomic User-Defined Gestures for Virtual Reality: A Pilot Study}, url={https://doi.org/10.1177/21695067231192530}, DOI={10.1177/21695067231192530}, abstractNote={ People are increasingly using virtual reality (VR) for work. As a result of extended use, fatigue and musculoskeletal disorders affecting the upper arms and shoulders are already becoming common among VR users. This pilot study presented a “virtual working area” (VWA) to reduce the risk of fatigue resulting from using gestures obtained in gesture elicitation studies, and explored how the distance to the user interface (UI) interacted with different functions (select, scroll) during a mock reading task. Results showed that keeping the hands within the VWA had the potential to reduce Rapid Upper-Body Limb Assessment (RULA) and Borg CR10 scores at clinically significant levels. Scores were worse when the UI was far away and for the select function, suggesting the design of virtual UIs can play a role in eliciting naturalistic yet ergonomic interactions. The results also provide effect sizes and variance estimates to plan future work. }, journal={Proceedings of the Human Factors and Ergonomics Society Annual Meeting}, author={Sanders, Nathan and Sener, Elif and Chen, Karen B.}, year={2023}, month={Sep} }
 @article{caine_catchpole_sasangohar_chen_hegde_souders_mcdonald_mclaurin_2023, title={Experiences with Postdoctoral Training in Human Factors: Mentor and Trainee Perspectives}, url={https://doi.org/10.1177/21695067231192205}, DOI={10.1177/21695067231192205}, abstractNote={ Postdoctoral training positions are becoming more common in the human factors and ergonomics (HFE) discipline. However, conversations related to training in the HFE discipline have largely focused on undergraduate and graduate education. This panel assembles both postdoctoral mentors and former trainees who collectively have a diverse set of HFE-related postdoctoral experiences. By panelists discussing their experiences, observations, and recommendations related to postdoctoral training with the audience, the panel session will support HFE faculty and students in making more informed decisions about if and how a postdoctoral experience (either as a mentor or trainee) could be a part of their career development in HFE. }, journal={Proceedings of the Human Factors and Ergonomics Society Annual Meeting}, author={Caine, Kelly and Catchpole, Ken and Sasangohar, Farzan and Chen, Karen B. and Hegde, Sudeep and Souders, Dustin and McDonald, Anthony and McLaurin, Elease J.}, year={2023}, month={Sep} }
 @article{hu_wang_zhu_chen_2023, title={Modeling Human-Machine Interaction System Reliability with Multiple Dependent Degradation Processes and Situation Awareness}, volume={7}, ISSN={["1793-6446"]}, DOI={10.1142/S0218539323500146}, abstractNote={ With the advancement in automation, the roles of machine operators have shifted from traditional physical commitments to controlling the automation process. The operators need to understand and assess the incoming information and make decisions accordingly, which will determine the next move of the process and further affect the machine’s health status/performance. Such awareness and understanding of the situation, as one of the critical prerequisites of decision-making and known as situation awareness (SA), needs to be addressed appropriately in accessing the reliability of the system with human–machine interaction (HMI). Hence, we propose the HMI system reliability model considering the machine has multiple dependent degradation processes, and each degradation process is affected by the interactions of internal machine degradation, random shocks, and SA. In addition, the impacts of SA and external factors on the system are reflected in the amount and rate of the machine degradation process. The proposed model is demonstrated by a simulated case, and the sensitivity analysis is conducted to analyze the impacts of model parameters on system reliability prediction. Finally, the performance of the proposed model is demonstrated by comparing it with the existing model. }, journal={INTERNATIONAL JOURNAL OF RELIABILITY QUALITY AND SAFETY ENGINEERING}, author={Hu, Yuhan and Wang, Rui and Zhu, Mengmeng and Chen, Karen B. B.}, year={2023}, month={Jul} }
 @article{wu_sekelsky_peterson_gampp_delgado_chen_2023, title={Scale Worlds: Iterative refinement, evaluation, and theory-usability balance of an immersive virtual learning environment}, volume={67}, ISSN={1071-1813 2169-5067}, url={http://dx.doi.org/10.1177/21695067231192534}, DOI={10.1177/21695067231192534}, abstractNote={ Feedback-based iterative refinement is important in the development of any human-computer interface. The present work aims to evaluate and iteratively refine an immersive learning environment called Scale Worlds (SW), delivered via a head-mounted display (HMD). SW is a virtual learning environment encompassing scientific entities of a wide range of sizes that enables students an embodied experience while learning size and scale. Five usability experts performed think aloud while carrying out four interactive tasks in SW and compared three different design options during A/B testing. Improvement features based on the feedback from an earlier SW usability evaluation as well as HMD-specific features were examined. Usability experts completed the post-study system usability questionnaire, the NASA task load index, and a bipolar laddering survey that collected subjective perception of specific SW features. Results show that the progress panel (an improvement feature) was informative while the instructions (another improvement feature) caused clutter. The experts indicated clear usability preferences during A/B testing, which helped resolve three sets of theory-usability conflicts. The overall assessment of SW paved a path for theory-usability balance and provided valuable insights for designing and evaluating usability in immersive virtual learning environments. }, number={1}, journal={Proceedings of the Human Factors and Ergonomics Society Annual Meeting}, publisher={SAGE Publications}, author={Wu, Linfeng and Sekelsky, Brian and Peterson, Matthew and Gampp, Tyler and Delgado, Cesar and Chen, Karen B.}, year={2023}, month={Sep}, pages={2382–2388} }
 @article{wu_chen_sekelsky_peterson_harper-gampp_delgado_2023, title={Shrink or grow the kids? Scale cognition in an immersive virtual environment for K-12 summer camp}, url={http://dx.doi.org/10.1109/vrw58643.2023.00203}, DOI={10.1109/VRW58643.2023.00203}, abstractNote={Virtual reality (VR) has been widely used for education and affords embodied learning experiences. Here we describe: Scale Worlds (SW), an immersive virtual environment to allow users to shrink or grow by powers of ten (10X) and experience entities from molecular to astronomical levels; and students' impressions and outcomes from experiencing SW in a CAVE (Figure 1) during experiential summer outreach sessions. Data collected from post-visit surveys of 69 students, and field observations, revealed that VR technologies: enabled interactive learning experiences; encouraged active engagement and discussions among participating students; enhanced the understanding of size and scale; and increased interest in STEM careers.}, journal={2023 IEEE CONFERENCE ON VIRTUAL REALITY AND 3D USER INTERFACES ABSTRACTS AND WORKSHOPS, VRW}, publisher={IEEE}, author={Wu, Linfeng and Chen, Karen B. and Sekelsky, Brian and Peterson, Matthew and Harper-Gampp, Tyler and Delgado, Cesar}, year={2023}, pages={721–722} }
