The role of belief in memory amplification for trauma events.

BACKGROUND AND OBJECTIVES: Trauma survivors often report trauma events inconsistently over time. Many studies, for example, have found that people report having experienced trauma events that they initially failed to report or remember, a phenomenon called "memory amplification." Other studies have found the opposite: people report experiencing fewer events over time. Nahleen, Nixon, and Takarangi (2019) asked participants at two time-points, with a six-month delay, whether they had experienced 19 sexual assault events on a yes/no scale. Participants reported fewer events over time, that is, memory for sexual assault did not amplify overall. In the current study, we assessed whether inconsistency in reports of trauma exposure over time may be attributed to changes in participants' belief that certain events were experienced. METHODS: We replicated Nahleen et al. (2019), but rather than respond to a yes/no trauma exposure scale, participants were required to rate the likelihood that each trauma event occurred on an 8-point scale (1 = definitely did not happen; 8 = definitely did happen). RESULTS: We found that participants believed that they were less likely to have experienced the sexual assault events at follow-up compared to initial assessment. LIMITATIONS: We could not corroborate trauma experiences or determine causality with our design. Further, not all of our findings were consistent with Nahleen et al. (2019). CONCLUSIONS: Sexual assault memories did not amplify over time, perhaps because, compared to other types of trauma, the idea of experiencing additional sexual assault events that were not actually experienced is less believable.

Does emotional or repeated misinformation increase memory distortion for a trauma analogue event?

In general, memory of highly negative and even traumatic events can distort. However, the effect of misinformation exposure on such memories requires further investigation given the inconsistent past findings. With two experiments, we investigated: (1) whether misinformation distorts memory for highly negative analogue events, (2) whether memory distortion is increased for more emotional and potentially traumatic details compared to unemotional details, and (3) whether repeated misinformation exposure further increases memory distortion for highly negative events compared to single exposure, a possibility that has not been investigated to our knowledge. In both experiments, participants viewed a trauma analogue film with some scenes removed. Twenty-four hours later, they were given three "eyewitness" reports describing the film's events. To manipulate misinformation repetition, either zero, one, or all three of the reports described removed scenes. To determine whether memory distortion is increased for emotional details, half of the removed scenes were more traumatic than the other half. Participants exposed to misinformation falsely remembered more removed scenes compared to participants who were not exposed to misinformation. Further, memory distortion was increased for emotional (vs. unemotional) aspects of the film. Repeated misinformation exposure, however, did not lead to significantly higher error rates compared to single exposure. The lack of perceptual overlap between our written misinformation and film test items may have limited false memories even with repeated misinformation. Alternatively, the repeated vs. single misinformation effect may exist but be very small, as suggested by our raw means and effect sizes.

Current PTSD symptomatology distorts memory for past symptoms.

Clinicians often rely on clients' retrospective reports of past symptoms to diagnose and treat Posttraumatic Stress Disorder (PTSD). However, there is limited research investigating memory for past PTSD symptoms. We asked sexual assault survivors to report their PTSD symptoms and then recall them 6 months later. Overall, symptom recall was consistent with initial reports. However, after dividing participants into PTSD-positive and negative groups, we found that people who were PTSD-negative at follow-up underestimated past PTSD symptom severity while people who were PTSD-positive overestimated past symptoms. For example, 2.8% of PTSD-negative participants versus 15.9% of PTSD-positive participants recalled experiencing 20+ more points on the PCL-5 at follow-up than at initial assessment. Further, people who adjusted over time greatly underestimated past symptoms unlike those who remained PTSD-positive. Our findings have important theoretical and clinical implications because they show that current symptom severity may influence the memory reconstruction of prior levels of adjustment.

When more is not merrier: shared stressful experiences amplify.

Sharing experiences with others, even without communication, can amplify those experiences. We investigated whether shared stressful experiences amplify. Participants completed the Cold Pressor Task at the same time as a confederate, or while the confederate completed another task. Importantly, participants in the shared (vs. unshared) condition experienced more sensory pain characteristics and reported more stress over time in relation to the task. Importantly, they reported thinking more about the confederate's thoughts and feelings. This mentalizing sometimes mediated effects, suggesting the task amplified when participants constructed mental representations of others' CPT experience (e.g. that it hurts) and incorporated it into their own responses.