Use of Peripheral Vision in the Decision to Brake

Abstract

The aim of this study was to determine whether the speed information collected at the peripheral retina is used to assess the time-to-collision ( TC) with a target. For this purpose, 12 male volunteers were asked to perform a braking task consisting of running up to an obstacle under three experimental conditions: normal vision, central vision (13°), and central vision + 4° restricted peripheral information, presented 50–54° off center. Analyses show that the greater peripheral information available, the later braking occurred. The idea is put forward that the method used by the subjects to obtain TC may have consisted of combining the running speed with the braking distance ( TC = BD/S). This partly challenges the ecological optics hypothesis (Lee, 1980) that TC is obtained entirely on the basis of the target expansion rate on the retina.