Abstract

Numerous studies have shown that clinically-significant anxiety is associated with a tendency to apply threat interpretations to stimuli or situations that can plausibly be interpreted in a neutral or benign fashion. Current thinking suggests that biases in appraisal and interpretation are not merely epiphenomena of disorder; but rather, markers and "transmitters" of underlying cognitive vulnerability. Intolerance of uncertainty has been identified as a potential cognitive vulnerability for generalized anxiety disorder (GAD), a condition characterized by excessive and uncontrollable worry. Individuals who endorse high levels of intolerance of uncertainty hold the view that uncertainty is stressful and upsetting; that uncertainty leads to the inability to take action; that uncertain events are negative and to be avoided; and that being uncertain is unfair. This thesis consists of three independent investigations of the relationship of intolerance of uncertainty to the processing of uncertainty. Using three different paradigms, individuals low and high on intolerance of uncertainty were compared on their appraisals of ambiguous scenarios. Collectively, the findings suggest (1) that individuals high on intolerance of uncertainty appraise ambiguous stimuli and events as less pleasant and more disconcerting relative to individuals low on intolerance of uncertainty; (2) that individuals with high levels of intolerance of uncertainty take longer to evaluate affectively-neutral stimuli compared to individuals with low levels of intolerance of uncertainty; (3) that degree of intolerance of uncertainty is a stronger predictor of appraisals of ambiguous situations than are GAD symptoms and mood variables; (4) that appraisals of ambiguous situations partly mediate the relationship of intolerance of uncertainty to worry; (5) that the appraisals of individuals high on intolerance of uncertainty appear to lack content-specificity; (6) that relative to individuals low on intolerance of uncertainty, those high on intolerance of uncertainty have a greater tendency to use anxious affect as information when appraising potentially threatening situations; and (7) that habitual use of thought suppression is associated with negative appraisals of ambiguous scenarios in individuals high on intolerance of uncertainty only. The findings are discussed within the context of conceptual models of worry and GAD as well as theories of normative decision-making under uncertainty.