Citation

Green M. Collision 2009; 4(2): 88-93.

Copyright

(Copyright © 2009, Collision Publishing)

DOI

unavailable

PMID

unavailable

Abstract

Perception-reaction time (PRT) is the interval between obstacle appearance and driver response initiation. PRT is often a critical factor in establishing accident causation. One popular opinion is that PRT is 1.1 seconds. This opinion stems from Olson and Sivak (Perception-Response Time to Unexpected Roadway Hazards, Human Factors, 28, 1986, 96-99.) This article criticizes the use of canned numbers such as the Olson value for PRT for three reasons. First, every research study has limited generality because it is conducted under a specific set of conditions. Second, the Olson study is only one of over 100 driver PRT studies, and these studies provide data for other sets of conditions. Third, the issue of driver PRT cannot be considered independently from larger topics such as perception, memory and learning. The Olson values represent the fastest that a driver can avoid an unexpected obstacle in highly optimized conditions. Factors such as low visibility, complexity, uncertainty, alertness and age may produce longer PRTs. However, it would be impossible to assign a precise number to cover all conditions.