Surprise leads to noisier perceptual decisions

doi:10.1068/i0411

Surprise leads to noisier perceptual decisions

Marta I Garrido

Wellcome Trust Centre for Neuroimaging, University College London, London WC1N 3BG, England

m.garrido@fil.ion.ucl.ac.uk

Raymond J Dolan

Wellcome Trust Centre for Neuroimaging, University College London, London WC1N 3BG, England

r.dolan@ucl.ac.uk

Maneesh Sahani

Gatsby Computational Neuroscience Unit, University College London, London WC1N 3AR, England

maneesh@gatsby.ucl.ac.uk

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Abstract. Surprising events in the environment can impair task performance. This might be due to complete distraction, leading to lapses during which performance is reduced to guessing. Alternatively, unpredictability might cause a graded withdrawal of perceptual resources from the task at hand and thereby reduce sensitivity. Here we attempt to distinguish between these two mechanisms. Listeners performed a novel auditory pitch–duration discrimination, where stimulus loudness changed occasionally and incidentally to the task. Responses were slower and less accurate in the surprising condition, where loudness changed unpredictably, than in the predictable condition, where the loudness was held constant. By explicitly modelling both lapses and changes in sensitivity, we found that unpredictable changes diminished sensitivity but did not increase the rate of lapses. These findings suggest that background environmental uncertainty can disrupt goal-directed behaviour. This graded processing strategy might be adaptive in potentially threatening contexts, and reflect a flexible system for automatic allocation of perceptual resources. prediction, change detection, uncertainty, attention, sensitivity, oddballs.

Cite as: Garrido M I, Dolan R J, Sahani M, 2011, "Surprise leads to noisier perceptual decisions" i-Perception 2(2) 112–120
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DOI: 10.1068/i0411

ISSN: 2041-6695 (electronic only)

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