Does severe traumatic closed head injury impair sense of humour?

It is now known that closed head injury (CHI) impairs interpersonal skills, disturbs and/or blunts mood and compromises emotional discriminativeness. This study tried to test whether sense of humour is also impaired or disturbed following CHI. Subjects were 42 CHI patients and 42 normal controls, matched for age, education and paternal occupation. Humour performance measures included time taken to rank jokes according to funniness and to classify them, stability of funniness rankings at re-test and ability to correctly classify jokes into 'mutilated' and 'intact' categories. Non-performance measures included total number of non-verbal vocalizations, and mean percentage of appreciation of the jokes. The CHI patients were highly significantly impaired on all aspects of performance but did not differ from the normals on non-performance measures. However, when vocabulary (WAIS-R) was co-varied out of the analyses only time to rank funniness remained significant. The results were interpreted to suggest a severe impairment of sense of humour, an important cause of which is a narrow lexicon, poor lexical semantic processing, or some other reading dysfunction, some of which probably antedated the CHI. It was concluded that measures of humour, vocabulary, and of pure affective performance such as prosodic and/or facial emotion discrimination could contribute to the rehabilitation process in severe CHI.