@article{hewitt_he_2022, title={Cognitive Load and Website Usability: Effects of Contrast and Task Difficulty}, volume={66}, ISSN={2169-5067 1071-1813}, url={http://dx.doi.org/10.1177/1071181322661051}, DOI={10.1177/1071181322661051}, abstractNote={ The contrast of a website doesn’t just affect its usability for low-vision individuals; it affects everyone. This study aims to evaluate the effects of contrast (low, medium, or high) on web browsing experience in normally-sighted individuals. Cognitive load associated with the task was assessed using the NASA task load index (NASA-TLX) and the usability of the website was assessed by the systems usability scale (SUS). We found that NASA-TLX scores significantly increased with the amount of time a task took, indicating an effect of task difficulty. The impact of contrast was reported during end-of-study interviews, but no significant difference was found between the three chosen contrast levels in NASA-TLX or SUS scores. This study is part 1 of a multi-part research project and future research will compare low-vision individuals to their typically-sighted peers. Together, the studies in this project aim to quantitatively determine the effects of contrast users’ web browsing experience to further accessibility research and web development guidelines. }, number={1}, journal={Proceedings of the Human Factors and Ergonomics Society Annual Meeting}, publisher={SAGE Publications}, author={Hewitt, Dylan H. and He, Yingchen}, year={2022}, month={Sep}, pages={1809–1813} }
 @inproceedings{he_kang_larson_flowers_legge_engel_2022, title={Letter and Word Recognition with Remapped Text}, booktitle={Association for Research in Vision and Ophthalmology Annual Meeting}, author={He, Y. and Kang, D. and Larson, C. and Flowers, C. and Legge, G.E. and Engel, S.}, year={2022} }
 @article{henderson_he_2022, title={Screen Reader Voices: Effects of Pauses and Voice Changes on Comprehension}, volume={66}, ISSN={2169-5067 1071-1813}, url={http://dx.doi.org/10.1177/1071181322661291}, DOI={10.1177/1071181322661291}, abstractNote={ This study seeks to investigate the effects of manipulating aspects of a text-to-speech (TTS) voice on the learning and comprehension of a short passage, as well as detection of aspects of the passage such as its organization and key information. Pauses and pitch changes were used to demarcate this type of information. Participants listened to the passages and answered a series of cued and uncued recall questions to measure comprehension and learning, followed by a task to identify header structure. Preliminary results show trends that adding pauses might be beneficial, but more participants are needed to provide conclusive evidence. This study will contribute to the body of research surrounding technology adoption, assistive technology, and how to improve AI voices for the purposes of learning, as well as our understanding of how we process auditory information. }, number={1}, journal={Proceedings of the Human Factors and Ergonomics Society Annual Meeting}, publisher={SAGE Publications}, author={Henderson, Cecelia A. and He, Yingchen}, year={2022}, month={Sep}, pages={1839–1843} }
 @article{hewitt_he_2021, title={Internet Accessibility for Blind and Visually-Impaired Users: An Evaluation of Official U.S. State and Territory COVID-19 Websites}, volume={65}, ISSN={2169-5067 1071-1813}, url={http://dx.doi.org/10.1177/1071181321651051}, DOI={10.1177/1071181321651051}, abstractNote={ During the COVID-19 pandemic, most health information was moved to an online format for easier dissemination. However, many of these health websites may not be accessible to users who are visually impaired, such as people who use screen readers and magnifiers. This study aimed to test the accessibility of 55 U.S. state and territory COVID-19 websites using 3 automated accessibility checker tools (MAUVE++, CynthiaSays, and AChecker). The homepage, testing, and vaccine pages for each state/territory were tested. Accessibility violations were categorized based on their relevance to visual impairment and compared between categories. Individuals who have vision loss but still access the websites visually are the most likely to be affected, with relevant accessibility violations detected in 81% of the checked cases. In addition, states/territories were ranked by their accessibility ratings. Our findings emphasize the need to improve the accessibility of public-facing health informational websites and provide suggestions for remedies. }, number={1}, journal={Proceedings of the Human Factors and Ergonomics Society Annual Meeting}, publisher={SAGE Publications}, author={Hewitt, Dylan H. and He, Yingchen}, year={2021}, month={Sep}, pages={154–158} }
