Metaphor comprehension deficit in schizophrenia with reference to the hypothesis of abnormal lateralization and right hemisphere dysfunction

Sixteen patients with schizophrenia are presented with 'literal', 'conventional metaphor', 'novel metaphor' and 'unrelated' expressions in minimal and sentence contexts. In both contexts, these patients have greater difficulty in processing conventional and novel metaphor expressions than in processing literal expressions. However, in the sentence context, performance improves significantly for conventional metaphors as compared with that for novel metaphors. The results are interpreted in the light of Rachel L.C. Mitchell and Tim J. Crow's theory of abnormal lateralization and right hemisphere dysfunction in schizophrenia. The difficulty in processing metaphors in general and novel metaphors in particular may be due to right hemisphere dysfunction in schizophrenic patients. Interestingly, 'task difficulty' is found to be an important parameter modulating metaphor comprehension in patients with schizophrenia and, therefore, may also be a crucial factor in deciding the hemispheric bias of metaphor processing.