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Expansion of direction space around the cardinal axes revealed by smooth pursuit eye movementsIt is well established that perceptual direction discrimination shows an oblique effect; thresholds are higher for motion along diagonal directions than for motion along cardinal directions. Here, we compare simultaneous direction judgments and pursuit responses for the same motion stimuli and find that both pursuit and perceptual thresholds show similar anisotropies. The pursuit oblique effect is robust under a wide range of experimental manipulations, being largely resistant to changes in trajectory (radial versus tangential motion), speed (10 versus 25 deg/s), directional uncertainty (blocked versus randomly interleaved), and cognitive state (tracking alone versus concurrent tracking and perceptual tasks). Our data show that the pursuit oblique effect is caused by an effective expansion of direction space surrounding the cardinal directions and the requisite compression of space for other directions. This expansion suggests that the directions around the cardinal directions are in some way overrepresented in the visual cortical pathways that drive both smooth pursuit and perception.
Document ID
Document Type
Reprint (Version printed in journal)
Krukowski, Anton E. (NASA Ames Research Center Moffett Field, CA United States)
Stone, Leland S.
Date Acquired
August 23, 2013
Publication Date
January 20, 2005
Publication Information
Publication: Neuron
Volume: 45
Issue: 2
ISSN: 0896-6273
Subject Category
Life Sciences (General)
Distribution Limits