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Separate visual representations for perception and for visually guided behaviorConverging evidence from several sources indicates that two distinct representations of visual space mediate perception and visually guided behavior, respectively. The two maps of visual space follow different rules; spatial values in either one can be biased without affecting the other. Ordinarily the two maps give equivalent responses because both are veridically in register with the world; special techniques are required to pull them apart. One such technique is saccadic suppression: small target displacements during saccadic eye movements are not preceived, though the displacements can change eye movements or pointing to the target. A second way to separate cognitive and motor-oriented maps is with induced motion: a slowly moving frame will make a fixed target appear to drift in the opposite direction, while motor behavior toward the target is unchanged. The same result occurs with stroboscopic induced motion, where the frame jump abruptly and the target seems to jump in the opposite direction. A third method of separating cognitive and motor maps, requiring no motion of target, background or eye, is the Roelofs effect: a target surrounded by an off-center rectangular frame will appear to be off-center in the direction opposite the frame. Again the effect influences perception, but in half of the subjects it does not influence pointing to the target. This experience also reveals more characteristics of the maps and their interactions with one another, the motor map apparently has little or no memory, and must be fed from the biased cognitive map if an enforced delay occurs between stimulus presentation and motor response. In designing spatial displays, the results mean that what you see isn't necessarily what you get. Displays must be designed with either perception or visually guided behavior in mind.
Document ID
19900013615
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Bridgeman, Bruce (California Univ. Santa Cruz, CA, United States)
Date Acquired
September 6, 2013
Publication Date
July 1, 1989
Publication Information
Publication: NASA, Ames Research Center, Spatial Displays and Spatial Instruments
Subject Category
Man/System Technology And Life Support
Accession Number
90N22931
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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