What is intelligence and how can it be measured?
Explain competing definitions of intelligence and evaluate how it is measured, including IQ testing and issues of reliability, validity and bias
Intelligence has been defined as a single general factor or many separate abilities. It is measured with standardised IQ tests, which raise questions of reliability, validity and cultural bias.
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What this dot point is asking
You need to outline competing definitions of intelligence, describe how it is measured, and evaluate the strengths and limitations of those measures.
Defining intelligence
There is no single agreed definition, but most include the ability to learn from experience, reason, solve problems and adapt to new situations. Theories differ in whether intelligence is one thing or many.
Theories of intelligence
- General intelligence (g)
- Charles Spearman argued that a single underlying factor, g, influences performance across all mental tasks, supported by the finding that scores on different tests tend to correlate.
- Multiple intelligences
- Howard Gardner proposed that there are several relatively independent intelligences (for example linguistic, logical-mathematical, spatial, musical, bodily-kinaesthetic, interpersonal, intrapersonal and naturalistic), arguing that a single score misses important abilities.
- Triarchic theory
- Robert Sternberg proposed three aspects: analytical (problem-solving), creative (dealing with novelty) and practical (everyday adaptive) intelligence.
- Fluid and crystallised intelligence
- Cattell distinguished fluid intelligence (reasoning and solving novel problems, which tends to decline with age) from crystallised intelligence (accumulated knowledge and skills, which tends to increase or hold).
Measuring intelligence
Intelligence is measured using standardised tests. Modern tests such as the Wechsler scales and the Stanford-Binet report an IQ score. Scores are standardised so that the population mean is 100 with a standard deviation of about 15, producing a normal distribution. Around two-thirds of people score between 85 and 115.
A test is standardised when it is administered and scored in a uniform way and compared against norms from a representative sample.
Evaluating the measures
Good psychological tests must be reliable, valid and free from bias:
- Reliability - the test produces consistent results. Test-retest reliability checks whether the same person scores similarly on different occasions.
- Validity - the test measures what it claims to measure. Predictive validity asks whether scores predict relevant outcomes such as academic performance.
- Cultural bias - items that assume knowledge, language or experiences common to one cultural group can disadvantage others, lowering validity. Culture-fair tests try to reduce reliance on language and culturally specific knowledge.
Other limitations: a single score may oversimplify a complex set of abilities, tests can be affected by motivation, anxiety and test-taking practice, and scores can be misused to label people.