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When is now? Perception of simultaneity

Stone, J.V., Hunkin, N.M., Porrill, J., Wood, R., Keeler, V., Beanland, M., Port, M. and Porter, N.R. (2001) When is now? Perception of simultaneity. Proceedings of the Royal Society B: Biological Sciences, 268 (1462). pp. 31-38. ISSN 1471-2954


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We address the following question: Is there a difference (D) between the amount of time for auditory and visual stimuli to be perceived? On each of 1000 trials, observers were presented with a light-sound pair, separated by a stimulus onset asynchrony (SOA) between-250 ms (sound first) and 250 ms. Observers indicated if the light-sound pair came on simultaneously by pressing one of two (yes or no) keys. The SOA most likely to yield affirmative responses was defined as the point of subjective simultaneity (PSS). PSS values were between-21 ms (i.e. sound 21ms before light) and 150 ms.

Evidence is presented that each PSS is observer specific. In a second experiment, each observer was tested using two observerstimulus distances. The resultant PSS values are highly correlated (r = 0.954, p = 0.003) suggesting that each observer's PSS is stable. PSS values were significantly affected by observer-stimulus distance, suggesting that observers do not take account of changes in distance on the resultant difference in arrival times of light and sound. The difference RTd in simple reaction time to single visual and auditory stimuli was also estimated; no evidence that RTd is observer specific or stable was found. The implications of these findings for the perception of multisensory stimuli are discussed.

Item Type: Article
Copyright, Publisher and Additional Information: © 2001 The Royal Society. Reproduced in accordance with the publisher's self-archiving policy.
Institution: The University of Sheffield
Academic Units: The University of Sheffield > Faculty of Science (Sheffield) > Department of Psychology (Sheffield)
Depositing User: Repository Assistant
Date Deposited: 30 Jun 2006
Last Modified: 06 Jun 2014 17:45
Published Version: http://www.journals.royalsoc.ac.uk/openurl.asp?gen...
Status: Published
Publisher: The Royal Society Publishing
Refereed: Yes
Identification Number: 10.1098/rspb.2000.1326
URI: http://eprints.whiterose.ac.uk/id/eprint/1433

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