 @article{perera_hey_chen_morello_mcconnell_ivy_2022, title={Checklists in Healthcare: Operational Improvement of Standards using Safety Engineering-Project CHOISSE-A framework for evaluating the effects of checklists on surgical team culture}, volume={103}, ISSN={["1872-9126"]}, url={https://doi.org/10.1016/j.apergo.2022.103786}, DOI={10.1016/j.apergo.2022.103786}, abstractNote={The CHOISSE multi-stage framework for evaluating the effects of electronic checklist applications (e-checklists) on surgical team members' perception of their roles, performance, communication, and understanding of checklists is introduced via a pilot study. A prospective interventional cohort study design was piloted to assess the effectiveness of the framework and the sociotechnical effects of the e-checklist. A Delphi process was used to design the stages of the framework based on literature and expert consensus. The CHOISSE framework was applied to guide the implementation and evaluation of e-checklists on team culture for ten pilot teams across the US over a 24-week period. The pilot results revealed more engagement by surgeons than non-surgeons, and significant increases in surgeons' perception of communication and engagement during surgery with a small sample. Mixed methods analysis of the data and lessons learned were used to identify iterative improvements to the CHOISSE framework and to inform future studies.}, journal={APPLIED ERGONOMICS}, publisher={Elsevier BV}, author={Perera, Gimantha N. and Hey, Lloyd A. and Chen, Karen B. and Morello, Madeline J. and McConnell, Brandon M. and Ivy, Julie S.}, year={2022}, month={Sep} }
 @article{wu_chen_2022, title={Examining the Effects of Gender Transfer in Virtual Reality on Implicit Gender Bias}, volume={12}, ISSN={["1547-8181"]}, url={https://doi.org/10.1177/00187208221145264}, DOI={10.1177/00187208221145264}, abstractNote={Objective To investigate the effect of gender transfer in virtual reality on implicit gender bias. Background Gender bias is a type of discrimination based on gender, which can lead to increased self-doubt and decreased self-esteem. Sexual harassment is a hostile form of gender bias that can cause anxiety, depression, and significant mental health issues. Virtual reality (VR) has been employed to help make people become aware of their biases and change their attitudes regarding gender, race, and age. Methods Forty participants were embodied in avatars of different genders and experienced sexual harassment scenarios in VR. A gender Implicit Association Test (IAT) was administered before and after the experience. Results There was a statistically significant main effect of participant gender ( F (1,36) = 10.67, p = .002, partial η2 = .23) on ΔIAT, where males and females reported a decrease (M = −.12, SD = .24) and an increase (M = .10, SD = .25) in IAT scores, respectively. A statistically significant two-way interaction between gender transfer and participant gender was revealed ( F (1,36) = 6.32, p = .02, partial η2 = .15). There was a significant simple effect of gender transfer for male participants ( F (1,36) = 8.70, p = .006, partial η2 = .19). Conclusions Implicit gender bias can be modified, at least temporarily, through embodiment in VR. Gender transfer through embodiment while encountering different sexual harassment scenarios helped reduce implicit gender bias. There was a tendency for individuals to increase bias for the gender of the avatar in which they embodied. Applications The current research provided promising evidence that a virtual environment system may be used as a potential training tool to improve implicit gender bias. }, journal={HUMAN FACTORS}, author={Wu, Linfeng and Chen, Karen B. B.}, year={2022}, month={Dec} }
 @article{wu_sekelsky_peterson_gampp_delgado_chen_2022, title={Immersive virtual environment for scale cognition and learning: Expert-based evaluation for balancing usability versus cognitive theories}, volume={66}, ISSN={2169-5067 1071-1813}, url={http://dx.doi.org/10.1177/1071181322661094}, DOI={10.1177/1071181322661094}, abstractNote={ While scale cognition and learning is a crosscutting concept that pervades science and can aid students in making connections across disciplines, students struggle to conceptualize and consider scales that go far beyond their everyday world experience. Virtual reality technology affords embodied learning experiences, which enable students to physically engage in learning activities in an environment with rich information. Scale Worlds is a virtual learning environment implemented in an immersive CAVE, which portrays scientific entities of a wide range of sizes. A user can scale themself up or down by powers of ten, in order to experience entities from an atom to the Sun. This paper reports on an expert-based usability evaluation of Scale Worlds, including three sets of A/B testing, by five usability experts. Outcomes of the usability evaluation will inform the refinement of Scale Worlds. The evaluation provides insights for usability evaluation and design in immersive virtual environments. }, number={1}, journal={Proceedings of the Human Factors and Ergonomics Society Annual Meeting}, publisher={SAGE Publications}, author={Wu, Linfeng and Sekelsky, Brian and Peterson, Matthew and Gampp, Tyler and Delgado, Cesar and Chen, Karen B.}, year={2022}, month={Sep}, pages={1972–1976} }
 @article{sesto_carroll_zhang_chen_terhaar_wilson_tevaarwerk_2022, title={Unmet needs and problems related to employment and working as reported by survivors with metastatic breast cancer}, volume={30}, ISSN={["1433-7339"]}, url={https://doi.org/10.1007/s00520-021-06755-z}, DOI={10.1007/s00520-021-06755-z}, abstractNote={By 2020, the US population living with metastatic breast cancer (MBC) has exceeded 165,000. A knowledge gap exists regarding the factors affecting work ability for these individuals. We sought to characterize the work status, importance of work, and work-related information needs for women living with MBC.We conducted an online survey using an MBC listserv and clinic flyers in 2014-2015. Respondents working at the time of MBC diagnosis were divided into "stably-working" and "no-longer-working" based on employment status at the time of survey. Comparisons were made with chi-square or two-tailed t test.Respondents (n = 133) were predominantly non-Hispanic White (93.2%); 72 were stably-working, while 61 reported no-longer-working. Those no-longer-working were older (54.0 vs 49.5 years old, p < 0.01, Cohen's d = 0.55), further from initial diagnosis of MBC (4.6 vs 3.3 years, p < 0.01, Cohen's d = 0.36), and reported high rates of life interference due to MBC (n = 51, 83.6% vs n = 39, 54.2%, p < 0.01, Cramer's V = 0.32). Stably-working respondents considered work to be important (n = 58, 80.5% vs n = 18, 29.5%, p < 0.01, Cramer's V = 0.57); the top reasons cited were financial and/or insurance (80.4%), importance of staying busy (67.9%), and desire to support themselves and family (64.3%). The stably-working respondents more often valued information on how to talk with employers or co-workers about diagnosis (n = 38, 57.6% vs n = 16, 27.1%; p < 0.01), legal rights in workplace (n = 43, 65.2% vs n = 22, 36.7%; p < 0.01), when to think about stopping work (n = 45, 68.2% vs n = 18, 30%; p < 0.01), and applying for disability (n = 42, 63.6% vs n = 26, 42.6%; p < 0.05), when compared to no-longer-working.The decision to stop working may represent a subsequent event driven by cancer progression. This research highlights the ongoing need of information targeting MBC to facilitate the management of employment and financial issues early in the MBC trajectory.}, number={5}, journal={SUPPORTIVE CARE IN CANCER}, publisher={Springer Science and Business Media LLC}, author={Sesto, Mary E. and Carroll, Cibele B. and Zhang, Xiao and Chen, Karen B. and Terhaar, Abigail and Wilson, Athena S. and Tevaarwerk, Amye J.}, year={2022}, month={Jan} }
