drive directed to the removal of noxious stimulation.This basic drive is activated by special sense organs in the form of free nerve endings embedded in the skin, internal organs, and blood vessels. Stimulation of these nerve endings produces sensations of pain via the hypothalamus and reticular formation. The sensations serve as warning signals of possible tissue damage, and whenever possible we react, usually reflexly, by moving away from the source of stimulation. This type of response works reasonably well for external stimuli such as sharp objects, but avoidance of pain is much more difficult when the source is internal. In such cases we may become dependent, and sometimes overdependent, on the use of various drugs, including the usual analgesics for physical distress and the tranquilizers for “psychic pain.”Preoccupation with pain and discomfort is immense, to judge not only by the enormous sale of pain-killing drugs, but by our endlessly repeated expressions “How are you ” “How is your health ” and ‘Take it easy.” Although many of us have been taught in childhood to override minor distress, others have been encouraged by oversolicitous parents to react with anxiety to the slightest discomfort. But in spite of these variations in response, it is an undeniable fact that a continual toothache or headache can make all other activities difficult if not impossible. It also seems true that extreme or annoying pain can generate more compelling motivation than any other drive.Some psychologists contend that pain motivation is basically different from that of other primary drives such as hunger, thirst, and sex, since it is directed toward the elimination of a source of stimulation rather than toward positive satisfaction. Others, however, point out that elimination of pain or discomfort—a dry throat, for example —is involved in all these drives, and that they are all directed toward survival of the individual or the species. The issue is still under debate. See DRIVE REDUCTION THEORY.Research on the psychology of pain has not advanced as far as research on the physiological mechanisms involved, nor as far as the use of drugs or surgery for relief. The subject is highly complex, and attempts have been made to attack it from a number of angles. First, studies show that pain ordinarily functions well as a warning system, since we can usually report the sensation before we are forced to wince or withdraw. However, large variations in pain sensitivity exist among individuals, and even within the same individual at different times. Organic and social factors may both be involved: a person with a hangover may be driven close to “madness” by sounds he would ordinarily not notice, and a player in a team game or a soldier in combat may be completely unaware of an injury that would ordinarily be excruciating. This point has been put to experimental test: Seidman et al. (1957) found that subjects will tolerate a stronger shock when the experience is presumably shared by a partner than when they are alone. It has also been found that a few people are bom with a total inability to feel pain. This is more of an affliction than a blessing since it prevents them from using pain as a warning signal.Second, there is evidence that the reaction to pain is largely a question of learning and training. Most children do not cry when they first fall, even if they injure themselves; but when their mothers have picked them up and anxiously asked, “Are you hurt ” a few times, they usually learn to wail as if they had been damaged for life. These reactions on the part of the mother, plus constant warnings about getting hurt, encourage the child to feel helpless and to exaggerate his slightest feeling of discomfort. Other parents, however, take the much more sensible course of encouraging a more stoical attitude. This difference in upbringing is one of the major factors that account for the variations in pain response in later life. Interestingly, similar variations can be produced experimentally in animals. Melzack and Scott (1957) have shown that dogs reared in isolation and with a minimum of stimulation did not show the usual emotional response to electric shocks, pin pricks, and even a flame held close to the nose. Pavlov (1927) and Mas- serman (1943) have also shown that even the physiological responses to painful stimuli such as pulse and respiratory changes can be extinguished by repeatedly pairing an electric shock with a food reward. This indicates that pain responses can be unlearned as well as learned.Third, psychologists have studied a number of special methods for relieving pain. They have shown experimentally that hypnosis can attenuate the reaction, and have helped to develop its use in childbirth, dentistry, and surgery. They have examined patients who have been subjected to prefrontal lobotomies for the alleviation of continual pain and have found that the sensation is still present, although it does not bring discomfort until attention is directed to it. In other words, the signal is still there but the patient is no longer able to interpret its symbolic meaning as a warning—a form of aphasia known as asymbolia. See APHASIA.The “placebo effect” has also been the subject of many experiments. Reactions to placebos are an impressive illustration of the power of suggestion, for it has been found that totally inert substances will frequently alleviate pain, provided the subject believes they are drugs that will actually do the job. Suggestion can, of course, produce the opposite effect as well: expectation can double our pain in the dentist’s chair. And speaking of dentists, the use of nitrous oxide (laughing gas) lends support to Pavlov’s experiment which showed that positive rewards can reduce the sensation of pain, for the gas puts the patient in a pleasant state of mind in which he feels some pain but is not bothered by it. See PLACEBO.The psychoanalytic theory has added still another dimension to the study of pain. More than any other investigator, Freud made therapists aware of the overwhelming power of “psychic pain.” This pain, which he termed anxiety, is a pervasive feeling of uneasiness and impending doom which he believed to stem from early traumatic experiences or unconscious conflicts. To rid himself of this distressing feeling, the individual unconsciously resorts to a wide variety of defensive reactions, the most important of which is repression. Excessive use of these reactions underlies the various forms of neurosis. Since anxiety is basically a feeling of imminent danger, Freud’s account of psychological pain conforms closely to the accepted interpretation of physical pain as a warning signal.