One explanation for trauma-related autobiographical memory problems is that they reflect more general cognitive deficits caused by intrusive thoughts about traumatic experiences. Adults with histories of childhood trauma such as sexual or physical abuse frequently report having recurrent and intrusive negative thoughts about their victimization experiences (e.g., Kuyken & Brewin, 1994). Individuals who experience intrusive thoughts characterize them as unpleasant and report engaging in effortful attempts to avoid them (Kuyken & Brewin, 1994). Concerted efforts to block intrusive thoughts, however, are typically unsuccessful and often lead to even more frequent intrusions (Kuyken & Brewin, 1994, 1995; Wegner, Schneider, Carter, & White, 1987). Kukyen and Brewin (1995) have argued that this combination of intrusive memories and efforts to avoid them drains limited storage and processing resources in working memory. The depletion of cognitive resources, in turn, is thought to increase the likelihood that the autobiographical memory retrieval process will be interrupted before a specific episode or episodic details are accessed (Williams, Chan, Crane, & Barnhofer, 2006). In other words, specific memories may have been encoded and stored, but resource-demanding intrusive thoughts impair the ability to retrieve them.
Consistent with this argument, frequent intrusive thoughts seem to be associated with poor autobiographical memory specificity. For instance, post-traumatic stress disorder (PTSD), which is characterized by intrusive memories of negative events, is related to problems retrieving specific personal memories (McNally, Lasko, Macklin, & Pitman, 1995). Moreover, several studies using the Impact of Events Scale (IES) to measure the frequency of intrusive thoughts (as measured by the IES intrusion subscale) and conscious attempts to avoid trauma-related memories (as measured by the IES avoidance subscale) have illustrated direct associations between measures of intrusive thoughts and overgeneral memory on the AMT. In their study of adult psychiatric patients who were exposed to war atrocities as children, Wessel, Merckelbach, and Dekkers (2002) found that higher intrusion and avoidance scores on the IES were associated with more overgeneral memories. Similarly, research with depressed adults illustrated that overgeneral memory is predicted by high levels of intrusion (Brewin, Reynolds, & Tata, 1999) and avoidance (Kuyken & Brewin, 1995) as measured by the IES. Finally, Park, Goodyer, and Teasdale (2004) found that an experimental induction of rumination about negative thoughts in depressed adolescents leads to an increase in overgeneral memories.
These findings notwithstanding, the support for the cognitive deficit explanation for trauma-related autobiographical memory disturbances is not overwhelming. To date, very few studies have actually examined working memory or broader cognitive functioning to determine whether poor autobiographical memory specificity in trauma victims can be explained by a depletion of cognitive resources. The investigations that have included such measures suggest that cognitive resources do not account for the particular autobiographical memory deficits linked to trauma and depression (de Decker et al., 2003; Raes et al., 2006; Wessel, Merckelbach, & Dekkers, 2002). For instance, Wessel et al. (2002) found that performance on a general neuropsychological memory test failed to predict rates of overgeneral memory among adults with childhood exposure to war-related trauma. Similarly, de Decker et al. (2003) reported that neither a measure of working memory nor a test of non-autobiographical episodic memory, as measured by immediate and delayed story recall, accounted for the links between adolescent inpatients' trauma exposure and their performance on the AMT. Thus, although intrusive memories and avoidance of such memories may well be associated with poor memory specificity, it does not appear that the underlying mechanism for overgeneral memory in abused persons is a deficiency in cognitive resources.
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