 @article{tevaarwerk_kwekkeboom_buhr_dennee_conkright_onitilo_robinson_ahuja_kwong_nanad_et al._2021, title={Reply to The Effects of Curative-Intent Cancer Therapy on Employment, Work Ability, and Work Limitations}, volume={6}, ISSN={["1097-0142"]}, DOI={10.1002/cncr.33566}, abstractNote={We thank Kobayashi et al for their informative comments. Our published article reports on a deliberately crafted study designed to assess changes in work outcomes (employment status, hours worked, work ability, and work limitations) as patients received curativeintent chemotherapy for diverse cancers. This study is unique in following these outcomes in a US population in a prospective, longitudinal manner both during the course of curative treatment and afterward. Another unique aspect of this study is that we started with patients who reported working at diagnosis and who expressed an intent to work during treatment or return to work after treatment. The published article represents our initial goal to describe the work outcomes observed, with ongoing analyses underway to explain the patterns observed. Kobayashi et al stated, “The authors collected information before the initiation of cancer treatment (baseline information).” We would like to clarify that our baseline survey was conducted before cycle 2 of chemotherapy (not necessarily before surgery or cycle 1). As discussed in our limitations, this means that nearly onethird of the patients were not working at the time of the baseline survey because they had already undergone surgery or received cycle 1 of chemotherapy. However, they all reported working before their cancer diagnosis. Kobayashi et al correctly observed that the study population was heterogenous from the standpoint of education, job type, and income. It was homogeneous with respect to the commonality of receiving curative chemotherapy and a stated intent to return to work. They also correctly noted that the sample size was smaller. Thus, we elected to start by describing the outcomes observed and will explore the impact of additional variables (eg, the duration of therapy and the cancer type) in future analyses. Kobayashi et al noted that stage may be an important variable, especially when one is considering a stage IV or metastatic population that is being treated palliatively. In curatively treated patients rendered free of evidence of the disease, it is the acute and persistent consequences of therapy that likely drive outcomes. Therefore, we set up our study to emphasize the commonality of receiving chemotherapy and intent of treatment rather than cancer stage. We also note that stage should be interpreted with caution: for instance, the American Joint Committee on Cancer staging system changes from version 7 to 8 had a profound impact on breast cancer. Additionally, stage may not reflect what treatment will be rendered, especially in a cancer population in which treatment is driven by receptor status (eg, breast). Kobayashi et al commented that the length of the time from the baseline to the end of treatment varied, and we will account for this and other variables (eg, the cancer type and the symptom burden) in future analyses. Finally, Kobayashi et al noted that the reasons for dropout from the baseline to the end of treatment might affect the outcomes observed. We noted in the Results section that of the 111 participants with a baseline survey, 4 developed cancer progression or died. Unfortunately, we do not have data about the remaining respondents who were lost to followup or their reasons for no longer participating. In summary, we are delighted to receive these thoughtful comments and hope that our explanations address the concerns noted by Kobayashi et al. We believe that our article and the study that it outlines are a positive step in better understanding drivers of survivor work outcomes, as called for by the National Cancer Institute.2 This study was previously presented at the Cancer Survivorship Symposium in 2017.}, journal={CANCER}, author={Tevaarwerk, Amye J. and Kwekkeboom, Kris and Buhr, Kevin A. and Dennee, Alexandra and Conkright, William and Onitilo, Adedayo and Robinson, Emily and Ahuja, Harish and Kwong, Roger W. and Nanad, Ranveer and et al.}, year={2021}, month={Jun} }
 @article{chen_chen_2023, title={Task-Oriented and Imitation-Oriented Movements in Virtual Reality Exercise Performance and Design}, volume={65}, ISSN={["1547-8181"]}, url={https://doi.org/10.1177/00187208211010100}, DOI={10.1177/00187208211010100}, abstractNote={Objective This study investigated the influence of game features and practice type on human kinematic and muscular performance in a virtual reality exercise (VRE). Participants demonstrated changes in shoulder flexion angle and muscle activation under different virtual scenarios. Background Conventional VRE studies often compared the outcomes between an experimental group that underwent exercise in VR and a real-world exercise control group, whereas comparisons between VRE programs are lacking. Besides, the attributes of VREs received little attention. Method Thirteen able-bodied participants performed upper extremity exercise movements in immersive VR using a head-mounted display. Participants performed task-oriented and imitation-oriented movements with different game features. Shoulder muscle activity (the deltoid, supraspinatus, and infraspinatus) and shoulder motion were collected. Results Practice type (task-oriented, imitation-oriented) significantly influenced the flexion angle of the shoulder complex ( F(1,11) = 9.53, p = .01), and the muscle activity of the supraspinatus ( F(1,9) = 12.61, p = .006) and the infraspinatus ( F(1,9) = 12.71, p = .006). Game features did not have a statistically significant effect on shoulder flexion angle or shoulder muscles’ activations. Conclusions Compared to imitation-oriented practice, task-oriented practice elicited more intensive shoulder movements and muscular efforts but also induced greater movement variations. Substantial differences across game features levels should be further investigated to have significant effects. Applications This research may help guide the design of future VREs. For strength training or rehabilitation where intensive practice is required, task-oriented practice should be considered; for movement learning where movement consistency is required, imitation oriented practice should be adopted. }, number={1}, journal={HUMAN FACTORS}, author={Chen, Ken and Chen, Karen B.}, year={2023}, month={Feb}, pages={125–136} }
