APPROXIMATE INFORMATION-SOURCES AND PERCEPTUAL VARIABLES IN INTERCEPTIVE TIMING

D.N. Lee suggested that people time actions that involve the intercept ion of a moving target using the information provided by the optic var iable tau (tau). Using tau to time interceptions involves approximatio ns that lead to errors in timing not reflected in human performance. T hus, it is to be expected that other perceptual information is used in stead of or in addition to tau. Two additional variables are theoretic ally important: the instantaneous angle between the target and interce ption point and the target's rate of change of direction. Data suggest that these 2 variables are used in addition to tau. The data also dem onstrate that when only the moving target is visible subjects do not r ely on tau information alone to time interceptions. Thus, the sensory source of other variables implicated in timing need not be vision, whi ch supports the idea that timing information is extracted multimodally . Other approximate sources of timing information are also ruled out a s the basis of human timing skills.