University of Southern California

USC Neuroscience

Bosco S Tjan

Associate Professor of Psychology

Research Topics

  1. Peripheral vision (object recognition, scene perception, reading)
  2. Visual impairments, retinal prosthesis, assistive technologies
  3. Neural (f)MRI (BOLD, ASL, DTI, Structural MR, MR Microscopy, various data analysis techniques)
  4. Visual psychophysics
  5. Bayesian observer models

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
  • Separating BOLD Nonlinearity from Neuronal Nonlinearity in Human with Achiasma
  • 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
Mailing Address:
University of Southern California
Department of Psychology, SGM 501
Los Angeles, CA 90089-1061
Office Location:
SGM 1017A
Office Phone:
(213) 821-2953
Lab Location:
SGM 1017A
Lab Phone:
(213) 821-2954
(213) 746-9082


  • Research Associate, NEC Research Institute, 1998-2000
  • Post-doc., Max-Planck Institute for Biological Cybernetics, 1997-98
  • Ph.D., Computer Science, University of Minnesota, 1997
  • B.Sc. (honor), Computer Science, University of Kansas

Research Images

Selected Publications

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Kwon, M., Nandy, A. S., & Tjan, B. S. (2013). Rapid and persistent adaptability of human oculomotor control in response to simulated central vision loss. Current Biology, -PubMed

Millin, R., Arman, A. C., Chung, S. T. L., & Tjan, B. S. (2013). Visual crowding in V1. Cerebral Cortex. doi:10.1093/cercor/bht159 -PubMed

Gold, J. M., Mundy, P. J., & Tjan, B. S. (2012). The perception of a face is no more than the sum of its parts. Psychological Science, 23(4), 427–434. doi:10.1177/0956797611427407 -PubMed

Nandy, A. S., & Tjan, B. S. (2012). Saccade-confounded image statistics explain visual crowding. Nature Neuroscience, 15(3), 463–469. doi:10.1038/nn.3021 -PubMed

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

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

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