 @article{chen_yen_sun_tevaarwerk_wiegmann_heidrich_sesto_2021, title={Usage of a Web-Based Workplace and Symptom Self-Management Intervention Tool to Improve Work Ability for Breast Cancer Survivors}, volume={9}, ISSN={["1543-0154"]}, url={https://doi.org/10.1007/s13187-021-02048-5}, DOI={10.1007/s13187-021-02048-5}, abstractNote={This work aimed to evaluate the usage of a web-based intervention (WISE: Work ability Improvement through Symptom and Ergonomic strategies) developed to improve work ability for women recently diagnosed with breast cancer. Twenty-two women undergoing adjuvant treatment for breast cancer were provided access to WISE. This website includes content pages (e.g., information on ergonomics, symptom management, and other work-related resources) and worksheets (e.g., journals to track symptoms or goals). It could be personalized based on individual work activities and symptoms. Measures assessed at 3 months included usage of the website and perceived usefulness. Thirteen of the 22 participants (60%) accessed WISE; 11 personalized their information. Content and worksheet pages had 97 and 79 visits, respectively. Most frequently visited pages were "setting goals" (i.e., prioritize and track symptoms; 45 visits) and "steps to creating your WISE plan" (i.e., incorporate symptom and ergonomic strategies; 16 visits). Median duration time was 11.05 (range 0.35-79.55) minutes. Usefulness of the content and worksheet pages assessed via a 7-point Likert scale (1 = strongly disagree, 7 = strongly agree) was 5.08 (SD = 1.59) and 4.26 (SD = 2.03), respectively. Participants were likely to recommend WISE to other women undergoing cancer treatment (mean = 6.11; SD = 1.05). The majority of participants personalized WISE work and symptom strategies. Overall, participants agreed that WISE content pages were useful and would recommend WISE for other breast cancer survivors. Results support that majority of breast cancer survivors, undergoing treatment with curative intent, accessed a web-based intervention that provided personalized information on workplace and symptom strategies.}, journal={JOURNAL OF CANCER EDUCATION}, author={Chen, Karen B. and Yen, Thomas and Sun, Wenjun and Tevaarwerk, Amye J. and Wiegmann, Douglas A. and Heidrich, Susan M. and Sesto, Mary E.}, year={2021}, month={Sep} }
 @article{tevaarwerk_kwekkeboom_buhr_dennee_conkright_onitilo_robinson_ahuja_kwong_nanad_et al._2021, title={Results from a prospective longitudinal survey of employment and work outcomes in newly diagnosed cancer patients during and after curative-intent chemotherapy: A Wisconsin Oncology Network study}, volume={127}, ISSN={["1097-0142"]}, DOI={10.1002/cncr.33311}, abstractNote={BackgroundPostcancer work limitations may affect a substantial proportion of patients and contribute to the “financial toxicity” of cancer treatment. The degree and nature of work limitations and employment outcomes are poorly understood for cancer patients, particularly in the immediate period of transition after active treatment. We prospectively examined employment, work ability, and work limitations during and after treatment.MethodsA total of 120 patients receiving curative therapy who were employed prior to their cancer diagnosis and who intended to work during or after end of treatment (EOT) completed surveys at baseline (pretreatment), EOT, and 3, 6, and 12 months after EOT. Surveys included measures of employment, work ability, and work limitations. Descriptive statistics (frequencies, percentages, means with standard deviations) were calculated.ResultsA total of 111 participants completed the baseline survey. On average, participants were 48 years of age and were mostly white (95%) and female (82%) with a diagnosis of breast cancer (69%). Full‐time employment decreased during therapy (from 88% to 50%) and returned to near prediagnosis levels by 12‐month follow‐up (78%). Work‐related productivity loss due to health was high during treatment.ConclusionsThis study is the first to report the effects of curative intent cancer therapy on employment, work ability, and work limitations both during and after treatment. Perceived work ability was generally high overall 12 months after EOT, although a minority reported persistent difficulty. A prospective analysis of factors (eg, job type, education, symptoms) most associated with work limitations is underway to assist in identifying at‐risk patients.}, number={5}, journal={CANCER}, author={Tevaarwerk, Amye J. and Kwekkeboom, Kris and Buhr, Kevin A. and Dennee, Alexandra and Conkright, William and Onitilo, Adedayo A. and Robinson, Emily and Ahuja, Harish and Kwong, Roger W. and Nanad, Ranveer and et al.}, year={2021}, month={Mar}, pages={801–808} }
 @article{deng_shirley_rose_geary_feltner_chen_hoyle_dutt_kaber_2019, title={A usability assessment of riding lawn-mowing equipment with varying levels of design standards compliance}, volume={78}, ISBN={1872-9126}, url={https://doi.org/10.1016/j.apergo.2019.02.003}, DOI={10.1016/j.apergo.2019.02.003}, abstractNote={The use of riding lawn equipment (RLE) is related to a significant number of accidents every year. To provide basis for product design and enhance user performance and safety, a usability and performance assessment of modern riding lawn-mowing tractor designs and features was conducted in a real-world test environment. Five current commercially available RLEs were tested with response measures including task performance time and accuracy, physiological workload, system usability scores (SUS), and subjective rankings of RLE models. This data was used to identify sensitivity of responses to variations in RLE design features and functionality. The data was also used to assess the validity of new tractor design standard conformance tool, the RLEval methodology. This tool made comprehensive evaluation of RLE models compliance with over 70 specific design standards and was applied by human factors experts. Experiment results revealed sensitivity of all response measures to design differences among the five RLE models, except the objective workload measures. Response measures including task performance, SUSs and subjective rankings showed partial agreement with the RLEval scores. In general, the study results demonstrated a comprehensive experimental methodology for usability and performance evaluations of RLEs as well as merit of using the RLEval as preliminary method to compare design features. Some aspects of the usability experimentation and the RLEval method appear to be complementary.}, journal={APPLIED ERGONOMICS}, publisher={Elsevier BV}, author={Deng, Yulin and Shirley, James and Rose, Tyler and Geary, Laura and Feltner, David and Chen, Karen and Hoyle, Jeffery and Dutt, Mohini and Kaber, David B.}, year={2019}, month={Jul}, pages={76–85} }
