ABSTRACT
Our neural machinery for visual orienting, like the rest of us, is the product of a long evolutionary history (Ingle, 1973). All vertebrates have primitive midbrain circuits for reflexively orienting the eyes toward salient events occurring in the visual periphery. In foveate mammals, including humans, these archetypal pathways function to align high acuity regions of the retina with objects of potential interest; but they must also be integrated with cortical mechanisms involved in strategic search under endogenous control. As mammals, humans have a phylogenetically new visual cortex that receives its dominant input from the retina through the thalamus (its lateral geniculate nucleus). This new system is superimposed on the ancient pathways from the retina to the midbrain, and these two systems must be coordinated to provide coherent experience and behavior.
