Conversational partners expect each other to communicate rationally and cooperatively and to contribute relevant and informative utterances. Occasionally, however, speakers produce trivial utterances which may violate our expectations of informativity. These utterances can prompt listeners to draw inferences about a speaker’s goals in producing such an utterance. Here we present two studies investigating how and when listeners derive informativity-based inferences. The results demonstrate that speaker knowledge plays an important role in the computation of inferences. Furthermore, the timecourse of the results suggests that these inferences do not always arise automatically and that their computation is costly.

Language use can be characterised as transparent, stating facts about the world, or non-transparent, requiring additional meaning to be inferred. The challenge faced by addressees is recognizing when language use is transparent or not. The current study investigates two factors that may influence how readily participants interpret utterances as instances of transparent or non-transparent language use; speaker knowledgeability and utterance form. When utterances involved negation participants were more likely to recognize this as non-transparent language use and infer that the situation is usually different. Whereas speaker knowledge did not influence how utterances were understood.

We present two experiments investigating the production of implicit constructions. Using a confederate scripting paradigm we find that after making an inference participants were more likely to subsequently produce an implicature. This effect occurred at a global and a local level and was unaffected by the perceived role of the conversational partner. Our findings demonstrate that the choice of whether to be implicit is determined by the activation levels of representations specific to implicatures and that inference and implications have overlapping processing representations.

Children struggle to derive scalar implicatures. Initially this was thought to relate to a lack of cognitive resources required for the computation. More recently however, there has been a shift towards the alternatives (what a speaker could have said but did not). The argument is that children struggle to make the scalar implicature associated with some because they are unaware of its relationship with the stronger alternative all. We present a priming study that investigates this. We show that children’s implicatures can be primed equally by alternatives in quantifier and ad hoc expressions. This suggests that children are aware of the scalar relationship between some and all, even if they choose not to derive the implicature.