The metacognitive model of OCD (Wells & Matthews, 1994; Wells, 1997, 2000), stresses the role of two types of metacognitive knowledge in the aetiology and maintenance of obsessive-compulsive symptoms: 1) beliefs concerning the meaning and power of thoughts and 2) beliefs about rituals. The first set of beliefs has been termed fusion beliefs and lead intrusions to be appraised as dangerous or important. The second domain, beliefs about rituals, guides the coping responses to these negative appraisals. It has two components: 1) declarative beliefs about the need to carry out rituals (e.g., "I need to perform my rituals otherwise I will never have peace of mind"), 2) a plan or program for monitoring and controlling action. Part of this plan is a goal which is indicated by a stop criterion or "stop signal." This thesis carried out a series of tests of hypotheses arising from the model, using studies with different populations and methodologies. Cross-sectional studies using different populations showed that, consistent with the model, metacognitive measures designed to assess thought-fusion, beliefs about rituals and stop signals were positively and significantly correlated with o-c symptom measures. A series of hierarchical regression analyses were also carried out, with the overlap between o-c symptoms and worry controlled. Results demonstrated that each metacognitive domain when entered in their hypothesised causal sequence explained incremental variance in obsessive-compulsive symptoms. Further analysis showed that metacognition remained a significant predictor when non-metacognitive beliefs (e.g., responsibility and perfectionism) which have been linked to OCD in other theories were controlled for. The hypothesised causal role of thought-fusion in o-c symptomology was examined in a prospective and an experimental study. The results showed that thoughtfusion was a significant positive prospective predictor of obsessive-compulsive symptoms independent of worry and non-metacognitive beliefs. Increasing thoughtfusion beliefs experimentally led to significant increases in OCD-like behaviours. These results are supportive of the hypothesised role of thought-fusion in the metacognitive model. The specificity of metacognitive beliefs was also assessed. Using a non-clinical population, the best independent metacognitive predictors of worry and obsessions were examined, with symptom overlap controlled. Different independent metacognitive predictors of worry and o-c symptoms emerged. Thought-fusion, beliefs about rituals and stop signals were independent predictors of obsessions but not worry, supporting their hypothesised specificity. Further support for specificity came from a study using a clinical population which showed that OCD patients had significantly higher scores than GAD patients on measures of thought-fusion and beliefs about rituals. The results provide further support for the metacognitive model. Theoretical and clinical implications are discussed as well as limitations of the thesis and directions for future studies.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:509861 |
| Date | January 2009 |
| Creators | Myers, Samuel G. |
| Publisher | University of Manchester |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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