UC San Diego

Aphasia is a language disorder that affects approximately 1 million US stroke survivors and results in impaired communication across modalities, often with detrimental effects on autonomy and quality of life. While the extent to which these domains are affected vary from person to person, a common symptom found in many individuals with aphasia is sentence comprehension impairment, which are most notable with complex (noncanonical) sentences that require establishing a long-distance relationship between non-adjacent sentence constituents. Of interest to the work presented here are the ways in which auditory sentence input is processed and interpreted. Evidence in the literature implicates lexical-level processing impairments, such as delayed and/or reduced activation of lexico-semantic information, as contributors to syntactic processing disruptions and sentence comprehension deficits. By limiting timely lexical activation during sentence processing, these impairments can also preclude successful lexical encoding and amplify the processing costs of similarity-based interference during syntactic retrieval (i.e., dependency linking). A series of studies are presented to explore three different approaches (processing time, attentional engagement, and semantic pre-activation) to facilitate lexical access and strengthen concomitant encoding of a target word in a sentence. The effects of these approaches on real-time lexical and syntactic processing during complex (object-relative) sentence processing was examined using eye-tracking-while-listening methodology in neurotypical college-age adults (YNC), older adults (age-matched controls, AMC) and individuals with aphasia (IWA). In each of these approaches, I ask whether enhancing the processing of a target lexical item during sentence processing will 1) facilitate its lexical access and encoding, 2) increase its availability for downstream syntactic retrieval operations, and 3) improve sentence comprehension. This novel area of exploration has the potential to improve our understanding of the interaction between lexical and syntactic levels within sentence processing and the cognitive and linguistic factors promoting lexical processing within a sentence context.