Bosco S. Tjan
Associate Professor of Psychology
Research Topics
- Peripheral vision (object recognition, scene perception, reading)
- Visual impairments, retinal prosthesis, assistive technologies
- Bayesian observer models
- Visual psychophysics
- Neural (f)MRI (BOLD, ASL, DTI, Structural MR, MR Microscopy, various data analysis techniques)
Research Overview
We study the human visual system by exploring neural computations that underlie the perception of form, a domain that includes object recognition, scene perception, and reading. Our research addresses a broad spectrum of topics from basic questions in object recognition to clinical applications. We approach these topics from the theoretical framework of optimal computation: by considering the computation and behavior of a mathematically optimal observer (an ideal observer) for the given stimuli, task, and known limitations of the human visual system. The tools that we use include psychophyiscal experimentation, fMRI, and mathematical modeling.On-going research projects:
- Form Processing in the Periphery
- Mid-Level Vision Systems for Low Vision
- Retinal Prosthesis and neural plasticity
- In vivo MR Microscopy of the human eye
- Uncertainty and the Order of Visual Processing in Cortex
- Visual Speech Perception and Neural Processing
- Development of a Digital Sign System for Indoor Wayfinding by Visually Impaired Pedestrians
Contact Information
- Web Site:
- Laboratory for Functional and Computational Vision
- E-mail:
- btjan@usc.edu
- Mailing Address:
- University of Southern California
Department of Psychology, SGM 501
Los Angeles, CA 90089-1061 - Office Location:
- SGM 1016
- Office Phone:
- (213) 821-2953
- Lab Location:
- SGM 1017
- Lab Phone:
- (213) 821-2954
- Fax:
- (213) 746-9082
Education
- B.Sc. (honor), Computer Science, University of Kansas
- Ph.D., Computer Science, University of Minnesota, 1997
- Post-doc., Max-Planck Institute for Biological Cybernetics, 1997-98
- Post-doc., NEC Research Institute, 1998-2000
Research Images
Selected Publications
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Wallace, J. M., & Tjan, B. S. (2011). Object crowding. Journal of Vision, 11(6):19, 1-17. -PubMed -Link
Sun, G. J., Chung, S. T. L., & Tjan, B. S. (2010). Ideal observer analysis of crowding and the reduction of crowding through learning. Journal of Vision, 10(5):16, 1-14 -PubMed -Link
Lu, Z., Li, X., Tjan, B. S., Dosher, B. A., & Chu, W. (2010). Attention Extracts Signal in External Noise: A BOLD fMRI Study. Journal of Cognitive Neuroscience, 23(5):1148-59. -PubMed
Chung, S. T. L. & Tjan, B. S. (2009). Spatial-frequency and contrast properties of reading in central and peripheral vision. Journal of Vision, 9(9):16, 1-19. -PubMed -Link
Li X, Lu ZL, Tjan BS, Dosher BA, Chu W. (2008) Blood oxygenation level-dependent contrast response functions identify mechanisms of covert attention in early visual areas. Proc Natl Acad Sci U S A. 105(16):6202-6207. -PubMed
Nandy, A. S., & Tjan, B. S. (2008). Efficient integration across spatial frequencies for letter identification in foveal and peripheral vision. Journal of Vision, 8(13):3, 1-20. -PubMed -Link
Nandy A.S. & Tjan, B.S. (2007). The nature of letter crowding as revealed by first- and second-order classification images. Journal of Vision, 7(2):5, 1-26. -PubMed -Link
Chung ST, Tjan BS. (2007) Shift in spatial scale in identifying crowded letters. Vision Res. 47(4):437-51. -PubMed
Tjan, B.S., & Nandy, A. S. (2006). Classification images with uncertainty. Journal of Vision, 6(4), 387-413, doi:10.1167/6.4.8. -PubMed -Link
Tjan, B.S., Lestou, V., & Kourtzi Z. (2006). Uncertainty and invariance in the human visual cortex. Journal of Neurophysiology (May 24, 2006; Epub ahead of print), doi:10.1152/jn.01367.2005 -PubMed
Chung S.T.L., Levi D.M.,Tjan B.S. (2005). Learning letter identification in peripheral vision. Vision Research 45(11):1399-1412. -PubMed