 @article{montezuma_sun_roy_caspi_dorn_he_2020, title={Improved localisation and discrimination of heat emitting household objects with the artificial vision therapy system by integration with thermal sensor}, volume={104}, url={http://dx.doi.org/10.1136/bjophthalmol-2019-315513}, DOI={10.1136/bjophthalmol-2019-315513}, abstractNote={AimTo demonstrate the potential clinically meaningful benefits of a thermal camera integrated with the Argus II, an artificial vision therapy system, for assisting Argus II users in localising and discriminating heat-emitting objects.}, note={Funding Information: Funding This study was funded by the University of Minnesota Center for Applied Translational Sensory Science, Minnesota Lions Vision Foundation and VitreoRetinal Surgery Foundation. Publisher Copyright: \textcopyright 2020 BMJ Publishing Group. All rights reserved.}, number={12}, journal={British Journal of Ophthalmology}, publisher={BMJ Publishing Group}, author={Montezuma, Sandra R. and Sun, Susan Y. and Roy, Arup and Caspi, Avi and Dorn, Jessy D. and He, Yingchen}, year={2020}, month={Mar}, pages={1730–1734} }
 @article{he_sun_roy_caspi_montezuma_2020, title={Improved mobility performance with an artificial vision therapy system using a thermal sensor}, volume={17}, url={https://experts.umn.edu/en/publications/2b86561d-2ba3-48f4-a603-573b60df76cc}, DOI={10.1088/1741-2552/aba4fb}, abstractNote={Objective. To evaluate the benefit of integrating thermal imaging into an artificial vision therapy system, the Argus II retinal prosthesis, in simplifying a complex scene and improving mobility performance in the presence of other persons. Approach. Four Argus II retinal implant users were evaluated on two tasks: to locate and approach target persons in a booth, and to navigate a hallway while avoiding people. They completed the tasks using both the original Argus II system (the ‘Argus II camera’) and a thermal-integrated Argus II system (the ‘thermal camera’). The safety and efficiency of their navigation were evaluated by their walking speed, navigation errors, and the number of collisions. Main results. Navigation performance was significantly superior when using the thermal camera compared to using the Argus II camera, including 75% smaller angle of deviation (p < 0.001), 48% smaller error of distance (p < 0.05), and 30% fewer collisions (p < 0.05). The thermal camera also brought the additional benefit of allowing the participants to perform the task in the dark as efficiently as in the light. More importantly, these benefits did not come at a cost of reduced walking speed. Significance. Using the thermal camera in the Argus II system, compared to a visible-light camera, could improve the wearers’ navigation performance by helping them better approach or avoid other persons. Adding the thermal camera to future artificial vision therapy systems may complement the visible-light camera and improve the users’ mobility safety and efficiency, enhancing their quality of life.}, note={Publisher Copyright: \textcopyright 2020 IOP Publishing Ltd. Copyright: Copyright 2020 Elsevier B.V., All rights reserved.}, number={4}, journal={Journal of neural engineering}, publisher={IOP Publishing Ltd.}, author={He, Yingchen and Sun, Susan Y. and Roy, Arup and Caspi, Avi and Montezuma, Sandra R.}, year={2020}, month={Aug} }
 @inproceedings{he_sun_johannsen_perry_herrera_roy_caspi_barbour_montezuma_2019, title={Characterizing the Visual Cortical Hemodynamic Response in Retinal Prostheses Users}, booktitle={Association for Research in Vision and Ophthalmology Annual Meeting}, author={He, Y. and Sun, S. and Johannsen, T. and Perry, J. and Herrera, A. and Roy, A. and Caspi, A. and Barbour, R. and Montezuma, S.R.}, year={2019}, month={May} }
