Metrical structure in planning the production of spoken words.

Abstract

According to most models of speech production, the planning of spoken words involves the independent retrieval of segments and metrical frames followed by segment-to-frame association. In some models, the metrical frame includes a specification of the number and ordering of consonants and vowels, but in the word-form encoding by activation and verification (WEAVER) model (A. Roelofs, 1997), the frame specifies only the stress pattern across syllables. In 6 implicit priming experiments, on each trial, participants produced 1 word out of a small set as quickly as possible. In homogeneous sets, the response words shared word-initial segments, whereas in heterogeneous sets, they did not. Priming effects from shared segments depended on all response words having the same number of syllables and stress pattem, but not on their having the same number of consonants and vowels. No priming occurred when the response words had only the same metrical frame but shared no segments. Computer simulations demonstrated that WEAVER accounts for the findings. Most theories of word production assume that the phonological representations constructed in planning utterances include separate representations of the segmental content of words and of their metrical properties, such as their syllable structure and stress pattern. This view is compatible with current linguistic theory, which allocates segmental and metrical information on separate representational tiers (e.g., Goldsmith, 1990; Kenstowicz, 1994). In addition, psycholinguistic models often contend that during speech planning, the metrical and segmental tiers are first retrieved, or generated, independently of each other and later combined (see Levelt, 1989, for an overview). Most of the evidence for this view comes from analyses of speech errors. The argument runs roughly as follows (see, for instance, Meyer, 1992, for a more extensive discussion). Speakers often commit sound errors, in which the intended and the actual utterance differ in a speech fragment smaller than a complete morpheme. Usually, these fragments correspond to individual segments or, less often, to clusters of two adjacent segments. This shows that, during speech planning, stored form representations are decomposed into their segments. Misplaced segments typically move from their target positions to corresponding positions in new syllables, for instance from one syllable onset (the prevocalic part of a