Making eye movements during imaginal exposure leads to short-lived memory effects compared to imaginal exposure alone

Attenuating conditioned fear using imagery-based interventions: An overview

A growing literature has sought to include mental imagery in fear conditioning studies. Imaginal extinction and imagery rescripting are mental imagery-based interventions that reduce conditioned fear. In the current study, we reviewed the recent findings on the efficacy of imaginal extinction and imagery rescripting as interventions to attenuate conditioned fear responses among healthy individuals. In accordance with the PRISMA guidelines, we conducted a literature search in four databases, PubMed, Scopus, Science Direct, and Web of Science to find published original empirical articles involving imagery-based interventions using a fear conditioning paradigm. The inclusion criteria were (i) use of an imagery-based intervention (either imaginal extinction or imagery rescripting), and (ii) use of a differential fear conditioning paradigm. 13 original articles reporting 15 experimental studies were included in the review. The review revealed that imagery-based interventions are effective in reducing conditioned fear. Although studies have shown that imaginal extinction and standard extinction have comparable effects in fear extinction, many studies have not been conducted to confirm the findings, or explore the underlying mechanisms. We also found the need for a standardized intervention protocol to enhance experimental control in intervention-based fear conditioning studies.

Bilateral eye movements disrupt the involuntary perceptual representation of trauma-related memories

Bilateral eye movement (EM) is a critical component in eye movement desensitization and reprocessing (EMDR), an effective treatment for post-traumatic stress disorder. However, the role of bilateral EM in alleviating trauma-related symptoms is unclear. Here we hypothesize that bilateral EM selectively disrupts the perceptual representation of traumatic memories. We used the trauma film paradigm as an analog for trauma experience. Nonclinical participants viewed trauma films followed by a bilateral EM intervention or a static Fixation period as a control. Perceptual and semantic memories for the film were assessed with different measures. Results showed a significant decrease in perceptual memory recognition shortly after the EM intervention and subsequently in the frequency and vividness of film-related memory intrusions across one week, relative to the Fixation condition. The EM intervention did not affect the explicit recognition of semantic memories, suggesting a dissociation between perceptual and semantic memory disruption. Furthermore, the EM intervention effectively reduced psychophysiological affective responses, including the skin conductance response and pupil size, to film scenes and subjective affective ratings of film-related intrusions. Together, bilateral EMs effectively reduce the perceptual representation and affective response of trauma-related memories. Further theoretical developments are needed to elucidate the mechanism of bilateral EMs in trauma treatment.

Omitting continuous memory recall from dual-task interventions does not reduce intervention effectiveness

In Eye Movement Desensitization and Reprocessing a patient recalls a traumatic memory, while simultaneously performing a dual-task (e.g., making horizontal eye movements, tapping a pattern). Earlier lab studies show that increasing the load of a dual-task -and leaving fewer resources for memory recall-results in larger decreases in memory vividness and emotionality compared to control conditions. Therefore, we investigated whether it is necessary to continuously and deliberately recall the memory next to performing high taxing dual-tasks. In two online experiments, participants (N = 172, N = 198) recalled a negative autobiographical memory and were randomly assigned to (1) Memory Recall + Dual-Tasks, (2) Dual-Tasks Only, or (3) No Intervention Control. The dual-tasks were complex pattern tapping and spelling out loud. Before and after the intervention the memory was rated on vividness, emotionality, and accessibility. High taxing dual-tasks, regardless of whether there was continuous memory recall, resulted in the largest reductions in all dependent variables compared to control. Unexpectedly, there was no evidence that the addition of continuous memory recall added to these reductions. These results suggest that continuous memory recall might not, or only minimally be needed for the beneficial effects of the dual-task procedure in EMDR might not be beneficial per se. We discuss the necessity of memory (re)activation, alternative explanations, and implications for practice.

The effect of imagery rescripting on prospective mental imagery of a feared social situation

BACKGROUND AND OBJECTIVES

Negative mental imagery appears to play a role in anxiety disorders and can involve aversive memories or anticipated future threats. Modulating aversive memories through imagery rescripting generally reduces negative memory appraisals and associated anxiety. This pre-registered two-day analog study investigated whether imagery rescripting of aversive memories also reduces negative imagery of future threats.

METHODS

On Day 1, socially anxious individuals (N = 52) were randomly assigned to imagery rescripting of an aversive memory or progressive relaxation (control condition). Before each intervention, they were asked to imagine a feared social situation that may happen in their future and evaluate this situation. They also rated the aversive memory before and after the intervention phase. The feared future situation was again evaluated at follow-up on Day 2.

