The technique was developed by psychologist J. Wolpe from his experiments on cats. Wolpe used classical conditioning to make cats afraid of their cage. He discovered that he could eliminate this fear by giving the cats food at locations progressively closer to the cage, however if they were too close, the cats would not eat. Wolpe hypothesized that the cats were undergoing a process called reciprocal inhibition (ie. anxiety inhibits feeding and feeding inhibits anxiety).
Thus, systematic desensitization has two components: graduated exposure to anxiety provoking stimuli and reciprocal inhibition (counterconditioning).
In humans, systematic desensitization typically involves three steps. The first step is to teach the client to relax. The second step is to create a rank-ordered hierarchy of anxiety provoking situations from least feared to most feared. The final step is to combine relaxation with imagining the things on the hierarchy, beginning with the least anxiety provoking.
Systematic desensitization has been shown to be effective in treating a wide range of phobias from fear of spiders to social phobia.
Other methods derived from systematic desensitization involve graduated real-life (in vivo) exposure to feared stimuli.
Source:
Thorpe, G. L. & Olson, S. L. (1997). Behavior Therapy: Concepts, Procedures, and Applications, Second Edition. Allyn & Bacon Publishers.
