Visual symmetry in objects and gap

Makin, Alexis and Rampone, Giulia and Wright, Alexander and Martinovic, Jasna and Bertamini, Marco (2014) Visual symmetry in objects and gap. Journal of Vision, 14,12. pp. 1-12. ISSN 1534-7362


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It is known that perceptual organization modulates the
salience of visual symmetry. Reflectional symmetry is
more quickly detected when it is a property of a single
object than when it is formed by a gap between two
objects. Translational symmetry shows the reverse
effect, being more quickly detected when it is a gap
between objects. We investigated the neural correlates
of this interaction. Electroencephalographic data was
recorded from 40 participants who were presented with
reflected and translated contours in one- or two-object
displays. Half of the participants discriminated regularity,
half distinguished number of objects. An event-related
potential known as the Sustained Posterior Negativity
(SPN) distinguished between reflection and translation.
A similar ERP distinguished between one and two object
presentations, but these waves summed with the SPN,
rather than altering it. All stimuli produced
desynchronization of 8?13 Hz alpha oscillations over the
bilateral parietal cortex. In the Discriminate Regularity
group, this effect was right lateralized. The SPN and
alpha desynchronization index different stages of visual
symmetry discrimination. However, neither component
displayed the Regularity · Objecthood interaction that
is observed in speeded discrimination tasks, suggesting
that integration of visual regularity with objectness is
not inevitable. Instead, both attributes may be
processed in parallel and independently.

Item Type: Article
Keywords: perceptual organization, visual symmetry, ERPs, objectness
Faculty / Department: Faculty of Science > Psychology
Depositing User: Giulia Rampone
Date Deposited: 30 Sep 2016 12:31
Last Modified: 04 Feb 2018 15:28

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