Children and adults use pragmatic principles to interpret non-linguistic symbols

A foundational principle of communication is that speakers should offer as much information as required during conversation. Thus, if a speaker offers a statement with limited information (e.g., “I like the candle” when asked about a gift containing a candle and a sweater), the listener often takes the speaker to imply that a more informative statement (“I like the candle and the sweater”) does not hold. Classic theories of communication have proposed that the principle of informativeness extends to purposeful exchanges beyond linguistic interactions, but relevant evidence so far is limited. In a set of studies, we adopt a simple visual-world paradigm to investigate whether 4- and 5-year-old children and adults expect drawings, like utterances, to be informative in accordance with the creator’s knowledge. We find that 5-year-olds and adults (but not 4-year-olds) apply the principle of informativeness to non-linguistic symbols; furthermore, the 5-year-olds’ success in this task depends on features of the symbols. We discuss the implications of these findings for debates over the mechanisms underlying pragmatic inference, as well as for children’s developing understanding of the symbolic function of drawings.