SPATIAL POOLING OF CONTRAST IN CONTRAST GAIN-CONTROL

We report psychophysical measurements of spatial pooling functions for contrast gain control. We use a nulling technique to measure the depe ndence of contrast induction on the spatial frequency of a sinusoidal contrast modulation. This dependence on spatial frequency, when transf ormed, provides the profile of a spatial pooling function. The measure d profiles are fitted well by Gaussians. We confirm earlier results th at the area over which spatial pooling takes places depends on the sca le of the modulated pattern. We also find that pooling functions are s imilar for achromatic and isoluminant stimuli. (C) 1996 Optical Societ y of America.