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Title: Cognitive%20Psychology


1
Cognitive Psychology
  • Attention

2
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3
What do these have in common?
  • You are driving to a lunch date, and accidentally
    take the route to your job. After you correct
    your route, as you are driving by the theatre, a
    red ball chased by a child suddenly appears on
    the street, and you screech your brakes. You get
    to the restaurant and try to find your friend,
    who has flaming red hair. The restaurant is
    packed, its hard to make-out faces, but you can
    see peoples hair so you look for red hair. When
    you get to your table your friend asks if you
    noticed the Star Wars promotion with two costumed
    people fighting with light sabers. As you talk
    about important but dull business, your mind
    keeps drifting to your exciting first date last
    night. You force yourself not to think about it,
    but it keeps coming back.

4
  • Innatentional Blindness (original experiment)
  • http//www.youtube.com/watch?vvJG698U2Mvo
  • Change Blindness (office) https//www.youtube.com/
    watch?vdiGV83xZwhQ

5
Change Blindness
  • Counter experiment http//www.youtube.com/watch?v
    mAnKvo-fPs0
  • Campus Door Demo
  • http//viscog.beckman.uiuc.edu/flashmovie/12.php
  • Construction door http//viscog.beckman.uiuc.edu/f
    lashmovie/10.php
  • Gradual Change http//viscog.beckman.uiuc.edu/fla
    shmovie/1.php

6
Aspects of Attention
  1. Detection.
  2. Filtering and selection.
  3. Search.
  4. Automatic processing.
  5. Concentration.

7
Architecture
  • The box model

Sensory Store
LTM
STM
Filter
Pattern Recognition
Selection
Input (Environment)
Response
8
Attention
  • In this model, attention is
  • The filter and selection boxes
  • The arrows.
  • The special job carried out by each of these
    boxes according to different theories of
    attention
  • (Yes, this is cheating)
  • In this model attention
  • Puts together information from various sources.
  • Gets information into STM
  • Works in imagery

9
Detection
  • Two kinds of thresholds
  • Absolute Threshold Minimum amount of
    stimulation required for detection.
  • Difference Threshold (Just Noticeable
    Difference) Amount of change necessary for two
    stimuli to be perceived as different.

10
Detection
  • Absolute Thresholds
  • Vision One candle, on a mountain, perfectly
    dark, 30 miles.
  • Hearing A watch ticking 20 feet away.
  • Smell A single drop of perfume in a three room
    apartment.
  • Touch The wing of a bee on your cheek.
  • Taste One teaspoon of sugar in two gallons of
    water.

11
Determining Thresholds
  • How to determine thresholds
  • Method of limits
  • Ascending Start with a value below the
    threshold, increase, ask for detection, increase
    At the point a person says detect, average
    that stimulus value with the value from the
    previous trial. Repeat to estimate threshold.
  • Descending Same, but start above threshold and
    work down.
  • Combining results from both directions will give
    you an estimate of the threshold.

12
Determining Thresholds
  • How to determine thresholds
  • Method of constant stimuli
  • Present a series of randomly selected stimulus
    values, ask for yes/no response for each. The
    value thats detected 50 of the time is the
    threshold.
  • These methods can be adapted to determine
    difference thresholds.

13
Determining Thresholds
  • We think thresholds work like a step function,
    but they dont. They are sigmoid or ogive curves

This graph represents an ogive-curve and how
detection really changes it is a gradual slope.
The threshold is defined as a 50 detection rate.
This graph represents a step function. Below the
threshold there is 0 detection. Above the
threshold, there is 100 detection. This is the
way we normally believe our perception to work.
14
Determining Thresholds
  • Difference Threshold
  • Webers Law K ?I / I
  • K is the Konstant
  • ? is the difference
  • I is the stimulus intensity
  • The formula states that the threshold for
    noticing a difference (whether its the length of
    a line or weight of a dumbell) is a constant
    ration between the old / background stimulus
    and the new / target stimulus.

15
Determining Thresholds
  • Early Researchers Noticed Thresholds Shift!

These are ogive curves for stimuli of the same
intensity but with different signal to noise
ratios or payoff matrix
  • How to get around this problem A model that
    accounts for signal to noise ratios and payoff
    matrixes ? Signal Detection Theory

16
Signal Detection
  • Can estimate detection (sensitivity) independent
    of bias.
  • Two kinds of trials
  • Noise alone Background noise only.
  • Signalnoise Background noise with signal.
  • Two responses from observer
  • Detect.
  • Dont detect.

