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Visual speech perception in foveal and extrafoveal vision : further implications for divisions in hemispheric projections

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posted on 09.09.2014, 13:48 by Timothy R. Jordan, Mercedes Sheen, Lily Abedipour, Kevin B. Paterson
When observing a talking face, it has often been argued that visual speech to the left and right of fixation may produce differences in performance due to divided projections to the two cerebral hemispheres. However, while it seems likely that such a division in hemispheric projections exists for areas away from fixation, the nature and existence of a functional division in visual speech perception at the foveal midline remains to be determined. We investigated this issue by presenting visual speech in matched hemiface displays to the left and right of a central fixation point, either exactly abutting the foveal midline or else located away from the midline in extrafoveal vision. The location of displays relative to the foveal midline was controlled precisely using an automated, gaze-contingent eye-tracking procedure. Visual speech perception showed a clear right hemifield advantage when presented in extrafoveal locations but no hemifield advantage (left or right) when presented abutting the foveal midline. Thus, while visual speech observed in extrafoveal vision appears to benefit from unilateral projections to left-hemisphere processes, no evidence was obtained to indicate that a functional division exists when visual speech is observed around the point of fixation. Implications of these findings for understanding visual speech perception and the nature of functional divisions in hemispheric projection are discussed.

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Citation

PLoS One, 2014, 9 (7), pp. e98273

Author affiliation

/Organisation/COLLEGE OF MEDICINE, BIOLOGICAL SCIENCES AND PSYCHOLOGY/Themes/Neuroscience & Behaviour

Version

VoR (Version of Record)

Published in

PLoS One

Publisher

Public Library of Science

eissn

1932-6203

Copyright date

2014

Available date

09/09/2014

Publisher version

http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098273

Notes

PMCID: PMC4102446

Language

en

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