 @inproceedings{he_toft-nielsen_sun_roy_caspi_montezuma_2019, title={Comparing Visual Evoked Potentials between Prosthetic Vision, Normal Vision, and Simulated Acuity Reduction}, booktitle={Vision Science Society 19th Annual Meeting}, author={He, Y. and Toft-Nielsen, J. and Sun, S. and Roy, A. and Caspi, A. and Montezuma, S.R.}, year={2019} }
 @article{scoring reading parameters: an inter-rater reliability study using the mnread chart_2019, url={http://dx.doi.org/10.1371/journal.pone.0216775}, DOI={10.1371/journal.pone.0216775}, abstractNote={Purpose First, to evaluate inter-rater reliability when human raters estimate the reading performance of visually impaired individuals using the MNREAD acuity chart. Second, to evaluate the agreement between computer-based scoring algorithms and compare them with human rating. Methods Reading performance was measured for 101 individuals with low vision, using the Portuguese version of the MNREAD test. Seven raters estimated the maximum reading speed (MRS) and critical print size (CPS) of each individual MNREAD curve. MRS and CPS were also calculated automatically for each curve using two different algorithms: the original standard deviation method (SDev) and a non-linear mixed effects (NLME) modeling. Intra-class correlation coefficients (ICC) were used to estimate absolute agreement between raters and/or algorithms. Results Absolute agreement between raters was ‘excellent’ for MRS (ICC = 0.97; 95%CI [0.96, 0.98]) and ‘moderate’ to ‘good’ for CPS (ICC = 0.77; 95%CI [0.69, 0.83]). For CPS, inter-rater reliability was poorer among less experienced raters (ICC = 0.70; 95%CI [0.57, 0.80]) when compared to experienced ones (ICC = 0.82; 95%CI [0.76, 0.88]). Absolute agreement between the two algorithms was ‘excellent’ for MRS (ICC = 0.96; 95%CI [0.91, 0.98]). For CPS, the best possible agreement was found for CPS defined as the print size sustaining 80% of MRS (ICC = 0.77; 95%CI [0.68, 0.84]). Absolute agreement between raters and automated methods was ‘excellent’ for MRS (ICC = 0.96; 95% CI [0.88, 0.98] for SDev; ICC = 0.97; 95% CI [0.95, 0.98] for NLME). For CPS, absolute agreement between raters and SDev ranged from ‘poor’ to ‘good’ (ICC = 0.66; 95% CI [0.3, 0.80]), while agreement between raters and NLME was ‘good’ (ICC = 0.83; 95% CI [0.76, 0.88]). Conclusion For MRS, inter-rater reliability is excellent, even considering the possibility of noisy and/or incomplete data collected in low-vision individuals. For CPS, inter-rater reliability is lower. This may be problematic, for instance in the context of multisite investigations or follow-up examinations. The NLME method showed better agreement with the raters than the SDev method for both reading parameters. Setting up consensual guidelines to deal with ambiguous curves may help improve reliability. While the exact definition of CPS should be chosen on a case-by-case basis depending on the clinician or researcher’s motivations, evidence suggests that estimating CPS as the smallest print size sustaining about 80% of MRS would increase inter-rater reliability.}, journal={PLOS ONE}, year={2019}, month={Jun} }
 @article{he_huang_caspi_roy_montezuma_2019, title={Trade-off between field-of-view and resolution in the thermal-integrated argus II system}, volume={8}, url={https://experts.umn.edu/en/publications/d367364c-9499-4a01-86ad-1405291d84de}, DOI={10.1167/tvst.8.4.29}, abstractNote={Purpose To investigate the effect of a wider field-of-view (FOV) of a retinal prosthesis on the users' performance in locating objects. Methods One female and four male subjects who were blind due to end-stage retinitis pigmentosa and had been implanted with the Argus II retinal prosthesis participated (aged 63.4 ± 15.4). Thermal imaging was captured by an external sensor and converted to electrical stimulation to the retina. Subjects were asked to localize and to reach for heat-emitting objects using two different FOV mappings: a normal 1:1 mapping (no zoom) that provided 18° × 11° FOV and a 3:1 mapping (zoom out) that provided 49° × 35° FOV. Their accuracy and response time were recorded. Results Subjects were less accurate