Exposure Therapy

# Overview
Exposure Therapy is a cognitive behavioral therapy technique for reducing fear and anxiety responses, especially phobia. It is similar to Systematic desensitization, though it works more quickly and produces more robust results. It is also very closely related to Exposure and response prevention, a method widely used for the treatment of Obsessive-compulsive disorder. It based on the principles of habituation and cognitive dissonance.
A typical example of the use of Exposure Therapy might be the treatment of a person with a phobia of snakes. The subject experiences an extreme revulsion when they encounter a snake; this would often not be associated with any feared consequence (they dont think its going to bite them) but rather with an evaluation of it as horrible or slimy. The sight of a snake triggers an unthinking state of arousal, which can be relieved by escaping from the situation. Such escape behavior (or, more precisely, the habit-strength of the arousal-escape connection) is thus reinforced, but it also strengthens the link between snakes and arousal (the stimulus-arousal connection). Thus, the next time a snake is encountered, the arousal response may be stronger or the stimulus may not need to be as powerful to evoke the same degree of arousal  it might be, for instance, that a photograph of a snake might have the same effect that a real snake had previously.
Exposure Therapy would consist of the client (instructed and guided by the therapist) exposing themselves to progressively stronger stimuli and thereby experiencing habituation.

# How to do Exposure Therapy?
Some of the rules for constructing a good program of Exposure Therapy are:
- The subject should have a final goal which should represent non-phobic behavior. This might be (for example) to hold a large snake and rub it against their cheek for several minutes.
- They should also have in mind a series of intermediate steps such that once they have partially habituated to one step the next is close enough to it that they can readily move on. Such a sequence is called a hierarchy. It may be explicit, in the form of a list of increasingly challenging tasks, or implicit, in the form of a set of principles for escalating the exposure. The therapist will decide which of these will be more useful for the subject. (A useful way of constructing such a hierarchy is the Method of Factors.
- At every stage the subjects self-exposure should be completely voluntary - a criterion that may be derived from the theory of cognitive dissonance. One important corollary of this principle is that, at every moment, the subject must have an easy way of terminating the exposure. By choosing not to escape - and therefore practising a competing response - the subject thereby weakens the arousal-escape connection.
- The arousal experienced at any point should be the maximum that the subject is prepared to accept (this is the main difference between Exposure Therapy and Systematic desensitization). It's useful if at each stage the subject asks themselves "is there anything more I could do?" By considering which factors they can manipulate they should be able to keep moving smoothly up their hierarchy.
- Research by Marks and Rachmann demonstrated that optimum results are obtained with daily practice lasting at least an hour; and that the daily session should be ended by allowing the level of arousal to fall off to around half its peak value. For this reason it's useful for the subject to keep a note of their arousal level on a 0-8 scale (where 0=no arousal and 8=intolerable arousal). Before this fall-off phase the level of arousal should be maintained at an uncomfortable but tolerable level.

# Recommended Reading
- Marks I (1979) Exposure therapy for phobias and obsessive-compulsive disorders. Hosp Pract. Feb;14(2):101-8.
- Marks I (1981) Cure and Care of Neuroses John Wiley & Sons Inc 0-471-08808-0
- De Silva P, Rachman S. (1981) Is exposure a necessary condition for fear-reduction? Behav Res Ther. 19(3):227-32.
- De Silva P, Rachman S. (1983) Exposure and fear-reduction. Behav Res Ther. 21(2):151-2.
- Cobb J. (1983) Behaviour therapy in phobic and obsessional disorders. Psychiatr Dev. Winter;1(4):351-65