Perceived direction during monocular viewing is based on signals of the viewing eye only.
Perceived visual directions are derived from combining retinal signals and oculomotor signals. Up to now the general belief is that the oculomotor signals of the two eyes are first pooled before they become available for perception of depth and direction. In this sense the eyes are believed to act together as one unit known as the cyclopean eye. This study, however, shows that during monocular viewing in daylight conditions, the perceived directions of objects are indicated by their retinal locus in combination with the angular position of the viewing eye only, the angular position of the closed eye being irrelevant. This result indicates that in binocular vision the integration of left and right eye signals first occurs after retinal and oculomotor signals have been integrated of each eye separately. This conclusion challenges the prevailing concept of cyclopean vision and current views about stereoscopic depth perception.
Helmholtz Institute, Utrecht University, P.O. Box 80.000, 3508 TA, Utrecht, The Netherlands. c.j.erkelens@phys.uu.nl
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D000328:Adult; D003867:Depth Perception / Q000502:physiology*; D005133:Eye Movements / Q000502:physiology; D006801:Humans; D008029:Lighting; D008875:Middle Aged; D011601:Psychophysics; D012160:Retina / Q000502:physiology; D015348:Vision, Binocular / Q000502:physiology; D015349:Vision, Monocular / Q000502:physiology*