What visual information is used by riders in jumping

Abstract The aim of the present study was to assess the use of visual information by horse-riders approaching an obstacle to be jumped. Two experiments are described: the first involved decreasing peripheral visual information during the obstacle approach phase, and the second consisted of analysing the visual exploratory strategies observed in subjects performing this part of the jumping sequence, in which vision plays a leading role. It was attempted to elucidate two main questions: does a horseman's assessment of his distance from an obstacle depend on his visual perception of the speed? And what visual exploratory strategies and more generally, what oculo-cephalic coordination did the subjects use and did these strategies vary depending on the characteristics of the obstacle? The results show that peripheral visual information plays only a minor role in a rider's control of his horse's locomotion, whereas temporal factors such as the horse's gait and the time-to-contact ( Tc ) with the obstacle were found to play an important, and possibly decisive role in this kind of activity involving severe spatio-temporal constraints. The visual exploratory strategies used were not found to differ significantly with changes in the obstacle characteristics. The riders consistently focused their gaze centrally towards the top of the obstacle and kept their heads in a fixed position. These patterns are compatible with the possibility that the rider's visual information processing may have been based on the retinal expansion rate of the obstacle, from which they may have deduced the Tc .