Information Used in Detecting Upcoming Collision

Abstract

In four experiments we examined the nature of the information used in judging whether events would or would not give rise to a collision in the near future. Observers were tested in situations depicting approaches between two objects (lateral approaches) and approaches between an object and the point of observation (head-on approaches), with objects moving according to constant deceleration or sinusoidal deceleration patterns. Judgments were found to be based, to a large extent, on the (in)sufficiency of current deceleration to avoid upcoming collision, as specified optically by tau-dot (τ̇). However, the information specified by tau (τ), that is the current (first-order) time remaining until contact, was also found to play a significant role. We deduce that judgment of upcoming collision is based on the detection of τ and its evolution over time, suggesting that observers are sensitive to Δτ rather than to τ̇ itself.