Electrophysiological priming effects confirm that the extrastriate symmetry network is not gated by luminance polarity.

Marco Bertamini,Alexis D. J. Makin,John Tyson‐Carr,Andrea Piovesan,Yiovanna Derpsch,Giulia Rampone

doi:10.1111/ejn.14966

Marco Bertamini, Alexis D. J. Makin + Show 4 more

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https://doi.org/10.1111/ejn.14966

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Abstract

It is known that the extrastriate cortex is activated by visual symmetry. This activation generates an ERP component called the Sustained Posterior Negativity (SPN). SPN amplitude increases (i.e., becomes more negative) with repeated presentations. We exploited this SPN priming effect to test whether the extrastriate symmetry response is gated by element luminance polarity. On each trial, participants observed three stimuli (patterns of dots) in rapid succession (500ms. with 200ms. gaps). The patterns were either symmetrical or random. The dot elements were either black or white on a grey background. The triplet sequences either showed repeated luminance (black>black>black, or white>white>white) or changing luminance (black>white>black, or white>black>white). As predicted, SPN priming was comparable in repeated and changing luminance conditions. Therefore, symmetry with black elements is not processed independently from symmetry with white elements. Source waveform analysis confirmed that this priming happened within the extrastriate symmetry network. We conclude that the network pools information across luminance polarity channels.

Highlights

Visual symmetry has been studied extensively (Bertamini, Silvanto, Norcia, Makin, & Wagemans, 2018; Cattaneo, 2017; Treder, 2010)
Models of symmetry perception consider how local element position signals are integrated to Abbreviations: ANOVA, analysis of variance; CI, confidence interval; Classical LORETA analysis recursively applied (CLARA), classical LORETA recursively applied; ECD, equivalent current dipole; EEG, electroencephalography; EOG, electrooculogram; ERP, event related potential; fMRI, functional Magnetic Resonance imaging; ICA, independent components analysis; LCD, liquid crystal display; Lateral Occipital Complex (LOC), lateral occipital complex; LORETA, low resolution electromagnetic tomographic analysis; principle component analysis (PCA), principal component analysis; PNG, portable network graphics; Sustained Posterior Negativity (SPN), sustained posterior negativity; TMS, transcranial magnetic stimulation
Gheorghiu, Kingdom, Remkes, Li, and Rainville (2016) tested whether symmetry perception is selective for low-level properties: For example, are symmetrical arrangements of black dots coded by one neural mechanism, and symmetrical arrangements of white dots coded by another neural mechanism? In other words, we can ask whether symmetry perception mechanisms are gated by luminance polarity

Summary

| INTRODUCTION

Visual symmetry has been studied extensively (Bertamini, Silvanto, Norcia, Makin, & Wagemans, 2018; Cattaneo, 2017; Treder, 2010). Early filter-rectification and/or second order mechanisms do not always render black and white elements informationally identical and thereby abolish all anti-symmetry costs Following these themes, Gheorghiu, Kingdom, Remkes, Li, and Rainville (2016) tested whether symmetry perception is selective for low-level properties: For example, are symmetrical arrangements of black dots coded by one neural mechanism, and symmetrical arrangements of white dots coded by another neural mechanism? They claimed that “symmetry detection mechanisms pool both luminance-polarities into one channel, and extrastriate visual areas sensitive to symmetry are not gated by luminance polarity” (page 487) This non-selectivity hypothesis is partially anticipated by the work mentioned above, such as the second-order predominance account of Tyler and Hardage (1996), and filter models with an early rectification stage (Dakin & Hess, 1997).

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Findings

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