Eye movement during recall reduces objective memory performance: An extended replication

The effectiveness of two novel approaches to prevent intrusions: A pilot study comparing Tetris_dualtask and imagery rescripting to control

BACKGROUND AND OBJECTIVES

Post-traumatic stress disorder (PTSD) is a global health problem. Although effective treatments for it exist, early interventions that prevent PTSD from developing are lacking. The aim of this pilot analogue trauma study was to compare the effects of two potential early intervention strategies, namely Tetris_dualtask and imagery rescripting (IR) to a no-intervention control group on intrusion frequency and the vividness and emotionality of aversive film memory.

METHODS

Sixty healthy students were subjected to the trauma film paradigm and randomly allocated to either: Tetris_dualtask, IR or no-intervention. Main outcomes were the number of film-related intrusions at one week and vividness and emotionality ratings of the most aversive film memory. Secondary outcomes were PTSD-like symptoms, intrusion intensity, and explicit film memory.

RESULTS

The Tetris_dualtask group reported significant fewer intrusions compared to the no-intervention group; whereas the IR group did not. No effect was found on vividness and emotionality ratings, PTSD-like symptoms, intrusion intensity, and explicit memory.

LIMITATIONS

The sample size was small, and analogue trauma in healthy individuals was examined, thus generalizability may be limited. Also, to increase comparability between interventions, the duration of Tetris_dualtask and IR was standardized. As a result, the IR intervention was shorter compared to other studies, which might have decreased its efficacy.

CONCLUSIONS

The results of this pilot study suggest that playing Tetris during retrieval of traumatic images, might hold potential as an early intervention strategy to reduce intrusions in the early aftermath of trauma and adversity. However, future large-scale replication research is needed.

Mental threat rehearsal increases fear generalization

BACKGROUND AND OBJECTIVES

Fear generalization to harmless stimuli characterizes anxiety-related disorders, but much remains unknown about its determinants. Based on studies showing that mental imagery of threat can increase conditioned fear responding, we tested whether it also facilitates fear generalization, and whether threat inflation moderates this effect.

METHODS

In a fear conditioning study, 120 participants first completed an acquisition phase, in which one of two pictures was followed by an aversive sound (human scream). Then, the sound was presented 11 times at an increasing (threat inflation) or constant volume (no threat inflation). Finally, a generalization stimulus was presented, and some participants were asked to imagine the last sound (threat rehearsal) and others were not (no threat rehearsal).

RESULTS

Bayesian informative hypotheses tests indicated that imagery-based threat rehearsal increased generalization of threat expectancy, and, combined with threat inflation, it also resulted in stronger generalized distress.

LIMITATIONS

due to the absence of a test phase, it is unclear whether our effects would transfer to other GSs and whether they would persist beyond the manipulation phase.

CONCLUSIONS

Mental imagery of threat may put individuals at risk for fear generalization. Future studies should examine whether modulating imagery may prevent clinical anxiety.

On the Effect of Bilateral Eye Movements on Memory Retrieval in Ageing and Dementia

It has been reported that performing bilateral eye movements for a short period can lead to an enhancement of memory retrieval and recall (termed the “saccade induced retrieval effect (SIRE)”). The source of this effect has been debated within the literature and the phenomenon has come under scrutiny as the robustness of the effect has recently been questioned. To date investigations of SIRE have largely been restricted to younger adult populations. Here, across two experiments, we assess the robustness and generalisability of the SIRE specifically in relation to disease and ageing. Experiment 1 employed a between subject’s design and presented younger and older participants with 36 words prior to completing one of three eye movement conditions (bilateral, antisaccade or a fixation eye movement). Participants then performed a word recognition task. Experiment 2 assessed the SIRE in individuals diagnosed with Alzheimer’s, Mild cognitive impairment and Parkinson’s by employing an online within subject’s design. Results showed no significant difference between groups in the number of words recognised based on eye movement condition. Neither experiment 1 or 2 replicated the SIRE effect therefore the findings from this study add to the growing number of studies that have failed to replicate the SIRE effect.

