Any complete explanation of human cognition must address the issue of ambiguity resolution. We are constantly confronted by indeterminate stimuli that need to be resolved in order for the cognitive system to function in an efficient and adaptive way. There is copious literature on the resolution of ambiguity in text comprehension, and abundant research on interpersonal processes and deciphering of ambiguous signals. The role of depression and dysphoria in ambiguity resolution has also been examined (e.g. Cane & Gotlib, 1985; Lawson & MacLeod, 1999), but the focus of the present chapter is on the influence of anxiety and anxiety related disorders on ambiguity resolution. In evolutionary terms, anxiety functions to alert the system to impending danger (e.g. Eysenck, this volume, 1992, 1997; LeDoux, 1996; Öhman, 1996), and this involves correctly interpreting ambiguous signals that could predict harm. There is evidence that an evolved neural substrate may be involved in the recognition of fear and danger, and that the amygdala plays a crucial role (e.g. Adolphs, Tranel, Damasio & Damasio, 1995; Calder, Young, Rowland, Perrett, Hodges & Etcoff, 1996; see also Lawrence, Murphy & Calder, this volume). However, Whalen (1998) proposes that the amygdala is maximally responsive to ambiguous information.

Experiments with verbal stimuli

Early studies into the resolution of ambiguity relied on self-report methodology. Seminal work by Andrew Mathews and colleagues (Butler & Mathews, 1983, 1987) demonstrated that anxious individuals rated negative outcomes of ambiguous scenarios as being subjectively more likely to happen and more costly than did the controls. Similar effects have been observed for depressed (Butler & Mathews, 1983) and socially phobic individuals (Amir, Foa & Coles, 1998; Stopa & Clark, 2000).