The blinking spotlight of attention
- *Centre de Recherche Cerveau et Cognition, Université Paul Sabatier, Université de Toulouse, 31062 Toulouse Cedex 9, France;
- †Centre National de la Recherche Scientifique, Unité Mixte de la Recherche 5549, Faculté de Médecine de Rangueil, 31062 Toulouse, France;
- ‡Department of Psychology, Harvard University, 33 Kirkland Street, Cambridge, MA 02138;
- ¶Helmholtz Institute, Utrecht University, 3508 TC Utrecht, The Netherlands; and
- ‖Laboratoire de Psychologie de la Perception, Université Paris Descartes, 45 Rue des Saint-Pères, 75270 Paris Cedex 6, France
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Edited by Dale Purves, Duke University Medical Center, Durham, NC, and approved October 19, 2007 (received for review August 6, 2007)
Abstract
Increasing evidence suggests that attention can concurrently select multiple locations; yet it is not clear whether this ability relies on continuous allocation of attention to the different targets (a “parallel” strategy) or whether attention switches rapidly between the targets (a periodic “sampling” strategy). Here, we propose a method to distinguish between these two alternatives. The human psychometric function for detection of a single target as a function of its duration can be used to predict the corresponding function for two or more attended targets. Importantly, the predicted curves differ, depending on whether a parallel or sampling strategy is assumed. For a challenging detection task, we found that human performance was best reflected by a sampling model, indicating that multiple items of interest were processed in series at a rate of approximately seven items per second. Surprisingly, the data suggested that attention operated in this periodic regime, even when it was focused on a single target. That is, attention might rely on an intrinsically periodic process.
Footnotes
- §To whom correspondence should be addressed. E-mail: rufin{at}klab.caltech.edu
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Author contributions: R.V., T.C., and P.C. designed research; R.V. performed research; R.V. analyzed data; and R.V., T.C., and P.C. wrote the paper.
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The authors declare no conflict of interest.
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This article is a PNAS Direct Submission.
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This article contains supporting information online at www.pnas.org/cgi/content/full/0707316104/DC1.
- © 2007 by The National Academy of Sciences of the USA