and took longer to complete the tasks with zoom out compared to no zoom. Localization accuracy decreased from 83% (95% confidence interval, 75%, 90%) with no zoom to 76% (67%, 83%) with zoom out (P = 0.07). Reaching accuracy differed between the two mappings only in one subject. Response time increased by 43% for the localization task (24%, 66%; P < 0.001) and by 20% for the reaching task (0%, 45%; P = 0.055). Conclusions Argus II wearers can efficiently find heat-emitting objects with the default 18° × 11° FOV of the current Argus II. For spatial localization, a higher spatial resolution may be preferred over a wider FOV. Translational Relevance Understanding the trade-off between FOV and spatial resolution in retinal prosthesis users can guide device optimization.}, note={Funding Information: The authors thank Jessy Dorn for her generous help in critically reviewing the manuscript. Sponsorship and article processing charges for this study were funded by the Center for Applied Translational Sensory Science at the University of Minnesota, the Minnesota Lions Vision Foundation, the VitreoRet-inal Surgery Foundation, and an unrestricted grant to the Department of Ophthalmology and Visual Neurosciences from the Research to Prevent Blindness (RPB), New York, NY, USA. Publisher Copyright: \textcopyright 2019 The Authors.}, number={4}, journal={Translational Vision Science and Technology}, publisher={Association for Research in Vision and Ophthalmology Inc.}, author={He, Yingchen and Huang, Natalie T. and Caspi, Avi and Roy, Arup and Montezuma, Sandra R.}, year={2019}, month={Jul} }
 @article{he_kwon_legge_2018, title={Common constraints limit Korean and English character recognition in peripheral vision}, volume={18}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85041078154&partnerID=MN8TOARS}, DOI={10.1167/18.1.5}, abstractNote={The visual span refers to the number of adjacent characters that can be recognized in a single glance. It is viewed as a sensory bottleneck in reading for both normal and clinical populations. In peripheral vision, the visual span for English characters can be enlarged after training with a letter-recognition task. Here, we examined the transfer of training from Korean to English characters for a group of bilingual Korean native speakers. In the pre- and posttests, we measured visual spans for Korean characters and English letters. Training (1.5 hours × 4 days) consisted of repetitive visual-span measurements for Korean trigrams (strings of three characters). Our training enlarged the visual spans for Korean single characters and trigrams, and the benefit transferred to untrained English symbols. The improvement was largely due to a reduction of within-character and between-character crowding in Korean recognition, as well as between-letter crowding in English recognition. We also found a negative correlation between the size of the visual span and the average pattern complexity of the symbol set. Together, our results showed that the visual span is limited by common sensory (crowding) and physical (pattern complexity) factors regardless of the language script, providing evidence that the visual span reflects a universal bottleneck for text recognition.}, note={Publisher Copyright: \textcopyright 2018 The Authors.}, number={1}, journal={Journal of Vision}, publisher={Association for Research in Vision and Ophthalmology Inc.}, author={He, Yingchen and Kwon, Mi Young and Legge, Gordon E.}, year={2018} }
 @article{calabrèse_to_he_berkholtz_rafianm_legge_2018, title={Comparing performance on the MNREAD iPad application with the MNREAD acuity chart}, volume={18}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85041090847&partnerID=MN8TOARS}, DOI={10.1167/18.1.8}, abstractNote={Our purpose was to compare reading performance measured with the MNREAD Acuity Chart and an iPad application (app) version of the same test for both normally sighted and low-vision participants. Our methods included 165 participants with normal vision and 43 participants with low vision tested on the standard printed MNREAD and on the iPad app version of the test. Maximum Reading Speed, Critical Print Size, Reading Acuity, and Reading Accessibility Index