Attention

Part 1

Selective Attention

What is attention?

Everyone knows what attention is. It is the taking possession by the mind, in clear and vivid form, of one out of what seem several simultaneously possible objects or trains of thought.

My experience is what I agree to attend to. Only those items which I notice shape my mind -- without selective interest, experience is an utter chaos. ..

(James, 1890, pp. 403-404)

What is attention?

But [attention's] towering growth would appear to

have been achieved at the price of calling down

upon its builders the curse of Babel…...For the

word `attention' quickly came to be

associated with a diversity of meanings that

have the appearance of being more chaotic

even than those of the term `intelligence'.

(Spearman, 1937, p. 133)

Attention

• Selective Attention: chooses stimuli for further

processing

– Perceptual tasks (detection)

– Involves frontal and parietal network often acting upon

occipital, and temporal cortices

• Divided Attention: allocating resources to multiple

tasks

– Tasks involve operating on a stimulus in some way

(central processes)

– Involves prefrontal areas involved in inhibition, working

memory

• Not entirely distinct constructs (or brain networks)

Today: Selective Attention

• Phenomena – Inattentional blindness & Change blindness

• Filter Theories – Early Filter

– Late Filter

– A reconciliation

• Multiple mechanisms of selective attention – Spatial Attention: Parietal Lobe

– Attention in Ventral Stream

– Object based attention

• Inattentional blindness (Neisser, Neisser &

Becklen, 1975)

– Focusing attention on one event leaves less

attention for others

• Change Blindness (Simon & Levin, 1997)

– The world contains more information than we can

absorb

– So we use stable world as our ‘memory’ as much as

possible.

– We have poor memory for visual detail across shifts

in attention.

• Unless accompanied by flicker or motion cues

– Door studies: we encode both people but fail to

compare

Filter Theories

Filter Theories

• There is limit on amount of information that can be

processed deeply

• All information gets into sensory systems

• Somewhere along the way, information is filtered – Early: btw sensory analysis & pattern recognition

– Late: just prior to response selection

• We can select what we process by using an Attentional Template

• Only selected information makes it into awareness and long-term memory

• Sometimes attention shifts automatically based upon bottom-up properties of stimulus

Attentional Template:

• Form:

– BLUE ITEMS.

– HORIZONTAL LINES

• Spatial:

– UPPER LEFT CORNER.

• Temporal:

– AFTER A TONE.

Broadbent Early Filter Model

"Higher Level Processes"

(E.g., Pattern Recognition)

Input (Sight, Sound, Touch, Smell, etc.)

Sensory Processing

Brief Sensory Store

Contextual Information

Dichotic Listening Task

The Unattended Message (Cherry, 1958; Moray, 1959)

• Properties Recalled: – Whether speaker had changed

– Male vs. female voice

– Human vs. musical instruments

• Properties Not Recalled: – Content of Message

– Whether or not it was grammatical

– What language it was in

• Easy to shift attention based on physical properties of stimulus

Broadbent Model of Attention (Early Filter)

• Attentional Template:

– based solely on physical properties of

stimulus

• Bottleneck/Filter:

– prior to pattern recognition/interpretation

Problems for early selection

What about Cocktail Party effect?

As I was saying, my theory

of attention clearly states...

....Professor Snedeker

is so kind and witty!

(Me!)

Treisman (1960)

Please shadow RIGHT EAR ONLY!!! "Jane and Susan liked to / me that was..."

"Jane and Susan liked to talk about books..."

"Birds yourself tell from / talk about books...."

Content of unattended message is getting through!

Context Effects

• Attended ear:

– “They were standing near the bank”

• Unattended ear:

– One of the following was presented

• “river”

• “money”

• Later participants interpreted “bank” as

– a riverbank if they heard “river”

– a financial bank if they heard “money”

Sensory

Processin

g

Input Pattern

Recognition

Late Filtering (Deutsch & Deutsch): Filter

Sensory

Processing Input

Filter

Pattern

Recognition

Early Filtering (Broadbent):

Problems with Early Filter Model

• Awareness of unattended channel depends on familiarity or importance (Cocktail party effect)

• People can shadow meaningful message that switch from ear to ear (Treisman, 1960)

• Interpretation of attended channel affected by content of unattended

• There is implicit memory for the unattended channel – Increased galvonic skin response to unattended

words paired with shock

Problems with Late Filter Model

• Even if relevance is controlled for – We are more likely to notice information in the

attended channel then in the unattended channel (e.g., 87% vs. 8%)

– Some selection occurring early

• If selection is late – Why do we feel like we’re consciously selecting early?

