Comments on Sharpley et al.

First, quick recap the discussion of Andrade et al. and Kavanagh et al. I proposed a distinction between fear reduction via distraction and fear reduction via desensitization and outlined a strategy for empirically differentiating between them. Both result in fear reduction, but fear levels reduced via distraction lead to a return of fear in response to the target fear stimulus when testing occurs in the absence of the distractor. I suggested that the results of Andrade et al. can be explained by either mechanism. However, the results of Kavanagh et al. favor the hypothesis that reductions in distress because of eye movements is best viewed as operating through distraction, not desensitization.

Now, onto the research by Sharpley, Montgomery, & Scalzo (1996). Actually, there are two studies by this group, both published in 1996. I'm pretty sure I know which one that Louise intended, but just for the sake of completeness, I will review them both. Both studies used healthy volunteers as subjects and focused only on the eye movement aspect of EMDR. Thus, they did not use the full protocol.

Study 1 (the one I think Louise was intending)

Sharpley, C. F., Montgomery, I. M., & Scalzo, L. A. (1996). Comparative efficacy of EMDR and alternative procedures in reducing the vividness mental images. Scandinavian Journal of Behaviour Therapy, 25, 37-42.

This study used a within-group design (everyone appeared in all conditions) to compare the effects of eye movements during mental imagery on image vividness with an eye roll technique used to induce hypnosis (RI for rapid induction procedure) and a relaxation condition where subjects were told, "Close your eyes, try to make your mind blank, and relax as much as you can." The order in which these three interventions was partially counter-balanced: of six possible combination of condition orders (1-2-3; 1-3-2; 3-2-1; 2-3-1; 2-1-3; and 3-1-2), subjects were assigned to three of them. In each condition subjects first formed an image of either a positive (3 subjects) or a negative (21 subjects) autobiographical memory and then rated the image vividness. Then the first intervention was administered and the subjects gave a second rating of image vividness. In between interventions, there was a 3-minute rest period, which the experimenter "used to discuss the subject's image (on the basis of the subject's written account), and to attempt to raise the degree of vividness back to its original level by discussion. Results revealed that there was a significant reduction in image vividness in the EMDR and RI conditions, but not eht relaxation condition. Moreover, image vividness was lower following EMDR than RI and relaxation. RI did not differ from relaxation. SUDs data are not reported. These data are easily fit within the distraction hypothesis. There is no evidence that the reduction in image vividness was anything more than a temporary effect. Indeed, the design and procedures of the study were predicated on the assumption that image vividness could be reinstated with a conversation.

Study 2

Sharpley, C. F., Montgomery, I. M., & Scalzo, L. A. (1996). An investigation of some hypothetical mechanisms underlying EMDR. Scandinavian Journal of Behaviour Therapy, 25, 87-98.
The authors tested the hypothesis that eye movements in EMDR induce relaxation by measuring three psychophysiological measures of arousal: heart rate (reductions in heart rate signifying relaxation), T-wave amplitude (greater T-wave amplitude signifying greater relaxation), and alpha wave activity (increases in alpha wave activity signifying greater relaxation). These measures were obtained while the person was reading from an encyclopedia; while they underwent a comprehension test on the material from the encyclopedia; slow eye movements (one L-R sweep every two seconds); medium eye movements (one L-R sweep every second); EMDR speed eye movements (two L-R sweeps every second); the eye roll induction procedure; and relaxation. Each phase lasted 30 seconds and always occurred in the order described (i.e., no counter-balancing). Results were mixed:

Heart rate: Compared to reading, significant heart rate reduction occurred for the eye roll condition and relaxation, but not for any of the eye movement conditions. However, if you look at the graph, heart rate basically declined over the course of time, suggesting a general habituation effect, getting used to the novel environment.

T-wave amplitude: This was highest for the EMDR condition, but the change was not statistically significant. Moreover, in the absence of proper counter-balancing, we can't be sure this isn't just an artifact of the passage of time.

Alpha-wave activity: Compared to reading, only the eye roll and relaxation conditions resulted in significant increases in alpha-wave activity. Again, however, this could simply reflect the passage of time.

In sum, there was little evidence in this study that EMDR results in a compelled relaxation response. Two of the measures suggested that either an eye roll hypnotic induction procedure or simple instructions to relax were effective in promoting relaxation as measured by brain-wave activity. However, the results could also reflect the fact that these two conditions were last and reflect the person adapting to the laboratory set up.

In sum of the studies by the Andrade/Kavanagh group and the studies by the Sharpley group, there is NO evidence thus far for a desensitization effect, much less "consistent" evidence for such.

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