Lashley's shift from bacteriology to neuropsychology, 1910-1917, and the influence of Jennings, Watson, and Franz

From 1910 to 1917, Karl S. Lashley's research moved from bacteriology to neuropsychology through intermediate stages of zoology, comparative psychology, and the psychology of learning. This shift is examined with particular reference to Lashley's associations with John B. Watson, Shepherd I. Franz, and Herbert S. Jennings. Watson's impact was substantial, for he attracted Lashley to comparative psychology and was the source of many of his later research interests. The bridge to neuropsychological research was provided by Franz who trained Lashley in the lesion method of investigating the brain bases of learning. The influence of Jennings, Lashley's Ph.D. supervisor, was most evident in the divergence of the post-1915 interests of Lashley and Watson. Lashley's search for brain mechanisms of learning, as contrasted with Watson's concern with behavioral prediction and control, mirrored a similar earlier difference between Jennings and Jacques Loeb.