Influence of exposure duration on the tuning of spatial channels

Abstract

Differences between the spatial frequency tuning curves of psychophysical mechanisms detecting temporally modulated and unmodulated sinusoidal gratings have been found in previous work with frequency specific adaptation. Using a subthreshold additivity technique, which avoids problems associated with the adaptation technique, we found no differences between curves for briefly flashed and steadily presented gratings at center frequencies of 1, 3, and 13.3 c/deg. Under both conditions the channels were narrow and symmetrical about the center frequency. Our results do not support simple analogies between the psychophysical mechanisms and electrophysiologically defined “sustained” and “transient” neurons.