A behavior modification technique used to combat phobias and other irrational fears.

Developed by Joseph Wolpe in the 1950s, desensitization is a treatment method which weakens the learned association between anxiety and feared objects or situations by strengthening another response—in this case, relaxation—that is incompatible with anxiety. Relaxation responses are strengthened through progressive relaxation training, first developed by Edmund Jacobson in the 1930s. Clients first tighten and then relax 16 different muscle groups in various parts of the body, releasing the tension and focusing on the resulting feelings of relaxation. Once people learn how their muscles feel when they are truly relaxed, they develop the ability to reproduce this state voluntarily and in a variety of situations.

Next, the client...