• Imaging studies show enhanced processing of attended information at early perceptual stages

Reconciling Competing Data

• Motivation

– Evidence for both early and late selection thus selection must be variable

– But our theory should predict when information will get through

– Perceptual load theory (Lavie) specifies conditions in which early and late selection occur

Perceptual Load Theory

• Assumption 1: Mental resources are limited

• Assumption 2: Must use whatever mental

capacity you have unless this is fully occupied

• Consequently

– If attentional resources are not fully occupied, they

“spill” to unattended channels => late selection

– If resources are fully occupied => early selection

Test of perceptual load theory

• Area MT (Middle Temporal) lobe is activated

when people see moving stimuli

Task

•Word overlaid on moving/still dots

•Attend to word, ignore dots

•Low load: upper or lower case?

•High load: bisyllabic or not? •Activity in MT is measured with fMRI

reform

Rees, Frith, & Lavie, 1997

Predictions

Task: attend to words, ignore dots

• Early Selection: Motion filtered out – Low activation of MT in both load conditions

• Late Selection: Motion not filtered out (pre-attentive processing) – High activation in MT in both load conditions

• Perceptual Load Hypothesis – High activation of MT in low load task

– Low activation of MT in high load task

Rees, Frith, & Lavie, 1997

BOLD signal in MT

during each task

Red-yellow = Areas where

Motion – Nonmotion was

greater during Low Load

task

Arrow = MT activation

Summary

• Processing of unattended stimuli depends

on the resources that are available

• High load task leads to early attenuation

• Low load task leads to late attenuation

Expectations influence allocation of

attention

• Wolfe et al

• Target frequency

influences probability

of detection

• Moral: Allocation of

attention depends on

experience

• Expectations can lead

to hasty decisions

Blue = 1% present

Yellow = 10% present

Red = 50% present

Some wrinkles

• Some argue that “face specific”

effects result from expertise

• Dog show experts show

inversion effect for recognizing

individuals of same breed (Diamond & Carey, 1986)

• Bird experts show greater

activation in FFA for birds than

cats (+ vice versa) (Gauthier, 2000)

• Experience with subtlely

different artificial objects

activation in FFA (Gauthier, 2000) Greebles (designed by Scott Yu for

Gauthier et al.)

Some wrinkles

• Some argue that “face specific”

effects result from expertise

• Dog show experts show

inversion effect for recognizing

individuals of same breed (Diamond & Carey, 1986)

• Bird experts show greater

activation in FFA for birds than

cats (+ vice versa) (Gauthier, 2000)

• Experience with subtlely

different artificial objects

activation in FFA (Gauthier, 2000) Greebles (designed by Scott Yu for

Gauthier et al.)

Does this mean that the face

processing system is not a

module?

Does this mean that it didn’t

evolve to identify faces?

• How might a module for face processing

become involved in processing other stimuli?

– If domain specific input is defined coarsely

– If innate template for input can be altered by

experience

– If domain specificity is a matter of degree (weaker

processing of less preferred input)

• What does it mean to say a system evolved for

face processing?

– That selection pressure was b/c it improved face

perception

– But actual stimlui that causes that could be much

coarser

• Ex: Bird feeding anything in its nest

Spatial Attention

Cuing Attention

1. Cue: Arrow pointing to left or right

2. Target: box present or absent on either left of right of screen

3. Response: press a button

• Cue can be

– Valid: points to target

– Neutral: points in both directions

– Invalid: points away

• How does cue affect performance?

Results Moral: Attention leads to more rapid processing of a stimulus

Can vary the kind of cues

• Exogenous Cue – Automatic bottom-up

– Flashing light

– Rapid Shift

• Endogenous Cues – Voluntary top-down

– Arrow/word

– Slower Shift

Spatial attention in the dorsal stream (Parietal Lobe)

Temporal Lobe

Parietal Lobe Superior

Inferior

Anterior Posterior

Frontal Lobe

Occipital Lobe

“What”

“Where”

When Attention Is Lost

• Right parietal lobe

damage often

spatial neglect

• Patients fail to attend

to objects on left side

if there are competing

objects on right side

Spatial Neglect

Writing

Reading

Spatial Neglect

Spatial Neglect

Artist Anton Raderscheidt

The basic steps for shifting

attention 1. Localize

Define new attentional template

2. Disengage

Erase old attentional template

3. Move

Execute new attentional template

4. Engage

Fully process newly attended features

Posner

Which process accounts for (left)

spatial neglect?

