Although recent research has demonstrated that intrusive memories of negative autobiographical events are an overlapping cognitive feature of depression and PTSD, there is still a general paucity of research investigating the prevalence and maintenance of these memories in depression. Accordingly, the current thesis represented a much-needed program of empirically-driven research that delineated the cognitive processes that underpin the manifestation, experience, and persistence of intrusive memories in depression. Firstly, Study 1 used descriptive and correlational methodologies to outline the content and features of these memories, and explored whether intrusion characteristics linked to intrusive memories in PTSD are also features of intrusive memories in depression. In accord with studies in PTSD samples, sensory features accounted for unique variance in the prediction of depression severity, over and above that accounted for by intrusion frequency. This commonality raised the possibility that cognitive management strategies linked to the persistence of intrusive memories in PTSD may also play a role in depression. Accordingly, Study 2 utilized a cross-sectional and prospective design to investigate whether negative appraisals and cognitive avoidance strategies, which are key to the persistence of intrusive memories in PTSD, similarly play a role in depression. The results demonstrated that assigning negative appraisals to one???s intrusive memory, and attempts to control the memory, were positively associated with intrusion-related distress, level of depression, and cognitive avoidance mechanisms. Additionally, negative appraisals and the use of cognitive mechanisms were predictive of depression concurrently, but not prospectively. Studies 3, 4, and 5 further investigated avoidant intrusion- response strategies by assessing the role of recall vantage perspective in mediating the effects of intrusion-related distress. Study 3 found that although field memories were not experienced as more distressing than observer memories, the results supported an association between an observer vantage perspective and cognitive avoidance mechanisms. As this study employed a correlational design, Study 4 addressed the question of directionality by experimentally manipulating mode of recall to ascertain whether shifting participants into a converse perspective would have differential effects on the reported experience of their intrusive memory. Results indicated that shifting participants from a field to an observer perspective resulted in decreased experiential ratings; specifically, reduced distress and vividness and increased detachment and observation. Also, as anticipated, the converse shift in perspective (from observer to field) did not lead to a corresponding increase in experiential ratings, but resulted in reduced ratings of observation. Study 5 attempted to investigate the stability of this memory orientation phenomenon by investigating mode of recall vantage perspective prospectively. Attrition of participants across the 12-month study limited analyses to the descriptive level, but illustrated that, at least for some individuals, recall vantage perspective remained stable across assessments periods. Collectively, the findings supported the notion that recall perspective has a functional role in the regulation of intrusion-related distress and represents a cognitive avoidance mechanism. Studies 6 and 7 employed experimental methodologies to investigate whether adopting an abstract/analytical mode of processing following a negative event would result in poor emotional processing, or increased distress associated with intrusive memories. Study 6 found no differences in either intrusion frequency or associated levels of distress across the processing conditions, as hypothesized. The results of Study 6 suggested that the predicted effects of ruminative self-focus on intrusion severity may be dependent upon the self-referential nature of the material being processed. Results of Study 7 indicated that inducing an analytical ruminative mode of processing resulted in participants rating their naturally occurring, self-referential intrusive memories as more negative, more distressing, and evoking a more negative emotional response compared to inducing distraction. Taken together, Studies 6 and 7 suggest the possibility that depressed individuals may get caught up in a ruminative cycle that, due to the documented effects of analytical self-focus, may exacerbate the emotional response elicited by the intrusions and perpetuate biased attentional focus towards them. Finally, Studies 8 and 9 explored suppression as a cognitive avoidance mechanism and addressed some methodological concerns regarding the measurement of this construct. Study 8 investigated the effects of repeated suppression using a method to index the frequency, duration, and associated levels of distress of an experimentally-induced intrusive memory, and assessed whether any observed effects were differentially linked to depressive symptomatology. Results supported a secondary rebound effect in those participants who were most successful at suppressing target intrusions. Study 9 was an investigation of the English version of the TCAQ (Luciano, Algarabel, Tom??s, & Mart??nez, 2005), an index of cognitive control. Study 9 evaluated the association between this measure and performance on a thought suppression task. The results indicated that low TCAQ-20 scorers experienced intrusions of a longer duration and rated these intrusions as more distressing than high TCAQ-20 scorers, supporting the validity of the measure. These findings highlight the role of suppression as a maladaptive mental control strategy and the potential for elevated intrusion-distress to perpetuate its use. Together, the findings of this program of research confirm the importance of intrusive memories in depression, and underscore the need for an empirically-supported model to account for the occurrence and maintenance of these memories.
| Identifer | oai:union.ndltd.org:ADTP/205214 |
| Date | January 2008 |
| Creators | Williams, Alishia , Psychology, Faculty of Science, UNSW |
| Publisher | Awarded by:University of New South Wales. |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | Copyright Alishia Williams, http://unsworks.unsw.edu.au/copyright |
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