Hemispheric Contributions to Figurative Language Comprehension After Unilateral Brain Damage: A Meta-Analysis of Lesion Side and Conventionality Interaction

Introduction

Previous studies revealed that individuals with brain damage exhibit distinctive patterns in figurative language comprehension. However, a systematic investigation of the mechanisms between figurative language deficits and moderating factors such as lesion side remains lacking. Moreover, while the right hemisphere has traditionally been emphasized in pragmatic processing, accumulating evidence now suggests that the contributions of the left and right hemispheres may depend on linguistic factors such as conventionality. A recent systematic review on idiom comprehension in aphasia has highlighted the critical role of stimulus characteristics, yet no quantitative synthesis has examined how conventionality modulates hemispheric contributions to figurative language processing after unilateral brain damage. This meta-analysis aims to: (1) quantify the overall difference between left- and right-hemisphere damaged (LBD and RBD) patients in figurative language comprehension accuracy; (2) examine whether conventionality moderates hemispheric differences; (3) explore potential moderators-including aphasia status, task type, and sample size-that may influence the LBD-RBD difference; and (4) compare impairment patterns of LBD and RBD patients relative to healthy controls across different conventionality levels.