Compare theories of intelligence including general intelligence and multiple intelligences, and evaluate how intelligence is measured and the reliability and validity of intelligence testing

What this dot point is asking

QCAA wants you to explain that intelligence is a contested concept, compare the major theories of what it is, describe how psychologists try to measure it, and evaluate the quality of those measurements in terms of reliability, validity and fairness. Use named theorists and named tests.

The answer

What is intelligence?

Intelligence is broadly defined as the capacity to learn from experience, reason, solve problems and adapt to the environment. The disagreement is over whether it is one general ability or many separate abilities, which shapes how it should be measured.

General intelligence (Spearman)

Charles Spearman (1904) used factor analysis on test scores and found that people who did well on one cognitive task tended to do well on others. He proposed a general intelligence factor, g, underlying all mental performance, plus specific factors (s) for particular tasks. The existence of positive correlations across diverse tests is the central evidence for g, and modern IQ tests are built on this idea.

Multiple intelligences (Gardner)

Howard Gardner (1983) rejected a single g, proposing several relatively independent intelligences, including linguistic, logical-mathematical, spatial, musical, bodily-kinaesthetic, interpersonal, intrapinterpersonal and naturalistic. His evidence included people with brain damage who lose one ability while keeping others, and savants with exceptional skill in one narrow domain. Critics argue some of these are better described as talents than intelligences, and the theory is hard to test empirically.

Triarchic theory (Sternberg)

Robert Sternberg (1985) proposed three types: analytical (academic problem-solving), creative (dealing with novelty) and practical (everyday street smarts). He argued traditional tests measure mainly analytical intelligence and miss practical and creative ability, which matter for real-world success.

Measuring intelligence

• Binet and Simon (1905) created the first practical intelligence test to identify French schoolchildren needing extra help, introducing the idea of mental age.
• The Stanford-Binet test produced the intelligence quotient (IQ), originally mental age divided by chronological age, times 100.
• The Wechsler scales (WAIS, WISC) are the most widely used today, giving separate verbal and performance scores as well as a full-scale IQ.

IQ scores are standardised so that the population mean is 100 with a standard deviation of 15, and scores follow a normal (bell-shaped) distribution, with about 68 percent of people scoring between 85 and 115.

Evaluating tests: reliability and validity

A good test must be both reliable and valid.

• Reliability is consistency: a test is reliable if it gives similar results on retesting (test-retest reliability) or across its items (internal consistency). Major IQ tests are highly reliable.
• Validity is whether the test measures what it claims to. Predictive validity (IQ predicts school performance reasonably well) is one form, but critics question whether tests capture the full breadth of intelligence.
• Cultural bias threatens validity: tests developed in one culture may disadvantage people from another by assuming particular language or knowledge. The Flynn effect, the steady rise in average IQ scores across generations, also shows that scores are sensitive to environment and education, not just innate ability.

Putting it together for an exam

Name the theory and theorist, state the core claim, then evaluate. For measurement questions, name the test, explain standardisation against the normal distribution, then judge reliability, validity and bias.