A meta-analysis of effectiveness studies on dialogue-based CALL, based on 17 studies and $k = 100$ individual effect sizes. We use Morris and DeShon’s (2002) formulas to compute comparable effect sizes across designs, and analyse them through a multilevel random-effects model. Results confirm that dialogue-based CALL practice has a significant medium effect size on L2 proficiency development ($d = 0.59$). Extensive moderator analyses on several learning outcomes of different types and features of dialogue-based CALL (type of interaction, modality, agent embodiment, etc.) confirm the effectiveness of form-focused and goal-oriented systems, system-guided interactions, corrective feedback provision, and gamification features. Significant effects for lower proficiency learners, and on vocabulary, morphosyntax, holistic proficiency and accuracy are established.

This article presents the results of a systematic review of the literature on dialogue-based CALL. Applications allowing a learner to have a conversation in a foreign language with a computer have been studied under different traditions (intelligent tutoring systems, dialogue systems, conversational agents, chatbots…). We attempt to offer a structured overview of these efforts into a conceptual framework, including an operational definition of dialogue-based CALL and a typology of systems (4 types: narrative, form-focused, goal-oriented and reactive systems) and types of dialogue, with their corresponding interactional, instructional and technological traits. We summarize the main results from empirical studies on such systems, and discuss the impact of dialogue-based CALL on motivation and L2 development.