Benjamin Backus, PhD
SUNY College of Optometry
33 West 42nd Street New York, NY 10036

Research Description

The main research focus of the Backus Lab is cue recruitment, a form of associative learning in human perception that optimizes the brain’s use of sensory signals, that was recently demonstrated in the Backus Lab using virtual reality displays.  Cue recruitment occurs unconsciously.  We are not generally aware that our visual systems are learning all the time how to interpret our retinal images.  However, the result of this natural process is that visual perception is highly reliable, so things usually appear within our visual percepts more or less as they should appear for us to act appropriately. 

In a cue recruitment experiment, some arbitrarily chosen new signal is put into correlation with cues that the visual system already trusts for perception, so the new signal becomes an “artificial cue.”  For example, binocular disparity is a trusted cue for depth perception that can be put into correlation with an artificial cue of whether an object moves up or down.  If the artificial cue acquires the ability to affect appearance (perceived depth, for example), it is said to have been recruited.  Our current work is aimed at understanding, within a Bayesian statistical framework, why visual cues are sometimes recruited quickly and sometimes slowly or not at all.  Other work in the lab aims to understand stereoscopic depth perception and motion perception from theoretical/basic and, especially recently, clinical perspectives. 

Dr. Backus currently has active grants to work on projects for the National Institutes of Health (“Cue reliability and depth calibration during space perception”), the National Science Foundation (“Pavlovian conditioning of visual perception”) and the Human Frontier Science Program (“Mechanisms of associative learning in human perception”). 


Vision Science, University of California at Berkeley, PhD, 1997

California Teaching Credential, Secondary Mathematics, Holy Names University, 1991

Cognitive Psychology, University of Pennsylvania, MA, 1987

Mathematics, Swarthmore College, BA, 1985

Career History

  • Associate Professor, Vision Sciences, SUNY Optometry, 2007-present

  • Assistant Professor, Dept. of Psychology, University of Pennsylvania, 2000-2007

  • National Institute of Health Postdoctoral Fellow (NRSA), Stanford University, 1998-2000

Grant Support

  • National Institutes of Health, "Cue Reliability and Depth Ccalibration during Space Perception", NEI # R01 EY013988, $1,125,000 (direct costs), 2003 - 2012.

  • National Science Foundation, "Pavlovian Conditioning of Visual Perception", BCS-0617422, $306,055 (total costs), 2007 - 2010.

  • Human Frontiers Science Program, "Mechanisms of Associative Learning in Human Perception", Principle Investigator, with co-investigators Marc Ernst (Max Planck Institute, Tuebingen, Germany), Guy Wallis (University of Queensland, Australia), and Michael Kearns (University of Pennsylvania, USA).  $1,046,500 (direct costs) 2006 - 2010.

  • University of Pennsylvania Research Foundation, "Rate of Recalibration of Motion Parallax for Depth Perception", $24,281 (2003-2004).


Wilmer, J.B., & Backus, B.T. (2009). Genetic and Environmental Contributions to Strabismus and Phoria: Evidence from Twins. Vision Research, in press.

Wallis, G., Backus, B.T., Langer, M., Hübner, G., Bülthoff, H. (2009). Learning Illumination and Orientation-Invariant Representations of objects through temporal association. Journal of Vision, 9(7):6, 1-8.

Backus, B.T. (2009). The Mixture of Bernoulli Experts: A Theory to Quantify Reliance on Cues in Dichotomous Perceptual Decisions. Journal of Vision, 9(1):6, 1-19.

Wilmer, J.B., & Backus, B.T. (2008). Self-reported Magic Eye Stereogram Skill Predicts Stereoacuity. Perception, 37, 1297-1300.

Saunders, J. A., & Backus, B. T. (2007).  Both Parallelism and Orthogonality are Used to Perceive 3-D Slant of Rectangles from 2-D Images. Journal of Vision, 7(6):7, 1-11.

Backus, B. T., & Haijiang, Q. (2007). Competition Between Newly Recruited and Pre-Existing Visual Cues During the Construction of Visual Appearance.  Vision Research,47, 919-924.

Saunders, J. A., & Backus, B. T. (2006). Perception of Surface Slant from Oriented Textures. Journal of Vision, 6, 882-897.

Saunders, J. A., and Backus, B. T. (2006). The Accuracy and Reliability of Perceived Depth from Linear Perspective as a Function of Image Size. Journal of Vision, 6, 933-954.

Haijiang, Q., Saunders, J.A., Stone, R.W., and Backus, B.T. (2006). Demonstration of Cue Recruitment: Change in Visual Appearance by Means of Pavlovian Conditioning. Proc Natl Acad Sci U S A, 103, 483-488.

Duke, P.A., Oruc, I., Qi, H., & Backus, B.T. (2006). Depth Aftereffects Mediated by Vertical disparities: Evidence for Vertical Disparity Driven Calibration of Extraretinal Signals During Stereopsis. Vision Research, 46 (1-2), 228-241.

Backus, B.T., & Oruç, I. (2005). Illusory Motion from Change Over Time in the Response to Contrast and Luminance. Journal of Vision, 5, 1055-1069.

Zabulis, X. & Backus, B.T. (2004). Starry Night: a Texture Devoid of Depth Cues.  Journal of the Optical Society of America,21:2049-2060.