were compared using linear mixed-effects models to identify any potential differences in test performance between the printed chart and the iPad app. Our results showed the following: For normal vision, chart and iPad yield similar estimates of Critical Print Size and Reading Acuity. The iPad provides significantly slower estimates of Maximum Reading Speed than the chart, with a greater difference for faster readers. The difference was on average 3% at 100 words per minute (wpm), 6% at 150 wpm, 9% at 200 wpm, and 12% at 250 wpm. For low vision, Maximum Reading Speed, Reading Accessibility Index, and Critical Print Size are equivalent on the iPad and chart. Only the Reading Acuity is significantly smaller (I. E., better) when measured on the digital version of the test, but by only 0.03 logMAR (p = 0.013). Our conclusions were that, overall, MNREAD parameters measured with the printed chart and the iPad app are very similar. The difference found in Maximum Reading Speed for the normally sighted participants can be explained by differences in the method for timing the reading trials.}, note={Publisher Copyright: \textcopyright 2018 The Authors.}, number={1}, journal={Journal of Vision}, publisher={Association for Research in Vision and Ophthalmology Inc.}, author={Calabrèse, Aurélie and To, Long and He, Yingchen and Berkholtz, Elizabeth and Rafianm, Paymon and Legge, Gordon E.}, year={2018} }
 @inproceedings{he_huang_caspi_roy_engel_legge_kuijk_koozekanani_montezuma_2018, title={Development of an electroencephalogram (EEG) protocol to map electrically-elicited visual responses in blind patients implanted with the Argus II retinal prosthesis}, booktitle={Association for Research in Vision and Ophthalmology Annual Meeting}, author={He, Y. and Huang, N. and Caspi, A. and Roy, A. and Engel, S. and Legge, G.E. and Kuijk, E.J. and Koozekanani, D. and Montezuma, S.R.}, year={2018} }
 @article{he_baek_legge_2018, title={Korean reading speed}, volume={150}, url={https://experts.umn.edu/en/publications/840921f7-7845-476b-b745-21be43f1aac5}, DOI={10.1016/j.visres.2018.06.013}, abstractNote={Evaluating the effects of print size and retinal eccentricity on reading speed is important for identifying the constraints faced by people with central-field loss. Previous work on English reading showed that 1) reading speed increases with print size until a critical print size (CPS) is reached, and then remains constant at a maximum reading speed (MRS), and 2) as eccentricity increases, MRS decreases and CPS increases. Here we extend this work to Korean, a language with more complex orthography. We recruited 6 Korean native speakers (mean age = 22) and measured their reading speed in central vision (0°) and peripheral vision (10° in the lower field). 900 Korean sentences (average 8.25 words) were created with frequently-occurring beginner-level words, presented using a rapid serial visual presentation (RSVP) paradigm. Data for English reading were obtained from Chung, Mansfield & Legge, Vision Research, 1998, for comparison. MRS was similar for Korean and English at 0° (713 vs. 787 wpm), but decreased faster with eccentricity for Korean. CPS was larger for Korean than for English regardless of eccentricity, but increased with eccentricity similarly for both languages. From 0 to 10°, MRS decreased by a factor of 6.5 for Korean and 2.8 for English, and CPS increased by a factor of 11.7 for Korean and 10.2 for English. Korean reading speed is more affected by retinal eccentricity than English, likely due to additional within-character crowding from more complex orthography. Korean readers with central-field loss may experience more difficulty than English readers.}, note={Publisher Copyright: \textcopyright 2018 Elsevier Ltd}, journal={Vision Research}, publisher={Elsevier Limited}, author={He, Yingchen and Baek, Sori and Legge, Gordon E}, year={2018}, month={Sep}, pages={8–14} }
