IQ tests

• IQ score: Binet & Simon

  • “Our purpose is to evaluate a child’s level of intelligence. It should be understood that this means separating natural intelligence from instruction. It is his intelligence alone that we seek to measure, by disregarding as far as possible the degree of instruction which the child has enjoyed.”
  • Age could be used as an independent criterion for intellectual competence in children
  • Aimed to identify whether a child was advanced or backward for his age.
• IQ score: Terman (1932)

  IQ = (Mental age / Chronological age) x 100
• IQ score: Wechsler

  IQ = (Actual test score x 100) / Expected score

  • Where the expected score was the average score obtained by a large representative sample.
  • IQ score is a reflection of an individual’s relative standing with respect to others of the same age. It is not an absolute score.
• Stanford-Binet Test

  Binet focused on a series of 30 short tasks related to everyday life, including:

  • Following a light with you eyes
  • Shaking hands
  • Naming parts of the 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. This test could determine a child's ‘mental age’

  Terman adapted this test for American children, introducing the Stanford-Binet test:

  • Adapted items
  • Added 40 new items
• Wechsler Test


  Initially standardised among 2,000 adults

  Subtests covered:

  • Arithmetic
  • Block design
  • Comprehension (e.g., What is the advantage of keeping money in a bank?)
  • Digit span
  • Digit symbol
  • Information – general knowledge
  • Object assembly – e.g., jigsaw puzzles
  • Picture arrangement, arrange cards to tell a simple story
  • Picture completion
  • Similarities (e.g., in what way are a lion and tiger alike?)
  • Vocabulary
• Ravens Progressive Matrices

  Based on the theory of Spearman’s ‘g’:

  • The abstract ability to see relationships between objects, event and information and draw inferences from those relationships.
  • Designed to minimise the influence of culture and language

  
• Problems with IQ Tests: Reliability

  IQ scores are not stable over time
• Problems with IQ Tests: Validity

  Do intelligence tests measure intelligence? (Face validity)

  • They measure what they claim to measure

  Do they predict what we expect? (Predictive validity)
• Problems with IQ Tests: Usefulness

  The predictive strength of intelligence tests fluctuates based on: time; demographics; context.
• Problems with IQ Tests: Administration

  Are they administered properly? (Styck & Walsh, 2016)

  • Examiner errors (one the Weschler tests) occur frequently and impact…scores’
• A complex history (Gibbons & Warne, 2019)

  • Origins of subtests predate ‘theories’ of test creation, but the subtests have lasted.
  • Some subtests are not rooted in assessing cognition, or based on theory
  • They hint at the idea of a ‘monopoly’ à Subtests/items on the Wechsler, Stanford, Binet and Raven’s Matrices often are seen as the ‘standard’, and so little inspiration is drawn from the work of modern cognitive science in creating/revising tests.
• Taking a step back, issues in the study of intelligence and IQ tests

  When surveyed, experts in intelligence research reported that the topic of intelligence (and heritability) is exploited and abused within science, but also in politics (Rindermann et al., 2020)

  Jackson and Winston (2020):

  • There is no ‘taboo’ on publishing research relating IQ to genes.
  • Those who do publish this type of research do not experience misrepresentation in the media, regular threats, or job loss.