Backus, B. T. & Matza-Brown, D. (2003). The Contribution of Vergence Change to the Measurement of Relative Disparity. Journal of Vision, 3:737-750.

Backus, B.T. (2002). Perceptual Metamers in Stereoscopic Vision. In Advances in Neural Information Processing Systems 14, ed. T.G. Dietterich, et al.  MIT Press.  1223-1230.

Banks, M.S., Backus, B.T. & Banks, R.S. (2002). Is Vertical Disparity Used to Determine Azimuth? Vision Research 42:801-807.

Backus, B.T., Fleet, D.J., Parker, A.J. & Heeger, D.J. (2001).  Human Cortical Activity Correlates with Stereoscopic Depth Perception. Journal of Neurophysiology, 86: 2054-2068.

Banks, M.S., Hooge, I.T.C. & Backus, B.T. (2001). Perceiving Slant About a Horizontal Axis from Stereopsis. Journal of Vision, 1: 55-79.

Ress, D., Backus, B.T. & Heeger, D.J. (2000).  Activity in Primary Visual Cortex Predicts Performance in a Visual Detection Task.  Nature Neuroscience,3: 940-945.

Wandell, B.A., Chial, S. & Backus, B.T. (2000).  Visualization and Measurement of the Cortical Surface.  Journal of Cognitive Neuroscience, 12: 739-752.

Backus, B.T. & Banks, M.S. (1999). Estimator Reliability and Distance Scaling in Stereoscopic Slant Perception.  Perception, 28: 217-242.

Backus, B.T., Banks, M.S., van Ee, R. & Crowell, J.A. (1999).  Horizontal and Vertical Dsparity, Eye Position and Stereoscopic Slant Perception.  Vision Research, 39: 1143-1170.

Van Ee, R., Bank, M.S. & Backus, B.T. (1999a).  An Analysis of Binocular Slant Contrast.  Perception, 28: 1121-1145.

Van Ee, R., Banks, M.S. & Backus, B.T. (1999b).  Perceived Visual Direction Near an Occluder.  Vision Research, 39: 4085-4097.

Banks, M.S. & Backus, B.T. (1998).  Extra-Retinal and Perspective Cues Cause the Small Range of the Induced Effect.  Vision Research,  38:187-94.

Banks, M.S., van Ee, R. & Backus, B.T.  (1997).  The Computation of Visual Direction: A Re-Examination of Mansfield and Legge (1996).  Vision Research,37:1605-13.

Banks, M.S., Ehrlich, S.M., Backus, B.T. & Crowell, J.A. (1996).  Estimating Heading During Real and Simulated eye movements.  Vision Research,  36: 431-444.

Other Writing

Backus, B.T. (2007). Does Television Cause Autism? A theoretical Account. University of Pennsylvania Institute for Research in Cognitive Science Technical Report, No. IRCS-07-01,

Backus, B.T. (2000).   Stereoscopic Vision: What’s the first step?  Current Biology, 10:R701-3. 

Banks, M.S. & Backus, B.T. (1999).  Horizontal and Vertical Disparity and Eye Position in Stereoscopic Slant Perception.  Chapter 3 in Vision and Action.  L.R. Harris and M. Jenkin, Eds.  Cambridge, England: Cambridge University Press.  33 pages.

Backus, B.T. (1997).  Uses of Dynamic Geometry Software for Teaching and Research in Optometry and Vision Science.  Chapter in Geometry Turned On: Dynamic Geometry, Theory and Application, James King, Ed.  New York: Mathematical Association of America.  7 pages.

Invited Talks

  • University of Arizona

  • Rutgers University

  • University of Texas, Austin

  • Harvard University

  • Vanderbilt University

  • University of Pennsylvania

  • MIT

  • New York University

  • UC Berkeley

  • National Institutes of Health

  • Salk Institute

  • Stanford University

  • Smith-Kettlewell Eye Research Institute

  • Utrecht University



  • Perception

  • Research Experience in Perception

  • Methods in Experimental Psychology

  • Sensory and Perceptual Adaptation

  • Perceptual Learning

  • Probabilistic Approaches to Perception


Postdoctoral students and collaborators

Sarah Harrison (SUNY)
Stuart Fuller (SUNY)
Anshul Jain (SUNY)
Peter Scarfe (SUNY)
Jeremy Wilmer (SUNY)
Jeffrey Saunders (U. Penn.)
Ipek Oruc (U. Penn.)
Xenophon Zabulis (U. Penn.)

Graduate students

Kelly Chajka (Vision Sciences, SUNY)
R. Ben Meade (Vision Sciences, SUNY)
Qi Haijiang (Bioengineering, U. Penn.)


Reviewing for journals

  • Journal of Vision

  • Vision Research

  • Perception

  • Nature Neuroscience

  • Perception & Psychophysics

  • Journal of the Optical Society of America A

  • Proceedings of the Royal Society Biological

  • Journal of Neurophysiology

  • Journal of Neuroscience

Grant Reviewing

  • National Science Foundation

  • Engineering and Physical Sciences Research Council (UK Government)

  • Natural Sciences and Engineering Research Council of Canada

Professional Affiliations

  • Vision Sciences Society

  • Association for Research in Vision and Ophthalmology

  • Society for Neuroscience

  • Sigma Xi

  • Association for Psychological Science

  • Optical Society of America