Abstract

An important question in understanding spatial pattern perception is how information from different spatial frequency bands is combined in a discrimination task. This question was approached by comparing discrimination between complex stimuli, containing components at multiple spatial frequencies, with discriminations between the individual components. The complex stimuli were square-wave gratings of different spatial frequencies, centered on 4 cycles/deg. Each grating was decomposed into two components: the fundamental; and the residue, consisting of the third and all higher harmonics. These components are far enough apart in the spatial frequency domain to activate nonoverlapping sets of mechanisms. Results from one observer are as follows: At low contrasts, discrimination between fundamentals is more accurate than discrimination between the corresponding residues; at intermediate contrasts, the two types of component are discriminated equally well; and at high contrasts, discrimination between residues is more accurate. At low contrasts, square-wave discrimination approximates the accuracy of discrimination between fundamentals; at intermediate contrasts, both components contribute to square-wave discrimination; at high contrasts, square-wave discrimination approximates the accuracy of discrimination between residues. However, over all contrasts, pooling of information from the different frequency regions is less than optimal.

© 1985 Optical Society of America