The second primary category, together with its other substrategies, contains "indirect strategies", and emphasizes out-of-class activities. Rubin (1987, pp. 22-27) refined her strategy classification scheme by proposing three different types of strategies, e.g., learning strategies, communication strategies and social strategies, according to their contribution to the process of language learning.
O'Malley and his colleagues conducted a major empirical research program in the 1980s with beginning and intermediate ESL learners. From the findings of their series of studies (e.g., Chamot & Kupper, 1989; O'Malley & Chamot, 1990; O'Malley et al., 1985), these writers categorized learning strategies into three broad categories: metacognitive strategies, cognitive strategies and social-affective strategies.Â
Synthesizing the earlier classifications and building upon her own research, Oxford (1990) presented an often quoted taxonomy, known as Strategy Inventory for Language Learning (SILL). Oxford first drew a general distinction between direct strategies and indirect strategies, as Rubin (1981, 1987) did. Direct strategies "directly involve the target language in the sense that they require mental processing of the language" (Oxford, 1990, p. 37). There are three main groups of direct strategies: memory strategies, cognitive strategies andÂ
compensation strategies. Each group of strategies processes the language differently and for different purposes.
Indirect strategies, on the other hand, "provide indirect support for language learning through focusing, planning, evaluating, seeking opportunities, controlling anxiety, increasing cooperation and empathy and other means" (Oxford, 1990, p. 151). The three groups of indirect strategies are metacognitive strategies, affective strategies and social strategies.
Each of these six strategy groups is further broken down into two levels with the first level including nineteen strategy sets and the second level including a total of sixty-two specific strategies. It is a very comprehensive taxonomy of language learning strategies and has been used in a considerable number of studies in various countries. Despite some criticism that the categorization of strategy groups in Oxford' strategy taxonomy sometimes is not sharp and clear, it is important to note that language learning strategies, whether direct or indirect, affective, cognitive or social, are interconnected and support each other.
Person and Learning Strategies
When a learner approaches a relatively challenging learning task, s/he adopts certain strategies to solve the problem. This problem-solving process is constrained by the learner's learning beliefs, attitude, affective state, motivation, learning experience and prior knowledge. Besides, age, gender, language aptitude, intelligence, self-concept/image, personality, cognitive and learning style also potentially affect the learner's employment of learning strategies. The intertwined totality of these person-dependent factors determines to a large extent how the learner approaches a task (Ellis, 1994; Gu, 2003).
SIGNIFICANCE FOR SECOND LANGUAGE LEARNING AND TEACHING
Language learning is a challenging and actually a daunting task for many who can not master a second language even though they have devoted much time and effort to it. To acquire a second language, the learners have to pick up a lot of both declarative knowledge and procedural skills and during the learning process, language learning strategies are important tools for learners' autonomous and active learning to develop their communicative competence and general linguistic proficiency (Oxford, 1990).
Learning strategies can help language learners to make their learning more efficient and enjoyable. Cognitive strategies help learners to use the language more or learn more efficiently. These strategies can directly facilitate learning so as to help achieve a specific learning goal. Metacognitive strategies, on the other hand, help the learners to plan and monitor their learning. They help the learners become more independent and personalize their learning by allowing them to take control over the learning process. Besides, social and affective strategies can help keep the learners motivated and deal with the frustrations of learning a new language.