17
Signal DetectionFour Situations
State of the world State of the world
Response Signal Noise
Yes (Present) Hit False Alarm
No (Absent) Miss Correct Rejection
18
Hits(response yes on signal trial)
Criterion
N
SN
Probability density
Say yes
Say no
Internal response
19
Correct rejects(response no on no-signal trial)
Criterion
N
SN
Probability density
Say yes
Say no
Internal response
20
Misses(response no on signal trial)
Criterion
N
SN
Probability density
Say yes
Say no
Internal response
21
False Alarms(response yes on no-signal trial)
Criterion
N
SN
Probability density
Say yes
Say no
Internal response
22
Signal DetectionSensitivity and Bias
  • We can estimate two parameters from performance
    in this task
  • Sensitivity Ability to detect.
  • Good sensitivity High hit rate low false
    alarm rate.
  • Poor sensitivity About the same hit and false
    alarm rates.
  • Response Bias Willingness to say you detect.
  • Can be liberal (too willing) or conservative (not
    willing enough).
  • For example, if the true signal to noise ratio is
    50 and you have a 75 detection rate, then your
    response bias is to be too liberal.

23
Signal DetectionSensitivity and Bias
  • Computing sensitivity or d (d-prime)
  • Is a measure of performance (like percent
    correct, or response time)
  • Typical values are from 0 to 4 (greater than 4 is
    hard to measure because performance is so close
    to perfect)
  • A d-prime value of 1.0 is often defined as
    threshold.

24
d-Prime
  • d-prime is the distance between the N and SN
    distributions
  • d-prime is measure in standard deviations
    (Z-Scores)
  • In SDT, one usually assumes the two underlying
    distributions are normal with equal variance
    (i.e., both curves have the same standard
    deviation)

25
Signal DetectionSensitivity and Bias
  • Computing bias
  • The criterion is the point above which a person
    says detect. It can be unbiased (the point
    where the distributions cross 1.0), liberally
    biased (lt 1.0), or conservatively biased (gt 1.0).

26
Signal DetectionSensitivity and Bias
  • Since sensitivity and bias are independent, you
    can measure the effect of different biases on
    responding to a particular value for
    detectability.
  • Influences on bias
  • Instructions (only say yes if youre absolutely
    sure).
  • Payoffs (big reward for hits, no penalty for
    false alarms).
  • Probability of signal (higher probability leads
    to more liberal bias).

27
Signal DetectionSensitivity and Bias
  • Receiver operating characteristic (ROC) curves
  • For a given detectability value, you can
    manipulate the hit and false alarm rates. An ROC
    curve shows the effect of changing bias for that
    level of detectability.

28
Sample ROC Curves
of Hits
29
Optimal Performance
  • Depending on the probability of a signal trial
    and the payoff matrix, the optimal placement of
    the criterion will vary.
  • p(N) value (CR) - cost (FA)
  • ?opt X
  • p(S) value (H) - cost (M)
  • You can compare performance to the ideal observer
    to assess the operator.

30
Examples of Visual Search
Is there a threat?
Wheres Waldo?
31
Search
  • How do you use attention to locate items in a
    complicated array? Two kinds of search Feature
    Search and Conjunction Search.
  • Feature search A single feature allows you to
    find the item you are searching for.
  • Find the blue S.

32
Search
X T X T
X T S X
T X X X
T T X T
33
Search
X T X T T T X T
X T X X T X T T
T X S T X X T X
X X T X T X T X
T X T T X T X T
34
size Treisman Gelade 80 Healey Enns 98
Healey Enns 99x
length, width Sagi Julész 85b Treisman
Gormican 88
line (blob) orientation Julész Bergen 83 Sagi
Julész 85a, Wolfe et al. 92 Weigle et al. 2000
closureJulész Bergen 83
colour (hue) Nagy Sanchez 90 Healey 96 Bauer
et al. 98 Healey Enns 99
density, contrast Healey Enns 98 Healey Enns
99
curvature Treisman Gormican 88
35
Search
  • How do you use attention to locate items in a
    complicated array?
  • Conjunction search You have to combine features
    to find the item you are searching for. This
    should take attention and be more difficult
    (Treisman, 1988).
  • Find the green T.

