defining intelligence - lecture 8

maltby- chapter- 11,12,23

what is intelligence- agreed upon yes/no?

no agreed, upon definition of intelligence.

sometimes called cognitive ability

what is intelligence- slight definition

A general mental capability that we all have
• But not everyone has the same level of this general mental
capability
→ There are individual differences in intelligence
Psychological trait
• Relatively stable over time
• Differ between people

what are intelligence tests used for

We use intelligence tests to measure intelligence
• There are lots of different tests of intelligence
• No single test is comprehensive
• No single test is a pure measure of intelligence

intelligence test are?

standardised situations designed to evaluate specific capabilities
• designed to provide an objective indication of an individual’s level of
performance on some limited aspect of functioning
• Each test is standardised in terms of the instructions, administration
procedures, and the items that are presented, which allows people to be
compared in terms of their ability to perform as instructed
Salthouse (2010, p. 6)

3 main features of good intelligence tests

variety of task

standardisation

norm referencing

variety of tasks

(very general ability)
• Intelligence tests need to assess a full range of abilities
• Assess overall intelligence, and specific strengths

standardisation of administration

Same location, same instructions, same environmental conditions
• Administered by a trained tester
• Controlled environment allows accurate comparison between people
• Ensure any differences in score is not due to differences in testing conditions

norm referencing

based on a representative sample
• Allow you to compare individual to normative sample
• Test large group of people of similar demographics

when are intelligence tests used?

• research

• selection (“psychometric testing”)

job candidate selection eg

• diagnosis

help determine if there learning difficulties/ disabilities and where the problem lies

• US: decisions about life or death

Individuals with intellectual disabilities (often assessed with intelligence tests) cannot be executed

Historically, people in the US assumed to have low intelligence could be forcibly sterilised

Binet intelligence test

1904: French Government commissioned Alfred Binet (1957-1911) to
develop ways to identify children who may need special education
• 1905: Along with Theodore Simon produced the Binet-Simon scale
• 30 short everyday tasks
• E.g., following a lit match with their eyes; counting coins; recalling sequence of digits; identifying missing words in sentences
• Items become increasingly difficult
• Assess different levels of intelligence
• Levels designed to match specific developmental levels:
• Ages 3 to 10
• Later extended to 12 to 15 years
• Determine a child’s mental age and compare to chronological age
• Age used at criterion of intelligence

stanford- binet

Lewis Terman: Binet-Simon test did not work well in the US
• Revised Binet-Simon test
• Developed for children aged 4 to 14 years
• Say which of 2 horizontal lines is longer (age 4)
• Copy a square (age 4)
• Arrange weights from highest to lowest (age 9)
• Mental arithmetic (age 9)
• Tested >1000 children to identify typical performance
• Standardised testing allow for assessment of one child by
comparing them to other children

intelligence quotient (IQ)

1912: William Stern
• Mental age varied among children proportionally to real age
• IQ = (mental age ÷ chronological age) * 100
• Set IQ to 100 as the average intelligence
1) 7 year old child with mental age of 7
2) 8 year old child with mental age of 10
3) 10 year old child with mental age of 6
1) IQ = 100
2) IQ = 125
3) IQ = 60

army alpha test

The Army Alpha test was a multiple-choice intelligence test developed during World War I to evaluate the intellectual abilities of recruits.

It was administered to large groups of soldiers and consisted of questions covering various subjects such as vocabulary, arithmetic, spatial awareness, and general knowledge.

The test aimed to efficiently assess soldiers' cognitive aptitude and help determine suitable roles within the military based on their scores.

army alpha test results

The findings from the Army Alpha test provided valuable insights into the intellectual capabilities of the soldiers. They revealed the diversity of cognitive abilities among recruits and helped identify individuals with particular strengths for different military roles.

Additionally, the test results contributed to the development of strategies for personnel selection and training during World War I and beyond. Overall, the Army Alpha test findings played a crucial role in optimizing the utilization of manpower within the military.

intelligence tests contain?

Contain items that vary in difficulty from very easy to very difficult

theories of intelligence

Charles Spearman (1863-1945)
• 1904: “General Intelligence: Objectively determined and measured”
• Relationship between data collected using a variety of different
types of intelligence tests using factor analysis
• Positive manifold: Positive correlations between all tests
• People who do well on one test tend to do well on them all
• General intelligence: general property that causes people to
perform well on a variety of different types of tests

spearman 2- factor theory of intelligence (s & g)

s: specific abilities
• Needed for performing well on the different intelligence tests
(vocabulary intelligence, reasoning intelligence, etc.)

