Introduction

In general, task-based researchers have not investigated the effect that performing tasks has on second language (L2) acquisition. Instead they have examined how task design features (e.g. a task with a tight or loose information structure) or implementation options (e.g. pre-task planning) impact on the way in which a task is performed. Researchers then theorize how task performance contributes to acquisition by, for example, suggesting that tasks that induce a focus-on-form (Long, 1991) promote the processes involved in acquisition (e.g. 'noticing'). Crucial to this line of research, then, is how the performance of tasks is measured and analysed. I shall consider four broad approaches to investigating task-based performance in this chapter.

Early research drew on Long's (1983) Interaction Hypothesis to examine the negotiation of meaning that occurs when communication problems arise and attempts are made to resolve them. This research was premised on the claim that negotiation of meaning aids acquisition by helping to make input comprehensible, providing learners with feedback on their production, and pushing them to produce output that is more target-like (Pica, 1992). The continuation of this line of research has drawn on what Gass and Mackey (2007) call the Interaction Approach, which explores how interaction helps learners to connect the external processes arising from the performance of task to the internal processes involved in acquisition. It has also been extended to include the negotiation of form as the structure of negotiation sequences is the same when negotiation is focused solely on linguistic form (i.e. there is no linguistic breakdown). Discourse analysis has afforded a variety of measures to capture the discourse moves found in negotiation sequences.

An alternative approach to investigating dialogic tasks draws on sociocultural theory (SCT). SCT, like the Interaction Approach, views language learning as dialogically based. However, whereas the Interaction Approach considers that interaction prompts the internal mechanisms responsible for learning, SCT sees acquisition occurring within interaction when learners act collaboratively to produce linguistic forms that they are not capable of producing independently.