36
Search
X T X T
X T T X
T X X X
T T X T
37
Search
X T X T T T X T
X T X X T X T T
T X T T X X T X
X X T X T X T X
T X T T X T X T
X T X T
X T T X
T X X X
T T X T
38
Simple feature search Look for an O
39
Simple feature search Look for something red
40
Conjunctive feature search Look for something red
AND O
41
Conjunctive Search
Response Time
Simple feature search
Number of Stimuli in Display
42
Properties of searches
  • Feature searches
  • Dont require attention (pop-out).
  • No help from location cueing (dont need it).
  • Conjunction searches
  • Require attention.
  • Affected by the number of distracters.
  • Helped by cueing the location.

43
Pop-Outs in Advertisement
44
Scan Paths
45
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46
Feature Conjunction Attention as Glue
The significance between conjunctive and
disjunctive searches is that it means that
individual features like color and size are
loaded pre-attentively (attention is not
required), but a conjunctive search requires
attention to bind the two features to the object
to a location in space. You need attention to
know an object is both red and large and where it
is. The integration may happen in the visual
cortex as a result of synchrony, with attention
affecting the tuning properties of sensory
neurons, and preparing other cognitive processes
like working memory.
47
Attention as GlueKeep your eye on the fixation
point below. A screen with colored letters will
be briefly flashed. Try to remember as many
letters with their colors as you can.

48
L
S
O
P
Q
M
Q
H
U
X
B
T
K
V
Z
49
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50
Attention as a Glue
  • What color was the X?
  • Do you distinctly recall a particular letter
    being a different color? How did that happen? How
    did a color in one location get associated with
    an object in another location?
  • This is attention as a glue

51
Treismans Feature Integration Theory
  • A two-stage theory of visual attention.
  • Stage 1. fast parallel for single features
  • Stage 2. Slow serial for conjunctions of single
    features.
  • Several primary visual features are processed and
    represented with separate feature maps that are
    later integrated in a saliency map that can be
    accessed in order to direct attention to the most
    conspicuous areas.
  • A parallel search, a red circle amidst green
    circles, takes no time no matter how many green
    circles (its cheap). A serial search, with
    conjunction features, like red circles amidst
    black circle and red triangles, requires you to
    check each distractor serially.

52
Automatic Processing
  • After practice, some tasks no longer require
    attention. Three criteria for automatic tasks
  • Occur without intention.
  • When the load is low
  • Required reaction times are short
  • The tasks are over-learnt or well-practiced
  • No conscious awareness/Cant be introspected.
  • Dont interfere with other activities.
  • Fast processes -- the brain does them
    automatically, they are a basic feature
  • You can tell how the process of automatization is
    going by doing dual task studies (primary and
    secondary).

53
Automatic Processing
  • Read the Words.
  • Say the colors
  • Which is harder?

54
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55
Automatic Processing
  • You did the Stroop task.
  • The interpretation is that you automatically read
    the word. If thats the task, the color doesnt
    interfere because you dont automatically
    register that. If youre supposed to name the
    color, automatic reading messes you up.

56
Filtering
  • So, thresholds shiftbut once set, then what?
    What happens when something gets over the
    threshold wherever it is? When does meaning
    become involved?
  • How do we choose what to attend to? Is the choice
    made early or late?

57
Themes
  • Early or Late? In other words, does something get
    chosen before or after (respectively) the
    stimulus gets stamped with meaning
  • What is attention?
  • Some sort of bottleneck or filter?
  • A capacity or resource (or several kinds)?
  • Can we learn something by looking for it in
    brains?

58
Filtering
  • Early Broadbent. Selection happens at the filter
    and sensory store before pattern recognition. The
    selection is made at the EARLY STAGE of crude
    physical analysis.

59
Filtering
  • Early Evidence
  • Dichotic listening. Two messages, one to each
    ear, played simultaneously.
  • Shadowing Repeat out loud everything in one ear.
    What do people (or what dont people) notice in
    the unattended ear?
  • Miss change of speaker.
  • Miss change of language.
  • Miss change of direction.

60
Filtering
7-4-1
3-2-5
  • Early Evidence
  • Filter flapping Two sets of numbers come in, one
    set in each ear.
  • Report by ear Easy.
  • Report in order Hard.
  • The argument is that the filter lets in all of
    one channel, then the other, no problem. To
    switch back and forth takes a lot of effort.

