Week 6: Structural and Capacity theories and Attentional Orienting

Question 1

Early selection theory VS Late Selection theory

Answer 1

Debate of where the filter is:
Before or after LTM (semantic mem)

Weak semantic activation on unattended channel
VS
Brief semantic activation on unattended channel

Question 2

Cost of Divided Attention
(Moray, 1970)
description

Answer 2

Objective:
How well we can distribute/divide attention across multiple sources of information.
Dicrotic sounds

Different cases:
1) Selective . (SEL)
Monitor for targets on 1 channel (oneside)
2) Exclusive OR (XOR)
Monitor both, no simultaneous targets
3) Inclusive OR (IOR)
Monitor both channels, simultaneous targets possible

Comparing:
simultaneous targets (AND trials) and non-simultaneous (OR trials)

Question 3

Cost of Divided Attention
(Moray, 1970)
Discovery

Answer 3

SEL > XOR > IOR

67%) (54%) (OR: 52%; AND: 31%

Question 4

Cost of Divided Attention
(Moray, 1970)
Implications

Answer 4

the findings were not in line with either theory:

Early Selection:
Predicts OR < SEL because there is attenuation with divided attention
Doesn’t predict AND < OR because attenuation shouldn’t depend on identity of stimulus:
the only thing that matter should be Target or nontarget but not that if they occur 2gether. so there shouldn’t be a dif.

Late Selection:
Predicts AND < OR because two simultaneous targets will both be selected by “pertinence” and compete to get through filter
Doesn’t predict OR < SEL because if there aren’t two targets, expect no competition

Question 5

Structural and Capacity Theories:

2 ways tt attention can limit performance

Answer 5

1) Structural (Bottleneck) Theories

2) Capacity (Resource) Theories

Question 6

Structural and Capacity Theories:

Structural (Bottleneck) Theories

Answer 6

1) Some neural structures can only deal with one stimulus at a time
2) Competition produces processing “bottleneck” (filter theory)

(ES: bottleneck getting into LTM; LS bottleneck getting out of LTM)

Question 7

Structural and Capacity Theories:

2) Capacity (Resource) Theories

Answer 7

1) Information processing is mental work
2) activation of neural structure
3) Limited capacity to activate structure

Question 8

Capacity Theories:

Kahneman, 1973

Answer 8

Focused Attention and Divided Attention:
Idea: we have a set amount of capacity (resources) and we have to allocate them and we can allocate them flexibly

Reduction of capacity produces deficit in divided attention tasks

Prediction:
there will be cost associated with dividing attention vs focused attention

Question 9

Capacity Theories:
Cost of divided attention.
Strayer and Johnston (2001)
(real world example)

Answer 9

Talking on a mobile phone interferes with driving (sharing capacity reduces accuracy and increases RT)
100 ms @ 60 km/h ~ 1.7 m
Fraction of red lights missed: 0.03 increased to 0.07 (double)

Both tasks needs cog. capacity:
doing both simultaneously requires one to divide ones attention.

Question 10

Capacity Theories:
Cost of divided attention. 
Dual Task Performance (Li et al., 2002)
Description & results
central tasks

Answer 10

2 tasks:
1) a group of randomly arranged letters shown for a short while, identify if letters same or different (Attention demanding central task)

2) Easy/Hard peripheral task:
(identify for animal from pic (EASY) or ask for “phase of disk”(HARD))

Participants were measured on % correct.

Difficult task much more affected by central load
(90% VS 50%)

Question 11

Inattentional Blindness:
Cartwright-Finch & Lavie (2007)
demanding central task
description and results

Answer 11

Participants asked to identify which arm of flashed cross is longer. (cross with blue(v) and green(h) line)

Clearly visible square not detected

Demanding central task uses all available capacity

Question 12

Study Capacity by Dual Task Trade-Offs

curve (quater circle)

Answer 12

 Attention operating characteristic (AOC)

 Vary proportion of attention allocated to two tasks in dual task paradigm

 “Graceful degradation” of performance as available capacity is reduced

 Shape of trade-off curve tells us about capacity demands of tasks

Question 13

Dual Task Trade-Offs:

Pros and Cons of Capacity Theory

Answer 13

new experiments it led to

Emphasises flexibility of attentional control

Shortcoming: vague (can always come up with a capacity
explanation) hard to falsify

Hindsight:
make capacity theories mathematically precise using decision-
making theories

Question 14

Attentional Orienting

Answer 14

shift of attention

Question 15

Issues of eye movement

Answer 15

Natural environment: movement in peripheral vision produces
saccadic eye movement, greater visual acuity in foveal vision

