How can people achieve successful communication when using novel signs? Previous studies show that iconic signs (i.e. signs that directly resemble their referent) enhance communication success. In this paper, we test if enculturated signs (i.e. signs informed by interlocutors’ shared culture) also enhance communication success. Children, who have spent less time in their linguistic community, have less cultural knowledge to inform their sign innovation. A natural prediction is that younger children's signs will be less enculturated, more diverse and less successful compared with older children and adults. We examined sign innovation in children aged between 6 and 12 years (N = 54) and adults (N = 18). Sign enculturation, diversity and iconicity were rated. As predicted, younger children innovated less enculturated and more diverse signs, and communicated less successfully than older children and adults. Sign enculturation and iconicity uniquely contributed to communication success. This is the first study to demonstrate that enculturated signs enhance communication.

The concept of duality of patterning (henceforth DP) has recently begun to undergo new scrutiny. In particular, the fact that Al-Sayyid Bedouin Sign Language (ABSL) does not appear to exhibit a layer of meaningless units (Sandler et al. 2011) casts doubt on the universality of DP as a defining feature of natural language. Why, then, do the vast majority of the world's languages exhibit DP? Two hypotheses have been suggested. The first is that DP is a necessary solution to the problem of conveying a large number of meanings; the second is that DP arises as a consequence of conventionalization. We tested these hypotheses in an experimental-semiotics study. Our results supported the hypothesis based on conventionalization but were inconclusive with regard to the hypothesis based on the number of meanings. At the same time, the task of measuring DP in an experimental-semiotics study presented interesting challenges, suggesting that the concept of DP may need some overhauling.