The effectiveness of dual-task interventions for modulating emotional memories in the laboratory: A meta-analysis

Dual-tasks (e.g., making horizontal eye-movements) while recollecting a memory are often used both in the lab and the clinic (such as in EMDR therapy) to attenuate emotional memories and intrusive mental images. According to working memory theory, dual-task interventions are effective because they limit cognitive resources available for the processing of emotional memories. However, there is still ongoing debate about the extent to which and under what conditions dual-task interventions are effective to interfere with emotional memories. In this meta-analysis, we assessed k = 53 laboratory studies investigating the effects of dual-task interventions on negative and positive memories. The effects were measured with the raw mean reduction in vividness and emotionality self-report ratings of emotional memories before compared to after the intervention on 100-point rating scales. Results showed that the dual-task interventions made both negative and positive memories less vivid (mean reduction negative images = 9.18, 95% CI [7.06, 11.29]; mean reduction positive images = 11.73, 95% CI [8.59, 14.86]) and less emotional (mean reduction negative images = 6.22, 95% CI [4.50, 7.94]; mean reduction positive images = 6.71, 95% CI [2.21, 11.20]). Several moderators were tested and are discussed in the light of working memory theory.

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.

Side effects of induced lateral eye movements during aversive ideation

BACKGROUND AND OBJECTIVES

Eye Movement Desensitization and Reprocessing (EMDR) is a treatment for posttraumatic stress disorder. It uses a dual-task approach, in which patients recall an aversive memory while making lateral eye movements. Research has shown that this 'eye movements' intervention reduces subjective memory vividness and emotionality. This study examined whether it also reduces memory accuracy on a visual discrimination task.

METHODS

Participants (68 undergraduates) underwent an aversive conditioning phase, in which two pictures of male faces were followed by shock. Then they recalled one face with (experimental condition) and one without (control condition) making lateral eye movements. Finally, they completed a stimulus discrimination test with slightly different faces shortly after the intervention and one day later.

RESULTS

Results showed that the eye movements intervention led to increased false-positive rates one day later.

LIMITATIONS

Our intervention targeted newly formed memory rather than consolidated memory.

CONCLUSIONS

The results inform theory about EMDR's mechanisms of change and suggest that the treatment may have side effects regarding memory accuracy.

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

BACKGROUND AND OBJECTIVES

A plethora of eye movement desensitization and reprocessing (EMDR) analogue studies has shown that, in the short term, making eye movements (EM) during brief imaginal exposure ("recall + EM") blurs memories more than just imaginal exposure ("recall only"). Yet, results of the few studies that included a follow-up test are inconsistent. We improved this paradigm's ecological validity by including an extended intervention phase and multiple assessments per phase. We hypothesized that recall + EM results in larger immediate and 24 h reductions in memory vividness, negative valence, and distress than recall alone. We explored the persistence of the effects, as well as the predictive value of memory characteristics and individual differences.

METHODS

Students (N = 100) selected a negative autobiographical memory and were randomized to recall + EM or recall alone; both interventions lasted 32 intervals of 24s. During the interventions they rated the memory after every four intervals.

RESULTS

After 4 × 24s intervention, recall + EM resulted in memory deflation, while recall only caused memory inflation. After the full intervention (i.e., 32 × 24s), both conditions resulted in immediate and 24 h reductions on all outcome measures. Crucially, memory effects in the recall + EM condition partially relapsed 24 h later, while the effects in the recall only condition persisted. Change patterns were hardly explained by predictive variables.

LIMITATIONS

We used a non-clinical sample; replication in clinical samples is warranted.

CONCLUSION

Making EM during imaginal exposure leads to short-lived effects compared to imaginal exposure alone. However, EM may offer a response aid for those who avoid imaginal exposure.

