Lecture 2 - Measuring individual differences Flashcards
What did Quetelet do?
Tried to define the ‘average man’ through statistics
- systematic application of statistical methods to humans
- he didnt just do physical properties, but psychological ones too
- developed Body mass index - aka Quetelet index
- he found that BMi sat on a normal distrubution graph - each individual could compared to the norms of this graph
- “weight increases as a square of the height”
In terms of depatures from the average, What was Galton interested in?
- significantly influenced by Quetelet
- looked at differences - those who deviated from the average
- More interested in those at the top end than the lower end
- Came up with standard deviation
What work did Spearman do?
- Developed statistical methods to study latent variables - underlying traits responsible for our intelligence
- notion of ‘g’
- Developed the use of factor analysis to find ‘g’
Outline factor analysis
- exploring patterns of correlations between items on a particular measure
- data-reduction - identify similarities
- trying to find general, underlying categories by fitting things into it
What did Spearman test kids with?
- memory
- spatial abilities
- math abilities
- vocab
Outline Positive manifold
Spearman found if you were intelligent with one domain, you were intelligent on the others
- supports underlying ‘g’
Outline spearmans theory of intelligence
General intelligence ‘g’ = mental energy that underlies intelligence. It is a deep fundamental mechanism
CAUSES
Specific Abilities ‘s’ = e.g. maths intelligence, spatial intelligence, verbal intelligence
g and s combine to create intelligence
What did Spearman inspire? A race to develop what?
inspired a race to develop a good intelligence test based off ‘g’
Outline the Wechsler Tests
Much broader domains that test a number of different abilities
- Wechsler -Bellevue Scale (1939)
- Wechsler Adult Intelligence scale (WAIS) 1955
- for ages 16-75 - Wechsler Scale for Children (WISC)
- 5-16
What did Terman (1916) contribute?
Intelligence quotient (IQ) IQ = 100 X (mental age ÷ chronological age)
Couldnt apply to adults as age would keep increasing but intelligence would be similar - so Wechsler came up with the WAIS instead
Outline the WEIS (1955)
- first to assess non-verbal/ spatial tests
- tested stuff like verbal comprehension, working memory, perceptual organisation, processing speed etc
- focused on comparing scores to others of the same age
IQ = 100 X (actual test score ÷ expected test score)
- did it to large groups to establish norms
- overall score is based on deviation from standardised norms - “deviation IQ”
Outline Raven’s Progressive matricies (1938)
- Based on concept of ‘g’
- a test that is free of cultural influence as it includes non-verbal problems and abstract reasoning
- made this one as it seemed western people did better on verbal tests - wasnt fair
- overall score is based on deviation from standardised norms
Outline thurstones 7 primary mental abilities
‘g’ is made up of:
- Perceptual speed
- Associative memory
- Spatial visualisations
- Number
- Verbal comprehension
- Word fluency
- reasoning
What did Thurstone criticise spearman of doing?
said all the things spearman measured had language skills behind them - which could explain why there is positive manifold
- so he made 7 distinct ones
Outline Cattell’s theory of intelligence
General intelligence ‘g’, is made up of 2 things:
- Gf - fluid intelligence - innate
- stuff like primary reasoning/ problem solving
- cant be taught - Gc - Crystallised intelligence - learned/ developed
- e.g. factual knowledge, education
Outline Carroll’s theory of intelligence
Three-Stratum Theory of Cognitive Abilities
- questioned what was in between ‘g’ general intelligence and ‘s’ specific intelligences
- Argued g was stratum 3
- then there was stratum 2 - visual, auditory, memory, cog speed, processing speed etc
- and then stratum 1
- then tests
- then specific abilities
Whats a limitation of Carrolls theory?
X - very complicated - cant really use for IQ tests
Outline the combined model of Cattell-Horn-Carrol
- suggests there are 16 broad intelligences, each of which divides into sub-categories
What did Tiedemann (1836) suggest?
