Intelligence

• Thompson - Moray House Test No.12, Scottish Mental Surveys, tested 95% of the Scottish cohort of 11 year olds, 70,805 children tested in 1947


  1932
• Intelligence


  A general mental ability - the capacity to learn from experience and to adapt from the environment
• Implicit Theories of Intelligence


  Constructs in a persons mind, used for formulating cross-cultural views, help understand or provide basis for explicit theories, data comes from asking people their notion of intelligence, drives the way people evaluate the intelligence of themselves and others
• Explicit Theories of Intelligence


  Conducted by scientists (experts), based on data collected, performance on tasks presumed to measure intelligence, constructs ie factors, components, schemata, tricky to agree on operational definition
• Intelligent person (layperson view)


  • Good at problem solving
  • Having good verbal ability
  • Having social competence
• Implicit theories of intelligence across cultures - Western culture rates speed of mental processing, ability to gather and assimilate, and sort quickly and efficiently as being evidence of intelligence, whereas non-Western cultures rate good cognition skills, good memory, social, historical, and spiritual aspects of everyday interactions as evidence of intelligence
• Savant syndrome


  Special ability usually accompanied by prodigious memory, 1 in 10 who have autism. Extraordinary, but narrow mental abilities - not seen as evidence of high intelligence. Raises question of multiple intelligences Feldman and Morelock (2012) - "exceptional mental performance in a sea of disability"
• g factor


  Statistical result used to refer to general intelligence, cognitive, and mental ability
• IQ

  Average IQ 85-115 with 68% of people. 16% <85, 2.5% <70, 50% >100, 2% 130-145, 0.1% >145, SD = 15
• Galton


  • Founder of differential and experimental psychology, intelligence is dealing with information gained through the senses. Wanted to measure differences in mental ability, founding psychometrics, "Anthropometric Laboratory" (1885), wanted a representative sample, thought it would only be reliable with a large sample, forefather of intelligence test
• Binet

  • Binet-Simon Scale (1905) - pragmatic approach, relying on practicality, common sense, and coping with the day-to-day world. Using childrens age as an independent criterion, forming the basis for modern IQ tests
• Binet-Simon scale tasks


  • Following a light match with your eyes
  • Naming parts of your body
  • Counting coins
  • Naming objects in a picture
  • Recalling a number of digits after being shown a long list
  • Word definitions
  • Filling in missing words in a sentence
• Terman

  • Stanford-Binet Test (1916) - revised Binet-Simon with 40 new items. Yerks - standardised test for US army, questions times and multiple choice style
• Wechsler Adult Intelligence Scale (WAIS)

  • 6 verbal tasks (information, comprehension, arithmetic, digit span, similarities, vocabulary) measuring knowledge and 5 performance tasks (picture arrangement and completion, block design, object assembly, and digit symbol) based on timing
• Wechsler Intelligence Scale for Children (WISC)


  • Using a range of cognitive abilities, believing there were many aspects to intelligence
• Wechsler - Adult Intelligence Scale IV

  • 15 mental tests, examining how quickly a person can make sense of chaos and complexity through multiple subtests - Verbal comprehension (similarities, vocabulary, information, comprehension), Perceptual Reasoning (block design, matrix reasoning, visual puzzles, figure weights, picture completion), Working Memory (digit span, arithmetic, letter-number sequencing), and Processing Speed (symbol search, coding, cancellation)
• Wechsler - WAIS


  All tests correlated 0.45, created a 3-level hierarchy of mental ability tests, clumping tests into cognitive domains of verbal comprehension (.7), perceptual reasoning (.52), working memory (.62), processing speed (.51), which combined to measure general intelligence (g). Wechsler stratified by age and other demographics, so the WAIS was a reflection of an individual's relative standing with respect to others in the same cohort
• WIAS

  IQ score = (Test Score/Expected Score)*100
• Raven's Progressive Matrices (1938)


  • Non-verbal approach, free of cultural and language differences, and can test 5y olds to advanced adults. Believed to measure abstract reasoning, educative ability, and reproductive ability. Very different to WAIS but correlations range from .4-.75. Participant meant to make meaning out of confusion, and is a useful marker of how well someone can mentally visualise a solution of a visual problems and understand rules
• Spearman (1904)


