| Recruitment mechanisms in speed and fine-direction discrimination tasks. | |
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MedLine Citation:
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PMID: 9463695 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The minimum information necessary to specify motion requires a change in position across time. Previous studies have shown that human motion measurements improve with more than two frames of motion. This study clarifies how motion information is integrated to produce the best speed and direction discrimination. Using random-dot kinematograms, fine-direction discrimination thresholds and speed discrimination thresholds are assessed as a function of dot lifetime. Specifically, we ask if performance on both tasks depends on dot lifetime in the same manner. If both speed and direction discrimination performance improve the same way with increasing dot lifetime, this would indicate that both tasks have the same integration limit and both tasks may depend on the same underlying mechanisms. Experiment 1 shows that for both tasks a four-frame dot lifetime is necessary for observers to reach asymptotic threshold levels. The absolute level of performance improves with increasing stimulus duration or signal-to-noise ratio, but the integration limit itself does not vary. Experiment 2 examines whether this integration limit is constrained by the number of frames or by the temporal duration of the dot lifetime. The data in Experiment 2 suggest that both a minimum number of samples and a minimal temporal integration period determine the integration limit for recruitment mechanisms. The results suggest that speed and fine-direction discrimination depend upon the same underlying motion mechanisms. These results are discussed in relation to possible underlying physiological substrates and computational models of motion measurement. |
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Authors:
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E K Festa; L Welch |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Vision research Volume: 37 ISSN: 0042-6989 ISO Abbreviation: Vision Res. Publication Date: 1997 Nov |
Date Detail:
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Created Date: 1998-03-02 Completed Date: 1998-03-02 Revised Date: 2006-11-15 |
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: 3129-43 Citation Subset: IM; S |
Affiliation:
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Department of Psychology, Brown University, Providence, RI 02912, USA. Elena_Festa@Brown.Edu |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Discrimination (Psychology)
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physiology* Humans Motion Perception / physiology* Photic Stimulation / methods Psychophysics Recruitment, Neurophysiological* Sensory Thresholds Time Factors |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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