What is IQ? Does it Change Over Time?

Development of Psychometrics Sir Francis Galton (mid 1800s) became interested in individual differences. From his work emerged the concept of measuring intelligence. Because Galton believed intelligence was inherited, his work also sparked controversy for a century. Galton coined the phrase: “Nature versus Nurture” - hereditary basis of intelligence by studying twins. Developed the field of psychometrics by applying statistical concepts, correlation and percentile to human intelligence.

The First IQ Tests Binet-Simon Scale: 1st measure of intelligence created by Alfred Binet & Theodore Simon Alfred Binet designed the tests for French schools to identify students who would benefit from support. Binet also developed concepts of: Mental Age: chronological age that most typically corresponds to a given level of performance child who does as well as the average 8-year- old is said to have a mental age of 8 Binet hoped they could use the test to help not label children

Stanford-Binet Intelligence Scale Lewis Terman (1916) revised & expanded Binet’s test for use in the USA Renamed: Stanford-Binet Intelligence Scale Became the “Gold Standard IQ Test” Utilized IQ formula & allowed for adult testing Increased the # of tasks required Binet = 54, Standford-Binet = 90

The Normal Distribution: A symmetric bell-shaped curve that represents the pattern in which many characteristics are dispersed in the population

An 8 year old has mental age of 10. What is his IQ An 8 year old has mental age of 10. What is his IQ? 125 A 12 year old has the mental age of 9. What is his IQ? 75 A boy has the mental age of 10 and an IQ of 200. How old is he? ?

50!!!

David Wechsler suggested IQ tests were limited because they measured intelligence only verbally. He devised a test included both verbal and performance components to compute a total IQ score. He also developed separate intelligence tests for adults (WAIS) and children (WISC) Unlike Stanford-Binet (which used a ratio IQ-mental age divided by chronological age…

The Flynn Effect Potential cause for the gap in intelligence scores amongst groups may by the stereotype threat Stereotype Threat: Reminded of a negative stereotype about a group they belong to prior to a test, results in lower scores Psychologists today work to create culture-fair tests that try to eliminate racial, ethnic, socioeconomic and gender bias