 @article{ho_lin_chen_2019, title={Examining Relationship between Driver Characteristics and Critical Target Identification Failures}, volume={2673}, ISSN={["2169-4052"]}, DOI={10.1177/0361198119842123}, abstractNote={ The main objective of this study was to examine driver demographic, anthropometric, and functional characteristics that may influence the ability of drivers in identifying critical targets (e.g., emergency vehicles) in the rear quarter blind spots while changing lane. This research employed a cost-effective approach using a consumer grade virtual reality apparatus to create driving scenarios. The experimental task was vehicle identification in various blind spots during a driving simulation. Logistic regression models were constructed to identify characteristics that were associated with critical target identification failures. Results from this experimental task indicated that factors contributed to vehicle identification error were age ( p < 0.01) and degree of functional rotation ( p < 0.1). The effect of participants’ baseline neck range of motion was statistically insignificant in the logistic regression models, which suggests that age and degree of functional rotation played a larger role in vehicle identification for this task. Findings may contribute to the design of related training and education programs for drivers in the future. }, number={8}, journal={TRANSPORTATION RESEARCH RECORD}, author={Ho, Yi-Mo and Lin, Jia-Hua and Chen, Karen B.}, year={2019}, month={Aug}, pages={192–197} }
 @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{chen_sesto_ponto_leonard_mason_vanderheiden_williams_radwin_2017, title={Use of Virtual Reality Feedback for Patients with Chronic Neck Pain and Kinesiophobia}, volume={25}, ISSN={["1558-0210"]}, DOI={10.1109/tnsre.2016.2621886}, abstractNote={This study examined how individuals with and without neck pain performed exercises under the influence of altered visual feedback in virtual reality. Chronic neck pain (n = 9) and asymptomatic (n = 10) individuals were recruited for this cross-sectional study. Participants performed head rotations while receiving programmatically manipulated visual feedback from a head-mounted virtual reality display. The main outcome measure was the control-display gain (ratio between actual head rotation angle and visual rotation angle displayed) recorded at the just-noticeable difference. Actual head rotation angles were measured for different gains. Detection of the manipulated visual feedback was affected by gain. The just-noticeable gain for asymptomatic individuals, below and above unity gain, was 0.903 and 1.159, respectively. Head rotation angle decreased or increased 5.45° for every 0.1 increase or decrease in gain, respectively. The just-noticeable gain for chronic pain individuals, below unity gain, was 0.950. The head rotation angle increased 4.29° for every 0.1 decrease in gain. On average, chronic pain individuals reported that neck rotation was feasible for 84% of the unity gain trials, 66% of the individual just-noticeable difference trials, and 50% of the “nudged” just-noticeable difference trials. This research demonstrated that virtual reality may be useful for promoting the desired outcome of increased range of motion in neck rehabilitation exercises by altering visual feedback.}, number={8}, journal={IEEE TRANSACTIONS ON NEURAL SYSTEMS AND REHABILITATION ENGINEERING}, author={Chen, Karen B. and Sesto, Mary E. and Ponto, Kevin and Leonard, James and Mason, Andrea and Vanderheiden, Gregg and Williams, Justin and Radwin, Robert G.}, year={2017}, month={Aug}, pages={1240–1248} }
 @article{xu_robertson_chen_lin_mcgorry_2017, title={Using the Microsoft Kinect (TM) to assess 3-D shoulder kinematics during computer use}, volume={65}, ISSN={["1872-9126"]}, DOI={10.1016/j.apergo.2017.04.004}, abstractNote={Shoulder joint kinematics has been used as a representative indicator to investigate musculoskeletal symptoms among computer users for office ergonomics studies. The traditional measurement of shoulder kinematics normally requires a laboratory-based motion tracking system which limits the field studies. In the current study, a portable, low cost, and marker-less Microsoft Kinect™ sensor was examined for its feasibility on shoulder kinematics measurement during computer tasks. Eleven healthy participants performed a standardized computer task, and their shoulder kinematics data were measured by a Kinect sensor and a motion tracking system concurrently. The results indicated that placing the Kinect sensor in front of the participants would yielded a more accurate shoulder kinematics measurements then placing the Kinect sensor 15° or 30° to one side. The results also showed that the Kinect sensor had a better estimate on shoulder flexion/extension, compared with shoulder adduction/abduction and shoulder axial rotation. The RMSE of front-placed Kinect sensor on shoulder flexion/extension was less than 10° for both the right and the left shoulder. The measurement error of the front-placed Kinect sensor on the shoulder adduction/abduction was approximately 10° to 15°, and the magnitude of error is proportional to the magnitude of that joint angle. After the calibration, the RMSE on shoulder adduction/abduction were less than 10° based on an independent dataset of 5 additional participants. For shoulder axial rotation, the RMSE of front-placed Kinect sensor ranged between approximately 15° to 30°. The results of the study suggest that the Kinect sensor can provide some insight on shoulder kinematics for improving office ergonomics.}, journal={APPLIED ERGONOMICS}, author={Xu, Xu and Robertson, Michelle and Chen, Karen B. and Lin, Jia-hua and McGorry, Raymond W.}, year={2017}, month={Nov}, pages={418–423} }
 @inproceedings{sesto_buhr_sun_chen_tevaarwerk_wiegmann_heidrich_2016, title={Effect of a web-based, decision support intervention to improve work ability in breast cancer survivors}, booktitle={Meeting of the American Physical Therapy Association}, author={Sesto, M. E. and Buhr, K. A. and Sun, W. and Chen, K. and Tevaarwerk, A. J. and Wiegmann, D. A. and Heidrich, S. M.}, year={2016} }
 @inproceedings{chen_xu_lin_radwin_2015, title={Evaluation of older driver functional range of motion using virtual reality}, DOI={10.1177/1541931215591206}, abstractNote={ The number of drivers over 65 years of age is increasing (Siren & Haustein, 2013; Sivak & Schoettle, 2012). Safe operation of a motor vehicle requires good vision, cognition, and motor function. Changes in these are part of the normal aging process (Anstey, Wood, Lord, & Walker, 2005; Desapriya et al., 2011). Reduced neck rotation range of motion (ROM) is associated with doubling crash risk (Isler, Parsonson, & Hansson, 1997; Marottoli et al., 1998). Trunk movement in driving is another consideration (Ashman, Bishu, Foster, & McCoy, 1994; Caragata, Tuokko, & Damini, 2009; Marottoli et al., 2007; Ostrow, Shaffron, & McPherson, 1992). This study used cost-effective immersive virtual reality (VR) technology to examine driver performance. The objective was to explore the functional rotation movement (e.g. overall rotation) of younger and older drivers during a blind spot checking task in VR containing moving virtual cars to represent a dynamic driving situation. The VR system included a steering wheel and pedal set (Logitech, CA), and a head-mounted display (Oculus VR, CA) for visual feedback and head rotational movement tracking. An active-marker infrared motion tracking system (Optotrak Certus System, NDI, Canada) tracked trunk motion for evaluating the contribution of truck movements to the overall ROM. Fourteen younger (8 female) and 12 older (7 female) healthy drivers with a valid driver license and normal vision were recruited from the local community under informed