the Canadian psychologist Donald Hebb noticed that the lab rats he took home as pets for his children outperformed others on problem-solving tasks when returned to the lab several weeks later. This seemed to show that early experience can have dramatic and permanent effects on brain development and function. Hebb reported these findings in his influential 1949 book, The Organization of Behavior, concluding that “the richer experience of the pet group... made them better able to profit by new experience at maturity—one of characteristics of the ‘intelligent’ human being.”
