REAL-TIME DISCOURSE COMPREHENSION ABILITIES IN HEALTHY ADULTS AND ADULTS WITH TRAUMATIC BRAIN INJURY

Abstract

Much of human social interaction, knowledge transmission, and cooperativeaction takes place through conversation. Although engaging in conversation is a common occurrence, the ability to understand conversation structure is a complex skill supported by dynamic interactions of linguistic and non-linguistic cognitive processes. When any of these processes break down, the social and occupational costs can be profound. This is often the case for individuals living with traumatic brain injury (TBI), as more than 75% of this population suffers from cognitive communication deficits secondary to their brain injuries. Gaps in knowledge about how best to facilitate rehabilitation with thispopulation persist because the specific cognitive mechanisms underlying conversational discourse abilities are unknown, even in healthy adults. One major hurdle to identifying these mechanisms is that much of the study of discourse for healthy adults and patients with TBI has taken the form of descriptive discourse analysis that considers conversations as a whole. Because a key feature of conversation is that it dynamically unfolds over time, new approaches must consider how conversation structures (i.e., topics) emerge, change, and interact with ongoing language comprehension and production processes. This work examined (1) sensitivity to topic structure shifts during naturalistic language tasks in healthy adults versus individuals with TBI (2) whether specific cognitive processes that may support understanding of topic transitions differ between healthy and TBI groups and (3) what effect topic structure has on online language comprehension processes. We found that shifts in topic structure affect both online language comprehension and production. Both healthy adults and adults with TBI were similarly sensitive to topic structures as they emerge. However, individuals with TBI may have differences in lower-level comprehension and production that become apparent during discourse tasks when fine-grained temporal processes can be measured. Taken together, the results of these studies can both inform theories of healthydiscourse processing and narrow the scope of possible reasons for conversational breakdown following brain injury, ultimately driving new directions in clinical research for cognitive-communication disorders.