Intelligence &
Reasoning
Your Implicit Theories of
Intelligence
Intelligent
Unintelligent

1986 Expert Definitions
Adaptation to environment
 Basic mental processes
 Reasoning, problem solving, decision
making
 Metacognition –

Intelligence
Consider Albert Einstein
(1879 - 1955)
German-born U.S. physicist
theory of general relativity
exploitation of atomic energy
won a Nobel prize in 1921
"einsteinium" named after
Einstein

How intelligent was Einstein?
Estimated IQ = 160
Can you think of others thought
to be intelligent?
And why?
What is IQ?

An estimate of intellectual ability

Wechsler - "capacity of the individual to act
purposefully, to think rationally, and to deal effectively
with [the] environment“

True IQ can not be known

It’s a quantification of a concept…

…except it’s an often misunderstood and misused
concept
History of Intelligence Testing







Sir Francis Galton (1822-1911)
Cousin of Darwin
English Intellectual
Correlation coefficient
Eugenics – forbidding certain
individuals to bear children, etc.
Pioneer in Intelligence
Invented first comprehensive test of
intelligence (Adults)
Galton cont’d

1.
2.
Two general qualities distinguished individuals
who were more intelligent from those less
intelligent
Energy = speed or neural quickness
Sensitivity = sensory acuity or accuracy
 Had people close their eyes and put objects that looked
and felt the same in order based on weight. Similar for
touch: wires of differing fineness, taste = salt, hearing =
pitch, smell = different amounts of perfume.

Intelligence is _______________________
Alfred Binet (1857-1911)

Found that Galton's tasks did not
discriminate between children and
adults

His work represented the beginning
of modern intellectual testing.

History of the Study of Intelligence
Binet and Simon (early 1900s)

1.
2.
3.
Higher-Order Mental Abilities Central to Intelligence
Direction: knowing what has to be done and how it
is accomplished.
Adaptation: task selection and monitoring.
Control: Ability to criticize one’s thoughts and
actions: If you notice the sum is smaller than one of
the numbers you realise you have to do it again.
History of the Study of Intelligence

Binet and Simon (early 1900s)

All forms of making judgments, decisionmaking, strategizing = executive functioning

Believed intelligence could be improved
through instruction and practice
General Intelligence




Charles Spearman’s Psychometric Model (1904)
Developed a new set of tests and the statistical
technique “factor analysis” to make sense of the
results. It finds patterns of correlations among scores
or measures of identify sets of underlying abilities.
FA finds patterns of correlations among scores
Identified two separate factors influencing
performance on intelligence tests:
g
= general intelligence
 s = specific ability
Spearman’s Psychometric
Model



g = general intelligence
 Used to explain why most intelligence tests
correlated with each other (ranging from 0.30 to
0.60)
 Some common denominator = biologically based
s = specific ability
 Used to explain why correlations were not perfect
 Learned ability
Score is a combination of both g and s
Two Kinds of g (general intelligence)



Raymond Cattell (1971) – worked with Spearman and
later modified Spearman’s theory to include two kinds of
g:
Fluid Intelligence
 Reason abstractly and think flexibly
 Perceive relationships or differences
 Peaks between 20-25 years of age and then
declines
Crystallized Intelligence
 Derived from previous experience
 Accumulated knowledge (words, cultural practices)
 Increases until age 50
Modern Intelligence Tests

Stanford-Binet Intelligence Test
Developed by Lewis Terman at Stanford in 1916
 Influenced by Binet & Simon


Grounded in competencies central to schooling
Identify body parts of a doll
 Similarities and differences (how are a dog and a
cat similar? different?)
 Arithmetic word problems

Binet-based tests, cont’d
Intelligence Quotient (IQ)
Mental Age = match the individual’s test score to the age
group whose average score was similar

e.g., Mental Age = 10

any child whose score was similar to an average 10-year-old

Mental age/actual (chronological) age x 100 = IQ
E.g., 10/10 = 1 x 100 = 100
E.g., 10/8 = 1.25 x 100 = 125
An IQ of 100 is average for your age group
This concept of IQ is not bad for children, but…Absurd to say
that a 20 year old who performs as well as a 60 year old has
an IQ of 300.




