Review: Sport Performance and the Two-visual-system Hypothesis of Vision: Two Pathways but Still Many Questions.

The two-visual-system hypothesis (TVSH) provides a framework for understanding the nature of the visual information athletes are likely to rely on during competition. If valid, the framework provides a valuable means of evaluating the likely efficacy of different vision training tools that claim to improve the sport performance of athletes.The TVSH has been used to explain that many of the existing methods of testing and training vision may be ineffective to improve on-field sport performance. The TVSH suggests that the visual pathway used to control actions on-field may be different-and rely on different visual information-to the pathway often tested and trained off-field. However, the central claims of the TVSH are increasingly questioned, and this has implications for our understanding of vision and sport performance. The aim of this article is to outline the implications of the TVSH for the visual control of actions in sport. We first provide a summary of the TVSH and outline how the visual information used to control actions might differ from that usually tested. Second, we look at the evidence from studies of sports that are (and are not) consistent with the TVSH and the implications they have for training vision. Finally, we take a wider look at the impact of the TVSH on the sport sciences and other complementary theories that hold implications for training vision to improve sport performance.