Increases of correct memories and spontaneous false memories due to eye movements when memories are retrieved after a time delay

Eye Movement Desensitization and Reprocessing (EMDR) is an effective treatment for post-traumatic stress disorder. However, literature on possible adverse memory effects of EMDR is scarce. Using the Deese/Roediger-McDermott (DRM) false memory paradigm, we examined the susceptibility to spontaneous false memories after performing eye movements, as used in EMDR. In Experiment 1, 72 undergraduates received word lists containing negative and neutral associated words and immediately after this they were given a free recall and recognition test. In Experiment 2, 68 undergraduates underwent the free recall and recognition test 48 h later. During the free recall phase in both experiments, participants either performed eye movements or not (control condition). In Experiment 1, the two conditions did not differ statistically with regard to correct and false recall/recognition. In Experiment 2, correct memory rates were higher in the eye movement than in the control condition and this was accompanied by an increase in spontaneous false memories on both free recall and recognition. Although our experimental approach is far removed from clinical practice, our findings suggest that eye movements as used in EMDR might amplify both correct and false memory rates.

Intrusive memories and voluntary memory of a trauma film: Differential effects of a cognitive interference task after encoding

Methods to reduce intrusive memories (e.g., of traumatic events) should ideally spare voluntary memory for the same event (e.g., to report on the event in court). Single-trace memory accounts assume that interfering with a trace should impact both its involuntary and voluntary expressions, whereas separate-trace accounts assume these two can dissociate, allowing for selective interference. This possibility was investigated in 3 experiments. Nonclinical participants viewed a trauma film followed by an interference task (Tetris game-play after reminder cues). Next, memory for the film was assessed with various measures. The interference task reduced the number of intrusive memories (diary-based, Experiments 1 and 2), but spared performance on well-matched measures of voluntary retrieval-free recall (Experiment 1) and recognition (Experiments 1 and 2)-challenging single-trace accounts. The interference task did not affect other measures of involuntary retrieval-perceptual priming (Experiment 1) or attentional bias (Experiment 2). However, the interference task did reduce the number of intrusive memories in a laboratory-based vigilance-intrusion task (Experiments 2 and 3), irrespective of concurrent working memory load during intrusion retrieval (Experiment 3). Collectively, results reveal a robust dissociation between intrusive and voluntary memories, having ruled out key methodological differences between how these two memory expressions are assessed, namely cue overlap (Experiment 1), attentional capture (Experiment 2), and retrieval load (Experiment 3). We argue that the inability of these retrieval factors to explain the selective interference is more compatible with separate-trace than single-trace accounts. Further theoretical developments are needed to account for this clinically important distinction between intrusive memories and their voluntary counterpart. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Modeling Hierarchical Versus Random Exposure Schedules in Pavlovian Fear Extinction: No Evidence for Differential Fear Outcomes

In exposure therapy, the client can either be confronted with the fear-eliciting situations in a hierarchical way or in a random way. In the current study we developed a procedure to investigate the effects of hierarchical versus random exposure on long-term fear responding in the laboratory. Using a fear conditioning procedure, one stimulus (CS+) was paired with an electric shock (US), whereas another stimulus was not paired with the shock (CS-). The next day, participants underwent extinction training including presentations of the CS-, CS+ and a series of morphed stimuli between the CS- and CS+. In the hierarchical extinction condition (HE; N = 32), participants were first presented with the CS-, subsequently with the morph most similar to the CS-, then with the morph most similar to that one, and so forth, until reaching the CS+. In the random extinction condition (RE; N = 32), the same stimuli were presented but in a random order. Fear responding to the CS+, CS- and a new generalization stimulus (GS) was measured on the third day. Higher expectancy violation, t(62) = -2.67, p = .01, physiological arousal, t(62) = -2.08, p = .04, and variability in US-expectancy ratings, t(62) = -2.25, p = .03, were observed in the RE condition compared to the HE condition, suggesting the validity of this novel procedure. However, no differences between the RE and HE condition were found in fear responding as tested one day later, F(1, 62) < 1. In conclusion, we did not find evidence for differential long-term fear responding in modeling hierarchical versus random exposure in Pavlovian fear extinction.

