VISUAL SELECTION, COVERT ATTENTION AND EYE MOVEMENTS

This chapter reviews work on visual attention. Attention is the process by which some objects or locations are selected to receive more processing than others. Two types of attention are discussed: covert attention is defined as paying attention without moving the eyes; overt attention is defined as selectively processing one location over others by moving the eyes to point at that location. Several models of covert spatial attention are discussed, including the idea that covert attention is like a spotlight or a zoom lens, and that covert attention might select information either early on in visual processing or later. The following section discusses possible relationships between covert and overt attention with three positions outlined: that they are independent; that a shift of overt attention is preceded by a shift of covert attention; or that covert attentional effects are a by-product of the overt orienting system (the pre-motor theory). The speed of covert attention and the neurophysiology of attention are discussed. Non-spatial attentional processes are reviewed including attention to objects and attention to visual properties. The chapter ends with an analysis of the role of attention within active vision, and argues that movements of the eye are the primary way in which attention is directed in vision.