consent approved by the New England Institutional Review Board. The task was to perform normal blind spot checking movements while driving. The average functional ROM and baseline neck ROM were 101.6° and 78.1° for younger drivers (age 18 to 35 years), and 71.9° and 63.5° for older drivers (age >65 years), respectively. Drivers on average turned 15.6° more when checking the blind spot than the baseline neck rotation ( F(1,24)=41.68, p<.001). Younger drivers on average turned 16.3° more than the older drivers ( F(1,24)=51.61, p<.001). There was a statistically significant interaction between situation (baseline and blind spot checking) and driver group ( F(1,24)=9.99, p=.004). Both driver groups engaged neck and trunk movements while checked blind spots, which differed from simple neck or trunk axial rotation. Since we found that the functional ROM was considerably greater than baseline neck ROM it suggests that drivers during a blind spot checking task move beyond typical neck ROM. This study demonstrated the potential of using readily available off-the- shelf VR for driver performance assessment. The results suggest that functional ROM, in addition to baseline ROM, should be considered when evaluating individual driving performance. The next step is to study if functional ROM measured using VR can be utilized for screening driving risks in aging. }, booktitle={International Annual Meeting of the Human Factors and Ergonomics Society}, author={Chen, Karen and Xu, X. and Lin, J.-H. and Radwin, R. G.}, year={2015} }
 @article{chen_xu_lin_radwin_2015, title={Evaluation of older driver head functional range of motion using portable immersive virtual reality}, volume={70}, ISSN={0531-5565}, url={http://dx.doi.org/10.1016/J.EXGER.2015.08.010}, DOI={10.1016/J.EXGER.2015.08.010}, abstractNote={The number of drivers over 65 years of age continues to increase. Although neck rotation range has been identified as a factor associated with self-reported crash history in older drivers, it was not consistently reported as indicators of older driver performance or crashes across previous studies. It is likely that drivers use neck and trunk rotation when driving, and therefore the functional range of motion (ROM) (i.e. overall rotation used during a task) of older drivers should be further examined.Evaluate older driver performance in an immersive virtual reality, simulated, dynamic driving blind spot target detection task.A cross-sectional laboratory study recruited twenty-six licensed drivers (14 young between 18 and 35 years, and 12 older between 65 to 75 years) from the local community. Participants were asked to detect targets by performing blind spot check movements while neck and trunk rotation was tracked. Functional ROM, target detection success, and time to detection were analyzed.In addition to neck rotation, older and younger drivers on average rotated their trunks 9.96° and 18.04°, respectively. The younger drivers generally demonstrated 15.6° greater functional ROM (p<.001), were nearly twice as successful in target detection due to target location (p=.008), and had 0.46 s less target detection time (p=.016) than the older drivers.Assessing older driver functional ROM may provide more comprehensive assessment of driving ability than neck ROM. Target detection success and time to detection may also be part of the aging process as these measures differed between driver groups.}, journal={Experimental Gerontology}, publisher={Elsevier BV}, author={Chen, Karen B. and Xu, Xu and Lin, Jia-Hua and Radwin, Robert G.}, year={2015}, month={Oct}, pages={150–156} }
 @article{chen_xu_lin_2015, title={Evaluation of older driver head functional range of motion using portable immersive virtual reality}, volume={70}, journal={Experimental Gerontology}, author={Chen, K.B. and Xu, X. and Lin, J.-H.}, year={2015}, pages={150–156} }
 @article{xu_chen_lin_radwin_2015, title={The accuracy of the Oculus Rift virtual reality head-mounted display during cervical spine mobility measurement}, volume={48}, ISSN={["1873-2380"]}, DOI={10.1016/j.jbiomech.2015.01.005}, abstractNote={An inertial sensor-embedded virtual reality (VR) head-mounted display, the Oculus Rift (the Rift), monitors head movement so the content displayed can be updated accordingly. While the Rift may have potential use in cervical spine biomechanics studies, its accuracy in terms of cervical spine mobility measurement has not yet been validated. In the current study, a VR environment was designed to guide participants to perform prescribed neck movements. The cervical spine kinematics was measured by both the Rift and a reference motion tracking system. Comparison of the kinematics data between the Rift and the tracking system indicated that the Rift can provide good estimates on full range of motion (from one side to the other side) during the performed task. Because of inertial sensor drifting, the unilateral range of motion (from one side to neutral posture) derived from the Rift is more erroneous. The root-mean-square errors over a 1-min task were within 10° for each rotation axis. The error analysis further indicated that the inertial sensor drifted approximately 6° at the beginning of a trial during the initialization. This needs to be addressed when using the Rift in order to more accurately measure cervical spine kinematics. It is suggested that the front cover of the Rift should be aligned against a vertical plane during its initialization.}, number={4}, journal={JOURNAL OF BIOMECHANICS}, author={Xu, Xu and Chen, Karen B. and Lin, Jia-Hua and Radwin, Robert G.}, year={2015}, month={Feb}, pages={721–724} }
 @inproceedings{gill_brennan_ponto_tredinnick_broecker_chen_2015, title={The living environments laboratory}, booktitle={IEEE VR}, author={Gill, E. and Brennan, P. and Ponto, K. and Tredinnick, R. and Broecker, M. and Chen, K.}, year={2015} }
 @inproceedings{ponto_chen_radwin_tredinnick_2014, title={Assessing exertions: How an increased level of immersion unwittingly leads to more natural behavior}, DOI={10.1109/vr.2014.6802074}, abstractNote={This paper utilizes muscle exertions as a means to affect and study the behavior of participants in a virtual environment. Participants performed a simple lifting task both physically using an actual weight and virtually. In the virtual environment participants were presented with two different types of virtual presentation methods, one in which the weights were shown as a 3D model in the Immersive Visuals scenario and one in which the weights were shown as a simple line in the bland scenario. In the virtual scenarios, the object is only lifted when the participant's muscle activity, measured by surface EMG, exceeds a calibrated minimum level as described in previous literature. We found that while participants were able to perceive the difference for various weights both physically and virtually, we found no significant differences in the perceived efforts between the presentation methods. However, while the participants subjectively indicated that their effort was the same for each of these presentation methods, we found significant differences in the muscle activity between the two virtual presentation methods. For all primary mover muscle groups and weights, the more immersive virtual presentation method led to exertions that were much more approximate to the exertions used for the physical weights.}, booktitle={IEEE VR}, author={Ponto, K. and Chen, Karen and Radwin, R. G. and Tredinnick, R.}, year={2014} }
