Attention - Cognitive Processes - Lecture Slides, Slides of Brain and Cognitive Science

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Attention

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.

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.

Broadbent’s Early Selection

Only the selected information gets through.

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.

Treisman’s Attentuation

Theory

All information passes through but some is weaker (attenuated).

Late Selection Theory

Shadow by ear

Shadow by meaning

Decide what to say

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

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.

Selective Attention

Neural Evidence (Visual)

 Attention consists of enhanced neural

response in a particular spatial location in the visual cortex.  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.

 Enhancement comes from V4 not V1.

Neural Evidence

Monkeys showed greater activity while waiting (b) when the original stimulus was on the saccade path.

Activity occurs on the opposite side from the stimulus.