Is Phonotactic Knowledge Grammatical Knowledge ?

Knowledge of phonotactic restrictions refers to one’s knowledge of how possible it is for a given sequence of sounds to constitute a word. For example, any native speaker of English is able to distinguish between the acceptability of the forms bnick and blick; however, the source of this knowledge is far from clear. Some have argued that ratings regarding a string’s possibility as a word are related to that string’s distance from an actual word or words (Greenberg & Jenkins, 1964), hence invoking access to the lexicon. On this account, a given non-word is compared to existing words in the lexicon, and the acceptability judgment is based on how close to a real word it is, and how many real words it is closely related to with respect to its phonological form (i.e., its phonological neighborhood density). For instance, a non-word like blick will have a high rating of acceptability by English speakers, not only by virtue of its similarity to actual words (e.g., it differs in only one phoneme from black), but also by the fact that there are many words in its phonological neighborhood, such as black, bliss, brick, etc. Listeners’ performances in a variety of tasks, such as lexical decision (Luce & Pisoni, 1998) or phoneme identification (Newman et al., 1996), show that listeners are sensitive to the similarity between a novel form and the lexical items in its phonological neighborhood. Another view is that the only factor that determines acceptability of a non-word is the grammar. The rendering of a judgment on well-formedness of a non-word relies on well-formedness constraints that are spelled out in the grammar, which means that the grammar is the sole linguistic component engaged in this task. On this view, the lexicon itself plays no role in deeming a form unacceptable, aside from the fact that grammatical constraints are ranked on the basis of words that are learned and stored in the lexicon. There have been attempts to provide a complete generative analysis that accounts for speakers’ phonotactic knowledge (e.g., Clements & Keyser, 1983; Hammond, 1999). For example, in the phonological analysis offered by Clements & Keyser (1983), a novel form such as bnik is judged as ungrammatical on the basis of a positive syllable structure condition that requires syllable-initial clusters to have the following parameters: [-sonorant][+sonorant, nasal]. A defect of current grammatical accounts of phonotactics is that they render simple up-or-down decisions concerning well-formedness and cannot account for gradient judgments. But when judgments are elicited in a controlled fashion from speakers, they always emerge as gradient, including all intermediate values. For example, speakers accept novel forms [bs] and [lrm] as well-formed, as opposed to [ritk] which they judge as ill-formed. Nevertheless, they rate [bs] higher than [lrm]. In addition to the fact that grammatical accounts are unable to capture speakers’ gradient judgments, they may not be empirically adequate. For example, Trieman et al. (2000) showed that adults are sensitive to the statistics of the lexicon. They identified VC pairs in English that could be transformed into less frequent pairs by switching the consonant members; that is, their stimuli were high frequency V1C1 – V2C2 pairs that could be transformed to low frequency V1C2 – V2C1 pairs (e.g., /m/ and /b/ transformed to /b/ and /m/). Subjects in their experiment were presented with monosyllabic nonword stimuli that were constructed based on the above-described VC pairs. This allowed Trieman et al. (2000) to control for phoneme frequency, while they tested for subjects’ implicit knowledge of rime frequencies. The subjects judged the higher frequency rimes as better than the low frequency rimes. The results of the study, therefore, reveal that native speakers are not sensitive simply to phoneme frequency, but they are sensitive to the frequency of sound sequences in a particular structure (e.g., rimes).