Reflections on Phonological Bootstrapping: Its Role for Lexical and Syntactic Acquisition

Abstract

“Phonological bootstrapping” is the hypothesis that a purely phonological analysis of the speech signal may allow infants to start acquiring the lexicon and syntax of their native language (Morgan & Demuth, 1996a). To assess this hypothesis, a first step is to estimate how much information is provided by a phonological analysis of the speech input conducted in the absence of any prior (language-specific) knowledge in other domains such as syntax or semantics. We first review existing work on how babies may start acquiring a lexicon by relying on distributional regularities, phonotactics, typical word shape and prosodic boundary cues. Taken together, these sources of information may enable babies to learn the sound pattern of a reasonable number of the words in their native language. We then focus on syntax acquisition and discuss how babies may set one of the major structural syntactic parameters, the head direction parameter, by listening to prominence within phonological phrases and before they possess any words. Next, we discuss how babies may hope to acquire function words early, and how this knowledge would help lexical segmentation and acquisition, as well as syntactic analysis and acquisition. We then present a model of phonological bootstrapping of the lexicon and syntax that helps us to illustrate the congruence between problems. Some sources of information appear to be useful for more than one purpose; for example, phonological phrases and function words may help lexical segmentation as well as segmentation into syntactic phrases and labelling (NP, VP, etc.). Although our model derives directly from our reflection on acquisition, we argue that it may also be adequate as a model of adult speech processing. Since adults allow a greater variety of experimental paradigms, an advantage of our approach is that specific hypotheses can be tested on both populations. We illustrate this aspect in the final section of the paper, where we present the results of an adult experiment which indicates that prosodic boundaries and function words play an important role in continuous speech processing.