The response to touch is not automatic
Touching, stroking, tickling, rubbing, slapping, kissing, or licking these areas can often create or increase sexual excitement. However, this response is by no means automatic. A great deal depends on a person's previous conditioning and on the circumstances under which the stimulation occurs. For instance, when a doctor touches a patient's erogenous zones in the course of a physical examination, there may be no sexual response at all. Neither is such a response likely in cases of rape. In short, psychological factors usually play a decisive role in tactile stimulation. (There are some exceptions to this rule, as in certain cases the body may produce a reflexive reaction to touch. For example, a man who suffers from a certain type of spinal cord injury can have an erection when his penis is fondled, although the stimulation may not register in his brain).