Cite as:
Morvan C, Wexler M, 2004, "Early compensation for smooth-pursuit eye movement in motion detection" Perception 33 ECVP Abstract Supplement

Early compensation for smooth-pursuit eye movement in motion detection

C Morvan, M Wexler

To detect object motion, the visual system has to differentiate between self-produced retinal image slip and retinal slip resulting from physical object motion. Indeed, when an observer moves (his body, head, or eyes), the retinal projection of the distal world moves on the retina, thus activating retinocentric motion detectors. To optimise the detection of motion, the system has to compute real or 'allocentric' motion from the information provided by the retina and the extra-retinal signals. From studies of compensation (the phenomenon by which retinal and extra-retinal signals are combined), it is not yet clear when and where this compensation occurs (Thier et al, 2001 NeuroImage 14 S33 - S39; Tikhonov et al, in press NeuroImage; Bach and Hoffmann, 2000 Vision Research 40 2379 - 2385), nor what happens before it takes place. We used a modified visual-search paradigm to characterise the reference frame of motion detection. We found that motion detection is already allocentric for stimulus durations as short as 150 ms. For shorter durations, motion detection is retinocentric. These results indicate that compensation occurs very quickly (150 ms) after image onset and that another mechanism, retinocentric, is available prior to that but in a sub-optimal fashion.

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