Document Detail

Exploring the third dimension with eye movements: better than stereopsis.
MedLine Citation:
PMID:  1949624     Owner:  NLM     Status:  MEDLINE    
Eye movements are usually presumed to be irrelevant for (or detrimental to) stereoacuity. When targets of interest are not adjacent, however, better discrimination of distance can be achieved by looking back and forth between them. In order to exclude ordinary stereopsis and examine this viewing strategy in isolation, judgements of apparent equidistance have been obtained for pairs of small targets separated horizontally by the angular spacing that corresponds to the fovea-to-blind-spot distance. Precise, stereopsis-like evaluations of relative distance can be made by fixating each of those targets in turn, even if they are not simultaneously presented but are instead shown in alternation. Sequential comparisons of stimuli are thus involved in this form of distance discrimination, but direct utilization of oculomotor information (vergence) is rendered unlikely because very brief target presentation is sufficient. Hence, the evidence argues for "sequential stereopsis": comparisons of the disparities of targets, both seen foveally, before and after saccades. This interpretation makes stringent demands on oculomotor coordination during saccades, but measurements of vergence "noise" indicate that this requirement can probably be fulfilled.
J T Enright
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Vision research     Volume:  31     ISSN:  0042-6989     ISO Abbreviation:  Vision Res.     Publication Date:  1991  
Date Detail:
Created Date:  1991-12-17     Completed Date:  1991-12-17     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0417402     Medline TA:  Vision Res     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  1549-62     Citation Subset:  IM    
Neurobiology Unit, A-002, Scripps Institution of Oceanography, La Jolla, CA 92093.
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MeSH Terms
Convergence, Ocular / physiology
Depth Perception / physiology
Discrimination (Psychology) / physiology
Distance Perception / physiology
Eye Movements / physiology*
Fixation, Ocular
Middle Aged
Optic Disk / physiology
Saccades / physiology
Sensory Thresholds / physiology
Vision Disparity / physiology*

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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