D. N. Lee suggested that people time actions that involve the interception of a moving target using the information provided by the optic variable tau (τ). Using τ to time interceptions involves approximations that lead to errors in timing not reflected in human performance. Thus, it is to be expected that other perceptual information is used instead of or in addition to τ. Two additional variables are theoretically important: the instantaneous angle between the target and interception point and the target's rate of change of direction. Data suggest that these 2 variables are used in addition to τ. The data also demonstrate that when only the moving target is visible subjects do not rely on τ information alone to time interceptions. Thus, the sensory source of other variables implicated in timing need not be vision, which supports the idea that timing information is extracted multimodally. Other approximate sources of timing information are also ruled out as the basis of human timing skills.