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Perceptual grouping in rapid visuomotor processing

  • Perceptual grouping is an integral part of visual object recognition. It organizes elements within our visual field according to a set of heuristics (grouping principles), most of which are not well understood. To identify their temporal processing dynamics (i.e., to identify whether they rely on neuronal feedforward or recurrent activation), we introduce the primed flanker task that is based on a firm empirical and theoretical background. In three sets of experiments, participants responded to visual stimuli that were either grouped by (1) similarity of brightness, shape, or size, (2) symmetry and closure, or (3) Good Gestalt. We investigated whether these grouping cues were effective in rapid visuomotor processing (i.e., in terms of response times, error rates, and priming effects) and whether the results met theory-driven indicators of feedforward processing. (1) In the first set of experiments with similarity cues, we varied subjective grouping strength and found that stronger grouping in the targets enhanced overall response times while stronger grouping in the primes enhanced priming effects in motor responses. We also obtained differences between rapid visuomotor processing and the subjective impression with cues of brightness and shape but not with cues of brightness and size. These results show that the primed flanker task is an objective measure for comparing different feedforward-transmitted groupings. (2) In the second set of experiments, we used the task to study grouping by symmetry and grouping by closure that are more complex than similarity cues. We obtained results that were mostly in accordance with a feedforward model. Some other factors (line of view, orientation of the symmetry axis) were irrelevant for processing of symmetry cues. Thus, these experiments suggest that closure and (possibly) viewpoint-independent symmetry cues are extracted rapidly during the first feedforward wave of neuronal processing. (3) In the third set of experiments, we used the task to study grouping by Good Gestalt (i.e., visual completion in occluded shapes). By varying the amount of occlusion, we found that the processing was in accordance with a feedforward model only when occlusion was very limited. Thus, these experiments suggest that Good Gestalt is not extracted rapidly during the first feedforward wave of neuronal processing but relies on recurrent activation. I conclude (1) that the primed flanker task is an excellent tool to identify and compare the processing characteristics of different grouping cues by behavioral means, (2) that grouping strength and other factors are strongly modulating these processing characteristics, which (3) challenges a dichotomous classification of grouping cues based on feedforward vs. recurrent processing (incremental grouping theory, Roelfsema, 2006), and (4) that a focus on temporal processing dynamics is necessary to understand perceptual grouping.

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Author:Filipp Schmidt
URN (permanent link):urn:nbn:de:hbz:386-kluedo-37973
Advisor:Thomas Schmidt
Document Type:Doctoral Thesis
Language of publication:English
Publication Date:2014/05/13
Year of Publication:2014
Publishing Institute:Technische Universität Kaiserslautern
Granting Institute:Technische Universität Kaiserslautern
Acceptance Date of the Thesis:2014/04/29
Date of the Publication (Server):2014/05/13
Tag:Closure; Grouping by similarity; Perceptual grouping; Response Priming; Self-splitting objects; Symmetry
Number of page:IX, 121
Source:Schmidt, F. & Schmidt, T. (2014). Rapid information processing of viewpoint-invariant symmetry. Psychological Research, 78, 37-54. Link: http://link.springer.com/article/10.1007/s00426-013-0478-8
Source:Schmidt, F., & Schmidt, T. (2013). Grouping principles in direct competition. Vision Research, 88, 9-21. Link: http://www.sciencedirect.com/science/article/pii/S0042698913001454
Faculties / Organisational entities:Fachbereich Sozialwissenschaften
DDC-Cassification:1 Philosophie und Psychologie / 150 Psychologie
Licence (German):Standard gemäß KLUEDO-Leitlinien vom 10.09.2012