ABSTRACT
Human languages are distinct from all other animal communication systems in having a set of elements (words) that combine systematically to form potentially novel larger units (sentences). What further distinguishes human language is the fact that this combinatorial feature is found at several different levels. For example, in all human languages, the words that combine to form sentences are themselves composed of parts (morphemes). Although there is great variability in how much within-word structure a given language has, it is nevertheless difficult to find a language that has no structure at the word level (be it the result of inflectional processes or stem-formation processes, including derivational morphology, compounding, or incorporation; cf. Anderson, 1985). Indeed, in her review of the Perkins (1980) sample of 50 languages chosen to represent the languages of the world, Bybee (1985) found that all languages have at least some morphologically complex words. Do the gesture systems invented by the deaf children we studied?
