Purchase this article with an account.
John P. Wann, Richard M. Wilkie; Can we judge heading “in an instant”?. Journal of Vision 2004;4(8):792. doi: 10.1167/4.8.792.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
A key component of controlling our locomotion through the world is optic flow. We have previously demonstrated that even when flow is highly degraded it can support accurate steering (Wilkie & Wann, 2002). But the coupling between perceived flow and action is less clear. In some models of locomotion perceived heading is considered as a fundamental part of control. We have promoted an alternative account whereby fixating points along your future path could be the basis of an efficient control solution. Here we aimed to establish whether observers could identify their instantaneous heading or their path by measuring how accurately they could identify each feature when travelling along straight, curved or changing paths. The results showed that when travelling along straight paths, with gaze initially averted, observers could accurately saccade to either their heading or path “in an instant” (?3°). On curved paths, however, they were more accurate at generating a saccade to a point on their future path (?5°) than to their instantaneous heading (?13°). We discounted the effects of OKN as a cause of this effect. We then tested observers ability to track changes in instantaneous heading or changes in path curvature. Participants could match path changes quite accurately, but they were unable to match the rate of change of heading. In light of these results we suggest it is unlikely that heading is primarily used by the visual system to support active steering.
This PDF is available to Subscribers Only