1. Localize

Predicts slower reaction time for all left targets

2. Disengage

Predicts slower reaction time to left targets only

when there is an incorrect cue pointing right

3. Move

Predicts slower reaction time for all left targets

4. Engage

Predicts slower reaction time for all left targets

Right Parietal Damage

Right (Ipsilateral) Target

FAST SLOWER (50 - 100 ms)

Correct Cue Incorrect Cue

Like normals

Right Parietal Damage

Left (Contralateral) Target

FAST MUCH SLOWER (500+ ms)

Correct Cue Incorrect Cue

Deficit to left

Only when miscued

Which process accounts for (left)

spatial neglect?

1. Localize

Predicts slower reaction time for all left targets

2. Disengage Right parietal lobe doesn’t send signal to disengage to

left parietal lobe (so stuck on right target)

3. Move

Predicts slower reaction time for all left targets

4. Engage

Predicts slower reaction time for all left targets

Evidence for right lateralized spatial

attention

• Corbetta et al (PET)

• Hold central fixation.

• Test Condition: Attend to Moving Dot,

which zips around in the left or right visual

field.

• Control Condition: Attend to fixation,

ignore the dot.

Attending to moving objects Corbetta et al.

Attention in left:

contralateral (right)

activation as

expected

Attention in right:

contralateral (left)

activation

And left activation as

well

Parietal Lobe

• Plays critical role in spatial processing

and spatial attention.

• Responsible for disengaging attention

from one location.

• Asymmetry: Right Parietal Lobe,

especially superior right parietal lobe, is

utilized for spatial attention more than

Left Parietal Lobe.

Attention in the Ventral Stream

Temporal Lobe

Parietal Lobe Superior

Inferior

Anterior Posterior

Frontal Lobe

Occipital Lobe

“What”

“Where”

Spatial attention modulates processing in

the ventral stream

Temporal Lobe

Parietal Lobe Superior

Inferior

Anterior Posterior

Frontal Lobe

Occipital Lobe

“What”

“Where”

As we move along temporal pathway

receptive fields get huge…..

V1 cell:

IT cells: (Inferior

Temporal)

(0.2 deg)

(25 deg)

Attention Mechanisms in IT Moran & Desimone (1985)

Cell in Inferior Temporal Cortex tuned to green bar

Fixation Point of Monkey

Cell fires

Moran & Desimone (1985)

Cell in Inferior Temporal Cortex tuned to green bar

Fixation Point of Monkey

Cell fires

Moran & Desimone (1985)

Cell in Inferior Temporal Cortex tuned to green bar

Monkey trained to attend to object on right

Fixation Point of Monkey

Cell fires

Moran & Desimone (1985)

Fixation Point of Monkey

Cell does not fire

Cell in Inferior Temporal Cortex tuned to green bar

Monkey trained to attend to object on left

Another way of thinking about attention:

Large receptive fields impose capacity limits

Exogenously Driven Selection:

Perceptual salience determines which stimulus is

represented at higher levels (b/c motion,

brightness…)

Endogenously Driven Selection:

Goals have top down influence on which stimulus

is represented

Object Based

Attention

What is the relation between

attention and object perception?

Treisman

• Object perception depends on attention

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Treisman data pattern

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Number of Items

RT

Conjunction

Feature

All Searches Are NOT Equal

A Is More Difficult Than B

A B

First Attention,

Then Object Perception

But attention also depends on objects

• Invalid Spatial Cueing less disruptive when

cue and target location are on same object (Egly, Driver & Rafal, 1994; Moore, Yantis, and Vaughan, 1998)

Response time for S << D C = cued location

S = same object target location

D = different object target loc.

Red

Red

Spatial Neglect:

Attention initially

deployed to

spatial location

(right visual field)

But sticks to

objects even if

they move

selective attention a synthesis

• Attention is many processes acting dynamically t

• Needed for many mid/high level processes

– Ex: binding features to objects

• Attention can be allocated in many ways

– Spatially

– By features

– To objects (outputs on mid-level vision)

• Attention is top-down

– Endogenous shifts (cueing paradigms), object based

• Attention can be bottom-up

– Priming, Exogenous shifts

Functions of Attention

• Screen out irrelevant stimuli

• Control the flow of information to slow

conscious processes

• Bind together features of a single stimulus

• Perceive the world more accurately (by

factoring in expectations)

• Perceive the world more quickly (by preparing

for what is likely to come)

• Do so in manner that is flexible enough to

be disrupted by truly novel

What does selective attention tell us about….

How Prof. Snedeker can decrease her chances of getting hit by a car as she is biking home from work….

Think about both the readings with obvious connections and those with the less obvious connections….