 @article{he_legge_2017, title={Linking crowding, visual span, and reading}, volume={17}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85030448573&partnerID=MN8TOARS}, DOI={10.1167/17.11.11}, abstractNote={The visual span is hypothesized to be a sensory bottleneck on reading speed with crowding thought to be the major sensory factor limiting the size of the visual span. This proposed linkage between crowding, visual span, and reading speed is challenged by the finding that training to read crowded letters reduced crowding but did not improve reading speed (Chung, 2007). Here, we examined two properties of letter-recognition training that may influence the transfer to improved reading: the spatial arrangement of training stimuli and the presence of flankers. Three groups of nine young adults were trained with different configurations of letter stimuli at 10° in the lower visual field: a flanked-local group (flanked letters localized at one position), a flanked-distributed group (flanked letters distributed across different horizontal locations), and an isolated-distributed group (isolated and distributed letters). We found that distributed training, but not the presence of flankers, appears to be necessary for the training benefit to transfer to increased reading speed. Localized training may have biased attention to one specific, small area in the visual field, thereby failing to improve reading. We conclude that the visual span represents a sensory bottleneck on reading, but there may also be an attentional bottleneck. Reducing the impact of crowding can enlarge the visual span and can potentially facilitate reading, but not when adverse attentional bias is present. Our results clarify the association between crowding, visual span, and reading.}, note={Funding Information: The authors would like to thank Dr. Susana T. L. Chung for her constructive comments on this paper and Mark Schatza for his help with data collection. The study was supported by NIH grant EY002934. Publisher Copyright: \textcopyright 2017 The Authors}, number={11}, journal={Journal of Vision}, publisher={Association for Research in Vision and Ophthalmology Inc.}, author={He, Yingchen and Legge, Gordon E}, year={2017}, pages={1?15} }
 @inproceedings{he_kwon_legge_2017, title={Training Peripheral Vision to Read Korean Characters Transfers to English}, booktitle={Vision Sciences Society 17th Annual Meeting}, author={He, Y. and Kwon, M. and Legge, G.}, year={2017} }
 @article{calabrèse_cheong_cheung_he_kwon_mansfield_subramanian_yu_legge_2016, title={Baseline MNREAD measures for normally sighted subjects from childhood to old age}, volume={57}, url={https://experts.umn.edu/en/publications/5237237d-a868-42de-96e3-aa2241e604bd}, DOI={10.1167/iovs.16-19580}, abstractNote={Purpose The continuous-text reading-acuity test MNREAD is designed to measure the reading performance of people with normal and low vision. This test is used to estimate maximum reading speed (MRS), critical print size (CPS), reading acuity (RA), and the reading accessibility index (ACC). Here we report the age dependence of these measures for normally sighted individuals, providing baseline data for MNREAD testing. Methods We analyzed MNREAD data from 645 normally sighted participants ranging in age from 8 to 81 years. The data were collected in several studies conducted by different testers and at different sites in our research program, enabling evaluation of robustness of the test. Results Maximum reading speed and reading accessibility index showed a trilinear dependence on age: first increasing from 8 to 16 years (MRS: 140–200 words per minute [wpm]; ACC: 0.7–1.0); then stabilizing in the range of 16 to 40 years (MRS: 200 ± 25 wpm; ACC: 1.0 ± 0.14); and decreasing to 175 wpm and 0.88 by 81 years. Critical print size was constant from 8 to 23 years (0.08 logMAR), increased slowly until 68 years (0.21 logMAR), and then more rapidly until 81 years (0.34 logMAR). logMAR reading acuity improved from −0.1 at 8 years to −0.18 at 16 years, then gradually worsened to −0.05 at 81 years. Conclusions We found a weak dependence of the MNREAD parameters on age in normal vision. In broad terms, MNREAD performance exhibits differences between three age groups: children 8 to 16 years, young adults 16 to 40 years, and middle-aged to older adults >40 years.}, number={8}, journal={Investigative Ophthalmology and Visual Science}, publisher={Association for Research in Vision and Ophthalmology Inc.}, author={Calabrèse, Aurélie and Cheong, Allen M Y and Cheung, Sing Hang and He, Yingchen and Kwon, Mi Young and Mansfield, J. Stephen and Subramanian, Ahalya and Yu, Deyue and Legge, Gordon E.}, year={2016}, month={Jul}, pages={3836–3843} }
