Chapter 6 Visual Attention

Attention

The process of focusing on some objects while ignoring others. Attention can enhance the processing of the attended object.

Attentional capture

Occurs when stimulus salience causes an involuntary shift of attention. For example, attention can be captured by movement.

Autism

A serious developmental disorder in which one of the major symptoms is the withdrawal of contact from other people. People with autism typically do not make eye contact with others and have difficulty telling what emotions others are experiencing in social situations.

Balint's syndrome

A condition resulting from damage to a person's parietal lobe. One characteristic of this syndrome is an inability to focus attention on individual objects.

Binding

The process by which features such as color, form, motion, and location are combined to create our perception of a coherent object. Binding can also occur across senses, as when sound and vision are associated with the same object.

Binding problem

The problem of how neural activity in many separated areas in the brain is combined to create a perception of a coherent object.

Change blindness

Difficulty in detecting differences between two visual stimuli that are presented one after another, often with a short blank stimulus interposed between them. Also occurs when part of a stimulus is changed very slowly.

Conjunction search

A visual search task in which it is necessary to search for a combination (or conjunction) of two or more features on the same stimulus to find the target. An example of a conjunction search would be looking for a horizontal green line among vertical green lines and horizontal red lines.

Covert attention

Attention without looking. Seeing something "out of the corner of your eye" is an example of covert attention.

Dishabituation

An increase in looking time that occurs when a stimulus is changed. This response is used in testing infants to see whether they can differentiate two stimuli.

Dual-task procedure

An experimental procedure in which subjects are required to carry out simultaneously a central task that demands attention and a peripheral task that involves making a decision about the contents of a scene.

Feature integration theory

A theory proposed by Treisman to explain how an object is broken down into features and how these features are recombined to result in a perception of the object.

Feature search

A visual search task in which a person can find a target by searching for only one feature. An example would be looking for a horizontal green line among vertical green lines.

Fixation

The brief pause of the eye that occurs between eye movements as a person scans a scene.

Focused attention stage (of perceptual processing)

The stage of processing in feature integration theory in which the features are combined. According to Treisman, this stage requires focused attention.

Habituation

Paying less attention to the same stimulus that is presented repeatedly. For example, infants look at a stimulus less and less on each successive trial. See also dishabituation.

High-load task

Task that involves more processing resources and that therefore uses more of a person's perceptual capacity.

Illusory conjunction

Illusory combination of features that are perceived when stimuli containing a number of features are presented briefly and under conditions in which focused attention is difficult. For example, presenting a red square and a blue triangle could potentially create the perception of a red triangle.

Inattentional blindness

A situation in which a stimulus that is not attended is not perceived, even though the person is looking directly at it.

Load theory of attention

Lavie's proposal that the amount of perceptual capacity that remains as a person is carrying out a task determines how well the person can avoid being distracted by task-irrelevant stimuli. If a person's perceptual load is close to perceptual capacity, the person is less likely to be distracted by task-irrelevant stimuli. See also high-load tasks; low-load tasks; perceptual capacity; perceptual load.

Low-load task

A task that uses only a small amount of the person's perceptual capacity.

Overt attention

Attention that involves looking directly at the attended object.

Perceptual capacity

The resources a person has for carrying out perceptual tasks.

Perceptual completion

The perception of an object as extending behind occluding objects.

Perceptual load

The amount of a person's perceptual capacity needed to carry out a particular perceptual task.

Preattentive stage (of perceptual processing)

An automatic and rapid stage of processing, proposed by Treisman's feature integration theory, during which a stimulus is decomposed into individual features.

Precueing

A procedure in which a cue stimulus is presented to direct an observer's attention to a specific location where a test stimulus is likely to be presented. This procedure was used by Posner to show that attention enhances the processing of a stimulus presented at the cued location.

Saccadic eye movement

Rapid eye movement between fixations that occurs when scanning a scene.

Saliency map

A "map" of a visual display that takes into account characteristics of the display such as color, contrast, and orientation that are associated with capturing attention.

Same-object advantage

The faster responding that occurs when enhancement spreads within an object. Faster reaction times occur when a target is located within the object that is receiving the subject's attention, even if the subject is looking at another place within the object.

Scene schema

An observer's knowledge about what is contained in typical scenes. An observer's attention is affected by knowledge of what is usually found in the scene.

Scene statistics

The probability of various things occurring in the environment.

Spatial attention

Attention to a specific location.

Stimulus salience

Characteristics such as bright colors, high contrast, and highly visible orientations that cause stimuli to stand out and therefore attract attention.

Task-irrelevant stimuli

Stimuli that do not provide information relevant to the task at hand.

Visual scanning

Moving the eyes to focus attention on different locations on objects or in scenes.

Visual search

A procedure in which a person's task is to find a particular element in a display that contains a number of elements.