Variability in the development of phonetic-phonological patterns by L2 learners

analyzing length gains in vowels preceding final voiced plosives in L2 English

Abstract

In Complex Dynamic Systems Theory (CDST), intra individual variability plays a functional role in the development of new patterns and skills in a Second Language (L2), serving as an indicator of developmental progress. In a recent study, Verspoor and de Bot (2022) argue that higher levels of variability are associated with greater developmental gains during periods of intensive learning. The authors propose the use of two measures  the Coefficient of Variation (CoV) and the Standard Deviation of Differences (SDd) – to quantify and compare variability across datasets involving multiple learners. The present exploratory study employs these measures to assess developmental gains related to a phonetic-phonological phenomenon in English as an L2. Drawing on longitudinal data from 11 Brazilian learners, we aim to investigate whether variability (operationalized as CoV and SDd) correlate with vowel length gains preceding the voiced plosives /b d g/ in syllable-final position in L2 English. In 12 recording sessions, participants produced monosyllabic words ending in voiced stop consonants. Between the first and second data collection points, learners – divided into three groups – received different pedagogical treatments: perceptual training only, perceptual training combined with explicit pronunciation instruction, or no training/instruction. Following the acoustic analysis, we calculated (a) vowel length gains for each stop consonant, (b) the CoV, and (c) the SDd of vowel length for each participant at each datapoint. Correlation analyses indicate that variability is positively associated with the increase in vowel length over the course of the study. These findings highlight the relevance of intra-individual variability in the development of new pronunciation patterns in the L2, especially in periods of accelerated learning.