Use of Global Optical Flow Rate and Discontinuity Rate Depends on Their Validity as Determinants of Egospeed

Abstract

Previous research found both discontinuity rate and global optical flow rate contribute to the perception of egospeed but differed in estimates of which source of information dominated. This research examined two methodological differences that may explain the conflicting results: frame rate, and the relative validity of discontinuity rate and flow rate as determinants of egospeed. Observers estimated egospeed perceived during simulations of self-motion. Discontinuity rate and flow rate were manipulated independently by varying velocity and altitude. Frame rates were consistent with Dyre (1997) and the validity of discontinuity rate and flow rate as determinants of egospeed was varied. We found the relative use of discontinuity rate and flow rate was related to the validity of these sources of information. Frame rate was not an important factor. These results suggest the visual system is sensitive to multiple sources of information for perceiving egospeed and adapts to the most optimal source.