RESULTS

Unexpectedly, no group differences were found on the main outcome measures. That is, negative memory appraisals reduced after both interventions. Likewise, in both groups, negative details decreased, and positive details increased in prospective mental imagery, and anxiety and avoidance towards the imagined event decreased. On the exploratory measures, the imagery rescripting group showed increased positive appraisals of memory and future threat, and decreased negative future-threat appraisals, compared to the progressive relaxation group.

LIMITATIONS

No passive control group was included, so potential time or placebo effects cannot be precluded.

CONCLUSIONS

The interventions had similar effects on the main outcomes and influenced mental imagery of future threats. Some differences were found on the exploratory measures that warrant further investigation with a passive control condition.

Can working memory account for EMDR efficacy in PTSD?

BACKGROUND

Although eye movement desensitization and reprocessing (EMDR) has been shown to be effective in the treatment of PTSD for years, it remains controversial due to the lack of understanding of its mechanisms of action. We examined whether the working memory (WM) hypothesis -the competition for limited WM resources induced by the dual task attenuates the vividness and emotionality of the traumatic memory - would provide an explanation for the beneficial effect induced by bilateral stimulation.

METHODS

We followed the Prisma guidelines and identified 11 articles categorized in two types of designs: studies involving participants with current PTSD symptoms and participants without PTSD diagnosis.

RESULTS

Regardless of the types of studies, the results showed a reduction of vividness and emotionality in the recall of traumatic stimuli under a dual-task condition compared to a control condition, such as recall alone. However, two studies used a follow-up test to show that this effect does not seem to last long.

CONCLUSION

Our results provide evidence for the WM hypothesis and suggest that recalling a traumatic memory while performing a secondary task would shift the individual's attention away from the retrieval process and result in a reduction in vividness and emotionality, also associated with the reduction of symptoms.

Boosting long-term effects of degraded memories via acute stress

Combining recall of an emotional memory with simultaneous horizontal eye movements (i.e., Recall + EM) reduces memory aversiveness. However, the long-term persistence of this effect is inconsistent across studies. Given that stress may aid in the consolidation of memories, we examined whether acute stress can boost the long-term effects of degraded memories. To test this, participants recalled two negative memories, which were assigned to a Recall + EM or Recall Only condition. Before and after each intervention they rated memory aversiveness (i.e., immediate effects) followed by a stress-induction or control procedure. After a 24h-period, participants rated each memory again (i.e., long-term effects). We found that Recall + EM produces immediate effects but that these effects dissolve over time. Moreover, acute stress did not boost potential long-term effects of Recall + EM. Degraded memories were not retained better by applying stress. We discuss these results and how long-term effectiveness may still be achieved.

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We examined whether stress boosts the long-term effects of degraded memories.

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Dual-task interventions robustly produce immediate memory degrading effects.

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Immediate memory degrading effects dissolve over time (24h later).

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The stress manipulation increased cardiovascular/neuroendocrine stress responses.

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Acute stress did not boost potential long-term effects of dual-task interventions.

A Case for Translation From the Clinic to the Laboratory

Laboratory procedures have been used for decades as analogues for clinical processes with the goal of improving our understanding of psychological treatments for emotional disorders and identifying strategies to make treatments more effective. This research has often focused on translation from the laboratory to the clinic. Although this approach has notable successes, it has not been seamless. There are many examples of strategies that work in the laboratory that fail to lead to improved outcomes when applied clinically. One possible reason for this gap between experimental and clinical research is a failure to focus on translation from the clinic to the laboratory. Here, we discuss potential benefits of translation from the clinic to the laboratory and provide examples of how this might be implemented. We first consider two well-established laboratory analogues (extinction and cognitive reappraisal), identify critical aspects of the related clinical procedures (exposure and cognitive restructuring) that are missing from these analogues, and propose variations to better capture the clinical process. Second, we discuss two clinical procedures that have more recently been brought into the laboratory (eye-movement desensitization and reprocessing and imagery rescripting). We conclude by highlighting potential implications of this proposed shift in focus for translational research.

