Beliefs about the speaker's reasoning ability influence pragmatic interpretation: Children and adults as speakers

The cooperative principle states that communicators expect each other to be cooperative and adhere to rational conversational principles. Yet do listeners keep track of the perceived rationality of the speaker and does it affect the derived inferences? In a between-subjects design, we ask participants to interpret ambiguous messages in the reference game paradigm which they are told were sent either by another adult or by a 4-year-old child. We find a strong effect of speaker identity: if sent by an adult, an ambiguous message is much more likely to be interpreted as an implicature, while if sent by a child, it is a lot more likely to be interpreted literally. We also observe substantial individual variability, which points to different beliefs and strategies among our participants. We discuss how these speaker effects can be modeled in the Rational Speech Act framework.