The induced asynchrony effect: Its role in visual judgments of temporal order and its relation to other dynamic perceptual phenomena

A context-induced “illusion” in visual judgments of temporal order, termed the induced asynchrony effect (IAE), is reported. It consists of an apparent ordering in time of two simultaneous light onsets, produced by the preceding, asynchronous offsets of two other lights. The joint effect of a real stimulus onset asynchrony and a preceding stimulus offset asynchrony bn judgments of onset order appears to be additive, given a Gaussian transformation of response probability. This result is shown to be consistent with a simple statistical decision model, which provides a conceptual framework for drawing inferences from temporal order judgment data. However, it is emphasized that certain interpretations of such models are not empirically testable on the basis of temporal order data alone. An attempt is made to relate the IAE to three other dynamic perceptual phenomena; all four effects may reflect a tendency of observers to perceive the velocity of apparent motion as being constant. Questions raised by the demonstration of the IAE are discussed, and directions for further research are suggested.