Mode of onset of simple phobia subtypes: further evidence of heterogeneity.

Previous research has demonstrated heterogeneity of the simple phobia diagnostic category. As a further test of the notion of heterogeneity of the DSM-III-R simple phobia diagnostic category, mode of onset was examined in a sample of simple phobic outpatients. Patients were separated into one of four subtypes: animal or insect, blood and injury, situational, and choking-vomit phobias. Careful study yielded five distinct mode-of-onset categories. Two researchers independently determined the mode of onset for the patients studied: direct trauma, spontaneous, vicarious learning, gradual, and lifelong. Significant mode of onset differences were observed across groups. Situational phobics reported a preponderance of spontaneous onsets as compared to the other groups studied. These results offer further evidence of the heterogeneity of the simple phobia diagnostic category and also support the contention that situational simple phobias are closely related to agoraphobia.