Abstract
It is well known that a moving stimulus appears to last longer. Proposed determinant factors of this temporal illusion include temporal frequency, speed, attention, cortical expenditure, etc., and recent works have demonstrated that illusory dilation occurs with the perceived speed of a moving plaid as well as that of a moving display whose motion is enhanced by simultaneous motion contrast. If perceived rather than physical motion has a stronger impact on time perception, illusory dilation may occur even in a physically stationary stimulus that is subjectively moving due to a motion illusion. To test this hypothesis, we took advantage of a vivid motion illusion termed visual jitter, namely, after adaptation to dynamic random noise, a physically stationary stimulus in a previously unadapted region appears to move in random directions, which reflect the retinal image motions concomitant with the observer's own fixational eye movements upon fixation of the stationary stimulus. Using a matching method, we quantified the apparent duration of a stationary stimulus for a fixed duration while the observer was experiencing the jitter aftereffect there. As a negative control, the apparent duration of the same stationary stimulus without adaptation was also measured. As a positive control, we further measured the apparent duration of a stimulus that was physically jittering on the monitor. We found that for a majority of observers, neither the physically jittering stimulus nor the subjectively jittering stimulus appeared to dilate, but for a substantial fraction of observers, both the physically jittering stimulus and the subjectively jittering stimulus appeared to last longer than the physically as well as subjectively stationary stimulus. In other words, those observers who experienced dilation in physical jitter also experienced dilation in perceived jitter. These results strengthen the idea that perceived motion is one of the most influential determinant factors of perceived duration.
Meeting abstract presented at VSS 2016