Multimodal communication and cognition: The role of gesture in language processing and word learning in individuals with traumatic brain injury

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PROJECT SUMMARY Communication is multimodal, containing speech and gesture. When people talk, co-speech gestures (spontaneous movements of the hands and arms) can visually depict information conveyed in speech but often communicate unique information not conveyed in speech. For example, a speaker might say, “I searched for a new recipe,” while making a typing gesture, conveying only in gesture that the speaker searched online rather than through a cookbook. Listeners must bind linguistic information from speech and visuospatial information from gesture to generate an integrated representation of a message. The benefits of gesture for communication and cognition are well-documented in neurotypical individuals. For example, gesture improves comprehension and memory for spoken information and facilitates word learning, abilities critical for academic and vocational success. However, gesture has not yet received the same attention in clinical populations with cognitive-communication disorders, such as traumatic brain injury (TBI). In this proposal, we examine whether the benefits of gesture extend to individuals with TBI, or if the very nature of their deficits prevent gesture’s facilitatory role in communication and cognition. Using a novel approach combining methods and theory from speech-language pathology, gesture studies, psycholinguistics, and neuropsychology, we test the ability of individuals with TBI to use gesture during multimodal language processing and word learning across three experiments. Aim 1 (Experiments 1 and 2) investigates the ability of individuals with TBI to integrate information from speech and gesture during multimodal language processing. Experiment 1 tests the effect of observing a narrator’s gestures on subsequent retellings of stories to determine whether individuals with TBI report information provided uniquely in gesture and integrate it into their representation of the stories across time. Experiment 2 uses eye-tracking to determine if individuals with TBI can use information from gesture to resolve referential ambiguity in a visual-world paradigm during rapid on-line language processing. Aim 2 (Experiment 3) investigates whether individuals with TBI benefit from observing and producing gesture during word learning. Exploratory Aim 3 examines the relation between speech-gesture integration and working memory abilities to explore individual differences in gesture processing and inform future confirmatory studies. Studying gesture along with speech is critical for providing ecologically valid assessments of language that more closely approximate the real-world communication contexts that characterize and enrich everyday life. The proposed research will directly advance the study of gesture in clinical populations by providing new insight into the ability to integrate speech and gesture in the context of multimodal language processing and testing whether gesture can be leveraged to support new learning in individuals with TBI. This research represents a new direction in TBI research and promises to offer novel and impactful contributions to theories of multimodal communication and to the nature of cognitive-communication deficits after TBI.