Abstract

Previous studies have shown that small displacements that are easily detected in normal viewing become invisible if they occur during a saccade. However, it is not clear what process is suppressed during a saccade; energy-based (short-range) motion, form-based (long-range) motion, and perception of position change can all contribute to the displacement detection. We measured motion detection during a saccade using a random-dot stimulus presented within a stationary frame. This stimulus has no identifiable form whose displacement can be noticed either directly or by activation of the form-based motion process. Therefore, the impression of motion produced by the displacement of this stimulus must be mediated by the energy-based motion process alone. Saccadic suppression was found for the stimuli when they were displaced a small distance (less than D_max) either in spatial coordinates or in retinal coordinates. This result implies that the energy-based motion process is suppressed during the saccade, and since this process is able to signal motion for stimuli with ISIs longer than the duration of saccades in our experiment (mean of 60 ms), it appears to be suppressed across the saccade as well.

© 1987 Optical Society of America