a1 McGill Vision Research Unit, Department of Ophthalmology McGill University, Montreal, Quebec, Canada
One of the most striking properties of the mammalian visual system is that it is only the central part of the visual field, the fovea, where vision is most acute. The superiority of the fovea is particularly evident in tasks requiring accurate spatial localization. It is currently thought that peripheral spatial uncertainty is a simple consequence of the decreased sampling grain of the peripheral field. We show that the topological fidelity of the afferent projection declines with eccentricity away from the fovea and that it is this rather than the sampling grain that underlies the poorer performance of the periphery in tasks involving spatial localization. The combination of normal sampling and a disordered topology results in the periphery having good sensitivity for detection but poor sensitivity for object recognition.
(Received January 03 1994)
(Accepted March 14 1994)
Reprint requests to: Robert F. Hess, McGill Vision Research Unit, Department of Ophthalmology, 687 Pine Ave West, H4-14, Montreal, Quebec, Canada H3A 1A1.