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Human Mental Abilities Intelligence or cognitive abilities…
A central aspect of Individual Differences or Differential Psychology Abilities Personality Preferences, beliefs, & tendencies, etc…
Everyone is in certain respects… (a) like all other people, (b) like some other people, (c) like no other people.
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Differential Psychology As a scientific discipline is concerned with…
Description, Explanation, & Prediction
…of reliable individual variation in human behaviour (e.g., ability test scores, responses on questionnaires, performance) rather than aggregated group differences per se
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Implicit Notions of Intelligence…
An intelligent person …
Has good problem-solving
skills
Thinks about things logically
Has a good memory
Processes information
quickly
Is highly educated
Has good reasoning skills
Is creative
Others …
Has a good store of information
Learns new things quickly
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What is intelligence?! Differences between ‘lay’ (or naïve) & scientific
approaches to understanding intelligence…
In every day life we observe, try to understand, & predict the behaviour of others
Based on… systems of culturally based beliefs & subjective evaluations of human behaviour & its potential causes
Implicit assumptions about causes of behaviour
Implicit assumptions about distributions
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‘Lay’ vs Scientific Approaches Judgments based on ‘lay’ understandings of
intelligence (& other psychological concepts) are useful in our day-to-day lives… but, are:
Imprecise Inconsistent Not useful as psychological (scientific) theories
Good news - bad news Good:
similar terminologies Bad:
similar terminologies
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What is intelligence?!
“Intelligence is a word with so many meanings that finally it has none” Charles Spearman (1927)
“Intelligence is what the tests test” e.g. Boring (1951)
Person ‘X’ is intelligent
Person ‘X’ performs well on
intelligence tests
Because …
Because …
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An “Intelligence” Test What is the capital of Turkmenistan?
Ashgabat Who wrote “At the Mountains of Madness?”
H. P. Lovecraft What is the most number of Oscars won by a film?
Name the film/films. 11: LotR: Return of the King, Titanic, and Ben-Hur
What is longest streak of consecutive NBA titles? Name the team. 8: Boston Celtics
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Intelligence is what intelligence test test?! As you can see from our “intelligence” test
there are big problems with this…
Doesn’t help our understanding of what intelligence actually is
Allows us to define intelligence as almost anything Problems with reliability and validity (which, we will
come back to later)
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Cognitive Abilities
There is a need to make a distinction between cognitive abilities & task performance
J. B. CARROLL (1993)
Cognitive tasks: ‘Any task in which correct or appropriate processing of mental information is critical to successful performance’
Cognitive ability: ‘Any ability that concerns some class of cognitive tasks, so defined’
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Intelligence as a construct Two levels:
Manifest variables – observable… What we can see (e.g., behaviour, test scores,
responses)
Latent variables – unobservable… What we infer – constructs (e.g., abilities, traits,
states)
Cognitive Ability
Task 1
Task 2
Task 3
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Constructs Theoretical (or hypothetical) terms which cannot be directly
observed, but are assumed to exist because they give rise to measurable phenomena
Constructs are not discovered, but constructed Description (& explanation) of behavioural & performance data Basis for prediction of behaviour
Constructs are defined by: Empirical indicators Relationships to other constructs Network of constructs (nomological network) = theory
THEREFORE: Theory & measurement are inextricably linked
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Psychological Assessment Psychometric tests do not provide a perfect index of cognitive ability
Behaviour (e.g., test performance) is often viewed as a function of person (e.g., cognitive ability) & situation (test context) factors
Performance in Situation X
Behaviour in Situation Y
? ?
