Attentional Processes

A large number of stimuli reach our sense organs at the very same time, yet we clearly do not notice all of them simultaneously -- only a selected few actually register in our awareness. The process through which certain stimuli get selected from a group of many competing stimuli is generally referred to as attention. Besides this core idea of selection, attention is also understood to involve several other properties: alertness (an individual's readiness to deal with stimuli about to appear, as seen in runners waiting tensely for the starting whistle), concentration (the focusing of awareness on certain specific objects while excluding others for the moment, as when a student focuses on a teacher's lecture while tuning out classroom noise), and search (looking for some specified subset of objects among a larger set, as when a parent scans a crowd of children to spot their own child). Because each of these requires real mental effort, attention can also be understood, in a practical sense, as a form of "effort allocation". Attention additionally has a focus -- the object or event on which our field of awareness is centred -- and a fringe, made up of objects or events that lie away from this centre and of which we remain only vaguely aware. …