Physiological Aspects of Visual Perception

To the Editor.—  Dr Denny-Brown's highly personal view of the primate visual system as propounded in his Bennett lecture (Arch Neurol 33:219, 1976) is sufficiently at variance with other work in the field that some comment is necessary. The division of visual perception into object vision-vision for cognitive detail-and panoramic vision-vision for spatial localization and behavioral import-is heuristically useful, and has been discussed in detail^. However, the bulk of behavioral and physiological evidence must assign the superior colliculus to participation in "panoramic" rather than "object" vision.Dr Denny-Brown's arguments hinge on the drastic effects of collicular ablation in his hands. He argues that "complete removal of the superior colliculus resulted in the same loss of visual object identification, binocular fixation, and visuosocial behavior that followed removal of area 17." Most other investigators have failed to show such dramatic deficits from collicular ablation. Thus, Rosvold et al² showed that monkeys with