No evidence for disruption of reconsolidation of conditioned threat memories with a cognitively demanding intervention

Simultaneous execution of memory retrieval and cognitively demanding interventions alter the subjective experience of aversive memories. This principle can be used in treatment to target traumatic memories. An often-used interpretation is that cognitive demand interferes with memory reconsolidation. Laboratory models applying this technique often do not meet some important procedural steps thought necessary to trigger reconsolidation. It remains therefore unclear whether cognitively demanding interventions can alter the reconsolidation process of aversive memories. Here, 78 (41 included) healthy participants completed an established 3-day threat conditioning paradigm. Two conditioned stimuli were paired with a shock (CS+ s) and one was not (CS-). The next day, one CS+ (CS+ R), but not the other (CS+), was presented as a reminder. After 10 min, participants performed a 2-back working memory task. On day three, we assessed retention. We found successful acquisition of conditioned threat and retention (CS+ s > CS-). However, SCRs to the CS+ R and the CS+ during retention did not significantly differ. Although threat conditioning was successful, the well-established cognitively demanding intervention did not alter the reconsolidation process of conditioned threat memories. These findings challenge current views on how cognitively demand may enhance psychotherapy-outcome.

Verbal suggestions fail to modulate expectations about the effectiveness of a laboratory model of EMDR therapy: Results of two preregistered studies

BACKGROUND AND OBJECTIVES

For many psychotherapies, like Eye Movement and Desensitization Reprocessing (EMDR) therapy, there is an ongoing discussion about the role of specific versus non-specific mechanisms in their effectiveness However, experimental research directly examining the potential role of non-specific mechanisms is scarce. Here, we address the role of a non-specific factor that is often put forward for EMDR, namely treatment effectiveness expectations, within a laboratory model of EMDR therapy.

METHODS

In a lab-based (N = 96) and an online experiment (N = 173), we gave participants verbal instructions to manipulate their treatment expectations. Instructions emphasized EMDR's effectiveness or ineffectiveness. Then, participants were asked to recollect an unpleasant autobiographical memory with or without making eye-movements.

RESULTS

In line with previous studies, we found significant reductions of reported vividness and emotionality of negative autobiographical memories in the eye-movements condition. These reductions did not differ between the verbal suggestions conditions in both experiments, suggesting a limited effect of treatment effectiveness suggestions.

LIMITATIONS

Treatment effectiveness expectations were not successfully manipulated by the suggestions manipulation. This suggests that treatment expectations may be more difficult to influence than anticipated, thus limiting the interpretation of our findings.

CONCLUSIONS

These findings tentatively corroborate the results of two earlier reports, suggesting that the effects of verbal suggestions about treatment effectiveness in a laboratory model of EMDR therapy may be limited.

Threat memory devaluation by a dual-task intervention: Testing return of fear and intrusive memory over 48 hours

BACKGROUND AND OBJECTIVES

In dual-tasking, individuals recall a threat-related memory while performing a demanding dual-task. This is a fruitful approach to reduce the unpleasantness and vividness of aversive memories and to reduce conditioned fear responses. Crucially, it remains unclear whether dual-tasking can also reduce conditioned fear responses and intrusive memories over time. In this pre-registered two-day fear conditioning paradigm, we examined whether a dual-task intervention reduces return of fear and the frequency of intrusive memories of an aversive film over time.

METHODS

On Day 1, 76 healthy participants underwent fear acquisition with aversive film clips. They were then randomly allocated to one of three conditions: dual-tasking, memory recall without a dual-task ('recall only'), or no task. Afterwards, they underwent an extinction phase and were asked to record intrusive film memories over 48 h. On Day 3, return of fear was assessed.

RESULTS

On Day 1, fear acquisition and extinction were successful. On Day 3, spontaneous recovery and renewal were evident, but, overall, participants reported few intrusions. The dual-task and recall only groups reported reduced unpleasantness of threat memory compared to the no task group, but they did not show reduced (return of) fear responses or fewer intrusions.

LIMITATIONS

Intrusion frequency was low in all three groups, which limits the detection of intervention effects.

CONCLUSIONS

Even though dual-tasking and recall only devalued threat memory temporarily compared to no task, these interventions did not reduce (return of) fear responses and intrusions. Future studies could focus on improving the potency of imagery-based interventions.

Does an unconditioned stimulus memory devaluation procedure decrease disgust memories and conditioned disgust? Results of two laboratory studies

Research has demonstrated that disgust can be installed through classical conditioning by pairing neutral conditioned stimuli (CSs) with disgusting unconditioned stimuli (USs). Disgust has been argued to play an important role in maintaining fear-related disorders. This maintaining role may be explained by conditioned disgust being less sensitive to extinction (i.e., experiencing the CS in the absence of the US). Promising alternatives to extinction training are procedures that focus on the devaluation of US memory representations. In the current study, we investigated whether such devaluation procedures can be successful to counter conditioned disgust. We conducted two laboratory studies (N = 120 and N = 51) in which disgust was conditioned using audio-visual USs. Memory representations of the USs were devalued by having participants recall these USs while they performed a taxing eye-movement task or executed one of several control tasks. The results showed successful conditioned disgust acquisition. However, no strong evidence was obtained that an US memory devaluation procedure modulates disgust memory and diminishes conditioned disgust as indicated by subjective, behavioral, or psychophysiological measures. We discuss the relevance of our results for methodological improvements regarding US memory devaluation procedures and disgust conditioning.

