EMDR or Eye Movement Desensitization and Reprocessing is a therapeutic strategy to facilitate the resolution of traumatic memory. This approach was pioneered by Dr. Francine Shapiro, who discovered that inducing bilateral stimulation, that is, by activating the right and left hemisphere of the brain in a rhythmic alternating fashion, traumatic memory could be more readily processed and integrated.
There are various ways to induce bilateral stimulation, but most commonly back and forth eye movement is guided by the therapist’s fingers. This eye movement simulates eye movement during REM (or rapid eye movement) sleep–the cycle of sleep in which memories are processed. Sets of this alternating form of eye movement are interspersed with the verbal processing of traumatic memory.
Other ways of inducing bilateral stimulation include tapping on alternating sides of the body or listening to a tone alternating from left to right ear. EMDR is often helpful in processing memories that may be difficult to put to words or may be stored primarily in the body. For more information please see this link.