Is the right hemisphere involved in idiom comprehension? A neuropsychological study.

Nonambiguous idiom comprehension was assessed in 15 right brain-damaged (RBD) and 12 left brain-damaged (LBD) aphasic patients by means of a string-to-picture matching task. Idiom comprehension was found to be severely impaired with a bias toward literal interpretation. The RBD patients, though impaired, performed significantly better than LBD patients; their performance was correlated with visuospatial abilities and was significantly affected by lesion site. The results of this study suggest that the performance of RBD patients in the comprehension of idiomatic sentences may be affected by (a) an involvement of the frontal lobe and/or (b) visuospatial deficits that may impair their performance on the picture-matching task.