Semantic extension in a novel communication system is facilitated by salient shared associations

Creative processes of semantic extension play a key role in language change, grammaticalisation, and (by hypothesis) the early origins and evolution of language. In this paper we report two dyadic interaction experiments studying the semantic extension of novel labels in controlled circumstances. We find that participants can use salient and shared associations in their perceptual environment (between colours and shapes) to bootstrap a communication system, and can then extend those labels figuratively, to convey both concrete and abstract targets, by exploiting shared understandings such as colours associated stereotypically with specific objects and emotions. By manipulating the presence of reliable statistical associations between colour and shape early in this process we show that such shared associations facilitate both an initial semantic extension and subsequent chaining of extensions; we also find that extensions relying on less certain grounding (e.g. between colours and emotions) lead to greater variability in how extensions are made. Our method can be used to test the creative processes of semantic extension under controlled conditions, and provides experimental purchase on the relationship between association and extension which have only previously been studied through correlational means.