The differential effects of trauma-focused interventions on voluntary and involuntary retrieval of distressing memories

Aleksic, Milena (2025): The differential effects of trauma-focused interventions on voluntary and involuntary retrieval of distressing memories: insights from analogue studies. Dissertation, LMU München: Fakultät für Psychologie und Pädagogik

Abstract

Post-Traumatic Stress Disorder (PTSD) is marked by recurrent, distressing memories of traumatic events. Trauma-focused psychological interventions aim to alleviate the distress caused by intrusive memories, but their objective is not to erase the traumatic memory entirely. For instance, a police officer might need to recall details of a past operation to improve future risk assessments, or a survivor of physical assault may require accurate memory recall to pursue legal action against their perpetrator. The effectiveness of trauma-focused interventions in alleviating intrusive memories is well-documented; however, their impact on voluntary memory remains poorly understood. Clinical theories propose that these interventions should selectively reduce intrusive memories, but preserve – or even enhance – the voluntary recall of event details, leading to more coherent and organized memory reports. In contrast, experts in legal psychology raise concerns that these interventions might unintentionally compromise the factual accuracy of voluntary memories. Interventions incorporating imagery-based techniques, such as Imaginal Exposure (IE), Eye Movement Desensitization and Reprocessing (EMDR), and Imagery Rescripting (ImRs), have been at the center of this debate. The primary aim of this thesis was to bridge these contrasting perspectives by systematically examining the effects of IE, EMDR and ImRs on both involuntary and voluntary retrieval of distressing memories across three analogue studies conducted with healthy participants. Study I and II assessed the effects of these interventions on experimentally induced memories, allowing for experimental control over memory content and assessment of memory accuracy. In Study I, a distressing memory was induced in N = 265 participants, using the Trier Social Stress Test (TSST). The following day, participants received IE, EMDR, ImRs, or no intervention (NIC). One week later, the accuracy of voluntary memory for the TSST was assessed using a cued recall task. Involuntary memories of the TSST were assessed via an app-based intrusion diary. Results indicated no group differences in memory accuracy, suggesting that none of the interventions impaired or enhanced memory accuracy compared to NIC. Regarding involuntary memory, none of the interventions significantly reduced intrusion frequency; however EMDR and IE reduced intrusion load (intrusion frequency weighted by distress). Although these findings are encouraging from a clinical perspective, they leave open the possibility that certain factors in the clinical application of these interventions might still increase the risk of memory distortions. Study II examined potential risk conditions under which ImRs might lead to memory distortions, focusing on whether instructions encouraging vivid and detailed imagination of changes to a memory increase this risk, and whether unclear or incomplete memories are particularly vulnerable. In a three-day online trauma film paradigm, a distressing memory was induced in N = 267 participants through an aversive film clip. To manipulate memory clarity and completeness, half of the participants viewed the original version of the film (with all sensory information clearly identifiable), while the other half viewed a version where visual and auditory blur filters obscured parts of the image and dialogue. The following day, participants were assigned to one of three conditions: ImRs with instructions to imagine and rescript the scene in as much sensory detail as possible; ImRs without such instructions; or a no-intervention control condition (NIC). On the third day, memory accuracy for the film clip was assessed using a cued recall task. Intrusive memories were assessed with a retrospective intrusion diary. Results showed no adverse effects of ImRs on memory accuracy. In fact, participants who received detailed sensory imagination instructions during ImRs exhibited greater memory accuracy compared to both those who did not receive these instructions and those in the control group, regardless of the initial clarity and completeness of the memory. No significant group differences were found in the frequency of intrusive memories. Building on these findings, Study III extended the investigation to autobiographical memories. A total of 182 participants provided a detailed verbal report of an aversive life event in a free recall task. They were then randomly assigned to one of four conditions: IE, EMDR, ImRs, or NIC. One week later, participants repeated the free recall task, and independent raters evaluated changes in memory consistency, disorganization, and coherence. Involuntary memory was assessed via an app-based intrusion diary the week before and after the intervention. Additionally, psychophysiological reactivity to intrusive memories was measured during an intrusion-sampling period in both experimental sessions. None of the interventions increased contradictions or omissions in memory reports compared to NIC, suggesting that they do not impair the ability to recall specific memory details or distort their content. IE, however, was associated with more additions to memory reports, though the accuracy of these added details remains unclear. Regarding memory disorganization and coherence, the findings were mixed. IE led to improvements in structural organization by reducing disorganized thoughts, while EMDR and ImRs enhanced contextual memory coherence, reflecting improved spatial and temporal orientation of the memory. In terms of involuntary memory, all interventions reduced intrusion load. However, only ImRs reduced the number of intrusive memories relative to NIC. No group differences were observed in psychophysiological responses to intrusions. In summary, this thesis makes an important contribution to the current literature by directly testing contrasting predictions regarding the memory effects of trauma-focused interventions. The findings challenge concerns that these interventions inherently risk distorting factual memory content, which has important implications for trauma survivors whose credibility might be questioned in legal contexts due to their treatment history. While the studies extend prior research by better modeling the complexity of memories typically addressed in clinical practice (Studies I and II) and examining autobiographical memories (Study III), their generalizability to traumatic memories and clinical populations remains limited. It is important to replicate the findings in these populations. Furthermore, the mixed results concerning intrusive memories and memory disorganization highlight the need to refine both experimental paradigms and theoretical frameworks to better account for the nuanced effects of trauma-focused interventions. Practical implications and directions for future research are discussed.

• Dokumententyp: Dissertationen (Dissertation, LMU München)
• Themengebiete: 100 Philosophie und Psychologie ; 100 Philosophie und Psychologie > 150 Psychologie
• Fakultäten: Fakultät für Psychologie und Pädagogik
• Sprache der Hochschulschrift: Englisch
• Datum der mündlichen Prüfung: 21. Mai 2025
• 1. Bericht­erstatter:in: Ehring, Thomas