Task-based pronunciation teaching and learning of L2 vowels in EFL learners: task complexity effects

Abstract

[eng] Second language (L2) pronunciation learning in foreign language instructional contexts is particularly challenging due to insufficient quantity and quality of L2 input. Decades of L2 speech acquisition research have demonstrated that L1 phonology exerts a strong influence in L2 phonological learning (Best & Tyler, 2007; Flege & Bohn, 2021). One way to mitigate the effects of L1 phonological interference may be to raise learners’ awareness of the relevant L2 pronunciation targets through tasks that encourage attention to pronunciation within meaning-based interaction. Although form-focused communicative approaches have been gaining interest in pronunciation teaching research (Darcy & Rocca, 2023), few investigations have applied task-based language teaching (TBLT) principles, which involve real-world processes of language use, to L2 pronunciation learning (Gurzynski-Weiss et al., 2017a). So far, none have assessed gains in L2 vowel perception, lexical encoding and production for the same participants after a pedagogical intervention. Furthermore, studies investigating whether the predictions of the Cognition Hypothesis (Robinson, 2011b) can extend to L2 phonology are relatively scarce. This doctoral dissertation seeks to contribute to task-based pronunciation teaching (TBPT) research by (1) examining the effectiveness of task design manipulation and (2) exploring the effects of increased task complexity on the pronunciation of two difficult English vowel contrasts (/iː-ɪ/, /æ-ʌ/); (3) assessing to what extent individual differences may mediate L2 vowel performance and gains; and (4) obtaining learners’ perceptions of TBPT and L2 vowel learning. A total of 92 bilingual Catalan/Spanish learners of English were divided into two experimental groups and a control group. Sixty-three experimental learners carried out 20 dyadic problem-solving tasks over 7 weeks. Participants were assigned to either simple (N=31) or complex (N=32) cognitive task complexity groups depending on the number of reasoning demands along resource-directing dimensions the tasks involved. Task completion required the distinction of the target minimal pairs (e.g., bean-bin, cat-cut), which learners were exposed to during the pre-task and consolidated in the post-task. Improvement in L2 vowel perception and lexical encoding was gauged through ABX discrimination and forced lexical choice and lexical decision tasks (accuracy and reaction time) respectively, and in production though delayed word and sentence repetition tasks (Mahalanobis distances between contrastive vowels and between non-native and native speakers’ productions). Additionally, we calculated the occurrence of pronunciation- focused language related episodes (P-LRE) and assessed learners’ individual differences in L2 experience, L2 proficiency, working memory and auditory selective attention. Results showed that the TBPT intervention enhanced the discrimination and lexical encoding of L2 vowel contrasts, and resulted in significantly more distinct and accurate vowel productions when they were elicited in words in isolation and sentences. Gains in vowel discrimination and vowel quality generalized to untaught lexical contexts and were retained 11 weeks after the intervention. Although simple and complex task groups improved L2 pronunciation after the TBPT intervention, performing cognitively demanding tasks led to greater long-term gains in the discrimination, lexical encoding and production of L2 vowels than performing simple tasks. However, increased task complexity did not have a significant impact on the frequency and duration of P-LRE. As for individual differences, working memory and selective attention explained larger inter- individual variation in L2 vowel performance than English experience, but learner factors were only weakly associated to L2 vowel gains. Last, learners expressed a general sense of enjoyment and learning after the TBPT intervention, but self-perceived L2 pronunciation improvement was especially evident in the complex group. Globally, the present study suggests that orienting learners’ attention to phonological form during oral communication is beneficial for L2 pronunciation development, and paves the way for further research in task design and manipulation so as to promote pedagogical practices for pronunciation learning in foreign language classrooms.

[cat] L’objectiu principal de la tesi doctoral és examinar l'efectivitat de manipular el disseny de tasques i els efectes de l'increment de la complexitat de les tasques en la pronunciació de dos contrastos vocàlics difícils de l'anglès (/iː-ɪ/, /æ-ʌ/) com a segona llengua (L2). També pretén investigar en quina mesura les diferències individuals poden interferir en la percepció/producció i en els guanys de les vocals de la L2, i obtenir les percepcions dels aprenents sobre l'aprenentatge de la pronunciació a través de tasques comunicatives (TBPT). Noranta-dos aprenents d’anglès bilingües català/castellà es van dividir en dos grups experimentals i un grup de control. Seixanta-tres aprenents experimentals van completar 20 tasques en parelles durant 7 setmanes i es van assignar a grups de complexitat cognitiva simple (N=31) o complexa (N=32). Millores en la percepció de les vocals de la L2 i la codificació lèxica es van mesurar mitjançant tasques de discriminació ABX i de decisió lèxica, respectivament, i millores en producció a través de tasques de repetició de paraules i frases amb demora. També es van avaluar les diferències individuals dels aprenents en relació a l’experiència en L2 i factors cognitius. Els resultats van mostrar que la intervenció TBPT va millorar la discriminació i la codificació lèxica dels contrastos vocàlics en L2, i va generar produccions vocàliques significativament més dissemblants i precises tant en paraules aïllades com en frases. Aquest aprenentatge es va generalitzar a nous contextos lèxics i es va mantenir 11 setmanes després de la intervenció. A més, realitzar tasques cognitivament exigents va produir més guanys a llarg termini en la discriminació, codificació lèxica i producció de les vocals de la L2 que realitzar tasques simples. Els factors cognitius van explicar una major variabilitat interindividual en la percepció/producció de les vocals de la L2 que l’experiència en anglès, però no van estar associats als guanys obtinguts a partir de la intervenció. Finalment, els estudiants van manifestar la seva percepció d'haver gaudit i après amb la intervenció TBPT. L’estudi conclou amb suggeriments per a futures investigacions i recomanacions pedagògiques per a l’ensenyament de la pronunciació a les aules de llengua estrangera.