Undershoot Bias in Lead-Vehicle Motion Extrapolation

Abstract

Studies in motion extrapolation have shown both undershoot and overshoot distortions. Recent evidence using a car-following context revealed an undershoot bias for younger participants. These studies have focused on the distortions themselves while neglecting to account for memory encodings of images in the extrapolation tasks and how they might be the basis of such distortions. This study was designed to test whether Pylyshyn's index theory could account for distortions in a lead-vehicle pull-away context. Participants viewed slide shows depicting a lead-vehicle pulling ahead along one of five trajectories before being interrupted with a spatial or non-spatial task. After the interruption, participants were required to determine if the vehicle location in the probe slide was expected given the motion trajectory prior to the interruption. The results showed a clear undershoot bias, therefore supporting the theory that the last encoded image before the interruption was most salient in memory