Attentional Selection for Locations, Features, and Objects in Vision

This chapter describes neurophysiological research in humans that provides insights into the neural mechanisms mediating the different modes of attentional function. It addresses mechanisms of location selection, with a particular focus on the neural operations that determine the spatial profile of the focus of attention. It discusses data indicating that the latter is not fixed, but varies depending on top-down (voluntary or goal-directed) requirements on target selection of a given task. The evidence reviewed here is pertinent to resolving a longstanding debate about the nature of what has been metaphorically referred to as the spotlight of attention. The chapter then reviews signatures of feature based selection and focuses on mechanisms and conditions underlying its operation in a spatially global way. Finally, it considers findings that have documented the operation of object-based attention and discusses mechanisms that grant priority over feature selection. In general, it is argued that attentional selection based on locations, features, or objects is not subserved by a single neural process, but that different neural mechanisms are coordinated to operate on a tight spatiotemporal scale, to enable the organism to perceive and act in a complex and rapidly changing environment.