Metaphor comprehension in right brain-damaged patients with visuo-verbal and verbal material: a dissociation (re)considered

Metaphor comprehension was investigated in 50 right-hemisphere damaged (RHD) patients and 38 control subjects in two experimental conditions: a visuo-verbal and a verbal test. In the visuo-verbal test, subjects had to match a metaphorical sentence with one of four pictures representing the correct metaphorical meaning, the literal meaning, a control metaphor and a control literal meaning. In the verbal test, a metaphorical sentence had to be matched to a correct written metaphorical interpretation, a literal or a control interpretation. On both tests, the number of correct metaphorical responses in the RHD group was lower than in the control group. However, RHD patients performed more poorly in the visuo-verbal than in the verbal condition. Interestingly, when they selected the wrong response, the RHD patients tended to select the literal one only in the visuo-verbal condition. Context does not seem to be responsible for the dissociation between the two tests. The influence of the RHD patients' major visuo-spatial deficits was also checked, to exclude their role in the tendency to be literal with visuo-verbal material. Results are discussed in the perspective of an integration deficit.