NYU/CNS : Faculty : Associates of CNS : Denis G. Pelli

How people recognize an object might seem trivial, because we do it so easily, but it has proven to be resistant to all attempts to understand and explain it. We have the hunch that there may be substantial similarities in the underlying algorithm of making a decision at any level, from identifying a letter to making social and economic decisions. We are creating a Decision Making Center at NYU to bring together researchers of decisions at all levels. Our past work has shown that letter identification begins with independent detection of features, and then integrates those features. We can say quite a bit about the feature detectors, and rather little about the feature integrator. Very briefly, the feature detectors are local in space and and spatial frequency, and have a tuning that scales in a nonlinear way with letter size. These results generalize to faces and line drawings of familiar objects. Currently we have had a minor breakthrough in understanding "crowding", which turns out to be feature integration over an inappropriately large area, and applies to all tasks in the peripheral visual field that require feature integration. This result has led to several quick successes in addressing old problems and seems to offer a window into the workings of the feature integration process.

E-mail: denis.pelli@nyu.edu

Selected Publications

Pelli, D.G. (1985) Uncertainty explains many aspects of visual contrast detection and discrimination. Journal of the Optical Society of America A 2: 1508-1532
Legge, G.E., Pelli, D.G., Rubin, G.S., and Schleske, M.M. (1985) Psychophysics of reading. I. Normal vision. Vision Research 25: 239-252
Pelli, D.G., Robson, J.G., and Wilkins, A.J. (1988) The design of a new letter chart for measuring contrast sensitivity. Clinical Vision Sciences 2: 187-199
Pelli, D.G. (1990) The quantum efficiency of vision. In Vision: Coding and Efficiency, ed. C. Blakemore, Cambridge, MA: Cambridge University Press.
Farell, B. and Pelli, D.G. (1993) Can we attend to large and small at the same time? Vision Research 33: 2757-2772
Solomon, J.A. and Pelli, D.G. (1994) The visual filter mediating letter identification. Nature 369: 395-397
Farell, B. and Pelli, D.G. (1998) Psychophysical methods. In A Practical Guide to Vision Research, eds. J.G. Robson and R.H.S. Carpenter, New York, NY: Oxford University Press
Pelli, D.G., Palomares, M., and Majaj, N.J. (2002) Crowding is unlike ordinary masking: Distinguishing feature detection and integration. Journal of Vision, in press
Majaj, N.J., Pelli, D.G., Kurshan, P., and Palomares, M. (2002) The role of spatial frequency channels in letter identification. Vision Research 42: 1165-1184
Pelli, D.G., Burns, C.W., Farell, B., and Moore, D.C. (2002) Identifying letters. Vision Research, in press