Individual differences and linguistic factors in the development of mid vowels in L2 Spanish learners: A longitudinal study

Abstract

This study was a longitudinal investigation into how learner individual differences (IDs) and linguistic factors shape developmental trajectories of second language (L2) production of the Spanish mid vowels /e/ and /o/. Adult English-speaking learners enrolled in 2nd semester (Intro II, N = 13) and 6th semester (Advanced II, N = 31) university-level Spanish courses completed a written elicitation production task three times over the course of a semester and measures of ID variables (i.e., L2 aptitude, working memory capacity, phonological short-term memory, L2 motivation, and L2 proficiency level) once during the semester. The production measure elicited /e/ and /o/ in tonic syllables of Spanish target words.

Acoustic analysis was used to measure vowel duration and normalized F1 and F2 formant values (Bark units) for each vowel. Since even native and bilingual speakers produce vowels within a range of acceptable values, development was operationalized as movement toward the mean duration and mean F1 and F2 Bark values of bilingual speakers, as well as minimization of the dispersion of these values.

Findings demonstrated that over the course of the semester, Intro II learners exhibited more movement toward the bilingual means than Advanced II learners. Statistical improvements were largely related to vowel duration, with less statistical change observed for F1 and F2 formant measures. The results also suggest that learners acquire accurate production of /e/ before /o/.

With regard to learner IDs, multiple regressions indicated a role for WMC, PSTM, and L2 proficiency level with the overall learner sample, yet the directionality of these correlations was mixed depending upon the production variable examined. L2 aptitude (LLAMA D) also emerged as a predictor of development in course level regressions. Most statistical correlations were observed at the Advanced II level, suggesting that cognitive IDs are more important at later stages of development for L2 phonology. This contrasts with Serafini & Sanz (2015), who found cognitive IDs to be important at earlier stages of development for morphosyntax.

These findings contribute to our understanding of L2 phonological development trajectories for Spanish vowels at different stages of acquisition and the role that learner IDs play in that development.