"Klahr, David"@en . . "David Klahr"@en . "David Klahr (born 1939) is an American psychologist whose research ranges across the fields of cognitive development, psychology of science, and educational psychology and has been a professor at Carnegie Mellon University since 1969."@en . . . . . . . . . "Developmental psychologist" . . "1939Z"^^ . . . . . . . .