Scaling of the extrastriate neural response to symmetry

Palumbo, Letizia and Bertamini, Marco and Makin, Alexis James (2015) Scaling of the extrastriate neural response to symmetry. Vision Research, 117. pp. 1-8. ISSN 0042-6989

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Abstract

Neuroimaging work has shown that visual symmetry activates extrastriate brain areas, most consistently the lateral occipital complex (LOC). LOC activation increases with proportion of symmetrical dots (pSymm) in a degraded display. In the current work, we recorded a posterior ERP called the sustained posterior negativity (SPN), which is relatively negative for symmetrical compared to random patterns. We predicted that SPN would also scale with pSymm, because it is probably generated by the LOC. Twenty-four participants viewed dot patterns with different levels of regularity: 0% regularity (full random configuration) 20%, 40%, 60%, 80%, and 100% (full reflection symmetry). Participants judged if the pattern contained “some regularity” or “no regularity”. As expected, the SPN amplitude increased with pSymm, while the latency and duration was the same in all conditions. The SPN was independent of the participant’s decision, and it was present on some trials where people reported ‘no-regularity’. We conclude that the SPN is generated at an intermediate stage of visual processing, probably in the LOC, where perceptual goodness is represented. This comes after initial visual analysis, but before subsequent decision stages, which apply a threshold to the analog LOC response.

Item Type:	Article
Additional Information and Comments:	“NOTICE: this is the author’s version of a work that was accepted for publication in Vision Research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Vision Research, [VOL 117, (December 2015)] doi:10.1016/j.visres.2015.10.002¨ Creative Commons Attribution Non-Commercial No Derivatives License
Keywords:	Symmetry; EEG; ERPs; Sustained posterior negativity; perceptual goodness
Faculty / Department:	Faculty of Human and Digital Sciences > School of Psychology
Depositing User:	Pauline Bray
Date Deposited:	25 Feb 2016 12:29
Last Modified:	26 Feb 2016 16:10
URI:	https://hira.hope.ac.uk/id/eprint/750

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