Impairment of inferential abilities based on pictorial stimuli in patients with right-hemisphere damage

Inferences are mental representations derived from the interaction between explicit linguistic information and an individual's world knowledge. The right hemisphere (RH) is the main region responsible for this ability, particularly with regard to pictorial stimuli. The aims of this study were to evaluate the performance of RH-damaged patients on an inference comprehension task based on pictorial stimuli and to compare the effect of different lesion sites on this performance. We compared the inferential abilities of 75 healthy controls and 50 patients with RH damage of vascular origin using 13 pictorial stimuli from the instrument "300 Exercises of Comprehension of Logical and Pragmatic Inferences and Causal Chains." RH-damaged patients performed worse than controls in comprehending logical and pragmatic visual inferences independent of lesion site (p < .0001). The subgroup with posterior lesions performed worse than the other subgroups.