Low-level visual processes and texture segregation

Parallel processing by a set of multiple mechanisms selectively sensitive along various dimensions of visual patterns - e.g., spatial frequency, orientation, direction-of-motion - seems to be one of the earlier states in the perception of form and objects. The evidence for these mechanisms - which comes primarily from neurophysiology and psychophysics using near-threshold patterns (patterns of such low contrast that they are imperfectly discriminable from a blank field of the same mean luminance) - and the properties of these mechanisms are briefly reviewed. The responses of these mechanisms to some texture patterns used to investigate the segmentation of the visual field into separate regions is illustrated.