g: general intelligence
• Required for performance on all types of intelligence tests
• Mental energy that underlies the specific factors (s)
• Performance on a specific test influenced by your specific ability
to perform those types of tests (s), but also your general
intelligence (g)

test of general intelligence

• David Wechsler (1896-1981)
• Working with APA/Yerkes on the Army intelligence tests
• Went to England to work with Charles Spearman and Karl Pearson
• Developed an intelligence test modelled on Spearman’s theory that intelligence covers a huge range of more specific abilities that all correlate with each other
1955
• Wechsler Adult Intelligence Scale (WAIS) adults aged 16 to 75
• Wechsler Scale for Children (WISC) ages 5 to 16

wechsler intelligence tests

People of all ages could take them
• Items covering a wide range of difficulty
• Very easy items to very difficult items
• Normative data: compare score to others
• Calculate the expected score for people of a particular age
• Representative samples including people from various demographics
• Social class, sex, region of the country
• Established norms for all ages
• Extensive testing of psychometric properties
• IQ calculated relative to other people with similar age
• IQ = (actual test score/expected score for age) * 100
• How much individual deviated from the average
• Scores designed to follow a normal distribution

wechslers intelligence test- today

Widely used today
• Wechsler Adult Intelligence Scale 4th Edition
• Wechsler Intelligence Scale for Children 5th Edition
• Revised and updated to improve biased norms, update
out of date norms (Flynn Effect), and replace/update out
of date items
• The Wechsler tests (and almost all other intelligence
tests) designed by white, middle-class, Western men
• Originally the normative sample collected for Wechsler
was entirely white
• Biased against non-white people, especially black children in school
• Revisions have tried to address this by removing items that are culturally influenced,
making sure the normative sample is truly representative of all ethnicities.

raven progressive matrices (rpm)

Developed by John C Raven (1902-1970) and published in 1938
• Based on Spearman’s theory of general intelligence:
• General intelligence is an abstract ability to see relationships
between objects and information; make inferences
• Developed a test thought to be free of cultural influences, free
of language and knowledge
• Assess non-verbal problem solving - abstract reasoning
• Still widely used today

what spearman notice that led him to propose the theory of general intelligence?

Performance on a wide range of ability tests are highly
correlated.
• Individuals who do well on one ability test tend to do well on
them all.

theories of intelligence - 7 primary abilities

Viewed intelligence differently to Spearman
• Not convinced that a general intelligence factor influenced all
aspects of intelligence
• Analysed data from a large number of tests and identified
several primary abilities
• 7 independent factors of intelligence that different people
possess to varying degrees
• Thurstone: Multi-factor approach to intelligence Associative memory (rote learning) Number (mathematics/arithmetic)
Perceptual speed Reasoning Space (spatial visualisation)
Verbal comprehension World fluency
(generate/use large number of words)

fluid and crystalised intelligence

Raymond B Cattell (1905-1998)
• Multi-factor approach: general intelligence (g) comprises 2 related
but distinct components
• Crystallised intelligence: acquired knowledge and skill
• Related to stored knowledge and cultural influences – reflects learning
• Assessed with general knowledge and vocabulary tests
• Increases throughout life
• Fluid intelligence: ability to solve abstract problems, free of
cultural influences
• Think abstractly, reason quickly, solve problems
• Independent of acquired knowledge and cultural influences
• Assessed with tests of reasoning and pattern recognition
• Increases to early adulthood, then declines.

hierarchical models of intelligence

Bridging the gap between:
• Theories of general intelligence (g)
• Multi-factor models of intelligence
• John B Carroll (1993): Hierarchical model of intelligence with 3
levels
• Stratum I: specific levels of intelligence (69 different cognitive abilities)
• Stratum II: 8 broad factors arising from specific abilities
• Stratum III: general level of intelligence (g)
• Based on factor analysis of 461 datasets collected over 50 years
• Combing g, fluid and crystallised intelligence, and specific abilities
into one comprehensive model of intelligence

salthouse 2004

33 studies combining data on 6,832 participants aged 18 to 95
• 16 cognitive tests assessing vocabulary (4 tests), reasoning (3 tests), spatial visualisation (3 tests), episodic memory (3 tests), processing speed (3 tests)
• Confirmatory factor analysis: specify model, test whether data are
consistent with the model
• 16 cognitive tests reduced to 5 factors
→ 5 broad domains of intelligence
• Each test had high loadings on one broad domain of intelligence
• Each broad domain of intelligence had high loadings on general
intelligence

multiple intelligences

Howard Gardner: Educational psychologist
• Disagreed with Spearman and the notion of ‘g’
• Originally proposed there were 7 distinct intelligences (Gardner,
1983)
• Linguistic
• Logistical-mathematical
• Spatial
• Musical
• Bodily kinaesthetic (using the body)
• Interpersonal (understanding and relating to others)
• Intrapersonal (understanding oneself)

structure intellect (SI) theory

Guildford (1977)
• Disagreed with Spearman
• Did not think ‘g’ existed
• Proposed that intelligence
resulted from 120 individual
intelligences
• Too complex (want parsimony)
• Little use and support for this
theory

psychometric of intelligence

WAIS: agreement that subtests are measuring specific abilities
(e.g., spatial ability, memory) that they are designed to assess
• Concurrent validity: agreement that different intelligence tests are
highly correlated → Assessing the same abilities
• Predictive validity: intelligence tests predict real world outcomes
(i.e., educational attainment, job performance)
• Disagreement that:
• General intelligence exists
• Intelligence tests assess intelligence (‘intelligence test assess one’s ability
to take intelligence tests’)