61
Filtering
  • Problem for early models
  • People detect their name on the unattended
    channel (cocktail party phenomenon).
  • Treisman (1960) If a shadowed story switches
    ears, people follow it, and then correct. They
    have to be attending to meaning to follow the
    story.

62
Filtering
  • Problem for early models
  • Example 1
  • I SAW THE GIRL/song was WISHING
  • me that bird/JUMPING in the street
  • Example 2
  • AT A MAHOGANY/three POSSIBILITIES
  • look at these/TABLE with her head

63
Filtering
  • Attenuation model
  • Everything in memory is active at some resting
    level. Some stuff thats important has a high
    resting level, making it easier to respond to
    (e.g., your name).
  • Other stuff has a low resting level, making it
    harder to respond to.
  • As you think about something, you raise its
    activity level.

64
Filtering
  • Attenuation model
  • The unshadowed ear is attenuated (the volume is
    low). This little bit of attention can reach
    something with a high resting level (your name, a
    story youre shadowing), but not some random bit
    of information.
  • So, no filter, just attenuation.

65
Filtering
  • Capacity model
  • You have a certain amount of attention, you can
    spread it around as needed. If you spend a lot on
    one task, then you have less for others.
  • Primary task Do well on this no matter what
    (main focus of resources).
  • Secondary task Also do this.
  • By manipulating the difficulty of the primary
    task and measuring the secondary task, we can see
    how attention allocation affects performance.

66
Filtering
  • Capacity model
  • For example, Johnston and Heinz (1978) had two
    tasks
  • Primary Shadow one ear for a change that is easy
    (gender) or a change that is hard (category).
  • Secondary Detect a light.

67
Filtering
  • Capacity model Johnston and Heinz (1978)

Primary Secondary
Shadow one list (control) 1.4 error 310 ms
Easy (gender) 5.3 error 370 ms
Hard (category) 20.5 error 482 ms
68
Filtering
  • Capacity model
  • What this implies is that the filter can be early
    (gender) or late (category), the amount of your
    resources that you allocate to it determines
    where the filter is.

69
Emotion Driving Attention
  • Detecting a Snake in the Grass (Ohman, Flykt,
    Esteves, 2001)
  • Stimuli snakes, spiders, mushrooms, flowers
  • Presented in 2x2 or 3x3 displays
  • Task Do all the pictures belong to the same
    category?

70
Emotion Drives Attention
  • Reaction time to detect target in ms.

Fearful Neutral
2x2 950 1010
3x3 950 1010
71
Emotion Drives Attention
  • The Emotional Stroop Effect
  • You are slower at naming a color of emotionally
    charged words than neutral words
  • Taboo words vs neutral words

72
Emotion Drives Attention
  • Classical Stroop

RED GREEN BLACK YELLOW BLUE RED BLACK
RED GREEN BLACK YELLOW BLUE RED BLACK
73
  • Attic

74
  • Bitch

75
  • Shit

76
  • Anus

77
  • Frame

78
  • Dyke

79
  • Senate

80
  • Note

81
  • Bank

82
  • Queer

83
  • Scrotum

84
  • Wife

85
Emotion Drives Attention
86
Emotion Drives Attention
  • Emotional Stroop effect occurs with
  • Taboo words
  • Alcohol words (beer) in alcoholics
  • Smoking words (cigarettes) in smokers
  • Spider words (web, crawl) in arachnophobics
  • Food pictures in females with anorexia
  • Threat words (disease) with people with anxiety
    disorders

87
The Dot Task Detection in PTSD
88
Mood and Attention Levels of Focus (Gasper
Clore, 2002)
  • Hypothesis Affective cues may be experienced as
    task-relevant information, which then influences
    global versus local attention.
  • Mood Manipulation Subjects randomly assigned to
    write about a happy or sad event in their lives
  • Each participant randomly assigned to a drawing
    chain, where the first person in each group saw a
    drawing of an African shield with the title of
    Portrait of a Man. In a later session, a 2nd
    person saw the 1st persons reproduction from
    memory, and so on.

