Perception of Egospeed from Absolute and Relative Motion

Abstract

Perceiving the speed of self-motion or egospeed directly from the view out a window is important in some vehicular control tasks. Recent research found that visual perception of egospeed is primarily based on global optical flow rate, which is directly related to the magnitude of both absolute and relative motion. The purpose of the present study was to determine whether the magnitude of relative motion affects egospeed estimates independently of the magnitude of absolute motion. Observers estimated their perceived egospeed during simulations of flight over three parallel planes. We manipulated the degree of relative motion by varying the interplane distance, the spacing between the two outer planes and the center plane. The results indicate that relative motion affects perception of egospeed independently of absolute motion. Hence, it is important to consider the magnitude of relative motion when designing head-up displays that present optical flow to augment speed information available through the windscreen.