Abstract

Visual physiology suggests that the contrast sensitivity for a flickering or drifting grating should fall off sharply at temporal frequencies above 20 Hz (as in a typical DeLange curve). But when the spatial frequency of the stimulus is higher than 2 or 3 cycles/deg, the flicker response curve flattens unexpectedly beyond 20 Hz. Even with stabilized (drifting) gratings and careful fixation, our subjects detect such stimuli at frequencies as high as 200 Hz. We attribute this high-frequency sensitivity, not to a neural mechanism, but to the destabilizing effect of microsaccades. Similar microsaccade effects also appear to influence the thresholds for steady stabilized gratings.

© 1988 Optical Society of America