Single value steps in first language acquisition

Preferably, the properties of grammar can be derived from the following factors: (i) The primary linguistic data as they are offered to the child. (ii) A language acquisition procedure. Hopefully, the language acquisition procedure is compatible with plausible assumptions about the neural abilities of human beings, but that is of no immediate concern here. The interaction of the primary data and the acquisition procedure can be studied by a closer look at the order of the child’s acquisition steps. What does the child acquire first and why? What does she acquire later and why? This is empirically a promising and by no means trivial approach. At the same time, we will argue against an assumption that is quite common in computational studies and also in mere grammatical studies of child language. People from Gold (1967) to Yang (2002) assume that the acquisition procedure has simultaneous access to all data at once. Our point will rather be that the acquisition procedure implies a natural selection of data (not based on UG assumption). Child language can be reconstructed as the result of successive steps in input reduction. The result is a series of successive intermediate grammars. Each grammar causes a new data-selection from the same type of input. Data-selection turns the poverty of a diffuse input stimulus into a focused stimulus by highly selective intake. Eventually, it may be shown that generative grammar is learnable without the postulation of grammatical a priories. 1 Input reduction Early child language is not only stereotype and repetitive, it is above all simplified. There is quantitative difference with the adult input. There are less lexical items, shorter sentences and less grammatical markings. More importantly, there is a qualitative difference as well. Certain grammatical properties are not present at all in early child language. They will not appear until other properties have been acquired first. This order in acquisition steps, first studied in Brown (1973), must be explained. Child language can be represented as a series of grammars Gi , each one one step more specified than its predecessor until the series ends with the target grammar Gn (Chomsky 1975: 119f). (1) Go ---Gi ⇒ Gi+1 ---Gn Each step is an invention that makes sense due to the preceding grammar and due to a new selection of data from the input, see (2). (2) Gi ⇒ Gi+1 + Di+1