Murphy, using concepts derived from Pavlovian conditioning, Sherrington's work on physiology of the brain, and general physiology, comes to the conclusion

that every memory based on the perception of external events and objects has its own drive to reach consciousness independent of the energy it may acquire from 'visceral drives'. He states that 'it is not only the instincts or instinctual residues in the psychoanalytic sense that are the dynamic pushes to behavior. They are of enormous importance and at times overwhelm the individual. But they are simply vivid exemplars of a very general tendency to energy release and redistribution in which the sensory and motor systems are as important as the visceral.'