Abstract
The influence of adaptation as a continuous function of time on the phenomenal velocity of an observer in simulated motion along the principle line of sight is investigated. The results of two distinct groups of observers are reported, one having high visual motion after-effect and the other zero visual motion after-effect characteristics. The differential influence of velocity adaptation for these two groups is shown to support a visual motion after-effect based on an adaptation hypothesis. The results are discussed in terms of both psycho-physical and nourophysical models. The relevance of the study to a certain class of road accidents is demonstrated.