Abstract

Under the general assumption that visual contrast detection occurs by a parallel array of linear detectors, either without probability summation or with probability summation of a commonly assumed type, it is shown that the set of functions representing subthreshold stimuli must be convex. Thus, for example, a planar plot of the threshold locus using multiples of any two functions as axes, must be convex (cannot bulge inward). If experimental evidence to the contrary were discovered, it would rule out detection by parallel linear detectors of the above type. One possible kind of such evidence would be an inward cusp of the threshold locus corresponding to one of a special class of stimuli to which the visual system might be specifically sensitive.

© 1978 Optical Society of America

Predictions of an inhomogeneous model: Detection of local and extended spatial stimuli

Francis Kretz, Françoise Scarabin, and Eric Bourguignat
J. Opt. Soc. Am. 69(12) 1635-1648 (1979)

Further evidence for four mechanisms mediating vision at threshold: Sensitivities to complex gratings and aperiodic stimuli

J. R. Bergen, H. R. Wilson, and J. D. Cowan
J. Opt. Soc. Am. 69(11) 1580-1587 (1979)

Spatial summation effects on two-component grating thresholds

R. Frank Quick, W. W. Mullins, and T. A. Reichert
J. Opt. Soc. Am. 68(1) 116-121 (1978)

A visual system model and a new distortion measure in the context of image processing*

William A. Pearlman
J. Opt. Soc. Am. 68(3) 374-386 (1978)

Visual Responses to Time-Dependent Stimuli.* II. Single-Channel Model of the Photopic Visual System

D. H. Kelly
J. Opt. Soc. Am. 51(7) 747-754 (1961)