iQ

IQ, or intelligence quotient, is a score derived from standardized tests designed to assess general cognitive abilities in relation to a large population. Most modern IQ tests yield a deviation IQ, where the average score is set at 100 and the standard deviation is 15. The concept aims to quantify relative cognitive performance rather than to measure any single skill.

Historically, the term originated from the idea of comparing mental age to chronological age, introduced by Wilhelm Stern in 1912. Early tests were developed for military and educational purposes and evolved into widely used instruments such as the Stanford-Binet scales and the Wechsler scales (WAIS for adults and WISC for children).

Test content typically covers verbal comprehension, working memory, processing speed, and perceptual/abstract reasoning, among other domains. Scores are interpreted with reference to normative samples. The Flynn effect describes a secular rise in average scores over the 20th century, leading to periodic restandardization of tests.

IQ scores have limitations and are subject to cultural, educational, and language influences. Critics argue that IQ tests do not capture creativity, practical intelligence, motivation, or social skills, and may reflect socio-economic factors. Bias and stereotype threat are ongoing concerns, and results should be contextualized within broader assessments.

Uses include educational placement, clinical assessment, and research into cognitive abilities. It is important to view IQ as one of many indicators of cognitive functioning rather than as a definitive measure of a person’s potential or worth.