Ines Blix

The overarching goal in the present project was to investigate memory processes in trauma-exposed individuals. In three studies, processes of remembering and forgetting were examined in trauma-exposed individuals who had experienced sexual abuse and non trauma-exposed controls.

Trauma-exposed individuals experience some degree of repetitive thoughts and intrusive memories. Deficits in intentional forgetting and retrieval-induced forgetting, both thought to be underpinned by inhibition mechanisms, have been proposed to be a cause of intrusive memories in the aftermath of trauma. The studies reported in paper I and II employed a variant of Retrieval Induced Forgetting task (RIF) and the Directed Forgetting task (DF) to investigate the relationship between trauma and forgetting mechanisms. By including trauma-specific cue words, in addition to neutral, positive and threat-related cue words, it was possible to test for trauma-specific effects. 

The results reported in paper I showed no differences in RIF between trauma-exposed participants and controls. However, we found a general tendency for eradicated RIF for emotional material. The finding that RIF does not work for emotional material might have different consequences for non trauma-exposed individuals as opposed to trauma-exposed individuals. For non trauma-exposed healthy individuals this tendency might be relatively harmless and perhaps be reflected in rumination over previous negative or positive experiences. In the aftermath of trauma, however, the very same tendency might have a more negative impact, because memories that repeatedly intrude into consciousness are experienced as very disturbing.

Uncomfortable intrusive memories from a traumatic experience might lead trauma victims to avoid such memories through intentional forgetting. Paradoxically, attempting to intentionally forget can have the effect that unwanted thoughts rebound with even greater persistence (Wegner, 1989). The findings in paper II showed that there was no difference between trauma-exposed and non trauma-exposed participants in correct recall of to-be-forgotten words of any valence, suggesting that the trauma-exposed participants were neither better nor worse than their non trauma-exposed peers in intentional forgetting.

In sum, the findings in paper I and II did not support a hypothesis of impaired inhibition mechanisms in trauma-exposed individuals. However, the results reported in paper II did show that trauma-exposed individuals had a higher level of “Intrusive“ recall of to-be-forgotten trauma words when asked to recall to-be-remembered words. Moreover, this tendency was related to symptoms of intrusion reported on the IES. This might suggest problems in source monitoring of trauma-related material in trauma-exposed individuals.

Paper III investigated the relationship between trauma exposure and specificity and temporal distribution of autobiographical memories and future directed thoughts. A relationship between trauma symptoms and reduced specificity of autobiographical memories was found, but no such relationship was found for future-directed thoughts. The results reported in paper III suggest that trauma symptoms only influence the specificity of mental time travel to the past, and not to the future. No difference in temporal distribution of future directed thoughts or autobiographical memories between trauma-exposed participants and controls was found.

In summary, this thesis contributes to the understanding of processes of remembering and forgetting in trauma-exposed individuals.

Publisert 15. nov. 2011 10:16