2.6 Measures of Intelligence

What intelligence tests measure

Intelligence is the ability to learn from experience, solve problems, and use knowledge to adapt. Standardized tests like the WAIS (Wechsler Adult Intelligence Scale) and Stanford-Binet measure mental abilities and yield an IQ (intelligence quotient) score comparing a person's performance to others their age.

Test quality: reliability and validity

A good test must be reliable (consistent results over repeated testing, e.g., test-retest) and valid (actually measures what it claims to measure). Content validity checks if items reflect the full range of material, while predictive validity checks if scores forecast future performance, like grades.

Normal distribution and standardization

IQ scores are standardized by testing a representative sample and establishing uniform procedures, producing a normal curve (bell curve) where most scores cluster near the mean (100) with fewer scores at the extremes. This allows meaningful comparison across individuals and groups.

Key terms

Intelligence

The ability to learn from experience, solve problems, and use knowledge to adapt to new situations.

IQ (Intelligence Quotient)

A score derived from standardized tests comparing an individual's performance to others in their age group.

Reliability

The consistency of test results across repeated administrations (e.g., test-retest reliability).

Validity

The extent to which a test actually measures what it is intended to measure.

Standardization

Establishing uniform testing procedures and norms by testing a representative sample, producing a normal distribution.

Try an AP-style question

A test is reliable if it…

1. measures what it claims to
2. yields consistent results
3. has no cultural content
4. predicts future success