Abstract

The Quick summation rule describing probability summation has proved a useful algorithm for predicting threshold changes obtained when the spatial extent of a stimulus is changed and has been successfully used in several models of threshold vision. In particular, for sine wave grating stimuli, the Quick summation rule predicts that thresholds should decrease as a power function of the number of cycles in the grating with an exponent of about −0.3 if the sensitivities of the mechanisms activated by the sine wave are approximately equal.

© 1987 Optical Society of America