Criterion-specific reduction of verbal fluency in right brain-damaged right-handers.

Thirty-five vascular right brain-damaged (RBD) and 20 control (C) subjects were submitted to a verbal fluency task for which acceptability criteria were either semantic or formal. Results showed that subjects with a vascular lesion limited to the right hemisphere do show a statistically significant reduction of verbal fluency as compared to controls, that this reduction in verbal fluency is only present when the criterion is semantic, and that such a reduction is independent from the frontal or non-frontal topography of the lesion. These results tend to agree with the general conception of a--non-exclusive--right-hemisphere contribution to lexico-semantic processing, and more specifically to its semantic aspects.