Wechsler Scales


Developed by David Wechsler in 1930s
Kept term “IQ” but adapted the meaning to compare
performance to the average person.
Verbal subtests: vocabulary, similarities,
information, comprehension, digit span, letternumber sequencing, arithmetic
 Performance subtests: block design, picture
completion, picture arrangement, object assembly,
matrix reasoning, digit-symbol coding, symbol
search

Wechsler Scales

Standardized Scoring:
compare your score to those from a
large sample of individuals of the
same age
 Mean = 100
 Standard deviation = 15
 We’ll see more on this later


WISC-III = ___________
David Weschler

Wechsler’s Innovations…
a. based the scoring scheme on the normal
distribution - discarded the idea of IQ based
on mental age
b. involve verbal and performance scales
c. relied less on verbal ability than previous
measures of intelligence
WAIS

Full Scale IQ
Verbal IQ
 Performance IQ

WAIS-III Verbal Subtests

Information:


Comprehension:


If you have 4 apples and eat 3 how many are left?
Similarities:


what should you do if you find a wallet on the street?
Arithmetic:


what is the capital of France?
How are dog and cat alike?
Vocabulary:

define chair, asylum,etc


Digit span:
 repeat number sequences in forward and reverse
order
Letter-Number sequencing:
 Repeat list of letters and numbers in chronological
order
WAIS-III Performance Subtests



Digit symbol:
 copy designs associated with different numbers
Picture completion:
 determine what is missing from a picture
Block design:
 arrange blocks to match a picture

Picture arrangement:


Object assembly:


put a puzzle together
Matrix Reasoning:


arrange pictures so they tell a story
Determine what goes next in a pattern
Symbol Search:

Determine if the target symbols match any of
the symbols in the search group
WAIS and Binet Tests

are individual tests

usually administered on an one to one basis
Two pitfalls:

expensive to administer

time consuming to administer
Common Uses - Past

Binet - detection of mental deficiencies or
giftedness in children and mental
deficiencies in adults

Terman-______________________

Wechsler- assess learning disabilities and
neuropsychological evaluation
More on INTELLIGENCE to
come later:
but for now, let’s look at tests
in general
Measures of psychological
constructs: applications and
strategies

What’s a psychological test?

Assesses of a sample of behaviour. Interpret it
cautiously (do we know the test is valid? Can we
infer from the sample to day-to-day reality?).
• Best to use more than one test (increases reliability +
trust in the result).
Ex: Applying to Grad School

graduate school criteria: GRE scores, references
letters, statement of purpose, experience,
publications, marks and personal interviews.
Participation in an Honours program also important
for Psychology.

Looking for more than high grades.

when assessing some psychological construct, use...
1.
2.


Assessing the person…
Rare for students
Publications
The higher the better
Higher
The
Better
Grades
Person
Know referees
Well…
Recommendation
GRE
Magic
Number
1800 (top
score 2400)
Letter of Is it clear? Do they
Intent know what they
want, and want to
research?
Categories of other Psychological
Tests
Personality
Mental Abilities
Others?
Personality Tests
Objective:
Projective
Minnesota Multiphasic
Personality Inventory.
Multiple scales with
multiple items.
Thematic Apperception Test –
personality said to be revealed
depending on stories told about pictures
of ambiguous scenes.
Mental Abilities Tests
 Mental
ability tests
1) Intelligence test
2) Aptitude
3) Achievement tests
Mental Abilities Tests

intelligence tests are intended to measure general
mental ability

aptitude tests are intended to measure specific types
of mental abilities: _________________________?

achievement tests are intended to gauge a person's
mastery and knowledge of various subjects: _______
What Makes a Test Good?

