‘Theories of anxiety’ looks at four key perspectives on anxiety. Firstly, Freud's views on psychoanalysis. Behavioural theories were led by John Broadus Watson's experiments on behaviourism that suggested conditioning was responsible for the development of phobias and these ideas were developed by O.H. Mowrer, Burrhus Skinner, and Joseph Wolpe, resulting in cognitive behaviour therapy (CBT). Cognitivism moved on from behaviourism by including the study of thoughts; its key insight is that anxiety arises from an ‘appraisal’ of a situation. An overview of neurobiological theories of anxiety and the advances in neuroimaging highlights Joseph LeDoux's work in identifying the amygdala region of the brain's limbic system, which seems to be responsible for fear reactions.