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Interpersonal Trust Influences the Cortical Tracking of Speech
Poster Session C, Thursday, October 1, 10:45 am - 12:45 pm, Wangari Maathai
Jaimy Hannah1, Giovanni Di Liberto1; 1The University of Dublin, Trinity College
Trust is a critical component of human communication, providing a foundation for understanding, information exchange, and social coordination. Most of the research on trust in speech communication has focused on how vocal characteristics such as pitch, prosody, and fluency impact perceived trustworthiness, demonstrating that listeners rapidly form trustworthiness impressions based on acoustic cues alone. However, little is known about how established trust with a speaker affects the way the brain processes speech during listening. Here we investigate this question via a two-stage experimental paradigm. In the first stage, trust is established via an investment-based game. Participants interacted with fictional characters (trust-building stage), each with a distinctive voice and level of trustworthiness, which was manipulated by varying the frequency of lie trials. In the second stage, participants listened to stories told by each character while EEG data were recorded (story-listening stage). Data from twenty young adults confirm a statistically significant correlation between the perceived and actual trustworthiness of the fictional characters, with trustworthiness ratings being unrelated to the acoustic differences across voices. Cortical speech tracking was quantified using temporal response function (TRF) analyses on the EEG data recorded during the story-listening stage. Trustworthiness established during the trust-building stage influenced the cortical tracking of speech in the subsequent story-listening stage. Specifically, cortical tracking was greater for low trust speakers, suggesting that lower trustworthiness may be associated with greater attentional and cognitive demand during speech perception. The effect of trustworthiness was specific to the strength of cortical tracking, with no differences observed in the spatiotemporal dynamics across trustworthiness conditions. One of the remarkable aspects of this result is that the influence of trust emerged using a simple speech listening task. Here, we also investigated the possibility that speech processing is even more influenced by trust in higher-stake scenarios, where trust plays a role in decisions with meaningful consequences in communication. To that end, a second experiment was designed, incorporating decision making into the story-listening stage wherein participants choose to follow or go against advice provided by the characters. Listeners are required to evaluate and act upon advice provided by the characters, allowing for a more direct investigation of how trust shapes both neural speech processing and subsequent decision making. Preliminary findings suggest that the impact of trust on speech perception is more pronounced when there are outcomes associated with the character interactions. Together, these findings demonstrate that socially acquired knowledge and experience with a speaker can shape neural responses during natural speech perception. The results highlight the importance of integrating social and communicative factors into neurophysiological accounts of speech processing, suggesting that the brain does not process speech in isolation from the social context in which communication occurs.
Topic Areas: Speech Perception, Computational Approaches