  • Factor analysis of intelligence, following Galton's work using correlations. Developed the term 'g'/'g-factor' and developed the 2-factor theory of intelligence. "The score of a mental test can be divided into 2 factors, one that is the same in all tests (general factor) and one that varies from one test to another (specific factor)"
• Spearman - specific intelligences


  Verbal, mechanical, spatial, and maths. General intelligence have all of these with g intertwining them
• Cattell - g

  Can be subdivided into Fluid and Crystallised intelligence
• Cattell - Fluid intelligence


  Primary reasoning ability, abstract thinking with no cultural link, better measured by Ravens, reasoning and novel problem solving, associated with working memory
• Cattell - Crystalised intelligence


  Acquired knowledge and skills (facts), related to the cultural and historical background, better tested by Weschler scales, due to experience, increases throughout life
• Elementary Cognitive Tasks (ECTs)


  Simple tasks to measure cognitive processes such as understanding stimuli, stimulus discrimination, visual search, retrieval of info/perceptual speech. Measuring response time through median reaction time, standard deviation of reaction time (individual variability in responses), and inspection time/evoked potential (time taken to process info, shorter delay thought to indicate higher intelligence
• Thurstone's 7 primary abilities


  • Word fluency (using words quickly and fluently)
  • Verbal comprehension (understanding meanings of words, concepts, and ideas)
  • Numerical ability (using numbers quickly to compute an answer)
  • Spatial visualisation (visualising and manipulating patterns and forms in space)
  • Perceptual speed (ability to grasp perceptual details quickly and accurately)
  • Memory (recalling information)
  • Inductive reasoning (deriving general rules)
• Thurstone suggested that there were seven separable, stable, and independent human mental abilities, and that each individual possesses different levels of these factors, and they do not depend on each other, despite being positively correlated
• Schmidt and Hunter (1998)


  • Intelligence tests and work performance - meta analysis on from 85 years decision making in job hiring research. Examined the predictive power of 19 different ways of selecting people for jobs. Strongest correlators were work sample test (.54), psychometric intelligence test (.51), structured interview (.51), integrity test (.41), unstructured interview (.38), and conscienousness test (.31). The weakest correlations were reference checks (.26), job experience in years (.18), years of eduction (.1), interests (.1), graphology (.02), and age (-.01)
• Deary (2007) - compared CAT scores and GCSEs, good predictor of gaining 5 or more GCSEs at A*-C, level of intelligence at 11 strongest predictor of late-life cognitive ability
• Scottish Mental Survey (1932) - larger number of girls in middle scoring group (90-110), larger number of boys in lower and higher groups with large % differences between boys and girls (17.2% and 15.4%)
• Tasks favouring women


  • Verbal ability
  • Perceptual speed
  • Object location memory
  • Word fluency
  • Fine motor coordination
  • Numerical calculation
• Measuring extent of resemblance in intelligence of MZ twins


  Comparing the variation of IQ scores within a twin pair and comparing the variation of IQ scores between twin pairs
• Test-retest reliability


  Reliability over time
• Flynn effect


  Scores on intelligence tests tend to fluctuate and change year to year. Flynn (1981) looked at 73 studies from 7500 US white participants age 2-48 and found a year on year rise in scores, finding that if participants averaged 100 on the original WISC (1947), then they averaged 108 on the WISC-R (1972)
• Explanations of Flynn Effect


  • Generations getting more intelligence (unlikely, too fast to be due to genetic changes)
  • Length of schooling (mainly relevant for verbal tests)
  • Test-taking sophistication (familiar with tests, does not explain differences between verbal and non-verbal scores)
  • Child-rearing practices (some evidence, programs have no lasting effect on IQ)
  • Cognitive stimulation hypothesis (little evidence)
  • Nutrition
• Higher intelligence scores tend to go with having thicker grey matter on the surface of the brain, healthier white matter connections overall, fewer white matter scars causing 'leakage', and potentially a larger brain over all, more nerve cells?
• Goriounova (2018)

  • Pyramidal cells are abundant in the cerebral cortex of every mammal studied, are primarily found in brain structures associated with advanced cognitive functions, and are the primary excitation units in the cortex, being integrators and accumulators of synaptic information. Individuals with a higher IQ possess larger/more complex dendrites and are able to sustain faster action potentials
• Higher intelligence scores correlate with larger whole-brain volume, thicker grey matter/cortical thickness on brain surface, larger/more complex dendrites, faster action potentials, good working memory mediated by PFctx, and highly connected higher-order brain networks