Abstract

The influential uncertainty model [J. Opt. Soc. Am. A 2, 1508 (1985)] attributes nonlinear contrast sensitivity near threshold to the inability of the observer to discriminate between the signal from stimulated locations and the noise from nonstimulated locations. We introduce an alternative interpretation, the distraction model, to describe the behavior of an observer who knows exactly which location was stimulated but may miss the test stimulus because attention has been distracted by irrelevant (noise) signals. For any stimulus sample, the observer is assumed to be certain of whether this sample is relevant or irrelevant to the stimulus. The nonlinear effects predicted by the distraction model without uncertainty are similar to those predicted by the uncertainty model.

© 1999 Optical Society of America

Noise location and the slope of the psychometric function for simple motion stimuli

Bryan L. Gros, David R. Pope, and Theodore E. Cohn
J. Opt. Soc. Am. A 16(3) 718-727 (1999)

Invariance of the slope of the psychometric function with spatial summation

Melanie J. Mayer and Christopher W. Tyler
J. Opt. Soc. Am. A 3(8) 1166-1172 (1986)

Spatial attention: effect of position uncertainty and number of distractor patterns on the threshold-versus-contrast function for contrast discrimination

John M. Foley and Wolfgang Schwarz
J. Opt. Soc. Am. A 15(5) 1036-1047 (1998)

Effects of aging on calculation efficiency and equivalent noise

Patrick J. Bennett, Allison B. Sekuler, and Linda Ozin
J. Opt. Soc. Am. A 16(3) 654-668 (1999)

Characterizing human perceptual inefficiencies with equivalent internal noise

Zhong-Lin Lu and Barbara Anne Dosher
J. Opt. Soc. Am. A 16(3) 764-778 (1999)