Figurative language and aggression after traumatic brain injury: Does sarcasm have a role in modulating aggressive behaviour?

Aggressive behaviour after traumatic brain injury (TBI) has been associated with general language impairments (Alderman, 2007). Figurative language has an important role in modulating emotional intensity (Dews & Winner, 1995), and sarcasm, a form of figurative language heavily linked to social cognition, is considered a socially appropriate communication of aggression (Haiman, 1998). The present research aimed to investigate the processing of sarcasm in individuals with TBI, and in healthy adults, in an attempt to explore whether possible deficits in linguistic performance may contribute to aggressive behaviour. A novel, auditory-visual, computer-based task was developed to test comprehension of factual and attitude (others’ intentions) information in sarcastic and literal contexts. Experiment One compared the performance of seven participants with severe TBI with seven matched, healthy control participants. Experiment Two compared 20 low aggressive with 20 moderately aggressive healthy young adults. Reaction time and accuracy data were statistically analysed with parametric and non-parametric tests, and the TBI data was also correlated with neuropsychological and behavioural data. In Experiment One, results suggested that TBI participants were as able as healthy control participants to comprehend sarcasm, given explicit prosodic and contextual cues, though they struggled with drawing literal inferences and did not benefit as much from priming when comprehending questions. Correlations suggested that their difficulties inferring others’ literal intentions related to poor emotion identification, and these difficulties also linked to aggressive behaviour. In Experiment Two, reaction times were significantly faster in literal contexts, on factual questions and on the second of the two questions presented. No statistically significant differences were found between the low and moderate aggression groups on their reaction times or error rates. Overall, these findings shed more light on the appreciation of sarcasm after TBI and the role that language, and in particular sarcasm, plays in modulating aggressive behaviour.