Speakers communicate more than what they explicitly state. For this reason, addressees rely on linguistic and extra-linguistic cues to recover different levels of explicit and implicit meaning. Presupposition triggers are one of these cues. These are linguistic expressions or constructions (e.g. change of state verbs, factive verbs, it-clefts, etc.) which trigger the recovery of propositions that the speaker presupposes, or takes for granted, for the purpose of the conversation.
This thesis investigates the phenomenon of presupposition within the framework of experimental pragmatics, and it comprises three studies based on the following experimental methods: judgement-tasks, EEG method and grip-force sensor method. This thesis combines a social perspective, which focuses on reputation-management via alternative discourse strategies (Study 1), with a cognitive perspective, which examines the cognitive costs and sensori-motor correlates associated with presupposition processing (Studies 2 and 3).
Study 1 examines the impact of different discourse strategies (saying, implicating and presupposing) on the attribution of speaker commitment towards the message communicated. By operationalizing commitment as a function of the reputational cost (drop of trust) related to the transmission of false information, Study 1 shows that presupposing is perceived as equally committal than saying and more committal than implicating.
Study 2 investigates the cognitive costs associated with targeting presuppositions in discourse continuations. By focusing on additive contexts introduced by the French discourse particle aussi, Study 2 shows that felicitous discourse continuations targeting a presupposition elicit the same ERP response than felicitous discourse continuations targeting an asserted context. This finding suggests that when presupposition processing is part of an appropriate, pragmatically felicitous, discourse strategy, it does not come with any additional cognitive costs.
Study 3 examines the sensori-motor correlates of processing action-related language in presuppositional constructions (complement clause of factive verbs) and non-presuppositional ones (complement clause of non-factive verbs). The results show that the former elicit a greater sensori-motor activation than the latter, thus revealing that presupposed information, whose truth is taken for granted, is processed differently from information whose truth has not been established in discourse.
Overall, this thesis contributes to the study of presupposition by providing empirical evidence in support of the theoretical distinction between different layers of meaning. On the one hand, it shows that their employment leads to different commitments in discourse and has implications on the interpersonal negotiation of trust. On the other hand, it shows that while presupposition processing is not inherently more costly from a cognitive perspective, its cognitive correlates (such as the engagement of the sensori-motor system) can differ from those mapping information with a different discourse status.