The temporal flexibility of attentional selection in the visual cortex.

Visual attention operates by biasing competitive interactions between neural representations, favoring relevant over irrelevant visual inputs. Attention can enhance the processing of relevant information using location-based, feature-based or object-based selection mechanisms. Studies using event-related potential and event-related magnetic field recordings, together with functional magnetic resonance imaging, show that the temporal sequencing of these different selection mechanisms is flexible. Depending on the specific processing demands of the experimental task, location-based, feature-based or object-based selection might be given temporal priority on a time scale of tens of milliseconds.