 @inproceedings{chen_ponto_sesto_radwin_2014, title={Influence of altered visual feedback on neck movement for a virtual reality rehabilitative system}, DOI={10.1177/1541931214581162}, abstractNote={ This paper investigates altering visual feedback during neck movement through control-display (C-D) gain for a head-mounted display, for the purpose of determining the just noticeable difference (JND) for encouraging individuals with kinesiophobia (i.e. fear avoidance of movement due to chronic pain) to effectively perform therapeutic neck exercises. The JND was defined as .25 probability of detecting a difference from unity C-D gain (gain=1). A target-aiming task with two consecutive neck moves per trial was presented; one neck move had varying C-D gain and the other had unity gain. The VR system was able to influence neck moves without changing locations of the target. Participants indicated whether the two neck movements were the same or different. Logistic regression revealed that the JND gains were 0.903 (lower bound) and 1.159 (upper bound) as the participants could not discriminate a 55° turn, ranging from 49.7° to 63.7°. This preliminary study shows that immersive VR with altered visual feedback influenced movement. The feasibility for rehabilitation of individuals with kinesiophobia will next be assessed. }, booktitle={International Annual Meeting of the Human Factors and Ergonomics Society}, author={Chen, Karen and Ponto, K. and Sesto, M. E. and Radwin, R. G.}, year={2014} }
 @article{chen_kimmel_bartholomew_ponto_gleicher_radwin_2014, title={Manually Locating Physical and Virtual Reality Objects}, volume={56}, ISSN={["1547-8181"]}, DOI={10.1177/0018720814523067}, abstractNote={Objective: In this study, we compared how users locate physical and equivalent three-dimensional images of virtual objects in a cave automatic virtual environment (CAVE) using the hand to examine how human performance (accuracy, time, and approach) is affected by object size, location, and distance. Background: Virtual reality (VR) offers the promise to flexibly simulate arbitrary environments for studying human performance. Previously, VR researchers primarily considered differences between virtual and physical distance estimation rather than reaching for close-up objects. Method: Fourteen participants completed manual targeting tasks that involved reaching for corners on equivalent physical and virtual boxes of three different sizes. Predicted errors were calculated from a geometric model based on user interpupillary distance, eye location, distance from the eyes to the projector screen, and object. Results: Users were 1.64 times less accurate ( p < .001) and spent 1.49 times more time ( p = .01) targeting virtual versus physical box corners using the hands. Predicted virtual targeting errors were on average 1.53 times ( p < .05) greater than the observed errors for farther virtual targets but not significantly different for close-up virtual targets. Conclusion: Target size, location, and distance, in addition to binocular disparity, affected virtual object targeting inaccuracy. Observed virtual box inaccuracy was less than predicted for farther locations, suggesting possible influence of cues other than binocular vision. Application: Human physical interaction with objects in VR for simulation, training, and prototyping involving reaching and manually handling virtual objects in a CAVE are more accurate than predicted when locating farther objects. }, number={6}, journal={HUMAN FACTORS}, author={Chen, Karen B. and Kimmel, Ryan A. and Bartholomew, Aaron and Ponto, Kevin and Gleicher, Michael L. and Radwin, Robert G.}, year={2014}, month={Sep}, pages={1163–1176} }
 @article{chen_ponto_tredinnick_radwin_2015, title={Virtual Exertions: Evoking the Sense of Exerting Forces in Virtual Reality Using Gestures and Muscle Activity}, volume={57}, ISSN={["1547-8181"]}, DOI={10.1177/0018720814562231}, abstractNote={Objective: This study was a proof of concept for virtual exertions, a novel method that involves the use of body tracking and electromyography for grasping and moving projections of objects in virtual reality (VR). The user views objects in his or her hands during rehearsed co-contractions of the same agonist-antagonist muscles normally used for the desired activities to suggest exerting forces. Background: Unlike physical objects, virtual objects are images and lack mass. There is currently no practical physically demanding way to interact with virtual objects to simulate strenuous activities. Method: Eleven participants grasped and lifted similar physical and virtual objects of various weights in an immersive 3-D Cave Automatic Virtual Environment. Muscle activity, localized muscle fatigue, ratings of perceived exertions, and NASA Task Load Index were measured. Additionally, the relationship between levels of immersion (2-D vs. 3-D) was studied. Results: Although the overall magnitude of biceps activity and workload were greater in VR, muscle activity trends and fatigue patterns for varying weights within VR and physical conditions were the same. Perceived exertions for varying weights were not significantly different between VR and physical conditions. Conclusions: Perceived exertion levels and muscle activity patterns corresponded to the assigned virtual loads, which supported the hypothesis that the method evoked the perception of physical exertions and showed that the method was promising. Application: Ultimately this approach may offer opportunities for research and training individuals to perform strenuous activities under potentially safer conditions that mimic situations while seeing their own body and hands relative to the scene. }, number={4}, journal={HUMAN FACTORS}, author={Chen, Karen B. and Ponto, Kevin and Tredinnick, Ross D. and Radwin, Robert G.}, year={2015}, month={Jun}, pages={658–673} }
 @article{chourasia_wiegmann_chen_irwin_sesto_2013, title={Effect of Sitting or Standing on Touch Screen Performance and Touch Characteristics}, volume={55}, ISSN={["1547-8181"]}, DOI={10.1177/0018720812470843}, abstractNote={Objective: The aim of this study was to evaluate the effect of sitting and standing on performance and touch characteristics during a digit entry touch screen task in individuals with and without motor-control disabilities. Background: Previously, researchers of touch screen design have not considered the effect of posture (sitting vs. standing) on touch screen performance (accuracy and timing) and touch characteristics (force and impulse). Method: Participants with motor-control disabilities ( n = 15) and without ( n = 15) completed a four-digit touch screen number entry task in both sitting and standing postures. Button sizes varied from 10 mm to 30 mm (5-mm increments), and button gap was 3 mm or 5 mm. Results: Participants had more misses and took longer to complete the task during standing for smaller button sizes (<20 mm). At larger button sizes, performance was similar for both sitting and standing. In general, misses, time to complete task, and touch characteristics were increased for standing. Although disability affected performance (misses and timing), similar trends were observed for both groups across posture and button size. Conclusion: Standing affects performance at smaller button sizes (<20 mm). For participants with and without motor-control disabilities, standing led to greater exerted force and impulse. Application: Along with interface design considerations, environmental conditions should also be considered to improve touch screen accessibility and usability. }, number={4}, journal={HUMAN FACTORS}, author={Chourasia, Amrish O. and Wiegmann, Douglas A. and Chen, Karen B. and Irwin, Curtis B. and Sesto, Mary E.}, year={2013}, month={Aug}, pages={789–802} }
