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Filipp Schmidt, Thomas Schmidt; Closure versus symmetry: rapid competition of two grouping principles in a primed flanker paradigm. Journal of Vision 2011;11(11):1088. doi: 10.1167/11.11.1088.
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© ARVO (1962-2015); The Authors (2016-present)
Grouping processes are exceedingly important to organize our environment into coherent units. However, perceptual grouping is no unitary process but a mixture of several coexisting mechanisms which seem to vary fundamentally in their time course and attentional demands. We performed two experiments to compare the time courses of two different perceptual grouping principles (grouping by closure and by symmetry) in response priming effects. Primes and targets were arranged in a flanker paradigm, such that two primes were presented side by side at the center of the screen. Targets appeared after a systematically varied stimulus-onset asynchrony (SOA) and flanked the primes. Primes and targets were stimuli from the same pool (Exp. 1: systematically produced shapes, Exp. 2: random shapes), where each single stimuli could be classified with respect to the both dimensions of closure-openness and symmetry-asymmetry. Participants should either respond to the openness or symmetry of the targets, whereat primes could trigger the same or conflicting responses. Response times and error rates showed differences in their magnitude and priming effects depending on SOA and response-relevant grouping principle. In general, grouping by closure was faster and more efficient than that by symmetry. We conclude that both principles are in fact considerably different regarding their time course and influences on the visuomotor system, especially with regards to early visual processing.
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