Abstract
Based on the Self-determination theory (Deci & Ryan, 2000, 1985), the present mix-method study aims to investigate how the manipulation of learner autonomy affects the motivation of vocabulary learning within the task framework (Dörnyei, 2000; Julkunen, 2001). Following recent conceptualization of motivation as dynamic and ever-changing (Dörnyei, 2005; Ushioda, 1996), an emphasis is placed on documenting learners’ motivation changes and identifying potential variables that are related to motivational fluctuation from a longitudinal perspective. The study lasted for fourteen weeks. With a between-group design, forty-eight undergraduate students from a public university were equally divided into an experimental group and a control group. Seven vocabulary learning tasks were implemented with two-week intervals throughout the research period. In the vocabulary learning tasks, the participants in the experimental group were free to choose their own target words to learn from reading passages, whereas the participants in the control group were required to learn the target words selected by the experimenter. Triangulated data from questionnaires, including task evaluation questionnaire (Ryan, 1982), Language Learning Orientations Scale (Noels et al., 2000), one-to-one interviews, and classroom observations were collected throughout fourteen weeks to offer both quantitative and qualitative analyses of learners’ motivation changes. The results show that participants’ task motivation and task engagement for vocabulary learning is significantly higher when they are provided with choices during tasks. Moreover, individual learners’ motivational retrospection and peer influences are important variables contributing to one’s motivational fluctuation. Pedagogically, the results may suggest effective motivating strategies for administering L2 vocabulary learning activities in classrooms.