A Test Must Be:
 Reliable
 Valid
 Reliable
= consistent
 Valid = measuring what it
is suppose to measure
Reliability and Validity
Target Practice …!
Reliability and Validity
Reliable but not valid
Reliability and Validity
Neither reliable nor valid
Reliability and Validity
Reliable and valid
Definition of Reliability
reliability = refers to test's precision,
dependability, consistency
A reliable test minimizes error and
provides repeatable consistent
results.
Classical Test Theory
Observed
score
=
True
ability
+
Random
error
Classical Test Theory


Suppose my true weight is 140 lbs
Suppose my scale is cheap (unreliable)

Assessed Weight
X = 135, 143, 141, 144

E = -5, 3, 1, 4

Types of Reliability
•
•
•
•
Test-retest
Alternate Forms
Internal Consistency
Inter-rater
(1) Test-Retest Reliability

Administering the
same test to the same
set of examinees on
two separate
occasions.
Test-Retest Reliability
Questionnaire (Completed 9/20)
Questionnaire (Completed 9/27)
___
4 I feel I do not have much proud of.
___
4 I feel I do not have much proud of.
___
3 On the whole, I am satisfied with myself
___
4 On the whole, I am satisfied with myself
___
2 I certainly feel useless at times
1 I certainly feel useless at times
___
___
1 At times I think I am no good at all
___
1 At times I think I am no good at all
___
4 I have a number of good qualities
___
4 I have a number of good qualities
___
3 I am able to do things as well as others
___
4 I am able to do things as well as others
(2) Alternate Forms

Two versions of the same
test with similar content.

Forms must be equal
(3) SPLIT HALF



Measures internal
consistency.
Correlate two halves such as
odd versus even items.
Works only for tests with
homogeneous content
(4) Interrater Reliability

Measures scorer or
inter-rater reliability

Do different judges
agree?
Cronbach’s alpha – commonly used for
assessing psychological tests. How well
do the items hang together? Does
someone who ranks one question as a
“5” rank most other questions as “5,” for
instance?
Example on next slide:
Is this a good measure of sleep
quality?
1 = Completely disagree, 5 = Completely agree
I had a good sleep last night.
 I tossed and turned last night.
 My life is full of stress.
 I woke up this morning feel refreshed.
 I feel awake enough to accomplish
today’s tasks.
 My bed is very comfy.

Validity
The ability of a test to measure
what it is supposed to measure.
Types of Validity
Face
 Content
 Criterion
 Construct
 Factorial

Types of Validity:
Face Validity
Concerns mere
appearance of
test –

Types of Validity: Content

Content - the degree to which the content of a
test is representative of the domain it's
supposed to cover.

Is it covering all aspects of the construct in
question? (sleep quality, intelligence, etc.)
Types of Validity: Criterion
Most important form of validity: criterion.
 Criterion validity: is estimated by correlating
subjects' scores on a test with their scores on
an independent criterion
 In other words: accuracy with which test scores
can be used to predict another variable of
interest (the criterion). For example:

Types of Validity: Construct

Construct – The extent to which a measurement
method accurately represents a construct and
produces an observation distinct from that
produced by a measure of another construct.

In other words: The degree to which inferences can
legitimately be made from the “working definitions”
in your study to the theoretical constructs on which
those definitions were based.
Construct validity cont’d

Construct validity involves generalizing from
your program or measures to the concept of
your program or measures. You might think of
construct validity as a "labeling" issue. When
you measure what you term "self esteem" is
that what you were really measuring?

Your “self esteem” scale might be measuring
some construct, but is it actually self esteem, or
might it be that you are actually assessing
another construct such as optimism or
confidence?
Back to our discussion of
intelligence…
Deviation IQ Scores

the intelligence quotient developed by Terman has now
been replaced by the deviation IQ

deviation IQ = scores that locate subjects precisely within
the normal distribution, using standard deviation as the
unit of measurement

average deviation IQ is set at 100
standard deviation of 15
a score of 100 lies at the 50th percentile


Deviation IQ Scores


based on deviation IQ scores, there are a variety of mental
classifications
these categories are arbitrary
55 to 70 = retarded
70 to 85 = borderline
85 to 115 = average
115 to 130 = superior
130 to 145 = gifted
Does school make you smarter?


