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Brain dynamics of speech act and common ground processing in communication
Poster C62 in Poster Session C, Friday, October 7, 10:15 am - 12:00 pm EDT, Millennium Hall
Rosario Tomasello1,2, Irene Sophia Plank3,4, Friedemann Pulvermüller1,2,3,4; 1Brain Language Laboratory, Freie Universität Berlin, 2Cluster of Excellence ‘Matters of Activity. Image Space Material’, Humboldt Universität zu Berlin, 3Berlin School of Mind and Brain, Humboldt Universität zu Berlin, 4Einstein Center for Neurosciences Berlin
What makes human communication exceptional is the ability to grasp speakers' intentions beyond what is said verbally during social interaction. This is because there is a many-to-many relationship between linguistic utterance forms and the various possible functions each of them may carry in specific communicative contexts. For instance, the expression "Here's a pen" can teach someone the meaning of a word, draw attention to a particular object, or offer that object on request. Linguistic-pragmatic theories define these functions as speech acts, and various pragmatic traits characterise them at the levels of propositional content, action sequence structure, related commitments, common ground and social aspects. A still controversial issue in current experimental pragmatic research addresses the latency of brain indexes signifying linguistic-pragmatic understanding of communicative functions and their relationship to other linguistic (phonological, semantic) and cognitive processes. Here we show that identical linguistic utterances conveying different communicative functions (request, naming, statement and question functions) in written, prosodic and gestural modalities triggered distinct ultra-rapid neural responses within 150ms after any perceptual differences and in parallel with early semantic processes. The patterns of activation reflected speech act function. For example, directive speech acts (e.g., requesting an object) specifically activated the cortical motor system, possibly reflecting the expectation of the partner’s action typically following it (e.g., grasping an object and handing it over). Although these results shed light on brain dynamics of speech act processing, they were driven by external differences in communicative contexts, gesture types or prosodic cues that defined the speaker's intention. In communication, understanding a speech act often goes beyond contextual, visual and linguistic input, where speaker's knowledge and assumptions shared with a partner (i.e. common ground) determine the communicative function. To close this gap, we designed different conditions with no differences in the external setup or the immediately preceding context, using, for example, the same critical utterances, speech act types and communicative visual environments. Specifically, the same question, "Which sea borders Croatia?" was posed either by a “student” as a means to obtain information from the partner (genuine question) or by a “tutor” to test the listener's knowledge (exam question). Crucially, these language games did not differ in linguistic form nor in the preceding context or expected verbal response, but clearly in the speaker's knowledge (about whether the speaker knows the answer or not) and thus in its communicative goal (to obtain information or evaluate knowledge). Distinct neural processes were elicited by the same question sentences if they were understood as genuine or exam questions, with the earliest differences appearing after the sentences’ second-words, 100, 180 and 400 ms after their occurrence. As differences occurred when the first content word appeared, this indicates that speakers process common ground and lexical-semantic information simultaneously, in line with some previous evidence. Overall, we show that speech acts are processed immediately in brain and mind, regardless of whether social, contextual, visual or common ground pragmatic traits determine speaker´s action, and that this enables the interlocutor to quickly recognize and understand communicative functions.
Topic Areas: Meaning: Discourse and Pragmatics, Speech Perception