Adjective position and referential efficiency in American Sign Language: Effects of adjective semantics, sign type and age of sign exposure.

Previous research has pointed at communicative efficiency as a possible constraint on language structure. Here we investigated adjective position in American Sign Language (ASL), a language with relatively flexible word order, to test the incremental efficiency hypothesis, according to which both speakers and signers try to produce efficient referential expressions that are sensitive to the word order of their languages. The results of three experiments using a standard referential communication task confirmed that deaf ASL signers tend to produce absolute adjectives, such as color or material, in prenominal position, while scalar adjectives tend to be produced in prenominal position when expressed as lexical signs, but in postnominal position when expressed as classifiers. Age of ASL exposure also had an effect on referential choice, with early-exposed signers producing more classifiers than late-exposed signers, in some cases. Overall, our results suggest that linguistic, pragmatic and developmental factors affect referential choice in ASL, supporting the hypothesis that communicative efficiency is an important factor in shaping language structure and use.