Lohr J M, Lilienfeld S O, Tolin D F, Herbert J D
Department of Psychology, University of Arkansas, Fayetteville 72701, USA.
J Anxiety Disord. 1999 Jan-Apr;13(1-2):185-207. doi: 10.1016/s0887-6185(98)00047-4.
Incremental validity and incremental efficacy have become important issues in the evaluation of psychological assessment and intervention procedures. Incremental validity in assessment is that shown by novel measures over and above established ones. Incremental efficacy is that shown by novel treatments over and above nonspecific and established treatment effects. In this paper, we critically examine the question of whether Eye Movement Desensitization and Reprocessing (EMDR) possesses efficacy above and beyond nonspecific treatment effects and components that are shared with well-established interventions. A review of recently published efficacy studies reveals that (a) the effects of EMDR are largely limited to verbal report indices, (b) eye movements and other movements appear to be unnecessary, and (c) reported effects are consistent with nonspecific treatment features. Examination of individual studies shows that control procedures for nonspecific features have been minimal. We analyze EMDR for nonspecific treatment features and suggest experimental controls to examine the incremental efficacy of EMDR.
