Cognitive ProcessesPSY 334

Chapter 3 – Attention

July 8, 2003

What is Attention?

Attention is the allocation of limited processing resources.

Visual features such as shape, color, texture, motion are processed in parallel.

Serial bottleneck – occurs when it is no longer possible to process in parallel. When does it occur – early vs late

selection How do we select what to attend to?

How we Experience Attention

Stream of consciousness -- we learn and remember what we attend to.

Paying attention results in a feeling of mental effort.

Can be directed internally but also pulled (attracted) by external events.

Varies with arousal and fatigue. Studied by looking at response

competition.

Auditory Attention

The response competition comes from having two ears.

Dichotic listening task – uses “shadowing.” Two different messages are presented,

one to each ear. Subjects are asked to speak what they hear.

People can attend to only one message at a time.

Three Theories

Broadbent’s filter theory Treisman’s attenuation theory Deutsch & Deutsch’s late selection

theory

Broadbent’s Filter Theory

People do not remember the content of the unattended ear. Voice or noise, sex, but little else.

Broadbent’s filter theory proposed that filtering occurs early in processing based on physical characteristics (pitch, ear). Neural evidence supports the ability to

select one ear to listen to. Cocktail party effect – attention switches

based on content of unattended ear.

Treisman’s Attenuation Theory

Treisman’s attenuation theory – subjects deemphasize but not filter out the unattended message. Meaning switched from one ear to the

other. Some subjects switch ears even when told

not to, following the semantic content. Semantic criteria apply to all messages,

filtered or not.

Late Selection Theory

Deutsch & Deutsch’s late selection theory – the limitation is in the response system, not the perception. Both messages are perceived but only one

can be shadowed at a time. The criterion for selecting what to say can

change – based on ear or meaning.

Testing the Theories

Dichotic listening task: Shadow one message but listen for a

target word in both ears (tap when heard). Late selection theory predicts no

difficulty hearing the target in either ear. Attenuation theory predicts less

detection in non-shadowed ear. 87% detection in shadowed ear 8% detection in non-shadowed ear

Echoic Memory

Glucksberg & Cowen demonstrated that unattended information can be kept in an echoic memory buffer for brief periods. Shadow a message, with digit presented to

non-shadowed ear. 25% of time, is asked immediately after

presentation, reported hearing the digit. 5% of time reported the digit, without cuing

Unattended material is lost within 5 seconds.

Visual Attention

We can choose where to fixate our eyes for greatest visual acuity. Other portions of the visual field are

attenuated. Visual attention need not be located

where the eyes are fixed. Posner – subjects can attend to objects

up to 24 degrees from the fovea. Shift of attention precedes eye movement.

Spotlight Metaphor

Spotlight can be broad or narrow (degrees of visual angle). Broad areas processed less well.

A narrow focal point gives optimal processing but it takes time to move the focus to other areas of the visual field.

We move our eyes around a complex visual stimulus. Neisser & Becklen’s shadowing task.

Neural Basis of Attention

Attention consists of enhanced neural response in a particular area of the brain.

The brain is organized topographically. By increasing neural activity in a particular

location, input to that location can be processed faster.

Specific details are “higher order” properties and take longer to recognize.

Iconic Memory

Visual sensory input can be remembered for a short time – up to 5 seconds. Retention time varies if a post-exposure

field is light (1 sec) vs dark (5 sec). Following one display with another display

“washes out” the first memory (icon). Visual sensory information must be

attended to and processed in order to be remembered longer.

Sperling’s Partial Report

The purpose of an icon is to retain an image until attention can focus upon it. How long does the icon last? How fast can attention move through it?

Subjects see an array of letters flashed briefly (50 ms), then report them back. After the array is gone, a tone is sounded. Subjects must report the letters in the row

corresponding to the tone (high, med, low).