Three main characteristics of imagery: 

1. It directly affects physiology.
2. Through the mental processes of association and synthesis, it provides insight and perspective into health.
3. It has an intimate relationship with emotions, which are often at the root of many common health conditions.

  Relax for a moment and imagine holding a juicy, yellow lemon. Feel its coolness, its texture, its weight in your hand. Imagine cutting it in half. Notice the cut surfaces-the pale yellow of the pulp, the whiteness of the inner peel, perhaps a seed or two. Carefully cut one of the halves in two and pick up one of the freshly cut lemon quarters. Imagine lifting this lemon wedge to your mouth. Smell its lemony scent. Now imagine biting into the lemon and sucking its sour juice into your mouth. What happened as you imagined doing that? Did you salivate or grimace? Did you have any other kind of physical reaction? Most people do-much more than if you simply asked them to salivate.

  This is a simple illustration of the type of physiological response that imagery can induce. If thinking of a lemon makes you salivate, what other more important effects on physiology might certain types of imagery have? For instance, can thinking of pain relief cause endorphins to be secreted?

  Research using biofeedback, hypnosis, and meditative states has demonstrated that people possess a remarkable range of self-regulatory capacities. Focused imagery in a relaxed state of mind is a common and central factor in most of these techniques.

  Imagery of various types has been shown to affect heart rate, blood pressure, respiratory patterns, oxygen consumption, carbon dioxide elimination, brain wave rhythms, electrical characteristics of the skin, local blood flow and temperature of tissues, gastrointestinal motility and secretions, sexual arousal, levels of hormones and neurotransmitters in the blood, and immune system function.

  Martin L. Rossman, M.D., co-founder of the Academy for Guided Imagery, says that imagery seems to arise from unconscious processes, body processes, and memories and perceptions from the part of the brain known as the cerebral cortex. Some imagery, however, having to do with smell or feelings, may arise from older, more primitive brain centers. Wherever its origin, imagery is believed to have its effect by sending messages from the higher centers of the brain through to the lower centers that regulate most of a person's physiologic functions, such as breathing, heart rate, blood flow and pressure, digestion, immunity, and temperature, as well as waking and sleeping rhythms, hunger, thirst, and sexual function.

  Recent research utilizing PET scans (a test involving radioactive material that is used to examine brain tissue) indicates what parts of the brain are active when a person is performing certain tasks. The PET scans seem to show that the optic cortex, the same part of the brain activated when a person is seeing, is activated when a person visualizes.

  Similarly, when people imagine hearing things, the auditory cortex is active, and when they imagine feeling sensations, the sensory cortex is active. Therefore, it appears that the cortex can create these imaginary realities and, in the absence of conflicting information, the lower centers of the nervous system respond to this information.

  This is one reason why health care professionals use sensory recruitment, an approach that uses as many senses in the imagery process as possible. Sensory recruitment increases the subjective reality of the image and probably increases the amount of information sent through the lower brain centers and autonomic nervous system, making it more likely to get the desired response.

  Dr. Rossman says that recovering from a serious or chronic illness may well demand more than simply imagining getting well. It may also require changes in one's lifestyle, attitudes, relationships, or emotional state. Imagery can help to develop the insight and self-awareness that it takes to deal with a chronic or life-threatening illness in more positive and constructive ways. This is due to the mental processes of association and synthesis that are central to imagery. Dr. Rossman explains, that imagery  gives the 'big picture' of a situation and can help people recognize how things are related in ways they might not expect. Becoming aware of these relationships may assist a shift in attitude or behavior that can be helpful in relieving, changing, or coping with illness or symptoms.

  Dr. Rossman recalls a woman whose chronic arm pain had not responded to medical treatment for two years. She kept seeing an image of her pain as pieces of iron. This made little sense to her until she was asked to describe the qualities of the iron. She described it as hard, cold, and rigid, and then immediately associated these qualities with her grandfather, whom she had been caring for during the past two years, as he displayed these same qualities. This association allowed her to deal with repressed feelings about her role as a caregiver and led to a rapid resolution of her arm pain as well as a great deal of personal growth.

  Emotions are physiologically distinct from one another and each affects human physiology in different ways. In fact, Dr. Rossman points out, many physical sicknesses are direct manifestations of emotions that are locked within the unconscious. Through imagery one can access those emotions and consciously change their effect on health.

  Emotions themselves are a normal, healthy response to life. Failure to acknowledge and express important emotions, however, can be an important factor in illness, and is unfortunately all too common. People often suppress those emotions they find to be the most distressing, such as fear, grief, and anger.

  The natural expression of emotion is often suppressed by family, friends, and society, as well. Dr. Bresler says, strong emotion has a way of finding routes of expression, and if it is not recognized and dealt with it can manifest itself indirectly in the form of physical pain and illness, or destructive behaviors like smoking, heavy drinking, and overworking, all of which can in turn lead to serious health problems. Studies conducted in England and the United States have found that 50 to 75 percent of all problems presented to a primary care clinic are emotional, social, or familial in origin, though they are being expressed by pain or illness.

  By directly accessing emotions, imagery can help the individual understand the needs that may be represented by an illness and can help develop ways to meet those needs. Imagery is also one of the quickest and most direct ways of becoming aware of emotions and their effects on health, both positive and negative. For example, one of Dr. Rossman's patients with inflammatory bowel disease reported that she imagined her bowels being "red, inflamed, and irritated." As this image was explored, she became aware of how her bowels responded to the irritation, frustration, and anger she frequently felt. By learning to recognize what triggered her frustration, and by developing more effective means to express herself when angry, she had progressively less trouble with her bowels. She also learned to use simple relaxation and imagery to imagine her own hands gently soothing her bowels with a cooling, calming balm whenever they became upset. A few minutes of doing this would relieve her abdominal pain and leave her feeling relaxed and at ease.