89
Local Global
  • Lesions in LH produce deficits in local
    perception
  • Lesions in RH produce deficits in Global

90
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91
Mood and Attention Levels of Focus (Gasper
Clore, 2002)
  • Happy Mood condition more likely than Sad Mood to
    contain schema-relevant details like title and
    facial features
  • Sad Mood drawings became less face-like down the
    chain but not Happy Mood drawings
  • Sad Mood drawing looked less like original

92
Mood and Attention Levels of Focus (Gasper
Clore, 2002)
  • Experiment 2 employed a task in which the same
    objects were sometimes the global and sometimes
    the local stimulus (Kimchi Palmer, 1982).
    Participants saw an overall shape (e.g., a
    triangle) made up of smaller geometric figures
    (e.g., triangles). Their task was to indicate
    which of two other figures (e.g., a square made
    of triangles or a triangle made of squares) was
    more similar to this target figure.

Result Sadder people base their decisions on the
local features, and report doing so.
93
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94
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95
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96
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97
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98
Posner Cueing Task
Peripheral Cue condition triggers exogenous
attention/ Reflexive attention Bottom-up
Central Cue condition triggers endogenous
attention / voluntary attention Top-down
99
Inhibition of ReturnThe Been There, Done That
Reflex
  • We are faster at unpredicted cues after a long
    enough pause
  • IOR prevents going over the same ground, promotes
    searches for novel stimuli

100
  • The findings from patients with brain damage led
    Posner to construct a model for attention that
    involves three separate mental operations
  • Disengaging of attention from the current
    location
  • Moving attention to a new location
  • Engaging attention in a new location to
    facilitate processing in that location.

101
Psychological Refractory Period (PRP)Timing the
Central Bottleneck
  • A Multiple sensory input
  • B Serial Decision maker
  • C Multiple action output

A
B
C
Stimulus 1
A
B
C
PRP
Stimulus 2
SOA
Time
Slope 1
102
Embodied cognition of attention is Cognition
Time-Pressured?
  • If we were designed to perform under pressure, we
    would be good at it.
  • But, the reality is that, under time pressure we
    fall apart
  • We actively avoid operating under conditions
    where we are time pressured
  • Most of daily behavior consists of mundane,
    routine behavior

103
Embodied Cognition is Time PressuredWilson, 2002
  • Summary
  • Perceptuomotor processes are time-pressured, but
    that does not illuminate cognitive performance
    under time pressure
  • Difficult to interpret whether cognition is time
    pressured means we evolved to perform under
    pressure or that our cognitive abilities must be
    understood in the context of coping with
    (unsuccessfully) or avoiding time pressures

104
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105
  • Line Bisection and flower drawing are examples of
    spatial-based neglect.
  • The dumb-bells are an example of object based
    neglect

106
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107
IMPLICIT ASSOCIATION TEST

108
CATEGORY SWITCH
?
?
Get Kristin's demo
?
?
?
?
109
WORD CATEGORIZATION
?
?
?
?
?
?
?
110
IMPLICIT ATTITUDES
111
IMPLICIT BELIEFS
2000
Reaction Time
1500
1000
500
0
Insects Good
Insects
Bad
112
Stereotype Threat(Beilock McConnell, 2004)
  • People perform in compliance with stereotypes
  • In one of the first studies on stereotype threat,
    Steele and Aronson (1995) had high-achieving
    African American and Caucasian students at
    Stanford University complete a portion of the
    graduate record exam (GRE).
  • Prior to doing so, some students were told that
    the test was diagnostic of intellectual ability
    whereas others were told that the test was a
    laboratory problem-solving task not diagnostic of
    intellectual ability.

113
Stereotype Threat(Beilock McConnell, 2004)
  • Results demonstrated that after controlling for
    SAT scores (to equate past academic performance),
    there was no difference in GRE performance
    between White and Black students for whom the
    test was not framed as diagnostic of intellectual
    ability.
  • Of those students who were told that the test was
    diagnostic of intellectual ability, however,
    African Americans performed significantly worse
    than Caucasians.
  • Steele and Aronson argued that informing students
    about the diagnosticity of the test activated the
    negative cultural stereotype that Blacks are not
    as intelligent as Whites, which contributed to
    the less-than-optimal performance of African
    Americans on a test assumed to gauge intelligence.

114
Stereotype Threat Memory or Attention(Beilock
McConnell, 2004)
  • How does stereotype threat work?
  • One proposal is that stereotype threat produces
    reduces working memory capacity
  • But past research has shown that stereotype
    threat effects are most pronounced for expert
    athletes, for whose abilities are highly
    proceduralized, relying little on working memory.
  • On the other hand, expert athletes choke when
    they start to pay too much attention to the steps
    of their automatized processes this increased
    attention can backfire and disrupt what should
    have been fluent, proceduralized execution. This
    idea is often termed the explicit monitoring
    hypothesis.

