Psych 335

Attention

Issues

• Capacity– We can’t respond to everything in the environment

– Too many pieces of information

– we can only actively respond to a subset of these

• Attention– The selection of relevant cues to respond to

– Cues may be externally or internally generated

Attention

• What is attention?– “The concentration of mental effort on sensory or mental

events”

• Phenomena– Switching vs. sharing attention

– Attention Capture

– Visual Search

– Selective attention- Stroop

Examples of Controlled vs. Automatic Processes

• Show 3 pairs of search demos

• Each member of each pair will have a few or a lot of items

• Search for a single target

Find the T:

TL

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• This was an automatic process: fast

Find the T:

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• This was an automatic process: still fast even with more distractors

Find the T:

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• Slower without color

Find the T:

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• This was a controlled search- slower, look at each letter

• Much slower than with colored T

Find the Red L

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• Slow: searching for a conjunction

Find the Red L

TLL

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• Even slower- searching for a conjunction

Data from Display Set-Size Experiment

Fast search done with automatic (preattentive) mechanismsDone in parallel

Slow search done with controlled (attentive) mechanismsDone in serial

Applications of Attentional Seach

• List search situations and decide if fall into preattentive or attentive search requiring focal attention

• E.g.– Search computer screen for icon

– scan crowd for people

– scan crowd for americans

– look for airplane in sky

• What makes things preattentive?– probably the amount of difference between the objects

– L’s and T’s are similar

– Red and blue are quite different

– Looking for small differences requires focal attention

Models of attention

• Filter Models– Recognition after Filtering

» Broadbent-or-

– Recognition before Filtering

» Broadbent’s critics

• Attentuation Models– Treisman

• Automatic vs. Controlled Processes– Also called Preattentive vs. Attentive Processes.

– Neisser

– Schneider and Shiffrin

Filter Models

• What is a Filter?

• A description of the response properties of the system

• Describes what a system responds to, and what it doesn’t respond to.

Types of Filter Models

Detection RecognitionInput

DetectionInput

Filter

Recognition

DetectionInput

Filter

Recognition

Recognition Before Filtering:

Recognition After Filtering (Broadbent):

Broadbent’s Filter Model

• Channels carry different types of information

• E.g. color, spatial frequency, pitch, hot, etc.

• Apply mental effort: selectively process info coming from a small set of channels

• We must do this: limited capacity processing and memory system– We just can’t deal with all the information at once

• However, can switch between channels

Broadbent’s Filter Model cont.• On the basis of some aspect of the stimulus or

our memories, we can switch between channels

• This switching may be voluntary or involuntary

• Switching takes effort, reduces performance– Broadbent’s dichotic listening techinque- present two digits

at once, one to each ear

– 8, 3, 2 in left ear

– 9, 1, 5 in right ear

– recall by ear (left or right): subjects respond “8 3 2 9 1 5”

– or in order: subjects respond “8 9 3 1 2 5”

– performance for latter task is reduced (65% to 20%)

– In second task subjects had to switch more often- hurts.

Broadbent’s Filter Model cont.

• Problems: Gray and Wedderburn (1960)– Easy to switch if information in the to-be-switched-to ear

is relevant

– e.g.: Story continues in alternating ears

• Problems: GSR experiments– Associate word with shock- hearing word elicits a GSR

response.

– When that word is presented in unattended channel, produces GSR response.

– Semantically similar words also elicit response- some semantic processing takes place in unattended channel.

Attenuation Models-Treisman

• Info in unattended channels is still processed– but at a reduced rate

– info in unattended channels is attenuated.

Treisman’s Attention ModelQuickTime™ and a

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Attention Capture

Failures of Selective Attention

• Attention is supposed to focus in on what you want to attend to

• Exclude irrelevant information

Stroop Task

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Stroop Task

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Stroop Task

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Stroop

• Failure of selective attention

• Race model– Word name is processed automatically

– Color is not so automatic

– Both arrive at the same time, we have a hard time attending to the relevant stimulus attribute

– Doesn’t happen upside down

Stroop Task.

Failure of Attention: Failure to Disengage

• Mind Develops Brain clip– infant- failure to disengage

Spatial Attention: Posner Task

A

Attention switches to here(but eyes don’tmove)

Target mightappear here:

A

or here:

Time

Fixation Point

Cue75%accurate

Sharing Attention: Dual Tasks

• Do two things at once: can they be performed at the same time?

• Do they interfere?

• Experiment has 3 conditions

• Task A alone

• Task B alone

• Task A and B together at the same time

Sharing Attention: Dual Tasks

• Example:

• Pat head and rub belly

• Now speed up just your belly

• If you can’t do it, it suggest that they share the same processing capacity

• Same brain area?

Sharing Attention: Dual Tasks

words per minute

Example:Task A: Driving without an accidentTask B: Talking on cell phone

Can you talk on your cell phone at the normal rate while still drivingwithout getting into an accident?

Normal Save Driving Speed: 30 mphNormal speaking rate: 80 wpm

Safe DrivingSpeed

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Central Executive Interactions

Pet Evidence-Right Parietal

Lesion Data- Attending to Different Spatial Scales