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Richard J Harris, Andrew W Young, Timothy J Andrews; The role of the pSTS in the pre-categorical coding of emotional expression. Journal of Vision 2012;12(9):783. doi: 10.1167/12.9.783.
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© ARVO (1962-2015); The Authors (2016-present)
Models of face perception suggest that information important for social communication (for example, facial expression) is processed in the posterior superior temporal sulcus (pSTS). Our aim was to determine the nature of the coding of facial expression in pSTS. In Experiment 1, fMR-adaptation was used to determine the sensitivity of pSTS to changes in facial expression and facial identity. Twenty participants were scanned while viewing faces in the following conditions: 1) same identity, same expression; 2) same identity, different expression; 3) different identity, same expression; 4) different identity, different expression. The pSTS was identified by an independent localiser scan in each participant. We found a release from adaptation in pSTS for changes in expression, but not for changes in identity. In Experiment 2, fMR-adaptation was used to investigate whether the coding of expression in the pSTS is categorical or continuous. Expression continua were generated by morphing between two expressions. From these morphed continua we selected within-category changes in expression (a 33% morph difference that did not cross the category boundary) and between-category changes in expression (a 33% morph difference that crossed the category boundary). Twenty-six participants were scanned while viewing faces in the following conditions: 1) same expression, same identity; 2) within-category expression change, same identity; 3) between-category expression change, same identity; 4) same expression, different identity; 5) within-category expression change, different identity; 6) between-category expression change, different identity. There was a release from adaptation for changes in expression, but not for changes in identity. Importantly there was an equivalent release from adaptation for within-category compared to between-category changes in expression. Our results show that pSTS is more sensitive to changes in expression than identity, and that its coding of expression is continuous rather than categorical. These findings are consistent with pSTS having a role in pre-categorical analysis of expression.
Meeting abstract presented at VSS 2012
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