The neuropsychological concepts found in Donald Hebb's The Organization of Behavior have greatly influenced many aspects of neuroscience research over the last half century. Hebb's ideas arose from a rich tradition of research. An underappreciated contribution came from pioneering studies at Yale University. Here, we wish to reconsider these developments, placing particular emphasis on the roles of the neurophysiologists John Fulton, J.J. Dusser de Barenne, and Warren McCulloch and the psychologists Donald Marquis and Ernest Hilgard. These neuroscientists all contributed significantly to the intellectual climate that gave rise to Hebb's remarkable synthesis.