Reflexive Attention Modulates Processing of Visual Stimuli in Human Extrastriate Cortex

Attention can be oriented reflexively to a location in space by an abrupt change in the visual scene. In the present study, we investigated the consequences of reflexive attention on the neural processing of visual stimuli. The findings show that reflexively oriented attention produces modulations in early sensory analysis at the same extrastriate neural locus as the earliest effects of voluntarily focused attention. In addition, stimulus processing was found to be enhanced at later stages of analysis, which reflect stimulus relevance. As is the case with behavioral measures of reflexive attention, these physiological enhancement effects are rapidly engaged but short-lived. As time passes between the initial attention-capturing event and subsequent stimuli, the extrastriate effect reverses, and the enhancement of higher order processing subsides. These findings indicate that reflexive attention is able to affect perceptions of the visual world by modulating neural processing as early as extrastriate visual cortex.