Effects of Situational Urgency on the Perception and Response Time to Lateral Collision Hazards 2021-01-0857

Situational urgency influences the perception and response time (PRT) interval of drivers confronting emergency collision hazards. However, a gap exists in our understanding of the movement characteristics of a collision hazard that directly contribute to a driver’s decision to initiate an evasive response. The aim of this experiment is to examine how the movement characteristics of intruding vehicles affect an oncoming driver’s PRT interval.

Fourteen subjects viewed first-person perspective recordings of a simulated vehicle travelling along a two-lane roadway. Collision hazards were introduced when stopped vehicles positioned at intersecting roadways unexpectedly intruded into the subject’s path. Subjects were instructed to ‘brake’ their vehicle by pressing a keyboard space bar when they perceived that evasive actions were required to avoid a collision. The duration of the PRT interval was considered as the time between the start of the intruder’s motion and when the ‘brake’ was applied. The time-to-impact (TTI) was manipulated by varying the intruders’ travel distance to impact and acceleration rate, resulting in 15 unique combinations of pre-impact hazard conditions.

Results revealed statistically significant main effects where relatively higher acceleration rates and shorter intruder travel distances produced the shortest PRTs. A statistically significant acceleration rate X travel distance interaction further revealed that PRT durations were dependent upon the particular combination of intruder motion parameters. However, the observed interaction effect was primarily driven by the time available between the start of an intruder’s motion and impact (i.e., TTI) which showed a significant linear trend.

Combined, these findings have extended our understanding of the perceptual processes governing driver performance and will aid in unifying the literature regarding driver PRTs to lateral collision hazards.