Miho Tomita, - Graduate School of Languages and Linguistics, Sophia University, Japan

This study examined the developmental patterns of second language (L۲) oral languageperformance as measured by complexity, accuracy, and fluency (CAF) and the relationshipbetween these three variables over time. A total of ۳۱ Japanese-L۱ university students,grouped into two proficiency levels (lower and intermediate), participated in a semester-longtask-based speaking course. Speaking tests involving impromptu speech tasks wereadministered four times over the ۱۵-week semester, and learners’ oral data were analyzed tomeasure CAF. The results indicated that syntactic complexity had mild growth over time,with some fluctuations. Lexical complexity showed a mild U-shaped curve with slightchanges in growth. Accuracy showed U-shaped trajectories, showing a decline followed bya steeper increase over time, and fluency exhibited steady growth over time. Regardingcorrelations between CAF, trade-off effects were evident between lexical complexity andsyntactic complexity and between lexical complexity and accuracy. We observed a positivecorrelation between accuracy and syntactic complexity and between fluency and syntacticcomplexity. Regarding the relation between fluency and accuracy, the results were mixed,and there was an observed trend towards significance between fluency and lexicalcomplexity. The findings also indicated that lower- and intermediate-proficiency learnershad similar change trajectories except for one syntactic complexity measure.

CAF, Complexity, Accuracy, Fluency, Speaking