| The discrimination of abrupt changes in speed and direction of visual motion. | |
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MedLine Citation:
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PMID: 10820621 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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A random dot pattern that moved within an invisible aperture was used to present two motions contiguously in time. The motions differed slightly either in speed (Experiments 1 and 3) or in direction (Experiments 2 and 4) and the subject had to discriminate the sign of the change (e.g. increment or decrement). The same discrimination task was performed when the two motions were temporally separated by 1 s. In Experiments 1 and 2 discrimination thresholds were measured with motion durations of 0.125, 0.25, 0.5 and 1.0 s and mean speeds of 2, 4, 8, and 16 degrees/s. In Experiments 3 and 4 thresholds were measured with aperture widths of 5 and 20 cm. The discrimination of contiguous motions progressively deteriorated with decreasing duration and mean speed of motion. For the lowest value of duration the Weber fraction for contiguous speeds was more than three times as the Weber fractions for separate speeds. For the same low value of duration the thresholds for discrimination of direction of contiguous motions were only about 50% higher than the thresholds for separate motions. The Weber fraction for contiguous speeds was ca. three times higher with the smaller aperture than with the larger one, provided the ratio 'aperture width mean speed' (i.e. the lifetime of the moving dots) was less than 0.3 s. Aperture width did not affect the discrimination of direction of contiguous motions. The discrimination of contiguous motions is discussed together with the known data for detection of changes in speed and direction. It is suggested that both, detection of changes in speed and discrimination of the sign of speed changes, may be performed by a common visual mechanism. |
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Authors:
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S Mateeff; G Dimitrov; B Genova; L Likova; M Stefanova; J Hohnsbein |
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: 40 ISSN: 0042-6989 ISO Abbreviation: Vision Res. Publication Date: 2000 |
Date Detail:
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Created Date: 2000-06-06 Completed Date: 2000-06-06 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: 409-15 Citation Subset: IM; S |
Affiliation:
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Institut für Arbeitsphysiologie, Dortmund, Germany. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adult Differential Threshold / physiology Discrimination (Psychology) / physiology* Female Humans Male Motion Perception / physiology* Time Factors |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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