12. Intelligence

12. Intelligence

1. Intelligence testing

   • Francis Galton: made the first attempt at creating a standardise test for rating persons intelligence. He hypothesised that intelligence should correlate with observable traits, such as reflexed, muscle grip and head size.
   • Alfred Binet: Mental vs. chronological age --> identify children who needed additional help.
   • Charles Spearman: factor analysis of intelligence. Noticed a correlation between how children did in one subject, and how they did in very different subjects.
   • 'G score' is the latent factor explaining correlation variables. When you get an IQ score, it is an estimate of the underlying g score.
     • Performance = s (specific to the task) - g (general intelligence factor)

2. Intelligence testing

   • Wechslet Adult Intelligence Test (1955): tested in the USA, aged 16-89, gender split, ethnic and religious mix reflective of the US population.
     • Vocabulary, tell examiner what certain words mean.
     • Verbal similiaties- what do two words have in common?
     • General knowledge
     • Comprehensions: questions about everyday life and society
     • Mental arithmetic
     • When all of the tasks are administered, there are substantial correlations between scored on all the tasks. = full scale IQ is a weighted average of all of them.
   • Nerve conduction velocity: the tiger you nerve conduction (so how fast signal are being transmitted around your body), the higher your IQ.

3. Hierarchical structure of intelligence: Salthouse (2004)

   • Specific factors: someone who performs well on one task, will tend to perform well on other cognitive tasks too.
   • Group factors:Not all intelligence tasks correlate equally highly. How well you do one one taks, depends on your general ability of intelligence and specific ability.
     • The unity of 'g' is mainly causes by some people not doing very well at any tasks, rather then people doing better at all tasks.
   • Stability of IQ tasks: Moray house test (1932): those who did better as children also did better as adults.

4. Factors of general intelligence

   • Fluid: the capacity to reason and solve novel problems, independent of any knowledge from the past. Gets worse with age.
   • Crystallised: ability to use skills, knowledge and experience. Increases with age.