Mechanisms of Selective Attention in the Human Visual System: Evidence from Neuroimaging

Abstract

In this chapter, we review evidence from functional brain imaging revealing that attention operates at various processing levels within the visual system including the lateral geniculate nucleus of the thalamus and the striate and extrastriate cortex. Attention modulates visual processing by enhancing neural responses to attended stimuli, attenuating responses to ignored stimuli, and increasing baseline activity in the absence of visual stimulation. These mechanisms operate dynamically on spatial locations, entire objects, or particular features, which constitute the units of selection. At intermediate cortical processing stages such as areas V4 and MT, the filtering of unwanted information is achieved by resolving competitive interactions among multiple simultaneously present stimuli. Together, these mechanisms allow us to select relevant information from the cluttered visual world in which we live to guide behavior.