A Neuroscience Perspective on the Recovery of Conversational Implicatures
In daily conversation,the listener needs not only to decode the context-invariant"sentence meaning",but also to infer the implicated meaning(conversational implicature)beyond the literal expression.Grice(1957)proposes a concept of conversational implicature and divides it into generalized conversational implicature(GCI)and particularized conversational implicature(PCI).Three mainstream pragmatic theories hold different views concerning the relationship between the two types of implicatures and have different predictions about their neurocognitive substrates.According to default theory,GCI is computed by an automatic and effortless system that supports default inferences,whereas PCI is computed by a separate one that supports context-sensitive inferences.In contrast,relevance theory holds that both PCI and GCI are derived from the same cognitive processes,which take contextual considerations into account from the beginning.Semantic minimalism offers a more balanced view that PCI is derived from fully context-based inferences,while GCI is derived from constraint-based inferences.Comparing the neurocognitive mechanisms underlying PCI and GCI comprehension would allow us to choose between these theoretical approaches.Prior neuroimaging studies have separately investigated the neural processes of comprehending PCI and GCI,and have revealed both the shared and distinct neural representation of them.Results have showed that PCI and GCI comprehension share the multivariate fMRI patterns of language processing;in contrast,the theory-of-mind-related pattern was only elicited in PCI comprehension,either at the whole-brain level or within dorsal medial prefrontal cortex.Moreover,a neural stimulation study provides causal evidence showing that stimulating the theory-of-mind-related brain region(right temporal-parietal junction)exclusively affected PI comprehension,but does not impact GI comprehension.This article points out that,compared to the default theory and the relevance theory,semantic minimalism is more consistent with findings of neuroimaging and brain stimulation research on conversational implicatures.Specifically,the pragmatic systems for generating PCI and GCI share a common core language network,which is responsible for the extra semantic activation and integration processes required for interpreting implicatures.In addition,a holistic,general pragmatic system for PCI generation also recruits the theory-of-mind network to support individuals'inference on the speaker's mental state in the current specific context,while a more limited,encapsulated pragmatic system for GCI generation recruits the dorsomedial prefrontal cortex,which functions on the basis of statistical facts about the speaker's intentions in past conversational exchanges.Taken together,the current findings about implicature generation and understanding shed new light on the cognitive mechanisms of conversational implicatures,and provide important constraints on constructing or reconstructing theories of conversational implicatures.
implicaturegeneralized conversational implicatureparticularized conversational implicaturelanguage networktheory of mind
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