Perception of an Illusory Contour as a Function of Processing Time

The temporal development of illusory contour figures was investigated with the use of backward masking to control the duration of processing. The integration of an illusory triangle is elicited after 100 ms of processing time. When a pattern yielding the impression of a brick background is added to the display the triangle is elicited after 100 ms, held as a viable construct for the next 200 ms, and then is no longer perceived. When the brick pattern is drawn so as to appear transparent, a sequence of four qualitatively different percepts arise, culminating in the perception of a triangle located behind the transparent pattern. These findings are consistent with a hypothesis-testing model in which the construct ‘triangle’ interacts with an increasing number of features of the stimulus array; at each interaction it may or may not be found to be consistent with the sensory evidence newly taken into account.