attentional blink Following the identification of a target in a rapid sequential stream of stimuli, there is temporary impairment in identifying a second target stimulus that occurs shortly after the first. It is as if attention has "blinked" after identifying the first target, preventing subsequent target detection.

binding problem The problem of determining which elementary visual features, such as color, shape, or size, belong to the same stimulus. Spatial attention allows elementary features to be bound or grouped together.

grouped-array representation A spatial representation that contains perceptual grouping information. Image features (e.g., line segments) are grouped to form larger structures, such as surfaces or regions.

neglect (also extinction) A neuropsychological disorder of visual attention that follows damage to the posterior parietal region. Patients with neglect fail to attend to events on the side of space opposite the lesioned hemisphere. As patients recover from neglect, they demonstrate extinction, a form of transient neglect that occurs when events occur on both sides of space simultaneously.

object-centered representation A representation of an object that encodes the properties of the object, such as parts, relative to a reference point on the object itself, such as a principle axis.

visual search The process used to find a visual target (i.e., how you find what you are looking for). Both elementary visual features, such as color, shape, or size, and focal visual attention combine to guide the search for a target.

At any given moment, the sensory systems in your brain are receiving thousands of simultaneous environmental inputs. Some of these inputs are relevant to your current behavior and others are irrelevant. The visual words printed on a page are relevant to reading, but the visual impression of the desk on which the pages lie is irrelevant to reading. Furthermore, some of the inputs in one modality have correspondences with inputs in another modality, as in the link between a person's visual appearance and the speech uttered by that individual. Because we cannot process all inputs simultaneously, there must exist processes that select some inputs and filter out others. These processes collectively are referred to as ''attention.''

The study of attention has a long history in both the cognitive and brain sciences. Although early research implicitly assumed that attention is a single, monolithic process, an emerging view that we endorse is that there are multiple forms of attentional selection. Attention can select stimuli at specific locations in vision, audition, or touch; attention also can select entire objects, not just locations. Furthermore, attention selects not only stimulus inputs but also mental functions such as behavioral goals or tasks: You can attend to the task of reading instead of the task of identifying a font type. To understand attention requires studying these multiple forms of selection, their similarities and dissimilarities, and their neural foundations.

Encyclopedia of the Human Brain Volume 1

Copyright 2002, Elsevier Science (USA).

All rights reserved.

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