This study aimed to investigate the psychophysiological correlates and the effectiveness of different dual-attention tasks used during eye movement desensitization and reprocessing (EMDR) (1)
“Abstract – Sixty-two non-clinical participants with negative autobiographical memories received a single session of EMDR without eye movements, or EMDR that included eye movements of either varied or fixed rate of speed. Subjective units of distress and vividness of the memory were recorded at pre-treatment, post-treatment, and 1 week follow-up. EMDR-with eye movements led to greater reduction in distress than EMDR without eye movements. Heart rate (HR) decreased significantly when eye movements began; skin conductance (SC) decreased during eye movement sets; heart rate variability (HRV) and respiration rate (RR) increased significantly as eye movements continued; and orienting responses were more frequent in the eye movement than no-eye movement condition at the start of exposure. Findings indicate that the eye movement component in EMDR is beneficial, and is coupled with distinct psychophysiological changes that may aid in processing negative memories.
This study was designed to examine effectiveness and psychophysiological correlates of different dual-attention tasks used in EMDR. The study is unique as it used a single EMDR session, with either fixed or varied rate eye movements (EMs), and compared results to a no-EM control, thus allowing for changes to be attributed to the effects of the eye movement component in EMDR. We found that a single EMDR session was effective at reducing the distress associated with negative autobiographical memories.
We also found that the EM component in EMDR was beneficial, and was coupled with distinct psychophysiological changes that may aid in processing negative memories. As hypothesized, when EMs were used in EMDR there was a greater reduction in distress associated with negative memories than when EMs were omitted from the procedure.
This research demonstrated that EMDR is associated with significant physiological dearousal within treatment. This study also established that the EMs in EMDR are accompanied by a number of physiological changes: HR decreased significantly at the onset of the EMs; SC decreased during EM sets; HRV increased significantly; RR increased during EM sets.
The effects of eye movements vs no eye movements in EMDR
The finding that a single session of EMDR-with EMs reduced self-reported distress associated with negative memories is consistent with Shapiro’s (1989) initial findings that introduced the procedure. Current results also support findings by Wilson et al. (1996) and Lee and Drummond (2008) who found that a single session of EMDR-with EMs leads to greater reductions in associated with distressing memories than EMDR-without EMs, and this effect was maintained at follow-up.
…Greater reductions in distress for EM over no-EM conditions have been consistently found (Andrade et al., 1997; Barrowcliff et al., 2004; Kavanagh et al., 2001; van den Hout et al., 2001; Kemps & Tiggerman, 2007). These non-clinical studies also often reported that thinking of a negative memory and engaging in EMs led to significantly greater reductions in the vividness of memories than exposure with no-EMs. Recently, Lilley and colleagues (2010) have replicated and extended the findings of analogue studies as they demonstrated that EMs, compared to no-EMs or a verbal task, reduced the distress and vividness of trauma images from a clinical population of PTSD patients awaiting treatment
…The rapid reduction of distress and vividness associated with negative memories using EMDR has also been noted by researchers who have used a single EMDR session to treat PTSD (Rogers et al., 1999).
The physiological effects of EMDR and correlates of the EM component within sessions Evident from this research is that EMDR is associated with significant dearousal within sessions, and that the EM component in EMDR evokes physiological changes that may aid in processing negative memories. This study demonstrated that EMDR led to dearousal from before to after treatment on all physiological variables examined (HR, HRV, SC, and RR), and the reductions in HR and RR were greater for the EM compared to the noEM condition.
Thus, the findings support previous research (Aubert-Khalfa et al., 2008; Sack et al., 2007; Wilson et al., 1996) that reported physiological dearousal within EMDR sessions. Surprisingly, empirical research that has examined the processes that occur during treatment of PTSD patients is scarce. This study demonstrates that onset of the EM component was associated with an immediate decrease in HR during EMDR treatment in a non-clinical sample.
This was also observed by Sack et al. (2008) and Elofsson et al. (2008) who used EMDR to treat PTSD patients. However, these findings extend those of past research, as it can be concluded that the decrease in HR is a distinct feature of the EMs because in the no-EM condition HR did not decrease significantly at the onset of exposure sets. In this study, HR continued to decrease slightly across the set when EMs were used, then increased slightly towards the end of the set. This is also in accordance with past findings (Elofsson et al., 2008; Sack et al., 2008). Like Elofsson and Sack, we attribute the changes in HR at the beginning of EM sets as concomitants of an orienting response (Obrist, 1981; Öhman et al., 2000; McCulloch & Feldman, 1996).
Consistent with an OR, the dearousal at the onset of the EMs, as indicated by reduced HR, was coupled with an increase in HRV, which for both EM and no-EM conditions continued to rise, indicating an increase in parasympathetic tone within EM/exposure sets.
We found that the number of SCRs decreased significantly from the start to the end of EMDR sessions for the EM condition, but not for the no-EM condition. Also at the start of treatment the number of SCRs was greater at the beginning of sets for the EM compared to the no-EM condition, but by the end of the sets the number of SCRs decreased in the EM condition to be the same as in the no-EM condition. In addition, at the start of treatment the amplitude of the SCRs decreased significantly within the stimulation sets only for the EM condition. This pattern of response is consistent with habituation to the eye movement stimulus both across the treatment session and within each stimulation set. However, contrary to OR theory, the amplitude of the SCRs did not decrease significantly from the start to the end of treatment for the EM condition.
In this study and past EMDR treatment studies (Sack et al., 2008; Elofsson et al., 2008), the physiological changes associated with EMs were consistent with the presence of a relaxation response. At the onset of EMs there was a clear decrease in sympathetic indices and an increase in parasympathetic tone.
EMDR is a complex therapy with a number of underlying processes simultaneously at play. We argue that the psychophysiological changes associated with the EMs in EMDR are primarily the result of two overlapping yet distinct influences: first, an OR as the EM component begins; and second, as the OR habituates to repeated EM stimulation the physiological profile becomes mixed with a stress, or defense response due to continued exposure to stressful memories. Like Sack and colleagues (2008) we propose dual-attention tasks in EMDR create orienting responses (ORs) and short-term dearousal which may aid in the processing and integration of trauma memories. Also, through the process of reciprocal inhibition, in which a relaxation response is paired with exposure to distressing memories, negative appraisals of distressing memories weaken, and avoidance of trauma memory processing decreases. Eye movements, as a dual-attention task, may also reduce distress to a tolerable level and create a cognitive and physiological state in which effective processing of trauma information can occur. The relaxation response associated with EMs in EMDR is clinically meaningful as it may serve to moderate arousal throughout treatment sessions. Thus, EMDR may be particularly suitable for patients who cannot tolerate the high stress associated with exposure.”
Schubert, S.J., Lee, C.W. and Drummond, P.D. (2011) The efficacy and psychophysiological correlates of dual-attention tasks in eye movement desensitization and reprocessing (EMDR). Journal of Anxiety Disorders, 25 (1). pp. 1-11..