The hare and the snail: dissociating visual orienting from conscious perception

A method for investigating attentional effects of peripheral visual objects, independently of perceptual identification, is described. We report an experiment using this method which shows that visual processing of peripheral objects differs radically, depending on whether participants move attention in response to an object or consciously perceive that object. When luminance contrast was reduced, conscious perceptual discrimination of peripheral letters was massively slower and less accurate—but both low and high contrast letters elicited rapid attentional orienting effects and these rapid orienting effects were equal in magnitude across low and high contrast. This pattern is consistent with known differences in luminance sensitivity between the dorsal and ventral visual processing streams, and with rapid dorsal–ventral interaction mediated via re-entrant feedback. Our findings show that the control system responsible for rapid movements of attention is exquisitely sensitive to visual form information at low levels of contrast, and involves a different neurocognitive pathway to that which gives rise to conscious perception.