Attention

Attention

A mechanism that selects information for continued cognitive processing.

Why is attention limited

People have limited attentional resources and cannot fully perform multiple demanding continuous tasks at the same time.

Parallel performance

Truly performing two tasks at the same time.

Do people perform two demanding continuous tasks in parallel

Usually no; performance declines because attention is limited or switches between tasks.

Dual task paradigm

A method that tests attention limits by having a person perform two continuous tasks at the same time.

Attentional resources

The limited mental resources required to perceive, think, and respond during a task.

What determines how many attentional resources a task needs

Task difficulty and context; for example, driving in a busy city requires more resources than driving on an empty back road.

Multiple resource theory

Tasks interfere less when they draw on different resource pools and interfere more when they use the same resources.

Wickens' resource dimensions

Processing stage, verbal versus spatial code, and input and output modalities.

Example of tasks that compete for the same resource pool

Playing a visual video game while visualizing a room; both require visual spatial resources.

Allocation of attention

Directing available attention toward the location, object, or task that is most important.

Can attention be allocated flexibly

Yes; people can direct attention to different areas and can broaden or narrow it, although splitting attention reduces performance.

Posner's spotlight view

Attention acts like one spotlight and cannot be split.

Sperling and Melchner result

People could divide attention between inner and outer letter arrays, but detection was lower when attention was split than when it was focused.

Automaticity

Performing a practiced task with few attentional resources and little conscious intention.

Effect of practice on attention

With practice, a task becomes more automatic and demands fewer attentional resources.

Selective attention

Selecting some information for processing while other stimuli receive little or no further processing.

Attention as a filter

Attention filters information so that selected stimuli receive further processing and unattended stimuli receive less processing.

Dichotic listening task

A task in which different auditory messages are played to each ear and the participant shadows or repeats the message in one attended ear.

Shadowing

Repeating aloud the message presented to the attended ear in a dichotic listening task.

Early selection model

Attention filters information early, after basic physical features are processed but before most meaning or semantics are processed.

Early selection evidence from dichotic listening

Participants notice physical changes in the unattended message, such as a voice or sound change, but usually do not notice changes in meaning.

Late selection model

Attention can sometimes select information after meaning has been processed.

Late selection evidence from dichotic listening

A meaningful unattended stimulus, especially a person's own name, can break through into awareness.

Why does hearing your own name support late selection

The name must receive some semantic processing before it can be recognized as personally meaningful.

Best conclusion about the attentional filter

The filter is flexible but is usually prioritized early; all stimuli receive basic physical processing and some unattended meaning can break through.

What does attention select

Attention can select spatial locations, but evidence shows it often selects whole objects.

Object based attention

Attention prioritizes one complete object over parts of two separate objects, even when distances are similar.

Disjunctive visual search

Searching for a target defined by one unique feature among distractors.

Example of a disjunctive search

Finding a Q among Ts when the Q has one distinctive feature.

Disjunctive search processing

Parallel processing; the unique target is salient and tends to pop out.

Effect of more distractors in a disjunctive search

Search time changes little because the target can be processed across the display in parallel.

Conjunctive visual search

Searching for a target defined by a combination of features that are shared separately by distractors.

Example of a conjunctive search

Finding a Q among Rs, Os, and Ts when each distractor shares one of the target's features.

Conjunctive search processing

Serial processing; focused attention is needed to inspect items one by one.

Effect of more distractors in a conjunctive search

Search time increases because more items must be inspected serially.

Why is conjunctive search harder than disjunctive search

The target does not uniquely stand out because distractors share its individual features.

Visual sampling

Measuring where and how people scan for information, using eye tracking, head turns, or gaze behavior.

Fovea

The central region of vision with the best visual acuity, contrast sensitivity, and color vision.

Why do people move their eyes during visual sampling

They move important information onto the fovea for detailed processing.

Smooth pursuit

A smooth eye movement used to follow a moving target.

Saccade

A rapid jumping eye movement used to shift gaze from one location or object to another.

When are smooth pursuits useful

When continuously tracking a moving object.

When are saccades useful

When quickly shifting attention between objects or locations that are far apart.

Supervisory control visual sampling

Sampling in a context where the operator already knows where and when information is likely to appear.