 @article{chourasia_a._k._sesto_2013, title={Effect of sitting orientation on touchscreen performance, touch characteristics, user preference, and workload}, volume={1}, DOI={10.1080/21577323.2013.847873}, abstractNote={OCCUPATIONAL APPLICATIONS Sitting in a parallel orientation in front of a touch screen (requiring twisting of the torso) was found to cause a decrement in touchscreen performance (36%–48%). However, the adverse effect of sitting orientation on performance could be ameliorated by interface design, most notably by using button sizes greater than 20×20 mm. Larger button sizes also benefit individuals with upper extremity motor control disabilities, and this information could be used to incorporate universal design in touchscreen interfaces. Larger button sizes also help in reducing the force-time integral during button activation. Touchscreens are widely used in occupational settings, such as retail, restaurants, and health care. The touchscreen performance findings from this study are applicable to touchscreen interface design for users with and without upper extremity motor control disabilities, and the touch characteristics findings are useful for ergonomists quantifying forces involved in touchscreen operation. TECHNICAL ABSTRACT Background: Touchscreens can be used in stand-alone kiosks, embedded in larger structures, such as walls, or arranged in multi-display configurations (e.g., a control station). As a result, users may not always be positioned in front of the screen and may instead operate it in a variety of orientations. Previous touchscreen research has not considered the effect of user sitting orientation on touchscreen performance, such as in terms of the number of errors (incorrect button activation), misses (touch that does not result in button activation), task completion time, and touch characteristics (e.g., force, dwell time [the time the button was pressed], and force-time integral). Purpose: This study evaluates the effect of sitting orientation on performance and touch characteristics during a digit entry task among individuals with and without motor control disabilities, including wheelchair users and non-users. Methods: Participants with (n = 21) and without (n = 21) upper extremity motor control disabilities (+MCD and −MCD, respectively) completed a four-digit entry task on a touchscreen in both front and parallel orientations to the touchscreen. Button sizes of 10×10 to 30×30 mm (5-mm increments) and two button gaps (3 or 5 mm) were used. Results: Accuracy was adversely affected, with errors (36%) and misses (48%) greater in the parallel orientation. Dwell time (12%) and force-time integral (21%) were also greater in the parallel orientation than in the front orientation. Larger button sizes (≥20 mm) lowered misses, errors, force-time integrals, and dwell times for both orientations. The +MCD group had a greater percentage of trials with misses (150%) and longer dwell times (66%) than the −MCD group, but in general, similar trends in performance and touch characteristics were observed for both groups across button sizes, button gaps, and sitting orientation. Conclusions: Decrements in touchscreen performance occurred in the parallel orientation compared to the front orientation. In addition, greater forces were exerted and greater workload was reported in the parallel orientation than in the front orientation. However, performance may be improved by using larger button sizes (≥20×20 mm). This may be especially important in critical touchscreen activities.}, number={4}, journal={IIE Transactions on Occupational Ergonomics and Human Factors}, author={Chourasia, A. O. Wiegmann and A., Chen D. and K., B. and Sesto, M.E.}, year={2013}, pages={235–245} }
 @article{chen_savage_chourasia_wiegmann_sesto_2013, title={Touch screen performance by individuals with and without motor control disabilities}, volume={44}, ISSN={["1872-9126"]}, DOI={10.1016/j.apergo.2012.08.004}, abstractNote={Touch technology is becoming more prevalent as functionality improves and cost decreases. Therefore, it is important that this technology is accessible to users with diverse abilities. The objective of this study was to investigate the effects of button and gap size on performance by individuals with varied motor abilities. Participants with (n = 38) and without (n = 15) a motor control disability completed a digit entry task. Button size ranged from 10 to 30 mm and gap size was either 1 or 3 mm. Results indicated that as button size increased, there was a decrease in misses, errors, and time to complete tasks. Performance for the non-disabled group plateaued at button size 20 mm, with minimal, if any gains observed with larger button sizes. In comparison, the disabled group's performance continued to improve as button size increased. Gap size did not affect user performance. These results may help to improve accessibility of touch technology.}, number={2}, journal={APPLIED ERGONOMICS}, author={Chen, Karen B. and Savage, Anne B. and Chourasia, Amrish O. and Wiegmann, Douglas A. and Sesto, Mary E.}, year={2013}, month={Mar}, pages={297–302} }
 @inproceedings{radwin r. g._k. b._k._tredinnick_2013, title={Virtual exertions: Physical interactions in a virtual reality CAVE for simulating forceful tasks}, booktitle={International Annual Meeting of the Human Factors and Ergonomics Society}, author={Radwin R. G., Chen and K. B., Ponto and K. and Tredinnick, R. D.}, year={2013} }
 @article{custer_rocque_wisinski_jones_donohue_koehn_champeny_terhaar_chen_peck_et al._2012, title={Development of a web-based survey tool to assess change in breast cancer (BrCa) survivor knowledge after receipt of cancer treatment summary and survivorship care plan (SCP)}, volume={72}, number={24 Suppl.}, journal={Cancer Research (Chicago, Ill. Online)}, author={Custer, J. L. and Rocque, G. B. and Wisinski, K. B. and Jones, N. R. and Donohue, S. and Koehn, T. M. and Champeny, T. L. and Terhaar, A. R. and Chen, K. B. and Peck, K. A. and et al.}, year={2012}, pages={2–11} }
 @inproceedings{chourasia_chen_wiegmann_sesto_2012, title={Effect of posture, button size and spacing on touch characteristics for disabled and non-disabled participants}, booktitle={International Conference on Applied Human Factors and Ergonomics}, author={Chourasia, A. O. and Chen, K. B. and Wiegmann, D. A. and Sesto, M. E.}, year={2012} }
 @article{sesto_irwin_chen_wiegmann_2012, title={Effect of touch screen button size and spacing on disabled and non-disabled user touch characteristics}, volume={54}, number={3}, journal={Human Factors}, author={Sesto, M. E. and Irwin, C. B. and Chen, K. B. and Wiegmann}, year={2012}, pages={425–436} }