The Flynn effect represents the secular increase in average scores on measures of intelligence. Richard Herrnstein and Charles Murray coined the term Flynn effect in The Bell Curve for James R. Flynn’s documentation and study of the tendency of intelligence quotient (IQ) scores to increase over time. IQ scores have increased by an average of 3 points per decade on conventional IQ tests since approximately the 1930s. Increases in IQ scores are observed by having different age cohorts take different normed versions of an intelligence test. For example, IQ scores are calibrated through standardization procedures using a sample of test takers to represent the general population. When IQ scores are normed, the average of the scores is typically scaled to a mean of 100. Approximately ...