<qa>  What is a marker of vulnerability for these disorders?A high degree of generalized anxiety is a component of many anxiety disorders and is regarded as a marker of vulnerability for these disorders. People with anxiety disorders and individuals with high degrees of anxiety have inappropriate expectations of unpleasant events. This study will investigate the development of expecting unpleasant events in healthy volunteers with varying degrees of anxiety using aversive conditioning models. A later phase of the study will enroll participants with anxiety disorders and compare their responses to those of healthy volunteers. 