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This Article Full Text Full Text (PDF) All Versions of this Article: 573/3/741    most recent jphysiol.2006.105387v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Taylor, M. J. Articles by Anderson, A. J. Search for Related Content PubMed PubMed Citation Articles by Taylor, M. J. Articles by Anderson, A. J. Related Collections Neuroscience

¹ The Physiological Laboratory, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK

One of the most important factors affecting the time taken to respond to a visual stimulus is contrast, and studies of reaction time can provide precise, quantitative information about the underlying signal processing. In this study we measured both saccadic and manual reaction times to step increments in target contrast. Our results over a range of initial contrasts are consistent with a simple model consisting of a noisy logarithmic transducer followed by a rise-to-threshold accumulator. A systematic comparison with previous contrast-processing models also shows that the commonly used method of linear regression may not be a particularly sensitive tool in deciding between them. We found similar parameters for the contrast processor in both saccadic and manual reaction times, as might be expected if a common target detection stage precedes each type of reaction.

(Received 15 January 2006; accepted after revision 11 April 2006; first published online 13 April 2006)
Corresponding author R. H. S. Carpenter: The Physiological Laboratory, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK. Email: rhsc1{at}cam.ac.uk