Emerging evidence that education influences
intelligence. However, effect may be due to students selfselecting for college & university (more able students
may stay in school longer, thus confounding results).
Research that is able to rule out other influences
indicates that education_____________________
Extremes of Intelligence

mental retardation (MR) and giftedness

MR = subnormal mental ability
accompanied by deficiencies in everyday
living skills

Less than two standard deviations below a
mean of 100.

the cutoff point is...
Mental Retardation
85% of persons classified as mentally
retarded have a score between_____
 which means they have about a grade
6 level of functioning and often can be
self-supporting

Causes of Mental
Retardation
organic causes such as Down
syndrome, hydrocephaly (“water on
the brain”)
 organic causes only account for 25%
of the known cases


cause is not known in 75% of the
cases
Retarded Savants

Severe mental handicaps




But retarded savants have spectacular islands of
ability or brilliance.
Some have skills that are remarkable in contrast to
the handicap; others have an ability that would be
spectacular even in a non-retarded individual.
6x more common in males than in females
Occurs for a very narrow range of skills: calendar
calculating, music (piano almost exclusively),
mathematical calculations, mechanical ability,
prodigious memory, or, rarely, unusual sensory
discrimination abilities (smell or touch).
How? One theory:


Underlying all savant abilities is a seemingly
limitless memory. Savant art, for example, is
remarkable not for its creativity but for its
realism – exact copies of animals or people
or scenes done from memory.
Savants do not have distractions; the brain
is dedicated entirely to the task at hand.
The rest of us get distracted – nine times
seven, carry the two, how did that stain get
on my shirt, and four sevens is…
Giftedness

Book of World Records: 4 year old Korean
boy with IQ over 200.

Many of us think of the gifted child as weak,
socially inept and emotionally troubled.

Terman (1921): gifted individuals tend to be
physically superior, emotionally adjusted and
socially mature.
Giftedness
Renzulli (1986) giftedness may be
the result of three things:
exceptional intelligence in a
specific domain, task-motivation,
and creativity  i.e. “brains” aren’t
enough – the person must be
creative and wish to put their
intelligence to use, too.
IQ tests reliable and valid?
Exceptionally reliable

But are intelligence tests valid?

Do they measure what they are supposed to measure?
 yes, intelligence tests usually measure one facet of
intelligence

the correlation between academic achievement and IQ is
.5 to .6
the correlation between number of years of school and IQ
is around .7. What other factors affect school
performance?

IQ tests are reasonably valid indexes of school-related
intellectual achievement
Layperson’s Conception

The limited ability of intelligence tests to tap the full
range of intellect is captured by the average
person's conception of IQ

the average person believes that IQ consists of
verbal, practical and social intelligence. IQ tests
generally fail to assess all of these factors,
although they certainly assess verbal abilities and
many analytical skills.
Influence of Environment

individuals raised in impoverished environments tend to be
lower in IQ . This is known as the cumulative deprivation
hypothesis.

parents who run an orderly household, are warm,
affectionate and highly involved with their children tend to
have children with higher IQ scores.

Homes that encourage exploration, experimentation and
independence also foster IQ scores.

Providing age appropriate toys and speaking articulately to
their children

Encouraging hard work and rewarding your children when
they do well is also quite important
Reaction Range

Are there upper limits to one’s intellectual potential?

Sandra Scarr has suggested that genetics or heritability
imposes limits on IQ scores - this is known as the reaction
range
We will discuss this topic again at the end of the
chapter when we take a closer look at heritability.

within this range, the quality of one's environment determines
where one will sit along this range

This may explain certain differences among cultural groups.

The implication of this theory suggests that so-called racial
differences are actually due to ______________________
Cultural Bias?

Another reason for so called racial
differences is related to cultural bias.

