ABSTRACT
Chapter summary
Intelligence involves abilities such as problem solving and reasoning. Of importance, it also involves successful adaptation to one’s cultural environment.
Intelligence tests assess IQ. It is a general measure of intelligence having a population average of 100 and with two-thirds of individuals having IQs between 85 and 115.
All good intelligence tests have high reliability (consistency of measurement) and validity (e.g., ability to predict career success).
Identical twins (even those reared apart) are more similar in IQ than fraternal twins. Thus, genetic factors influence individual differences in IQ.
There are numerous complex gene X environment influences on individual differences in IQ. Of importance, individuals with high genetic ability are more likely than those with low genetic ability to select cognitively stimulating environments (e.g., going to university; reading numerous books).
The impact of genetic factors on individual differences in intelligence is much greater in adolescents and adults than young children because the former select and control their environment to a greater extent.
316The rapid rise in IQ in recent decades (the Flynn effect) is due to several environmental factors (e.g., increased years of education in many countries).
Factor theories propose that intelligence has a hierarchical structure with a general factor (“g”) at the top level, approximately 7 factors at the second level, and numerous very specific factors at the third level. Such theories are descriptive rather than explanatory.
Gardner proposed an approach based on multiple intelligences which has been influential within education. However, he exaggerated the independence or separateness of these intelligences.
There is an important distinction between ability emotional intelligence and trait emotional intelligence: ability EI relates mainly to intelligence whereas trait EI relates mainly to personality.
Ability EI predicts job and academic performance beyond the effects of IQ and personality. However, its predictive power is much less than that of IQ.
Trait EI is very similar to (or identical with) a general factor of personality consisting of high openness, conscientiousness, extraversion and agreeableness plus low neuroticism. It is associated positively with relationship satisfaction, happiness, and negatively with loneliness. It is hard to establish the direction of causality with such findings.
