background

• what do psychologists mean by intelligence?

  intelligence refers to a combination of cognitive abilities that enable individuals to understand things, plan, reason learn from experiences, problem solve and effectively interact with the world around them
• theories of intelligence-

  1. Charles Spearman (1904)
  2. John Horn and Raymond Cattell (1966)
  3. Howard Gardner (1983)
• Charles Spearman (1904)


  spearman noticed that people who performed well on one cognitive test tended to do well on other cognitive tests too. he believed that this showed a general overview of the individuals mental ability and called this 'general intelligence' which he referred to as 'g'. he later identified specific forms of intelligence (such as math, vocabulary and logic) which he called 's'
• John Horn and Raymond Cattell (1966)


  Horn and Cattell suggested that g is not a single form of intelligence, but has two main parts which they called fluid and crystallised.

  • fluid intelligence is the ability to reason in abstract ways and solve problems logically without experience. it is therefore independent of how much practice or education you have had.
  • crystallised intelligence is your ability to acquire knowledge through learning and experience. for example, being able to understand what you are reading and to pass exams both depend on your level of crystallised intelligence.
• Howard Gardner (1983)


  Gardner argued that there are eight separate 'intelligences'. we all process these intelligences, but in greater or lesser amounts. for example, an individual could have high level interpersonal intelligence, moderate logical-mathematical intelligence, but little musical intelligence. also, some of these intelligences are valued in western culture more highly than they are in others, especially in terms of education (e.g. verbal-linguistics and mathematical-logical). but other intelligences (e.g. naturalistic) have greater status in other cultures (ethnocentrism)
• what biological factors could affect intelligence?

  1. prenatal development
  2. genetic factors
  3. assortative mating
• prenatal development - premature birth and nutrition


  premature birth and nutrition- premature babies that were breastfed had higher cognitive skills at age 7-8. premature babies development of cognitive skills are more susceptible of the impact of nutrition. study's found that children who lacked a nutritious diet showed the most improvement in IQ (Schoenthaler et al 1991)
• prenatal development - toxic substances

  toxic substances- Goldschmidt et al (2008) found heavy and regular use of cannabis led to

  • first trimester - linked to children having lower verbal reasoning scores on intelligence tests at 6 yrs old
  • second trimester- affected memory and overall scores
  • third trimester - the most negatively associated with IQ

  potential cofounding variables could impact intelligence apart from smoking cannabis
• genetic factors

  extensive research using twins and adoption studies. genetics account for 25-50% of intelligence (Leeuwen 2007). Scarr and Weinberg (1978) found there was a stronger correlation between biological relatives than adopted relative, suggesting intelligence is affected by genetics more than environment.

  Deary (2011) demonstrated that individual differences in intelligence is caused by a number of genes rather than one in particular. each of these genes have a small impact on a persons individual intelligence
• assortative mating


  this is based on evolutionary psychology and is the idea that individuals will seek a mate of similar intelligence to themselves. this results in offspring having similar intelligence to their parents