IQ tests are slanted in favor of white
middle class Americans at the
expense of lower-class minorities. The
tests ask questions that depend on
having access to certain ideas and
opportunities.
Cultural Slant?
These days the slant on IQ tests is
modest
 IQ differences are more likely to be the
result of impoverished environment than
test bias.
many school districts are shifting away from
IQ tests to achievement and aptitude
tests
 more of an emphasis toward specific
abilities

Attacks on IQ Construct

Flynn


IQ tests merely measure abstract problem
solving ability, not intelligence
Lezac

Global IQs are impure and meaningless
IQ doesn't predict success in life.
IQ tests are misused
IQ Tests Do Not Measure…
Other Conceptions of
Intelligence

Horn
 Two Factor Theory

Sternberg
 Triarchic Theory

Gardner
 Multiple Intelligences

Goleman
 EQ
Horn

Two Factor Theory of Intelligence:

Fluid Intelligence - non-verbal, relatively culture
free, independent of specific instruction (i.e. memory
of digits).

Crystallized Intelligence - acquired skills and
knowledge that are dependent on exposure to a
culture as well as to formal and informal education
(i.e. vocabulary).
Robert Sternberg

Triarchic Theory
Analytical
 Creative
 Practical

Sternberg’s
Triarchic Theory of Intelligence:
1)
Componential intelligence (mental abilities
most closely related to success on traditional
IQ and achievement tests => analytical ability).
2)
Experiential Intelligence (creative thinking
and problem solving => creative ability).
3)
Contextual Intelligence (practical intelligence
or “street smarts” => practical ability).
Howard Gardner
Multiple Intelligences

To Gardner (1985, 1993), an intelligence is any skill universal
to humans and that is organised through a system of mental
symbols and rules for manipulating or structuring them.

Postulates distinct brain mechanisms underlying each
intelligence, which is why brain injury or developmental
disorders can affect intelligences differently.

Gardner has identified what he thinks are seven distinct
intelligences: linguistic, logical-mathematical, spatial ,
musical, bodily-kinesthetic, interpersonal, intrapersonal.

Three of his intelligences are measured by standard IQ tests
(linguistic, logical-mathematical, and spatial). The others are
not usually considered as part of intelligence.
 Some
say Gardner has stretched the
definition of intelligence too far. The nonstandard aspects of intelligence that he
describes are called talents by others. [is
this all just semantics?]
 Part
of his message is that some abilities
are overly valued at the expense of other
abilities.
 There
is little statistical or other objective
evidence for his seven separate
intelligences, however.
Emotional Intelligence:
Goleman




(1) awareness of and ability to manage one’s
emotions
(2) the ability to motivate oneself
(3) empathy
(4) the ability to handle relationships successfully
IQ Stability?

generally stable by age 7 or 8 but not
set in stone -- in some people there
can be substantial changes

how could these changes take place?
... knowledge of words, brain damage,
what else?
Nature or Nurture?
Nature: biological inheritance, genes
 Nurture: environmental conditions
 Both are essential for any trait to develop
 Are differences in intelligence among
individuals due more to differences in their
genes or environments?

Controversial Topic
Galton emphasized heritability (influence of genetics versus
environmental influences)
typical estimates of heritability and intelligence lie to
between: 50 & 70%
consensus for intelligence hovers around 60% contribution
from genetics (others argue more or less)
Review

When genetics or another reason puts a
limit on possible IQ, what is this called?


What American test was created to
demonstrate cultural bias?


Reaction Range
Chitling Test
Who argued that IQ tests are impure and
meaningless?

Lezac
Let’s examine HERITABILITY
Do you think the differences among this class group
in extroversion are due mainly to differences in the
environments in which you grew up, or do you
think they are due mainly to differences in your
genes?

Hereditability: degree to which variation in a
particular trait, within a particular group of
individuals ____________________________
 In other words, heritability is the proportion of
variance that’s caused by genetic differences
among individuals within groups.
Heritability

Heritability = __________variance due to genes___________
variance from genes + variance from environment

(i.e. genetic variance / total variance)

Heritability applies to GROUPS, not to individuals.
Heritability cont’d

Suppose you were all adoptive siblings, all raised in
the same home by the same parents. Do you think the
differences among you in extroversion would be due
more to genes or more to environment?
 Assuming being raised in the same home reduces
the environmental contribution to typical variability,
the remaining variability will be due more to genes.

