Constructing Scientific Psychology

Intelligence Testing and the Machine Analogy

Hull's conflict with Lashley took place on three levels. On the most obvious level, theirs was a dispute about the structure and function of the nervous system. Lashley believed the brain functioned as an equipotential system, as a whole, and that a certain amount of brain tissue was necessary, regardless of its location, for proper functioning. For Hull, the nervous system was a mosaic of discrete connections between stimulus and response, each particular connection activated by an impinging stimulus.

On a disciplinary level, they clashed about the proper relationship of psychology to the other sciences: for Lashley, psychology was completely reducible to the biology of the brain and closely connected to neurology and embryology. But Hull believed that psychology was the most basic of the social sciences and should work toward their unification, without reference to the “molecular” sciences. And on the most basic level, they were divided on the issue of the relative importance of heredity and environment in determining behavior.