| Motion coherence thresholds in infants--different tasks identify at least two distinct motion systems. | |
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MedLine Citation:
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PMID: 12705955 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Optokinetic nystagmus (OKN) can be demonstrated from birth, but behavioural discrimination tasks such as habituation and preferential looking do not reveal any sensitivity to motion direction until a few weeks of age. This study compared coherence threshold for motion direction for OKN and preferential looking responses using closely comparable stimuli, in infants between 6 and 27 weeks of age. Infants were tested with two random dot motion displays, a uniform area of moving dots for OKN responses and a display in which a region was segmented on one side by differential motion direction for preferential looking responses. Coherence thresholds for each response were determined by a staircase method. For OKN responses, mean coherence thresholds were between 20% and 25%, with no significant improvement in OKN performance throughout the age range. Preferential looking thresholds were significantly higher than OKN thresholds. Preferential looking thresholds improved significantly with age, but remained higher than OKN thresholds throughout the age range tested. Experiments varying direction reversal frequency and stimulus area indicated that these differences were not simply a consequence of the spatial and temporal non-uniformity of the preferential looking stimulus. The differences in sensitivity levels and age trends for OKN and preferential looking responses we have found suggest that different directional mechanisms are involved in the two responses. We discuss the possibility that, in early infancy, OKN and preferential looking reflect the performance of subcortical and cortical directional mechanisms respectively. |
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Authors:
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A J S Mason; O J Braddick; J Wattam-Bell |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Vision research Volume: 43 ISSN: 0042-6989 ISO Abbreviation: Vision Res. Publication Date: 2003 May |
Date Detail:
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Created Date: 2003-04-22 Completed Date: 2003-07-21 Revised Date: 2009-11-03 |
Medline Journal Info:
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Nlm Unique ID: 0417402 Medline TA: Vision Res Country: England |
Other Details:
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Languages: eng Pagination: 1149-57 Citation Subset: IM |
Affiliation:
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Department of Psychology, Visual Development Unit, University College London, Gower Street, London WC1E 6BT, UK. alexandra.mason@ucl.ac.uk |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adult Attention / physiology Humans Infant Infant, Newborn Motion Perception / physiology* Nystagmus, Optokinetic / physiology Psychophysics Sensory Thresholds / physiology* |
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