 @inproceedings{he_legge_2016, title={Crowded Letter Recognition in Peripheral Vision Is Not Solely Determined by Target-Flanker Cortical Distance}, booktitle={Vision Sciences Society 16th Annual Meeting}, author={He, Y. and Legge, G.}, year={2016} }
 @article{he_scholz_gage_kallie_liu_legge_2015, title={Comparing the visual spans for faces and letters}, volume={15}, url={https://experts.umn.edu/en/publications/8205f19e-ac64-42ad-9036-b06bde0377b6}, DOI={10.1167/15.8.7}, abstractNote={The visual span-the number of adjacent text letters that can be reliably recognized on one fixation-has been proposed as a sensory bottleneck that limits reading speed (Legge, Mansfield, & Chung, 2001). Like reading, searching for a face is an important daily task that involves pattern recognition. Is there a similar limitation on the number of faces that can be recognized in a single fixation? Here we report on a study in which we measured and compared the visual-span profiles for letter and face recognition. A serial two-stage model for pattern recognition was developed to interpret the data. The first stage is characterized by factors limiting recognition of isolated letters or faces, and the second stage represents the interfering effect of nearby stimuli on recognition. Our findings show that the visual span for faces is smaller than that for letters. Surprisingly, however, when differences in first-stage processing for letters and faces are accounted for, the two visual spans become nearly identical. These results suggest that the concept of visual span may describe a common sensory bottleneck that underlies different types of pattern recognition.}, note={Publisher Copyright: \textcopyright 2015 ARVO.}, number={8}, journal={Journal of vision}, publisher={Association for Research in Vision and Ophthalmology Inc.}, author={He, Yingchen and Scholz, Jennifer M. and Gage, Rachel and Kallie, Christopher S. and Liu, Tingting and Legge, Gordon E.}, year={2015} }
 @article{chen_he_zhu_zhou_peng_zhang_fang_2014, title={Attention-dependent early cortical suppression contributes to crowding}, volume={34}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84905699299&partnerID=MN8TOARS}, DOI={10.1523/JNEUROSCI.1140-14.2014}, abstractNote={Crowding, the identification difficulty for a target in the presence of nearby flankers, is ubiquitous in spatial vision and is considered a bottleneck of object recognition and visual awareness. Despite its significance, the neural mechanisms of crowding are still unclear. Here, we performed event-related potential and fMRI experiments to measure the cortical interaction between the target and flankers in human subjects. We found that the magnitude of the crowding effect was closely associated with an early suppressive cortical interaction. The cortical suppression was reflected in the earliest event-related potential component (C1), which originated in V1, and in the BOLD signal in V1, but not other higher cortical areas. Intriguingly, spatial attention played a critical role in the manifestation of the suppression. These findings provide direct and converging evidence that attention-dependent V1 suppression contributes to crowding at a very early stage of visual processing.}, number={32}, journal={Journal of Neuroscience}, author={Chen, J. and He, Y. and Zhu, Z. and Zhou, T. and Peng, Y. and Zhang, X. and Fang, F.}, year={2014}, pages={10465–10474} }
 @inproceedings{he_legge_2014, title={Training as Part of a Word Game Increases Reading Speed in Peripheral Vision}, booktitle={Vision Sciences Society 14th Annual Meeting}, author={He, Y. and Legge, G.}, year={2014} }
 @inproceedings{he_legge_2013, title={Developing A Word-Puzzle Game to Increase Reading Speed in Peripheral Vision}, booktitle={9th Asia-Pacific Conference on Vision}, author={He, Y. and Legge, G.}, year={2013} }