The effects of dual-tasks on intrusive memories following analogue trauma

Patients with post-traumatic stress disorder frequently and involuntarily experience intrusions, which are strongly linked to the trauma hotspot. Voluntary memory characteristics (i.e., vividness and unpleasantness) of this hotspot can be reduced by performing a dual-task, such as making horizontal eye movements, which is frequently used in Eye Movement Desensitization and Reprocessing. We tested whether such dual-task interventions would also reduce involuntary memory (i.e., intrusions). Moreover, we examined if changes in hotspot vividness and unpleasantness predicted intrusion frequency. Additionally, we examined whether the effects were dependent on dual-task modality. We tested this in three experiments. Participants watched a trauma film and performed one of the interventions 10-min post-film (1) Recall + Eye movements, (2) Recall + Counting, or (3) No-Task Control. Before and after the intervention, participants rated the hotspot vividness and unpleasantness. They recorded intrusive memories about the film in a diary for a week. Unexpectedly, we found that hotspot vividness and unpleasantness ratings were not affected by the intervention. However, the prolonged (experiment 2), but not standard (experiment 1), dual-task interventions resulted in a lower number of intrusions, regardless of modality. However, this effect was not replicated in experiment 3. We discuss potential explanations and present suggestions for future research.

Dual-tasking during recall of negative memories or during visual perception of images: Effects on vividness and emotionality

BACKGROUND AND OBJECTIVES

Several treatments are effective in reducing symptoms of post-traumatic stress disorder. We tested the effectiveness of an experimental intervention that consists of elements from two of these: virtual reality (VR) exposure therapy and eye movement desensitization and reprocessing. The latter is characterized by a dual-task approach: the patient holds a traumatic memory in mind while simultaneously making voluntary eye movements, resulting in reduced vividness and emotionality of the traumatic memory. If the experimental intervention is effective, it could provide a useful approach for highly avoidant individuals.

METHODS

Participants recalled negative memories induced by a VR paradigm. The experimental group viewed VR screenshots that represented these negative memories while carrying out a dual-task. One control group recalled negative memories while carrying out the same dual-task (a standard dual-task condition) and another merely viewed the VR screenshots. Pre-to-post changes in self-rated memory vividness/emotionality were measured.

RESULTS

The results indicate that viewing a screenshot only was outperformed by both dual-task interventions in terms of reductions in vividness/emotionality. Furthermore, the dual-task interventions had a comparable impact on vividness, but the screenshot variant led to greater decreases in emotionality.

LIMITATIONS

Changes in memory vividness/emotionality were only assessed shortly after the interventions and no measures of avoidance behavior were included in the study.

CONCLUSIONS

Looking at an image in VR that represents a memory while carrying out a dual-task may be at least as effective as recalling the memory during the dual-task. Interestingly, visually supporting a negative memory does not seem to prevent memory degrading by dual-tasking.

Retrieving and Modifying Traumatic Memories: Recent Research Relevant to Three Controversies

The purpose of this article is to review recent research that is relevant to three controversies concerning memory for trauma. First, we briefly review the debate about recovered memories of childhood sexual abuse, summarizing a third interpretation distinct from both the repression and false-memory accounts. Second, we address new findings related to claims that memories of trauma, especially in people with posttraumatic stress disorder, are especially fragmented and disorganized. Third, we discuss research designed to test whether eye movements in eye-movement desensitization and reprocessing therapy are effective.

