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Optic flow, egocentric direction and walking

Herlihey, Tracey A 2010. Optic flow, egocentric direction and walking. PhD Thesis, Cardiff University.

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This research explored two aspects of visually guided walking (1) what is the role of optic flow in the recalibration of misperceived direction while walking, and (2) how does a change in perceived direction map onto a change in walking direction. Data from five studies investigating adaptation to displaced direction (by prism glasses) suggested the following. First, optic flow is important in the recalibration of perceived direction. Further, processing optic flow is attentionally demanding, such that when cognitive load is increased, recalibration decreases. The results also demonstrated that the timecourse of recalibration changed as a function of the presence, or absence, of optic flow. With regards to the relationship between egocentric direction and walking direction, we demonstrated that a change in visual straight ahead could be mapped onto a change in target-heading error. We found that this relationship held when we unpacked the data according to the direction of displacement to which observers were exposed. The important relationship between visually perceived direction and walking direction was also highlighted in a patient study, using patients whose perception of direction was endogenously shifted after a right hemisphere stroke. Taken together, the results of this thesis help to highlight the role of optic flow in the recalibration of perceived direction, and the role of perceived direction in the visual guidance of walking. It is argued that optic flow promotes rapid recalibration of visual direction, and that change in perceived visual straight ahead can be mapped onto a changed in walking direction.

Item Type: Thesis (PhD)
Status: Unpublished
Schools: Psychology
Subjects: B Philosophy. Psychology. Religion > BF Psychology
R Medicine > RE Ophthalmology
ISBN: 9781303195785
Date of First Compliant Deposit: 30 March 2016
Last Modified: 19 Mar 2016 23:29

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