| The simple reaction time to changes in direction of visual motion. | |
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MedLine Citation:
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PMID: 9989445 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Recently Dzhafarov et al. presented a model explaining data on simple reaction time (RT) to unidimensional velocity changes. The authors suggested that having a motion with an initial velocity V0, the velocity change detection system is reinitialized by means of a "subtractive normalization" process. Therefore, any abrupt change from V0 to V1 is detected as if it were the onset of motion with a speed equal to /V1-V0/. They derived that the RT is a function of /V1-V0/(-2/3). We tested this model for the case of two-dimensional velocity changes. Our subjects observed a random dot pattern that moved horizontally, then changed the direction of motion by an angle alpha in the range between 6 degrees and 180 degrees without changing the speed V. Speeds of 4 and 12 deg/s were used. The subjects reacted as quickly as possible to the direction change. The RTs asymptotically decreased with increasing alpha; with 12 deg/s speed the RTs were shorter than those obtained with 4 deg/s. It was shown that the data can be well described as a function of /V1-V0/(-2/3)=(2Vsin(alpha/2))(-2/3). An extension of the "subtractive normalization" hypothesis for the case of two-dimensional velocity changes is proposed. It is based on the assumption that the velocity vector V1 after the change is decomposed into two orthogonal components. Alternative explanations based on the use of position or orientation cues are shown to contradict the data. |
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Authors:
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S Mateeff; B Genova; J Hohnsbein |
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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: Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale Volume: 124 ISSN: 0014-4819 ISO Abbreviation: Exp Brain Res Publication Date: 1999 Feb |
Date Detail:
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Created Date: 1999-04-14 Completed Date: 1999-04-14 Revised Date: 2009-11-11 |
Medline Journal Info:
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Nlm Unique ID: 0043312 Medline TA: Exp Brain Res Country: GERMANY |
Other Details:
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Languages: eng Pagination: 391-4 Citation Subset: IM; S |
Affiliation:
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Institute of Physiology, Sofia, Bulgaria. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Humans Models, Biological Motion Perception / physiology* Photic Stimulation / methods Reaction Time / physiology |
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