Identifying and modifying negative self-referent cognition in individuals with depressive symptoms
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Major Depressive Disorder (MDD) and other depressive disorders are associated with serious impairment. A greater understanding of the factors and biases that help maintain current depressive symptoms is important in helping to ameliorate the effects of these symptoms. Beck (1967) has argued that biases in self-relevant information processing play an especially important role in the maintenance of depression. Negative self-referent beliefs are theorized to lead to negative cognitive biases that amplify the effects of negative life stress, culminating in the symptoms of depression. This dissertation focuses on negatively biased self-reference. It provides evidence for the strong linkage between self-reference and depressive symptoms (Study 1), shows that electrocortical measures of greater elaborative processing in response to negative information are associated with increased self-referential decision-making (Study 2), and demonstrates a method of modifying negatively biased self-referent processing (Study 3). Study 1 investigated the psychometric properties of a task used to measure negative self-referent processing, the self-referent encoding task (Derry & Kuiper, 1981). Study 1 found that the number of negative and positive words endorsed as self-referential, and the rate of accumulation of information to make the decision about whether each word was self-referential, were robustly predictive of depressive symptoms. Evidence also indicated that these indices of the SRET were psychometrically sound and had strong test-retest reliability. Study 2 used event-related potentials (ERPs) in conjunction with the SRET to show that the endorsement of self-referential words occurred in a later, elaborative stage of neurocognitive processing and not in the early stages of information processing that are associated with the perception of stimuli. Participants diagnosed with MDD showed greater late, posterior ERP waveforms to negative vs. positive words when compared to healthy controls. Study 3 shifted behavioral indices of negative self-referent processing on the SRET by using a future-oriented, guided positive self-reference training. Participants in the active condition had greater increases in their positive self-referent processing over two weeks than those who received a neutral control training. The results of these studies bring together three levels of analysis in order to better measure, understand, and ultimately change negatively biased self-referent information processing associated with depression.