Mind and body are two parts of a complex organism controlled by the nervous system, which acts on information received from the senses. The way a person perceives and reacts depends on his mood, his state of health, his diet, his body temperature and his level of consciousness.
There is considerable evidence that every thought or emotion has some related physical effect, and that every change within the nervous system should have some psychological effect.
Although the precise nature of these correlations is not always known, the view that body and mind are constantly interacting in some way is now accepted by most psychologists.
The relationship between mind and body is particularly apparent in emotional states, especially those of fear and anger. When a person is in the grip of a powerful emotion his body undergoes changes, just as it does when he is asleep, ill or under the influence of drugs or alcohol. Most people are familiar with such sensations as a dry mouth when they are nervous, or a racing heart when they are afraid or excited. Such physical changes can be measured – for instance, by recording pulse rate and breathing, or by measuring the dilation of the pupils of the eyes.
An emerging trend in this area of research is that different individuals have different physiological ways of responding to the same emotional situation.
The fact that these physiological responses are not automatic in the same manner as simple reflexes such as the knee jerk has some intriguing implications and applications. It is possible that these responses may be subject to voluntary control. This is a rather heretical suggestion, since it has long been held that physiological responses such as heart-rate and blood pressure are involuntary reflexes that are beyond the province of learning. But if these responses can be modified by learning, then a whole new range of therapeutic possibilities is opened up. For example, if it is possible to teach people to lower their blood pressure, it is likely that we can dramatically reduce premature death due to heart attacks.
The key concept in whether involuntary responses are subject to learning involves knowledge of the state of a particular system in the body. We do not, for example, generally know whether our blood pressure is high, low or normal. However it is now quite easy to provide an individual with electronic ‘feed-back’ to indicate blood pressure – perhaps in the form of an instrument that sounds a tune when the blood pressure drops below a certain value. This procedure is commonly referred to as biofeedback.
It is by now abundantly clear that a variety of emotional and stressful events can influence the body. These influences can be beneficial and adaptive in the short term; however, prolonged stress can lead to headaches, asthma, ulcers and heart disease. Furthermore, even when obvious stress-induced diseases do not occur , stress can complicate many other disease processes.
This area of the study of the interactions between emotional stress and disease is referred to as psychosomatic medicine. It has been estimated that from 50-80% of medical problems have a significant psychosomatic component.