Mini IQ Test

What IQ Actually Measures

IQ tests attempt to measure general intelligence, often called the g factor - A statistical construct representing the variance shared across diverse cognitive tasks. When you measure performance on many different mental tasks (verbal, numerical, spatial, memory, speed), there is always a substantial positive correlation among them, as if a single underlying dimension of cognitive ability influences all of them. This general factor, first described by Charles Spearman in 1904, is what IQ tests primarily measure.

Modern intelligence theory distinguishes multiple components: fluid intelligence (Gf) - The ability to reason with novel problems, independent of learned knowledge - And crystallized intelligence (Gc) - Accumulated knowledge and verbal reasoning. The Cattell-Horn-Carroll (CHC) model, now the dominant framework, further distinguishes eight to ten broad abilities including visual-spatial (Gv), processing speed (Gs), short-term memory (Gsm), and long-term retrieval (Glr). This test samples four of these: pattern reasoning (Gf), spatial (Gv), verbal (Gc), and numerical (Gq).

For the purest measure of fluid intelligence - The g-loaded component this test targets most directly - Also try our Raven's Progressive Matrices test, considered the gold standard for culture-fair fluid IQ assessment. For how matrix-style reasoning relates to general intelligence, see pattern recognition vs IQ.

IQ Test History

The first practical intelligence test was created by Alfred Binet and Théodore Simon in 1905, commissioned by the French government to identify students needing educational support. Binet's test measured "mental age" - The age at which the child's performance was typical. William Stern introduced the Intelligence Quotient in 1912: IQ = (mental age / chronological age) × 100. Modern tests no longer use this ratio; instead they use standardized scores with a mean of 100 and standard deviation of 15.

David Wechsler developed the Wechsler Adult Intelligence Scale (WAIS) in 1939, which became the clinical gold standard. Unlike Binet's single score, Wechsler provided subscale scores across verbal and performance domains. Today's WAIS-IV measures four index scores: Verbal Comprehension, Perceptual Reasoning, Working Memory, and Processing Speed.

Processing speed tests like our Processing Speed Test and Reaction Time Test measure the Gs component - One of the Wechsler index scores that declines most noticeably with age. Our explainer on what processing speed means in cognitive testing covers this index in depth.

IQ Score Distribution - Bell Curve

The Flynn Effect

One of the most striking findings in intelligence research is the Flynn Effect: IQ scores have been rising by approximately 3 points per decade in industrialized nations since the early 20th century. This means that someone who scored average in 1950 would score below average by today's norms, and someone from today scoring average would be in the top quartile by 1950 norms.

The Flynn Effect is too rapid to be genetic - It must reflect environmental changes. Proposed explanations include improved nutrition (particularly in early childhood), better education focused on abstract reasoning, reduced exposure to environmental lead, more cognitively stimulating environments and media, greater familiarity with the test-taking format, and reduced infectious disease burden in childhood.

Interestingly, the Flynn Effect has slowed or reversed in several developed nations since the 1990s, including Scandinavia, the UK, and France. This deceleration may reflect nutrition and education approaches to their biological ceiling, or possibly increasing screen time and reduced formal reading. The effect is most pronounced on fluid intelligence tasks - Exactly the type of reasoning tested in Raven's Progressive Matrices.

Limitations of IQ Testing