Who gave ‘Mental Age’ concept?

CONCEPT: In early intelligence testing, a child’s cognitive performance was expressed relative to age norms rather than as a raw score. ‘Mental Age’ is the chronological age at which a child’s test performance is typical — e.g., a child performing at the level typical of 8-year-olds is said to have a mental age of 8, regardless of their actual (chronological) age.

APPLICATION: Alfred Binet, working with Théodore Simon, had published their original Binet–Simon scale in 1905. In their 1908 revision, they organized test tasks by the age level at which most children could solve them, and rated a child’s performance against those age norms — this age-referenced score, introduced in the 1908 revision, is exactly the ‘Mental Age’ concept.

CROSS-CHECK / CONTRAST with the other names offered:

• Thorndike — known for the laws of learning (effect, exercise, readiness) within connectionism, a distinct line of work from the concept this question is about.

• Cattell — known for coining the term ‘mental test’ in 1890 as a general label for cognitive measurement, a different, earlier contribution from the concept this question is about.

• Stern — known for formalizing the Intelligence Quotient (IQ) as a ratio-based score, a later and distinct development built on top of the concept this question is about.