Answer:
constructed the first successful intelligence test
Step-by-step explanation:
Alfred Binet, a psychology expert and Theodore Simon, a psychiatrist expert, both in 1905, constructed an intelligence test, in which, the result showed the difference or distinguish between those who are are mentally normal and those suffering from mental incapabilities or "slowness", among children.
Both Binet and Simon, started the idea of attaching "mental age" to a particular test scores.