Internal reliability

• Items on an intelligence test should correlate highly
• Internal reliability of intelligence tests are usually high (but some error

Test-reset reliability

Intelligence is assumed to be relatively stable
• Test-retest should be high
• But intelligence test scores do fluctuate
• 1 week test re-test can fluctuate by up to 15 IQ points (Benson, 2003)
• Not designed to be administered more than once
• Practice effect: get better if repeated
• Difference between stability of intelligence and stability of intelligence tests

stability of intelligence

Correlations between intelligence test scores 6-7 decades later
are high, but not perfect
• Critics (Benson, 2003) do not think this correlation is high
enough to demonstrate stability of intelligence
• Benson (2003): fluctuation in the predictive strength of
intelligence tests
• The longer the time between the test of intelligence and the
measurement of performance the weaker the relationship
• But intelligence test scores early in life predict health outcomes
decades later (Lecture 10)

flynn effect- intelligence scores are increasing

Average intelligence test scores are increasing over time
• Flynn (1999): participants who took old and new versions of
intelligence tests, always score higher on the old test
• Average of 100 on WISC-R, average of 108 on WISC
• Flynn (1984): 73 studies, 7,500 white participants aged 2 to 48
who had taken 2 or more versions of an intelligence test
between 1936 and 1978
• Average IQ increased by 14 IQ points during this time
• 0.3 IQ points per year

flynn effect- why?

Originally proposed it was due to better schooling
• Flynn (1994): data from 20 countries
• Highest rises in non-verbal tests (fluid intelligence)
• ‘Culture free’ tests
• Increase of ~15 points per generation
• Lower rises in verbal tests (crystallised intelligence)
• Increase of ~9 points per generation
• Replicated many times

flyn effect explanations

Flynn (1994): Intelligence tests do not measure intelligence,
instead intelligence tests correlate with intelligence
• Abstract problem-solving ability has risen through the
generations
• Assumed due to environmental reasons
• Too quick to be caused by biological change

an end to the flynn effect

Some evidence the increase in IQ seen across generations is
slowing down/stopping (at least in European men)
• Sundet et al. (2004): Norwegian male conscripts from 1950s to
2002
• Non-verbal IQ increased from 1950s to 1990s by 16-17 IQ points
• IQ stopped increasing after mid 1990s
• Teasdale and Owen (2005): 500,000 young Danish men, tested
between 1959 and 2004
• Intelligence test scores peaked in late 1990s
• Declines to pre-1991 levels

flynn effect unknown

Gain seems to be caused by decreasing prevalence of low scores
• Fewer low scores dragging the average down
• IQ scores have increased over time everywhere
• Improved more rapidly in the developing world compared to the
developed world (Wongupparaj, 2015)
• Cause: unknown
• Consequence: Intelligence tests need to be re-normed every decade or so

intelligence tests: criticisms

Intelligence is much more than what can be assessed on
intelligence tests
• Intelligence tests cannot be valid as no test can cover the
different theoretical interpretations of intelligence
• Intelligence is complex and cannot be reduced to a number
• Do intelligence tests assess what they claim to measure?
• Yes – very good evidence for this
• Do intelligence tests measure intelligence?
• It depends on how intelligence is being defined

defining intelligence: summary

Intelligence is a very general mental ability that differs between
people
• Some theories of intelligence emphasise:
• One very general mental ability (general intelligence; g)
• Broad domains of intelligence
• Hierarchical models of intelligence (g and broad domains)
• Multiple intelligences (no such thing as a general intelligence)
• Flynn effect: intelligence tests scores are increasing over time
• Although there is good evidence that scores on a range of tests
are highly correlated, intelligence and intelligence testing have
been criticised by ma

benson 2003: criticism

Benson (2003): In special education, IQ tests are often used to
classify learning difficulties/disabilities
• IQ-achievement discrepancy: comparing children’s achievement
to their IQ score
• Achievement scores 1SD or more below their IQ scores=learning
disability
• E.g., score an IQ score of 100, but a reading score of 80 =dyslexia
• Error: there is fluctuation within and between intelligence tests
• Must consider this when making decisions based on intelligence
tests
• My take: Intelligence tests should be used along with a number of educational tools