Topic 2.8 Notes – Intelligence and Achievement

What Intelligence Is

Psychologists usually define intelligence as the ability to learn from experience, reason, solve problems, and adapt. That sounds simple, but there is no single definition everyone agrees on. The big debate is whether intelligence is one broad mental ability or several different abilities.

Spearman’s general intelligence

Charles Spearman noticed that people who do well on one mental task often do fairly well on others too. Using factor analysis (a statistical method that finds patterns among scores), he argued for g, or general intelligence.

• g = a broad mental ability shared across many tasks
• s = specific abilities needed for particular tasks

So your score on a math task might reflect both your overall reasoning power and your specific math skills.

Gardner’s multiple intelligences

Howard Gardner argued that intelligence is not one score. He proposed several distinct intelligences.

• Linguistic
• Logical-mathematical
• Spatial
• Musical
• Bodily-kinesthetic
• Interpersonal
• Intrapersonal
• Naturalistic

This helps explain why someone can be amazing with people, music, or movement without looking like a top test-taker. A common criticism is that some of these may be better described as talents than fully separate intelligences.

Sternberg’s triarchic theory

Robert Sternberg said intelligence has three parts:

• Analytical intelligence = solving academic and logical problems
• Creative intelligence = handling new situations and producing original ideas
• Practical intelligence = dealing effectively with everyday life

This theory matters because school success does not capture everything we mean by being “smart.”

How Intelligence Is Measured

Early intelligence testing

Alfred Binet and Théodore Simon created early intelligence tests to identify students who needed extra educational support. They used mental age, which means the level of performance typical for a certain age group.

Lewis Terman later revised this work into the Stanford-Binet.

The historical IQ formula was:

$$IQ = \frac{\text{mental age}}{\text{chronological age}} \times 100$$

So a 10-year-old performing like an average 12-year-old would have an IQ of 120. Modern IQ testing does not use this formula. Today, IQ is based on deviation scores, with an average of 100. That is why IQ scores are usually shown on a bell-shaped curve centered at 100.

IQ scores on a normal distribution

Psychometric rules for a good test

Psychometrics means the measurement of psychological traits. A useful intelligence test needs three things.

Validity

• Construct validity asks whether the test actually measures intelligence.
• Predictive validity asks whether the score predicts something later, like school performance.

Reliability

• Test-retest reliability means similar scores on separate test dates.
• Split-half reliability means two halves of the test give similar results.

One testable idea students miss a lot is this. A test can be reliable without being valid. If it consistently measures the wrong thing, it’s still reliable.

Culture, Bias, and the Uses and Misuses of IQ

Intelligence scores reflect both ability and the testing situation.

• Sociocultural responsiveness means making tests fairer by reducing irrelevant language or cultural barriers and using appropriate norms.
• Stereotype threat happens when fear of confirming a negative stereotype lowers performance.
• Stereotype lift happens when favorable comparison to another group boosts performance.

The Flynn effect is the long-term rise in IQ scores across generations, linked to nutrition, health care, education, technology, and SES. That shows environment shapes test performance.

Historically, IQ tests were also misused. During World War I, the Army Alpha and Army Beta sorted recruits. Test results were later used by the eugenics movement to justify limits on jobs, education, military rank, and immigration in the 1920s.

One of the biggest AP points here is interpretation:

• there is more variation within groups than between groups
• group averages overlap a lot
• poverty, discrimination, stress, health, and unequal schooling affect scores
• you should never use group membership to judge one individual’s intelligence

Achievement, Aptitude, and Mindset

An achievement test measures what you have already learned.

• examples: unit tests, final exams, end-of-course tests

An aptitude test predicts future performance or ability to benefit from training.

• example: the SAT is often treated as more aptitude-oriented

An intelligence test aims at broader cognitive ability than either one subject test.

Carol Dweck studied mindsets.

• Fixed mindset = intelligence is set
• Growth mindset = intelligence can develop through effort, strategies, instruction, and feedback

Growth mindset often leads to persistence and better strategy use. One important limit is that it does not mean “just try harder.” Improvement depends on effective methods and real opportunities too.