One of the earliest of such investigative lines was inaugurated by work done by Hebb⁽¹⁾ in contrasting the development of rats blinded in infancy with normal rats. The two groups were tested subsequently by a rat intelligence test. A far greater degree of intelligence was observed in maturity in the controlled rats than in the blinded animals.

Cameron E. et al. (Sensory deprivation: effects upon the functioning

human in space systems , Brooks Air Force base speech, 1960)

⁽¹⁾ Hebb, D.O. (1947) The effects of early experience on problem solving at maturity. Am. Pshycol., 2:306-307.