Suppose all of you were genetic clones. Now would
the differences be due more to genetics or to
environment?
 In this case, all differences must be due to
environment, and heritability = __________
Heritability cont’d

Thus, heritability for any given multiply-influenced trait
can be high or low depending on the degree to which
members of a population differ in the relevant genes or
in relevant aspects of environments.

Differences among people can be accounted for in part
by the genetic differences among them. Heritability is a
measure of how big that part is.
An increase in the genetic diversity of a group increases
the “heritability coefficient.”
An increase in the environmental diversity of a group
decreases the heritability coefficient.


Results from Twin Studies





IQs of identical twins correlate more strongly than
IQs of fraternal twins
Gap widens in adulthood
Studies suggest that genetic differences account for
about ½ IQ variance in children and adolescents
and more among adults
In childhood environment – home/school – choices
are constrained and thus contribute more to IQ. The
environment constrains genetics.
In adulthood, environments are chosen based on
genetics. Genetics constrain the environment.
Role of Culture
Most heritability studies conducted
with white, North American and
European , upper middle-class
samples
 Because theses samples are more
uniform (participants are more similar)
than representative samples of the
entire population, heritability is high
 When more environmental variation is
introduced, heritability will decrease

Cultural Origin of IQ
Differences
John Ogbu
 Studied Black-White differences in US,
Buraku-Ippan and Korean-Ippan differences
in Japan
 Minority groups, on average, typically score
lower on IQ tests than majority culture
 Due to caste status: membership is
determined at birth, unlike social class, which
is acquired after birth and can change
throughout life

Involuntary minorities
 Showed that when Buraku-Japanese children
moved to the U.S., they performed as well as
Ippan-Japanese children living in Japan and
in the U.S.
 Same for Korean children in U.S. compared
to Korean children living in Japan
 Social designation, not biology, that
contributes to group differences

Problem Solving
PSYCO 105
Inductive Reasoning
Infer a new principle or proposition
from a set of observations of facts
 Hypothesis construction
 Educated guess
 But: biases exist in people’s strategies


Biases lead to incorrect inferences
Representativeness

The text describes how we judge the likelihood of things
in terms of how well they seem to represent or match a
particular prototype.
Linda is a 31, single, outspoken, and very bright. She
majored in philosophy in university. As a student, she
was deeply concerned with discrimination and other
social issues, and she participated in antinuclear
demonstrations. Which statement is more likely:
Representativeness

While representativeness works well most of the
time, it leads to errors when its conclusions run
counter to the laws of chance.

Information that seems typical or representative
is often ______________________________

If a test to detect a disease whose
prevalence is 1 in 1000 has a false
positive rate of 5% (i.e. the
percentage of times the test
mistakenly indicates the disease is
present), what are the chances that a
person found to have a positive result
actually has the disease, assuming
you know nothing else about the
person?
Base-Rate Fallacy



The base-rate fallacy is the tendency to ignore
or underuse base-rate information and instead
to be influenced by the distinctive features of
the case being judged.
Ward Casscells and his colleagues gave this
problem to physicals and med students at four
Harvard Medical School teaching hospitals.
They obtained an average response of
_____________________________
The correct answer is about _______________

The base rate indicates that the majority of
people do not have the disease, and the
vast majority of positive tests come from
people who do not have the disease.

Which of the following are the more
frequent causes of death in the United
States?
Which country has the larger
population?
Availability Bias

_________________________________________
Fischoff et al. (1977) report that the more ___________
cause of death is actually more prevalent. However, _____
___________________________________________
 Similarly, Brown & Siegler (1993) report that less familiar
countries have ________________________________

Other examples?

