Mental age

Psychologists often remark that girls are more emotionally mature than boys at around the age of puberty.

[2] During much of the 19th century, theories of intelligence focused on measuring the size of human skulls.

[3] Anthropologists well known for their attempts to correlate cranial size and capacity with intellectual potential were Samuel Morton and Paul Broca.

[3] Mental age was first defined by the French psychologist Alfred Binet, who introduced the Binet-Simon Intelligence Test in 1905, with the assistance of Theodore Simon.

He created an experiment that was designed as a test to be completed quickly and was taken by children of various ages.

Binet's theories suggested that while mental age was a useful indicator, it was by no means fixed permanently, and individual growth or decline could be attributed to changes in teaching methods and experiences.

[3] Henry Herbert Goddard was the first psychologist to bring Binet's test to the United States.

[7] An individual's "deviation IQ" is then estimated, using a more complicated formula or table, from their score's percentile at their chronological age.

Binet did not believe these measures represented a single, permanent, and inborn level of intelligence.

After World War I, the concept of intelligence as fixed, hereditary, and unchangeable became the dominant theory within the experimental psychological community.