University of Southern California

USC Neuroscience

Bosco S. Tjan

Associate Professor of Psychology

Research Topics

  1. Object recognition
  2. Scene perception
  3. Letter identification
  4. Reading
  5. Spatial vision
  6. Bayesian ideal observers
  7. Signal detection theory
  8. Visual psychophysics
  9. Neural imaging (fMRI)

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, most of which we approach 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
  • 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.S., Computer Science, University of Kansas, 1987
  • 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

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Selected Publications

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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

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

Chung ST, Tjan BS. (2007) Shift in spatial scale in identifying crowded letters. Vision Res. 47(4):437-51. -PubMed

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

Chung S.T.L., Levi D.M.,Tjan B.S. (2005). Learning letter identification in peripheral vision. Vision Research 45(11):1399-1412. -PubMed

Tjan, B. S., & Liu, Z. (2005). Symmetry impedes symmetry discrimination. Journal of Vision, 5(10), 888-900, doi:10.1167/5.10.10. -PubMed -Link

Chung S.T.L., Legge G.E., & Tjan B.S. (2002). Spatial-frequency characteristics of letter identification in central and peripheral vision. Vision Research 42(18):2137-2152. -PubMed

Newell F.N., Ernst M.O., Tjan B.S., & Bulthoff. H.H. (2001). Viewpoint dependence in visual and haptic object recognition. Psychological Science 12(1) 37-42. -PubMed