Abstract
Failures of perception often support inferences about processing limitations: bottlenecks, and limited attention, for instance, as revealed by the attentional blink, change blindness and other examples. Motion silencing is a striking illusion that has been interpreted along these lines. The illusion is that observers fail to see individual dots changing color when the dots constitute a larger disc which is rotating as a whole (but not a stationary disc), a failure thought to be caused by too much information to process at once. Using methods that closely follow the original illusion report, we investigated the alternative hypothesis that silencing reflects the erroneous inference that detected color changes were spuriously caused by the rotating motion. We support this hypothesis, first, by demonstrating a situation in which color changes are perceived despite large amounts of motion energy. Specifically, with randomly moving dots inside of a confined space observers perceive color changes as robustly as they do when the dots remain unmoving. If color changes can be perceived in the presence of motion, then motion itself cannot be the limiting factor. Second, we used a pair of controlled stimuli to demonstrate that the illusion obtains only when the visual system has reason to infer an underlying object upon which all the dots are set. Specifically, when two groups of oppositely translating dots were presented, participants saw a three-dimensional rotating cylinder and critically, when the dots changed colors, the silencing illusion obtained. When the two sets of dots translated in the same direction, removing the cylinder percept, silencing was reduced (p < 0.001). A limitation caused by motion should be equally present when dots translate in the same or opposite directions. That silencing is only present when an underlying object is implied reveals the illusion as an interpretive error.