115
Stereotype Threat Memory or Attention(Beilock
McConnell, 2004)
  • Do stereotype threats reduce working memory
    capacity, or do stereotype threats prompt
    explicit monitoring of automated procedures
  • Expert male golfers perform a putt, before or
    after hearing a stereotype (men are poorer
    putters than women) or receiving control
    information (putting performance differs as a
    function of skill level).
  • Experts who received stereotype did worse

116
Stereotype Threat Memory or Attention(Beilock
McConnell, 2004)
  • Now how to determine it is attention? Introduce a
    dual-task
  • Experiment 2 (Beiock et al, 2003)
  • Two groups with stereotyped and non-stereotyped
  • One group performs putting alone
  • Second group putts while listening for target
    word
  • Results. Performance was the same for putters in
    the dual single task who had no stereotype
    threat. For putters with stereotype threat,
    performance was better in dual-task condition
    (Stereo-type Threat affects attention, not
    memory)

117
The End
118
Quizz
  • You drove home and did not stopping at the store.
  • This was due to a search failure because the sign
    for the store did not pop-out.
  • You have a lot on your mind, and you are easily
    distracted
  • Going to the store is a conscious decision, but
    you were filtering based on perceptual features
  • Driving home is an automatic process
  • Driving home is a conditioned response

119
Quizz
  • Youre walking to class and thinking about a quiz
    thats coming up. Someone calls your name, but
    you dont hear them.
  • a) Your ROC curve is high.
  • b) This counts as a hit
  • c) You are filtering for perceptual features
  • d) You are filtering for categorical or semantic
    information
  • e) You didnt study and you cant hear people
    while throwing-up

120
Concentration
  • Our last topic has to do with the task of paying
    attention.
  • Sometimes you have to concentrate on something in
    which you have no interest.
  • Sometimes you have to not think about something
    in which you have an interest.

121
Concentration
  • Wegner, Schneider, Carter, and White (1987).
  • Try not to think of a white bear.
  • Five minutes, measure the number of times people
    do it.
  • Or, try to think of it.
  • Both are hard, with less activity later on.

122
Concentration
  • Wegner, Schneider, Carter, and White (1987).
  • After suppression, its easier to keep thinking
    about a white bear.
  • After expression, its still hard not to think of
    a white bear at first, but people adapt.

123
Embodied cognition of attention is Cognition
Time-Pressured?
  • Cognition happens in real-time or runtime
  • Cognition must cope with predators, prey,
    stationary objects and terrain as fast as the
    situation dishes them out.
  • How do you get robots to think about walking on
    uneven terrain, or to swing from branch to
    branch, or looking around a crowded room looking
    for a soda without bumping into something
  • Story of legalizing sightdogs.

124
Embodied cognition of attention is Cognition
Time-Pressured?
  • Examples for
  • Skilled hand movements, or time-locked
    perceptuomotor activity (catching, throwing,
    tying, walking)
  • Inhibition Of Return
  • Exogenously driven attention
  • Examples Against
  • PRP
  • Task-switching
  • Trade offs between speed and accuracy in attention

125
Quizz
  • You are looking for a friend at a party. This
    person has brown hair and is very tall.
  • You are performing a serial search, that will be
    affected by the number of people there
  • You are performing two serial searches, and the
    person will pop-out
  • You are performing a conjunction search which
    will be affected by the number of people there
  • You are performing a conjunction search and the
    person will pop-out because there is nobody
    else there with those two qualities.

126
Quizz
  • The Titanic hitting an iceberg would be a pretty
    good example of a
  • hit
  • miss
  • false alarm
  • correct rejection

127
Quizz
  • Bob, an electrician, is trying to see how faint
    he can make a light. He starts by turning the
    light ON to its maximum, then turning it down
    until he cannot see it.
  • a) Difference detection methods of limits
    ascending
  • b) Difference detection method of constant
    stimuli random
  • c) Absolute thresholds method of limits
    descending
  • d) Absolute thresholds constant stimuli random

128
Quizz
  • In Signal Detection Theory, which of the
    following is not true
  • attention requires more hits than false alarms
  • there is a normal distribution for signal and one
    for noise with the distance apart measured in
    Z-scores
  • d-prime measures the difference between signal
    and noise
  • bias and sensitivity are independent
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