 One expression of Dewey’s early psychology (and Jamesean turn) was his seminal critique of the reflex arc concept (1896), written at Chicago. The “reflex arc” model of behavior was an increasingly influential way to explain human behavior empirically and experimentally using stimulus-response (cause-effect) pairings; it sought to displace other, less observable and testable approaches that relied upon “psychic entities” or “mental substance”. In the reflex arc model, a passive organism encounters an external stimulus causing a sensory and motor response; for example, a child sees a candle (stimulus), grasps it (response), burns her hand (stimulus), and pulls her hand back (response). This, it argued, makes explicit the event’s basic stimuli and responses, replete with connections satisfactorily describable in mechanistic and physiological terms—and all without recourse to mysterious and unobservable entities.