“Covert” attention – movement independent of eye movements

Attention shifts precede eye movements and can occur without them

Question 16

Attentional Orienting likened to moving spotlight:

why? (2)

Answer 16

Enhanced Processing VS degraded processing

Selective enhancement for stimuli “illuminated by the beam”

Expresses selective, limited- capacity idea in spatial terms

Question 17

Studying the Spotlight of Attention
Spatial Cuing Paradigm Attentional Costs and Benefits (Posner 1978)
description

Answer 17

Attract attention to A, present stimulus at A or B, compare performance: (Slide 21- 25)
Places
Fixation Field
Cue field (wait for specified SOA 100~300ms)
Present Stimulus: (left box or right box)

MEASURE RT

Question 18

(Posner, 1978)

types of trials and results (3)

Answer 18

Valid: Cue same with Stimuli (80%)

invalid: Cue opp with Stimuli (20%)

neutral trials: both left and right r cued. used as Baseline to compare valid and invalid

Question 19

(Posner, 1978)

results

Answer 19

Benefits:
 Faster RT with valid
cue

Costs:
 Slower RT with invalid
cued

Very flexible: can be used with RT or accuracy, and to compare all kinds of stimuli

Question 20

Causes of Cuing Effects from the results of (Posner, 1978)

Answer 20

Costs and benefits can be due to:

1) Switching Time
2) Unequal Capacity Allocation

Question 21

Costs and benefits of Cuing Effects:

1) Switching Time

Answer 21

Time to move the spotlight

Costs of disengaging from wrong location, benefit from engaging at correct location before stimulus

Question 22

Costs and benefits of Cuing Effects:

2) Unequal Capacity Allocation

Answer 22

 RT depends on capacity allocated to location

 Neutral: capacity spread across locations; focused: capacity concentrated on one location

Question 23

difficulty with finding the underlying causes of Effects between:

1) Switching Time
2) Unequal Capacity Allocation

Answer 23

Hard to test between these alternatives

Question 24

Attentional Orienting:
Orienting Systems (2)

Answer 24

1) Top-down (decide to shift attention)
2) Bottom-up (something captures attention)

Need to be able to focus attention, exclude irrelevant stimuli; also to respond to unexpected threats

Question 25

Is there 2 attentional orienting control system? Observations

Answer 25

1) Need both kinds of systems to function

2) Clinical patients show deficits of both kinds: failure to focus attention, failure to disengage attention

Question 26

Two systems engaged by

different kinds of cues

Answer 26

Endogenous(voluntary) VS 
Exogenous cues(reflexive)

Cognitive (Central cue; symbolic): need to interpret
Direct (Peripheral cue; spatial): 60ms

These 2 systems have different properties

Question 27

Evidence for Separate Orienting Systems:

1) Different time course of central and peripheral cuing

Answer 27

Cuing Effect: MRTinvalid - MRTvalid
Peripheral effect peak < central effect peak
Peripheral effect peaks rapidly (100~150ms), central effect peaks slowly (300ms)
Thus using different processes (systems).

Question 28

Evidence for Separate Orienting Systems:

Different effects of load (Jonides, 1981)

Answer 28

2 tasks:

1) Pri task: Retain Digits in mem (mem task)
2) Sec task: Detect spot of light cued/uncued location (Orienting task)

Voluntary orienting slowed by memory load; reflexive orienting is not

Consistent with different capacity demands of two systems

Question 29

Inhibition of Return: defination and purpose

Answer 29

People respond more slowerly to stimuli at locations where they previously (at least 300 ms earlier) viewed a task-irrelevant stimulus

Ecological argument: Allows efficient search of complex environment.

Prevents repeated search of same location. Don’t need to maintain a “mental map” of locations that have been searched

Question 30

Evidence for Separate Orienting Systems:
Inhibition of Return
finding

Answer 30

Facilitation(benefit) and Inhibition(cost) of short/long SOA

Mean RTs with peripheral cues and long SOAs are longer at cued locations than at miscued locations

If there is a delay of 300ms or more after a peripheral cue. target detection at that location is slowed down.
=>normally facilitatory effect has reversed to become inhibitory.

Found only with peripheral cues, not with central cues

Question 31

Summary of Multiple sources of evidence for two systems

Answer 31

 Effects of SOA and cue type: Reflexive system is faster, more transient; voluntary is slower, more sustained

 Affected differently by load: Suggests voluntary system is under more cognitive control

 Reflexive shows inhibition of return, voluntary doesn’t. Suggests reflexive controlled by different processes