Does valence contribute to the effects of dual tasking in aversive autobiographical memory? Some unexpected findings

BACKGROUND AND OBJECTIVES

Lab experiments show that engaging in a working memory task while recalling an aversive memory reduces emotionality and vividness of memories. Studies targeting lab induced negative memory with valenced secondary tasks show promise, but work is needed on autobiographical memories to make it more in line with the original dual tasking research and PTSD treatment in clinical populations. In this study, we address this gap by evaluating differential effectiveness of valenced dual tasks on emotionality and vividness of aversive autobiographical memories.

METHODS

University students (N = 178) recalled an aversive autobiographical memory while rating either positive pictures, negative pictures, or while looking at a cross in the exposure only condition. Participants were randomized to one of three aforementioned conditions and rated their memories before and after each intervention on emotionality and vividness.

RESULTS

Against expectations, memories became more emotional and vivid regardless of condition. With regard to vividness, this effect was characterized by an interaction effect: memories became more vivid in the exposure only condition than in the combined dual tasking conditions. All effect sizes were small.

LIMITATIONS

Working memory load in the dual tasking conditions might have been insufficient.

CONCLUSIONS

The current study did not extend findings with regard to (valenced) dual tasking and revealed a possible sensitization effect of script driven autobiographical memory induction. Our study highlights the importance of aspects such as the total amount of exposure and characteristics of memory induction, specifically the addition of a script driven approach to the usual self-initiated memory activation in dual tasking research.

Taxing working memory to modulate mental imagery of the 9/11 terrorist attacks following media exposure during childhood: a pilot study in young adult UK residents

BACKGROUND AND OBJECTIVES

Media trauma in civilians is linked to intrusive imagery-based memory symptoms. We investigated whether mental imagery of the 9/11 terrorist attacks following media exposure is dampened by taxing working memory (WM).

METHODS

Forty-five young adult UK residents, who were exposed to the 9/11 terrorist attacks as children via the media, identified a personally-relevant mental image of the attacks. They were then randomly allocated to: (1) recall + Tetris, (2) recall + eye movements (EMs), or (3) recall-only. Ratings on imagery vividness and emotionality were provided at three time points: pre-, post-manipulations, and at 24-hr follow-up.

RESULTS

Repeated measures ANOVAs revealed that recall + Tetris and recall + EMs (relative to recall-only) significantly reduced imagery vividness and emotionality from pre- to post-manipulations, but not to follow-up.

LIMITATIONS

A passive control group is needed to fully rule out the role of natural memory decay; the follow-up was exploratory and took place outside the laboratory with reduced experimental control.

CONCLUSIONS

Aversive memory imagery from media trauma in civilians can be dampened by taxing WM, at least temporarily, which could be therapeutically useful. The use of such cognitive techniques may also hold relevance for public health approaches to address the impact of collective trauma.

No evidence for the inverted U-Curve: More demanding dual tasks cause stronger aversive memory degradation

BACKGROUND AND OBJECTIVES

Simultaneously making eye movements and recalling a memory leads to competition in working memory (WM), which reduces memory vividness and emotionality. The dose-response relationship between WM taxation and aversive memory degradation is predicted to be either linear (i.e., more cognitively demanding tasks exhibit stronger effects) or follow an inverted U-curve (i.e., there should not be too little, but also not too much taxation).

METHODS

Participants (N = 44) recalled four aversive autobiographical memories under four conditions that differed in WM taxation: complex, intermediate, simple, or no counting. Before and after each intervention, and at 24 h follow-up, participants recalled the aversive memory and rated it on vividness and unpleasantness. Using a Bayesian approach the linear and inverted U-shape relationships were directly compared.

RESULTS

Pretest to posttest drops in vividness and unpleasantness became larger with increased WM taxation of the counting conditions. There was no support for either hypotheses from pretest to follow-up for memory unpleasantness, whereas for memory vividness anecdotal evidence was found for a linear relationship.

LIMITATIONS

A reaction time (RT) task was used to select counting tasks of varying difficulties. However, the validity of this task appears to be compromised under very strenuous conditions. Higher levels of WM taxation might have been possible with more difficult counting tasks.

CONCLUSIONS

There is strong evidence for a linear dose-response relationship between WM taxation and memory degradation immediately after the intervention, and some unconvincing evidence for this pattern one day later. There was no evidence for an inverted U-curve.