Speed, size, and edge-rate information for the detection of collision events

In the present study an alternative analysis to + was considered that was b ased on perceived speed and size and that assumed constant deceleration for the detection of collision events. Observers were presented with displays simulating a 3-D environment with obstacles in the path of observer motion. During the trial, observer motion decelerated at a constant rate and was f ollowed by a blackout prior to the end of the display. Observers had to det ect which trials resulted in a collision. The results indicate that collisi on detection varied as a function of the size of the obstacles, observer sp eed, and edge rate-findings not predicted by an analysis of +. The results suggest that observers use an analysis based on speed and size information. A model that assumes constant deceleration is proposed for braking control .