Generalisation of threat expectancy increases with time

Excessive fear generalisation is a feature characteristic of clinical anxiety and has been linked to its aetiology. Previous animal studies have shown that the mere passage of time increases fear generalisation and that brief exposure to training cues prior to long-term testing reverses this effect. The current study examined these phenomena in humans. Healthy participants learned the relationship between the presentation of a picture of a neutral male face and the delivery of a mild shock. One group was immediately tested with a novel picture of a somewhat different male face (generalisation test). Another group was tested one week later. A third group was also tested one week later and was additionally exposed to the training picture prior to testing. During picture presentations, shock-expectancy ratings were obtained as a measure of fear. Fear generalisation increased from the immediate test to the 1-week follow-up test. This result could not be attributed to level of neuroticism or a general increase in fear (incubation). Furthermore, the time-dependent increase in fear generalisation vanished following brief exposure to the training picture. Results indicate that human fear generalisation is a temporally dynamic process and that memory for stimulus details can be re-established following a reminder treatment.

How Does Eye Movement Desensitization and Reprocessing Therapy Work? A Systematic Review on Suggested Mechanisms of Action

Background: Eye movement desensitization and reprocessing [EMDR] is an innovative, evidence-based and effective psychotherapy for post-traumatic stress disorder [PTSD]. As with other psychotherapies, the effectiveness of EMDR contrasts with a limited knowledge of its underlying mechanism of action. In its relatively short life as a therapeutic option, EMDR has not been without controversy, in particular regarding the role of the bilateral stimulation as an active component of the therapy. The high prevalence of EMDR in clinical practice and the dramatic increase in EMDR research in recent years, with more than 26 randomized controlled trials published to date, highlight the need for a better understanding of its mechanism of action.

Methods: We conducted a thorough systematic search of studies published until January 2018, using PubMed, ScienceDirect, Web of Knowledge and Scopus databases that examined the mechanism of action of EMDR or provided conclusions within the framework of current theoretical models of EMDR functioning.

Results: Eighty-seven studies were selected for review and classified into three overarching models; (i) psychological models (ii) psychophysiological models and (iii) neurobiological models. The evidence available from each study was analyzed and discussed. Results demonstrated a reasonable empirical support for the working memory hypothesis and for the physiological changes associated with successful EMDR therapy. Recently, more sophisticated structural and functional neuroimaging studies using high resolution structural and temporal techniques are starting to provide preliminary evidence into the neuronal correlates before, during and after EMDR therapy.

Discussion: Despite the increasing number of studies that published in recent years, the research into the mechanisms underlying EMDR therapy is still in its infancy. Studies in well-defined clinical and non-clinical populations, larger sample sizes and tighter methodological control are further needed in order to establish firm conclusions.

The effect of bilateral eye-movements versus no eye-movements on sexual fantasies

BACKGROUND AND OBJECTIVES

Bilateral eye-movements (EMs) and visual mental imagery both require working memory resources. When performed together, they compete for these resources, which can cause various forms of mental imagery to become impaired (e.g., less vivid). This study aimed to examine whether EMs impair sexual fantasies (a form of mental imagery) in the same manner.

METHODS

Eighty undergraduates (40 males, 40 females) took part in four counterbalanced conditions: (1) EMs and an experience-based sexual fantasy; (2) EMs and an imagination-based sexual fantasy; (3) experience-based sexual fantasy only; and (4) imagination-based sexual fantasy only. In each condition, the vividness, emotionality, and arousability of the sexual fantasy were rated pre- and post-task. All three variables were predicted to decrease in the EM conditions.

RESULTS

Sexual fantasies were reported as less vivid, positive, and arousing after performing concurrent EMs relative to fantasising only, for both memory- and imagination-based sexual fantasies. There were no gender differences. Demand did not appear to account for the effects.

LIMITATIONS

Self-report measures were used rather than objective measures. Working memory taxation and capacity were not directly assessed. Also, negatively appraised sexual fantasies were not targeted and a 'no intervention' control was not included.

CONCLUSIONS

Bilateral EMs were effective at impairing the phenomenological properties of sexual mental imagery, extending the literature on EM effects. Given the potential clinical implications, future research should focus on validating and extending these results, for example, by targeting negatively appraised sexual fantasies (including problematic and offense-related) and incorporating a 'no intervention' condition.