Argued that the size of the brain was an indicator of our mental energy
Outline McDaniel (2005)
Found that brain size and IQ correlated (.03)
- no study has ever found a negative correlation
What did Toga & Thompson (2005) find?
Found evidence for heritability of brain size
Define Elementary cognitive tasks
very simple tests that assess cognitive processing speed and processing accuracy
- reaction time is key
- intelligence is determined by speed and accuracy of response
√ - dont require any previous knowledge
What did Deary et al (2001) found with ECT’s
moderate correlation ebtween IQ and RT tests
Give an example of Jensen’s RT elementary cognitive tasks
The jensen box
- supports the notion of ‘g’ as no previous knowledge/ background intelligence is required
- 8 lights on it, with finger on bottom middle one
- as soon as a light comes on, the speed to press it is measured
- Speed of pprocessing is seen as an underlying marker of intelligence
X - is there a cultural bias?
Outline Inspection time tests
Show two lines, then they are covered up and they are asked which one was shortest
- the time you get before they are covered up gets less and less
- the shortest time at which you can still get it right is an indicator of your intelligence
What makes a good psychometric test?
- Reliability
- Validity
- Length of test - depends on participant, e.g. if they are a kid - but will also get tired and wont do as well in later questions
- standardisation of administration and ease of scoring
- Comparison
- Value of findings
Limitations of psychometric tests?
X - stability of these traits over time? - tests only every done once, may improve/ change after the test
X - Predict how we will be in other environments or not? E.g. how good for a job we are?
X - Practice effects - over tested?
Define internal reliability
The items correlate well with each other
- suggest they are measuring the same construct/ latent variable
Define test-retest reliability
Extent to which the responses of a measure remain stable over time
Define reliability
consistency of a measure over time or across different circumstances
How has internal reliability been seen on intelligence tests?
- they are constantly being developed/ revised
- items that are low on this have been omitted
How has test-retest reliability been seen on intelligence tests? - Benson (2003
- assumes intelligence is stable
- X - Benson (2003 - found that scores on IQ tests fluctuate - depends on alertness that day, practice effects
- lack of standardisation - pressure to do well
- different instructors
Outline Jones & Bayley (1941)
Berkely Growth Study
- Cohort of children tested annually from 1928
- IQ at 18 was positively correlated to IQ at 6 and at 12 years
- shows test-retest reliability
Outline Deary et al (2004)
Scottish mental survey
- found correlation of .73 between age 11 and 77
- Intelligence at 11 also predicted survival beyond 76 and levels of physical fitness and indepdence
X - is this cause and effect - or does socio-economics have a role? - better schooling at 11 = better health care
Define Validity
Does a test measure what we intended it to? - does this actually study intelligence - established by: •comparing to other studies • predictive?
What did Neisser et al (1996) find about the validity of intelligence tests?
They have High levels of concurrent validity with other intelligence tests
What did Laidra, Pullma & Allik (2007) find aout the predictive abilities of intelligence tests?
Performance on Ravens was the best predictor of GPA
Define the Flynn effect
The substantial and sustained increase in inteligence scores over time
What did Flynn (1987, 1994) find?
on average, non-verbal tests showed increases of 15 IQ points per generation (on ravens)
Verbal tests were only 9 points
What effects did Flynn explain this effect with?
these Environmental factors are meaning we do better at tests now a days - because of these things
- Length of schooling - stay in school?
- Test-taking sophistication - exposure to tests
- Parenting styles - involved in school work
- Nutrition
- Environmental change (visual stimuli - devces)
what results should be careful of publishing?
Ones that could harm stereotypes of culture
What are cultural issues with this?
- Is it possible to achieve a culture free test?
- Testing for group differences has stimulated social change - by proving there are no intelligence differences between genders, classes and ethnicities
How did Benson (2003) argue we should use the results of intelligence tests?
- help people understand their results
- identify weaknesses and help those areas
