The impact of trauma exposure on explicit and implicit memory

ABSTRACT

Objectives: The present study aimed to determine whether explicit and implicit memory systems are modulated by the type of content (neutral, emotional trauma-related and generally-emotional) in sexual abuse victims who did not develop PTSD, compared to non-exposed controls.

Design: A mixed-factorial design with Content (neutral, trauma-related, generally-emotional) as a within-subject variable and Group (victims, controls) as a between-subject variable was used in two experiments.

Methods: In both experiments, participants were required to learn three stories presented orally: a neutral, an emotional trauma-related (sexual abuse) and a generally-emotional story. In Experiment 1, participants’ memory was tested with two explicit tasks (free recall and Remember/Know/Guess) and one implicit task (word-fragment completion task). In Experiment 2, a modified version of the word-fragment completion task was presented, followed by an awareness questionnaire to ensure the implicit character of the test.

Results: Victims showed lower performances with neutral contents, relative to controls, in explicit and implicit tasks. However, this difference was not observed with trauma-related contents suggesting this information is preferentially processed by trauma-exposed participants (with increased attentional resources).

Conclusions: Our results show that trauma exposure may itself be associated with implicit and explicit memory alterations, even for individuals who did not develop PTSD.

KEYWORDS:

• Trauma
• sexual abuse
• explicit memory
• implicit memory
• women

Acknowledgements

We thank three anonymous reviewers for their positive and constructive comments.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

1 We specified potentially because the perception of a harrowing situation is subjective. The same event may be traumatic for an individual and not for another. In the rest of this paper, we did not mention the term potentially when we referred to a potentially traumatic situation to lighten the text, but its use was implied.

2 Brewin et al. (2007) did not compare non-trauma-exposed groups with trauma-exposed groups without PTSD.

3 We later labeled RKG recognition paradigm to specify that the main task is recognition.

4 Authors specified that “the negative words were not selected as being specifically trauma-relevant, although some could be.”

5 The objective of this manipulation was to observe whether differences between groups varied as a function of time. Tapia, Clarys, El-Hage, et al. (2007) suggested that explicit memory alterations for neutral material in PTSD patients could ensue from impairment information retention. We supposed that differences between victims and controls for neutral contents could have been accentuated with time whereas the group effect could have stagnated or evolved in a reverse direction for trauma-related contents. However, no interaction or main effects of time was observed (in explicit and implicit memory), so we will not discuss time effects further. We presented averaged data of the two test periods for each dependent variable.

6 When participants implicated in at least one moderate car accident were excluded from the analyses in free recall, the partial interaction between the content (neutral, generally-emotional) and the group was not significant, F(1, 30) = 1.83, p = .186, suggesting that the attentional bias in victims was specific to the trauma-related contents.

Additional information

Funding

This research was supported by the Fonds de Recherche du Québec – Santé, with a Chercheur Boursier fellowship awarded to Isabelle Blanchette.