Multiple paths to sentence interpretation: Case studies of older adults and persons with aphasia

It is commonly assumed that persons with aphasia (PWA) may adjust their sentence processing due to chronic difficulty with sentence comprehension. We tested the hypothesis that variation in the paths to sentence interpretation is normal, i.e., it is present in different populations, including neurotypical older adults and PWA with good comprehension. Two neurotypical older adults and two PWA with little to no sentence comprehension difficulty were tested using multimodal eye-tracking and behavioral tasks. All participants were screened for good sentence comprehension accuracy. Eye-movement analyses when listening to semantically implausible sentences like “The cop was handcuffed by the robber” revealed differences between the two controls and between the two PWA in fixations to the syntactically compatible versus semantically compatible pictures, despite high accuracy across the board. Differences in linguistic cognitive control between the two PWA corresponded with differences in the efficiency of resolving competition between multiple interpretations. These results illustrate the need to distinguish comprehension paths from comprehension outcomes. Eye-tracking can reveal path differences between individuals, which can be harnessed to improve theoretical understanding of sentence comprehension and clinical approaches for customizing treatment for different PWA.