<Tr> <Th> Spouse (s) </Th> <Td> Laure Balbiani </Td> </Tr> <Tr> <Td_colspan="2"> Scientific career </Td> </Tr> <Tr> <Th> Fields </Th> <Td> Psychology </Td> </Tr> <Tr> <Th> Influences </Th> <Td> John Stuart Mill </Td> </Tr>

Who developed the concept of mental age and published the first successful test of intelligence