 @article{he_legge_yu_2013, title={Sensory and cognitive influences on the training-related improvement of reading speed in peripheral vision}, volume={13}, ISSN={1534-7362}, url={http://dx.doi.org/10.1167/13.7.14}, DOI={10.1167/13.7.14}, abstractNote={Reading speed in normal peripheral vision is slow but can be increased through training on a letter-recognition task. The aim of the present study is to investigate the sensory and cognitive factors responsible for this improvement. The visual span is hypothesized to be a sensory bottleneck limiting reading speed. Three sensory factors-letter acuity, crowding, and mislocations (errors in the spatial order of letters)-may limit the size of the visual span. Reading speed is also influenced by cognitive factors including the utilization of information from sentence context. We conducted a perceptual training experiment to investigate the roles of these factors. Training consisted of four daily sessions of trigram letter-recognition trials at 10° in the lower visual field. Subjects' visual-span profiles and reading speeds were measured in pre- and posttests. Effects of the three sensory factors were isolated through a decomposition analysis of the visual span profiles. The impact of sentence context was indexed by context gain, the ratio of reading speeds for ordered and unordered text. Following training, visual spans increased in size by 5.4 bits of information transmitted, and reading speeds increased by 45%. Training induced a substantial reduction in the magnitude of crowding (4.8 bits) and a smaller reduction for mislocations (0.7 bits), but no change in letter acuity or context gain. These results indicate that the basis of the training-related improvement in reading speed is a large reduction in the interfering effect of crowding and a small reduction of mislocation errors.}, number={7}, journal={Journal of Vision}, publisher={Association for Research in Vision and Ophthalmology (ARVO)}, author={He, Y. and Legge, G. E. and Yu, D.}, year={2013}, month={Jun}, pages={14–14} }
 @article{he_legge_yu_2013, title={Sensory and cognitive influences on the training-related improvement of reading speed in peripheral vision}, volume={13}, url={https://experts.umn.edu/en/publications/da05ed5c-4fd8-48ca-a6f5-3b003de1f7d7}, DOI={10.1167/13.7.15}, abstractNote={Flickering 560-nm light appears brighter and less saturated than steady light of the same average intensity. The changes in appearance are consistent with the visual signal's being distorted at some nonlinear site (or sites) within the visual pathway at which new temporal components, not part of the original waveform, are produced. By varying the input stimulus to manipulate these new temporal components--called distortion products--and measuring our observers' sensitivity in detecting them, we derived the temporal attenuation characteristics of the early (prenonlinearity) and late (post-nonlinearity) stages of the L- and M-cone pathway that signals brightness. We found that the early stage acts like a band-pass filter peaking at 10-15 Hz with sensitivity losses at both lower and higher frequencies, whereas the late stage acts like a two-stage low-pass filter with a corner frequency near 3 Hz. Although brightness is often associated with the fast achromatic or luminance pathway, these filter characteristics, and particularly those of the late filter, are consistent with comparable features of the L-M chromatic pathway that produce mainly chromatic distortion products (Petrova, Henning, & Stockman, 2013). A plausible site for the nonlinearity is after surround antagonism from horizontal cells. Modeling suggested the form of the nonlinearity to be initially expansive but possibly with a hard limit at the highest input levels.}, number={7}, journal={Journal of vision}, publisher={Association for Research in Vision and Ophthalmology Inc.}, author={He, Yingchen and Legge, Gordon E. and Yu, Deyue}, year={2013} }
 @inproceedings{he_legge_2013, title={Uncrowding the Visual Span: Does It Improve Reading?}, booktitle={Vision Sciences Society 13th Annual Meeting}, author={He, Y. and Legge, G.}, year={2013} }
 @inproceedings{he_legge_2012, title={Reduced crowding accounts for enlargement of the visual span after training}, booktitle={Vision Sciences Society 12th Annual Meeting}, author={He, Y. and Legge, G.}, year={2012} }