4 attention class1

7/29/2019 4 Attention Class1

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Lecture 4: Attention

Psyc 317: Cognitive

Psychology


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Todays agenda

Selective attention

Different theories: early-selection,

attenuation, late-selection, perceptualload

Divided attention

Effect of: practice, task difficulty, task

type

Attention & visual processing

Overt & covert attention


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What is attention?

Everyone knows what attention is. William James, 1890

No one knows what attention is.

Harold Pashler, 1998

Attention is a well-studiedphenomenon, but hard to define


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What is attention?

The ability to focus mental resources on

something

Attention is limited Think of attention as a pool of resources

To attend to something: To pay attention

to it

Attended ear - Paying attention to words in

that ear


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Focusing on just one thing

Cocktail party metaphor: You are

talking to someone at a party with a

lot of other people making noise. You are able to filter out other noise

and focus just on the person youre

talking to. How do you do that?


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Four theories of attentional

selection Early-selection theories

Broadbents Filter Model

Triesmans Attenuation Model Late-selection theory

Perceptual load theory


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Thats a lot of theories!

In a way, they are all competing

The theories were developed

chronologically One theory proposed, had problems, led

to a new theory

The development of these theories

tell a story - keep that in mind!


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Cherrys Dichotic Listening

Colin Cherry (1953) - Dichotic

Listening

Present different messages to each ear

Subjects paid attention (attended) to

one ear and ignored the other

Repeat the attended message out loud -

shadowing


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Dichotic Listening Results

Participants shadowed the attended

message easily

When asked about the unattendedmessage, they could only report sex

of voice

No content was remembered, evenwhen the unattended stream was the

same word presented 35 times!


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Broadbents Filter Model

An early-selection model - filtering

occurs before incoming stimuli are

analyzed to the semantic level


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Parts of the filter model

Sensory store - Holds incoming information for a

short period of time

Filter - Analyzes messages based on

physical characteristics like tone of voice,

pitch, location of stimulus (which ear)

Detector - Information is processed to

determine meaning Short-term memory - Holds information for general processing


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Auditory Channels

Each ear is thought to be a different

channel that information can come

in from It is difficult to switch attention from

one channel to another


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Broadbents Split-Scan

Study Present letters at the same time to

each ear:

-)

:-)

:-)

H M

R S

W P


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Broadbents Split-Scan

Study Two conditions:

1.) Repeat back all letters in any order

2.) Repeat back letters in the order theywere presented

Condition 1 (Any Order):

H, R, W, M, S, P

Condition 2 (In Order):

H, M P?

:-)

:-)

:-)

H M

R S

W P


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Split-Scan Results

Condition 1 (repeat back in any order)

65% correct letter report

Would report all letters presented to one ear

first Condition 2 (repeat back in presented

order)

20% correct letter report

Harder to switch channels to report backletters


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The filter model explains

How we can pay attention to one ear

and ignore stimuli coming into the

other ear

Why we prefer to process stimuli that

come in to one ear all at once asopposed to switching channels


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Problems with filter model

Back at the cocktail party.

Youre talking to your friend and

ignoring all the otherconversations

Until someone across the room says

your name. Then you turn your head. But you were supposed to be

ignoring other conversations - what

happened?


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Other evidence

against

Moray (1959) -Subjects heard theirname in the

unattended stream Gray & Weddeburn

(1960) - Shown:

Response should have

been Dear 7 Jane But subjects said Dear

Aunt Jane


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Triesmans attenuation

model Still an early-selection theory

Instead of a filter, an attenuator

analyzes incoming messages Physical characteristics

Language - Groups of syllables/words

Attended messages are given morepriority


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Attenuation: Box & arrow


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Attenuation: The Dictionary

Unit The message gets passed on to the

dictionary unit

Threshold =

Smallest signal

strength that can

just be detected

Easily detected


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Attenuation explains

Hearing your own name when that

stream is supposed to be ignored

Switching channels in order to makea complete sentence

But a specific dictionary unit? Thatseems like a cop-out.


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Problems with early

selection MacKay (1973)

Ambiguous sentences: They were

throwing stones at the bank Bank = Financial institution or side of a

river?


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MacKay Method & Results

Dichotic listening

Attended stream: Ambiguous sentence

They were throwing stones at the bank. Unattended stream: Biasing word

River or Money

The biasing word had an effect!

