Nuclear vowel priming and anticipatory oral postures: evidence for parallel phonological planning?

ABSTRACT

Linguistic and psycholinguistic theories of speech planning typically assume serial phonological encoding. However, under some neurally-inspired speech models, phonological elements are initially co-active in a parallel planning space. Research using acoustic reaction times has perhaps mistakenly attributed execution-level phonetic effects to serial encoding. We used motion-tracked digital video to measure lip posture. In two form-preparation experiments, participants were sometimes primed with the nuclear vowels of CVC words. All words contained either /i/ (spread lips; e.g. “seed”) or /u/ (rounded lips, e.g. “soup”). The initial consonants were uncertain. Analyses emphasised oral postures preceding stimulus presentation. In Experiment 1, participants’ early postures anticipated the upcoming vowel when it was primed. Experiment 2 included two pairs of vowel-primed blocks. The words of one /i/-block began with rounded consonants. Primed vowels influenced anticipatory articulation except when superseded by conflicting demands from likely initial consonants. We discuss the implications for parallel encoding.

KEYWORDS:

• Articulation
• form preparation
• gestural timing
• parallel encoding
• phonological priming
• trajectory analysis

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Peter A. Krause http://orcid.org/0000-0002-8718-9824

Notes

1 Proctor, Shadle, and Iskarous (2006) found that some speakers partly distinguished different sibilants based on lip protrusion (with /s/ using relatively retracted lips compared to /∫/). This raises the possibility that one or more sibilant initial segments might show reduced accommodation to the rounding status of the nuclear vowel, compared to the other initial segments in our inventory. However, we remind the reader that Liu et al. (2018) found positive evidence for differential coarticulation of rounded and unrounded vowels during initial /s/ productions. Nonetheless, at the suggestion of an anonymous reviewer, we performed an exploratory re-analysis of Experiment 1's results with the initial segment's manner of articulation (fricative versus plosive) as a factor. This failed to qualitatively change any of the results we report below. Further, horizontal lip aperture did not participate in three-way interactions with context and target vowel at any of the critical video frames.

2 Astute readers will note the non-independence of the fixed factors for target vowel, prior vowel, and the context × target vowel interaction. Specifically, in homogeneous blocks, target and prior vowels would always be the same. We assessed possible multicollinearity by determining the variance inflation factors (VIFs) for all the fixed factors. These fell below the “high” range in all cases (all VIFs < 5). Coefficients for the context × target vowel interaction uniformly pointed in the expected direction for all fitted models, with p-values well below the upper threshold for statistical reliability. We therefore concluded interpretation of our results to be unhindered by this non-independence.