Abstract
Important aspects of our visual environment give rise to informative time-varying signals. I examined temporal processing experimentally, using a variety of size-modulating visual stimuli. The visual stimulus modulated sinusoidally in size at 5 HZ, subjects’ ability to tell whether the rate increased, decreased, or remained constant was tested. The depth of the size modulation varied: 5%, 10%, 20%, and 40%. Subjects categorized the direction of change as increasing, constant, or decreasing across the four modulation depths. The direction of rate change could linearly increase from 3.9 Hz to 6 Hz, remain constant at 5 Hz, or linearly decrease from 6 Hz to 3.9 Hz. Subjects’ mean identification accuracy increased linearly with the log of modulation depth, and variance in response times lessened as modulation depth increased. The results demonstrate how perceptual decision-making is affected by modulation depth.