If money, the ambiguous sentence was

more likely interpreted as financial

institution


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What does this mean?

The unattended stream was being

processed, and it wasnt a name or

another low-threshold word Not early-selection

Not an attenuator

The word was actually beingprocessed to the semantic level (to

its meaning)


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Late-selection theories


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So whats right?

Early selection

We can totally ignore an unattendedstream

Attenuation

unless its our own name, then itcaptures our attention

Late selection or not. Words in the unattended

stream can also be processed.


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So whats right?

Theres evidence for EVERYTHING!

Thats no good.

Lavie (1995) - Where the filtering

occurs depends on task load

How much of a persons cognitiveresources are used in a task


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Perceptual Load Theory

High-load task: Difficult, requiring

most of someones cognitive

resources Only selected items are processed

Low-load task: Easier, cognitive

resources are left over Can process additional information


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Flanker Introduction

Is the center letter an H or S?

Easy/Compatible:H H H H H

Hard/Competing:

S S H S S


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Flanker Compatibility Task

Decide whether one of the shapes in

the circles is a square or diamond

Ignore shapes outside of the circle(flanker)


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Two types of flankers

Compatible: Outside shape is same

as target (makes search faster)

Competing: Outside shape isdifferent than target (makes search

slower)


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Green & Bavelier (2003)

Low load: Only one shape in circle

Flankers

Compatible Flanker Competing Flanker

RT: Which one is faster?


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Green & Bavelier (2003)

High load: Lots of distractor shapes

in circlesCompatible Flanker Competing Flanker

Must ignore


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Green & Bavelier:

Predictions Low-load task: Its easy. Lots of

cognitive resources left, might as

well process extra stuff (the flanker)

High-load task: Its hard. All

cognitive resources used in theprimary task; none left to process

extra stuff (the flanker)


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Green & Bavelier: Results

Increase in RT for

competing flanker

How much does the competing flanker hurt performance?


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What does this mean for

attentional filtering theories?

High-load task = Attentional resources fully

used

No resources left to process extra stimuli

Early selection - throw out more stimuli (based on

physical characteristics)

Low-load task = Attentional resources left

over Resources are left to process extra stimuli

Late selection - process stimuli further (up to the

semantic level)


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Attention & Video Gamers

Same study on experienced video

gamers

Competing distractor

had same effect in

both load conditions

This means attention

could process more

information in both

conditions


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Outline

Selective attention

Different theories: early-selection, attenuation,

late-selection, perceptual load

Divided attention

Effect of: practice, task difficulty, task type

Visual attention

Visual attention phenomenon

The distribution of visual attention

Hemispatial neglect


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Divided Attention

Can we pay attention to more thanone thing at a time?

Yes! Think about driving, listening tothe radio and planning dinner

What factors affect our ability todivide attention?

Practice

Task Difficulty

Task Type


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The Effect of Practice

Spelke, et. al (1976)

Task: Read short stories and take

dictation (write words spoken tothem)

At first, performance was awful

After 85 hours of practice,performance was much better


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Schneider & Shiffrin (1977)

The divided attention task well be

talking about

Give subjects a memory set - up to 4letters or numbers


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Consistent Mapping

Condition Then, present 20 frames VERY fast

4 possible positions; any/all filled

Distractors were from the othercategory

If memory set was numbers, distractors

were letters


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Was an object from the memory setpresent anywhere in the stream?

When one number/letter was in the memoryset, it was never a distractor on the next trial

A distractor on the current trial was never inthe memory set on the next trial

Schneider & Shiffrin

Methods


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Schneider & Shiffrin Results

Beginning: 55% accurate

900 trials: 90% accurate

600 trials: Participants reportedautomatic processing (no need to try

hard to do the task)

Occurs without intention Uses few cognitive resources


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Automatic performance by

600 trials


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Automatic processing outside the

lab Occurs for well-practiced tasks

Examples?

When people starting thinking aboutthings, they make errors

Ever try explaining shoe-tying to a small

child?


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Can you reduce automatic

processing?

What if you increase the number of

characters in the memory set and in

each frame? Little effect on performance - still peak

at 90% accuracy at ~ 900 trials

So this doesnt seem to increase task

load


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What does that mean?

Participants performed tasks in

parallel

Required little attention Could divide attention 4 ways easily

Could deal with all the information

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