Most ppl fear flying > driving



Jaws: swimmers fear sharks now



Plane crashes more vivid and memorable
Flying actually much safer – ppl know this and still
feel fear
No factual data to support this
(It’s a risk, but typically a small one).
When thinking of buying a new car, whose testimony
is more persuasive – that of a friend who has had
problems that a particular model, or that of
Consumer Reports, which on the basis of dozens or
more reports recommends the car?
Do the media sometimes lead us to have a
distorted view of the frequency of certain
events by overexposing us to some events and
underexposing us to others?

The FBI classifies crime in the U.S. into two
categories – violent crimes (murder, rape, robbery,
assault, etc.) and property crimes (burglary, car
theft, etc.).
 What percentage of crimes would you estimate are
violent rather than property crimes?
 What percentage of accused felons plead insanity?
 What percentage of those pleading insanity are
acquitted?
 What percentage of convictions for felony crimes
are obtained through trial instead of plea
bargaining?
Ranking Countries by
Population


Dr. Norman Brown and colleagues (2002) have
continued to examine this issue.
Participants were primed with selected country names
then asked to estimate populations of 109 countries
 __________

Chinese – Canadian comparisons:
 Chinese students estimated larger
populations for Asian countries
 Non-Chinese Canadian students
estimated larger populations for
European countries
 Populations for countries equally
familiar and unfamiliar were
estimated similarly
Imagine 4 cards
Card 1: Black circle (black triangle on the back)
Card 2: Red circle (black triangle on the other side)
Card 3: Red triangle (black circle on the other side)
Card 4: Black triangle (red circle on the other side)
Assuming each card has a triangle on one side and a circle on
the other, which card or cards need to be turned over to TEST
THIS STATEMENT: “Every card that has a black triangle on
one side has a red circle on the other’”
Card 1: Black circle (black triangle on the back)
Card 2: Red circle (black triangle on the other
side)
Card 3: Red triangle (black circle on the other
side)
Card 4: Black triangle (red circle on the other side)
Confirmation Bias
______________________________
 Leads to errors


Can have implications for our social
judgments. Eldar Shafir (1993) presented
research participants with the following
scenario:

Imagine that you serve on the jury of an only-child
sole custody case following a relatively messy
divorce. The facts of the case are complicated by
ambiguous economic, social, and emotional
considerations, and you decide to base your
decision solely on the following few observations. To
which parent would you award sole custody of the
child?

Parent A, who has an average income, average
health, average working hours, a reasonable rapport
with the child, and a relatively stable social life. OR

Parent B, who has an above-average income, minor
health problems, lots of work-related travel, a very
close relationship with the child, and an extremely
active social life.
Here’s the twist:

½ were asked to choose which parent to
AWARD custody to and the other ½ to choose
which parent to DENY custody:
Confirmation Bias

David Levy’s (1997) Tools of Critical Thinking devotes a
number of chapters to common cognitive biases like this.

We often employ strategies for eliciting information from
others that supports our initial beliefs about them. For
example, in one study college students were instructed to
conduct interviews with other students to assess the
presence of certain personality traits. Half were asked to
determine if the person was an extrovert and have asked
to determine if the person was an introvert.


The interviewers asked extrovert-related questions when
they wanted to see if someone was an extrovert. Ex: What
would you do if you wanted to liven up a party?
They asked introvert-related questions to decide if the person
was an introvert. Ex: What factors make it really hard for you
to open up to people?
As you can imagine, ____________________
Tree-Planting Problem
You have 10 trees to plant on a large, flat area
of your rural Alberta farm. They must be
planted in a pattern so that the ten trees form
Mental Sets
Well established habits of perception or
thought patterns
 Tree-Planting Problem:


Solving problems and using insight
provides a sense of satisfaction. The
solution to a riddle of the joy of a joke
may come in our sudden
comprehension of an unexpected
ending or double meaning.

Consider the game Mindtrap (Great
American Puzzle Factory, Inc.), which
includes the following teasers:
What number is next in this series: 10, 4, 5, 11, 15…?
Aside from the fact that it doesn’t make much sense, what
is so unusual about this sentence: