Perceived Onset Simultaneity of Stimuli with Unequal Durations

Temporal-order judgment was investigated for a pair of visual stimuli with different durations in order to check whether offset asynchrony can disturb the perception of the order/simultaneity of onset. In experiment 1 the point of subjective simultaneity was estimated by the method of adjustment. The difference in duration of the two stimuli in the pair was either 0 or 50 ms. It was found that the subject shifts the onset of the shorter stimulus towards the offset of the longer one to obtain a satisfying impression of simultaneity even though the subject was asked to ignore the events concerning the stimulus offset. In experiments 2 and 3 the method of constant stimulus was applied. Both experiments indicate that subjects, in spite of instruction, take into account the offset asynchrony in their judgment.