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Abstract
The depressive realism effect refers to a phenomenon in which depressed individuals are more realistic at assessing the relationship between two events (referred to as contingency learning) than non-depressed individuals (Alloy & Abramson, 1979). The main aim of this thesis was to investigate the depressive realism effect by: (i) replicating the effect and (ii) understanding its potential mechanisms.
Experiments 1 to 5 (Chapter 2) aimed to replicate the depressive realism effect by comparing the accuracy of assessments of contingencies made by unselected participants who received either a positive or a negative mood induction. Despite the effectiveness of the mood induction procedures, across these five experiments, there were no differences between the assessment of contingencies provided by participants in the positive and negative mood induction conditions. These findings suggested that negative mood alone was not sufficient to elicit the depressive realism effect. Thus, consistent with the original study by Alloy and Abramson (1979), in Experiment 6 (Chapter 3) a high dysphoric sample was employed. The depressive realism effect was replicated in this experiment, such that high dysphoric participants made more accurate assessments of contingencies than did low dysphoric participants. This replication suggested that studying a high dysphoric sample may be critical to detect the depressive realism effect.
Experiments 7 to 14 investigated the role of various mechanisms that have been theorised to account for the depressive realism effect. Specifically, the results of Experiment 7 (Chapter 3) suggested that information presented early in a task had no impact upon participants assessments of contingencies. Experiments 8 - 12 (Chapters 4 & 5) did not find evidence to support the proposal that information processing biases, in particular expectations and memory biases, play a role in the depressive realism effect. Further, the depressive realism effect was not replicated in Experiments 9 and 10 in which a high dysphoric sample was examined. Together, these findings prompted the conclusion that the depressive realism effect is small and difficult to replicate. Finally, Experiments 13 and 14 (Chapter 6) did not find evidence to support the notion that rumination increases participants realistic assessment of contingencies, in either in high dysphoric or clinically depressed samples.
In summary, the consistent finding across the studies in this thesis was that high dysphoric individuals were no more realistic at assessing contingences than were their low dysphoric counterparts. Importantly, a critical examination of studies in the literature and a consideration of the pattern of findings obtained in this program of research prompted the conclusion that the depressive realism effect, when it does emerge, might in fact be accounted for by cognitive processes that are well-established to play a role in depression (e.g., mood congruent processing and a pessimistic attributional style), instead of high dysphoric and clinically depressed individuals abilities to accurately calculate contingencies. The implications of the findings for the theories of the depressive realism effect and clinical practice are discussed in detail in Chapter 7.