Detecting, localizing, and identifying feature singletons in visual search: how post-selective, but not pre-attentive, processing differs as a function of task set
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1
Ludwig-Maximilians-University Munich, Germany
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2
Birbeck College, University of London, United Kingdom
Over the last decades, the visual search paradigm has proved to be a test bed for competing theories of visual selective attention. In the standard paradigm, participants are presented with a display that can contain a target item amongst a variable number of distractor items, with reaction time (RT; and accuracy) being the critical performance measure(s). Interestingly, the information required to decide upon the correct motor response is highly variable across search studies, being based on, for instance, the presence, spatial location, or identity of the target item. This raises the question whether estimates of the time taken for (1) visual selection, (2) deciding on the motor response, and (3) executing it generalize across search tasks, or whether they are specific to the demands of a particular task. To examine this issue, we presented physically identical stimuli in four different search tasks – requiring target localization, detection, discrimination, and ‘compound’ responses – and combined RT performance with two specific parameters of the electroencephalogram that are directly linkable to either pre-attentive or post-selective levels of processing. Behaviourally, reactions were fastest for localization, slowest for compound, and of intermediate speed for detection and discrimination responses. At the electrophysiological level, this effect of task affected the elicitation of the stimulus- and response-locked LRP (indexing motor response decisions), but not PCN (indexing visual selection), component. This dissociation demonstrates that only the stage of pre-attentive visual coding, which mediates focal-attentional selection of the target, generalizes across task sets, whereas processes that occur after target selection are dependent on the nature of the task.
Keywords:
Attention,
visual search
Conference:
XI International Conference on Cognitive Neuroscience (ICON XI), Palma, Mallorca, Spain, 25 Sep - 29 Sep, 2011.
Presentation Type:
Poster Presentation
Topic:
Poster Sessions: Neurophysiology of Cognition and Attention
Citation:
Töllner
T,
Rangelov
D and
Müller
HJ
(2011). Detecting, localizing, and identifying feature singletons in visual search: how post-selective, but not pre-attentive, processing differs as a function of task set.
Conference Abstract:
XI International Conference on Cognitive Neuroscience (ICON XI).
doi: 10.3389/conf.fnhum.2011.207.00319
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Received:
22 Nov 2011;
Published Online:
28 Nov 2011.
*
Correspondence:
Dr. Thomas Töllner, Ludwig-Maximilians-University Munich, Munich, Germany, thomas.toellner@psy.lmu.de