?‘Manifest’ or observable
‘Latent’ or unobservable
Cognitive Factors
Non-Cognitive Factors
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A (Brief) History: Galton
Francis GALTON [1822-1911] – the founder of modern individual differences psychology: Developed a variety of (psychophysical)
measuring instruments (e.g., Galton whistle) Developed the first anthropometric laboratory
Data on a large number of psychological & physical measures (across a sample size of thousands) was obtained
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Galton
Drew attention to statistical distributions (esp. the Gaussian normal curve) that might describe many physical & psychological characteristics
Developed regression techniques leading to the construction of the coefficient of correlation
Pioneering research in behaviour genetics: work on regression techniques and the normal curve were combined - the concept of "regression to the mean"
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Galton
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Galton Hereditary Genius (1869) claimed that
intellectual genius tended to run in families: “I have no patience with the hypothesis that the sole
agencies creating differences between men are steady application and effort”
Inquiries into the Human Faculty … (1883) laid the foundations for a theory of cognitive abilities Claimed tests should be used to identify mental
strengths & weaknesses
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Galton Galton’s efforts to measure intelligence were
ultimately a failure:
Tests measured: body length, reaction time, visual acuity & body breadth - only RT could be regarded as anything like a cognitive ability
Failure was due to the variables selected
“All the information that reaches us passes through the avenue of the senses; the more perceptive the senses, the larger the field on which our intelligence can act”
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A (Brief) History: McKeen Cattell
James McKEEN CATTELL [1860-1944]
Main figure behind the mental testing movement during the 1890s - credited with coining the term ‘mental test’
Developed an extensive test battery - administered to many college students - included tests of RT, sensory discrimination, word associations, picture-naming speed & others
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A (Brief) History: Wissler Clark WISSLER [1870-1947]
Attempted to associate results from tests with ‘other’ estimates of intelligence – reasoned that test scores should relate to academic performance
Conducted the first extensive application of the correlational method (1901)
Found disappointingly low correlations between test scores (including RT) & college grades
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A (Brief) History: Spearman Charles SPEARMAN [1863-1945]
One of the first to use correlation coefficients in large-scale empirical research
Developed the statistical method of factor analysis
Proposed the g-factor theory of intelligence that has supporters to this day
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A (Brief) History: Binet Alfred BINET [1857-1911]
Shifted emphasis to examine ‘higher mental processes’ - designing tests to measure ‘complex’ abilities (The Stanford-Binet IV is still used today)
An attempt to ensure ‘defective children receive the benefits of tuition’ - no clear definition regarding mental retardation - developed ‘mental age’ IQ
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A (Brief) History: Binet Tasks varied widely – although most relied on
understanding language or the ability to reason with verbal or non-verbal material
The scale & revisions formed the basis for the development of intelligence scales (both individual & group) in a number of countries & languages
Development & refinement of tests was accompanied by evolution of statistical techniques
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Defining Tests
A measure of a sample of behaviour
Since one sample is likely to provide an unreliable estimate - tests provide several samples of the behaviour of interest (i.e., items)
The final measure is some function of an individual's response (i.e., appropriately marked items)
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Test Items
To provide a meaningful estimate of the behaviour of interest, items should be based on:
Some meaningful theory about the nature of cognition (cognitive tests)
Drawn from a well-defined domain (achievement tests)
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Uses of Tests
“Mental tests are psychology’s greatest contribution to society” (Anastasi & Urbina, 1999)
Tests are employed in many areas, including: Education Personnel selection Clinical assessment
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Criticisms of Tests During the 1970s, mental testing came
under attack by social scientists
The main criticisms concerned: Bias in psychological test The static nature of intelligence test scores
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Bias in Testing
Significant differences between groups: Racial differences - black vs. white Gender differences - male vs. female Age differences - young vs. old Socio-economic differences - rich vs. poor
CLAIM: differences b/w groups are not real, BUT … a consequence of bias in mental tests
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Bias in Testing A large number of studies examining the
issue of bias were conducted during the 1980s
It is now generally accepted that:
Most tests when used appropriately contain little bias
Psychometric tests don’t hurt people - people hurt people
Other assessments proposed as replacements for psychological tests often demonstrate more bias
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Static Nature of Test Scores
Psychometric tests provide only a single score - the final outcome of a problem solving process
This score is the sum of coded answers to test items & places an individual relative to others taking the same test
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Static Nature of Test Scores This score has nothing to say about:
The way a person thinks The steps underlying the solution process The nature of cognitive processing employed
This line of criticism has prompted: New ways of testing intelligence (e.g., adaptive
testing, dynamic assessments) Theory (rather than operationally) based
psychometric test paradigms
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Summary Intelligence as a latent construct…
The distinction between cognitive abilities & cognitive task performance
Theory development is linked to greater sophistication in assessment/measurement
Psychometric tests contain little bias when used appropriately & represent better options in assessment than alternatives
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Think about how stupid the average person is; now realise half of them are dumber than that. (George Carlin)