Target search visual sampling

Scanning for a target whose location is unknown.

Mental model in visual sampling

Expectations about where, when, and how often events will occur in different information channels.

Conclusion 1 from visual sampling research

Mental models guide sampling, and expertise refines those models.

Conclusion 2 from visual sampling research

People adapt slowly when event rates change; they keep sampling the formerly high rate area for a while.

Conclusion 3 from visual sampling research

Display arrangement affects sampling; people tend to scan horizontally more than vertically or diagonally.

Conclusion 4 from visual sampling research

Imperfect memory causes imperfect sampling; people may recheck locations because they forget what they already inspected.

Conclusion 5 from visual sampling research

A useful preview or priming of what to expect improves sampling, but too much preview can overload working memory.

Conclusion 6 from visual sampling research

Processing strategy affects sampling; too much information can lead to cognitive tunneling and lost situational awareness.

Cognitive tunneling

Focusing on one indicator or source of information to the detriment of other relevant information.

Why does cognitive tunneling harm performance

The operator stops sampling the broader environment and loses situational awareness.

Useful field of view or UFOV

The area around fixation from which a person can effectively obtain information without moving their eyes.

Typical useful field of view

Roughly 1 to 5 degrees of visual angle.

Factors that affect UFOV

Scene density, age, and search training or practice.

Dwell time

The time the eyes remain fixed on a location so the person can identify or comprehend information.

When is longer dwell time needed

When targets are harder to find or harder to identify.

Display driven processing

Attention guided by display features such as contrast, salience, color, placement, or alerts.

Conceptually driven processing

Attention guided by meaning, goals, expectations, and mental models.

How do experts differ in target search

Experts use better mental models to look in more useful locations and recognize relevant information more effectively.

Typical visual search pattern

Search often begins in the upper left and is concentrated near the center; display edges receive less attention.

Drury model

A model predicting inspection performance and the time needed to find flaws in a product.

Drury model prediction

Detection rises with search time at first, then levels off; after a point, additional search time produces little additional benefit.

Design implication of the Drury model

Give inspectors enough time to find likely flaws, but recognize that searching indefinitely is inefficient.

Symbol coding

Using multiple dimensions, such as color, shape, size, height, and placement, to support quick holistic identification.

Why do multiple symbol codes help

Redundant cues make information easier and faster to identify.

Menu design prediction

Users should be able to locate needed information in about 2 to 3 clicks.

Recommended number of menu items

About 3 to 10 items; too many items are harder to remember and navigate.

Embedded menus

Deeply nested menus that make information harder and slower to locate.

Heads up display or HUD

A display that overlays cues on the real world so users can view the environment and display information together.

Benefit of a HUD

It reduces the need to look away from the real world while accessing relevant information.

Object display

One integrated indicator that communicates several related pieces of information at once.

Auditory attention

Using sound to make information or locations salient and guide attention.

Redundant auditory and visual signals

Presenting the same information through sound and vision to increase signal strength and provide more ways to receive it.

Why is contextually relevant sound effective

A meaningful voice or sound is more salient and is more likely to gain attention.

Limitation of auditory signals

Sound is less spatially precise and directional than vision.

When can spatial audio help

Spatial audio paired with visual information can help people locate targets faster.

Why can a phone conversation be more distracting than a passenger conversation

A passenger shares awareness of the driving environment, while a caller cannot see contextual events.

Inattentional blindness

Failing to notice a visible and salient but unexpected object because attention is occupied by another task.

Drew, Vo, and Wolfe X ray study task

Radiologists searched five chest CT scans for lung nodules while their eye movements were tracked.

Unexpected object in the X ray study

A gorilla, more than 48 times the size of an average lung nodule, was inserted into the final CT scan.

Main X ray study finding

20 of 24 radiologists, or 83 percent, failed to report seeing the gorilla.

Why was the X ray study surprising

Even expert radiologists missed a large, clearly visible unexpected object while doing a task in their own area of expertise.

Eye tracking finding in the X ray study

12 of the 20 radiologists who missed the gorilla looked directly at its location.

Main conclusion of the X ray study

Looking directly at something does not guarantee awareness; attention determines whether visible information is consciously noticed.