Complexity, Accuracy, and Fluency

This entry provides an introduction to theories of complexity, accuracy, and fluency (CAF) as a tripartite conceptualization of task-based second language performance. It locates these constructs within task-based language teaching (TBLT), gives definitions of each, and outlines measurement options in each case. The entry argues that, though CAF was originally developed for research purposes, the three areas have become increasingly important for pedagogy. Task complexity, task conditions and characteristics, and learner factors can all have an impact on CAF selectively in task performance. Two contrasting theories, Skehan's limited attention capacity hypothesis and Robinson's cognition hypothesis, are discussed as general operating principles to understand how CAF can be influenced by task factors. Pedagogical suggestions are linked to the three performance areas, and consider the impact of different task characteristics, of planning (pre-task and online), and of repetition. It is also proposed that the post-task stage can have particular importance for the development of complexity and accuracy.