The noun-verb distinction in two young sign languages

Many sign languages have semantically related noun-verb pairs, such as 'hairbrush/brush-hair', which are similar in form due to iconicity. Researchers studying this phenomenon in sign languages have found that the two are distinguished by subtle differences, for example, in type of movement. Here we investigate two young sign languages, Israeli Sign Language (ISL) and Al-Sayyid Bedouin Sign Language (ABSL), to determine whether they have developed a reliable distinction in the formation of noun-verb pairs, despite their youth, and, if so, how. These two young language communities differ from each other in terms of heterogeneity within the community, contact with other languages, and size of population. Using methodology we developed for cross-linguistic comparison, we identify reliable formational distinctions between nouns and related verbs in ISL, but not in ABSL, although early tendencies can be discerned. Our results show that a formal distinction in noun-verb pairs in sign languages is not necessarily present from the beginning, but may develop gradually instead. Taken together with comparative analyses of other linguistic phenomena, the results lend support to the hypothesis that certain social factors such as population size, domains of use, and heterogeneity/homogeneity of the community play a role in the emergence of grammar.