collaborative l2 interactivity in diverse zpd-based proximal contexts and interactional competence development

central to vygotsky-inspired sociocultural theory (sct) is the notion of zpd seen by sla researchers as a useful framework within which l2 teaching and learning can take place. van lier (2004) argues that the zpd could be activated in diverse proximal contexts (pcs) and is not limited to the expert-novice scenario. . this study probed whether iranian efl learners' collaborative task performance within different zpd-based pcs results in their development of interactional competence (ic). young's (2011) ic model was used for developing an ic test (ict) employed at the pretest and posttest times. three intact efl listening-speaking classes at a university at southwest of iran were randomly assigned to the expert-novice, equal-peers, and control (non-zpd) conditions. the co-constructed interactions of the groups in (a)symmetrical zpd-based conditions were audio-recorded for further analysis of participants' l2 ic development. a triangulation (quantitative and microgenetic) data-analysis approach was adopted. the results showed that whereas both zpd groups (equal-peers and expert-novice) outperformed the non-zpd group on ic posttests, no statistically significant difference was found between participants' ic development in symmetrical and asymmetrical pcs. further, microgenetic analysis of the zpd groups' interactions demonstrated how participation and activity in different pcs can effectively trigger awareness of mechanisms and norms of l2 spoken interaction and, in turn, result in ic development. the findings point to the applicability of diverse zpd-adjusted pcs, composed of equal or unequal participants, in efl classrooms and also the efficacy of zpd-based interactive scenarios for students' development of l2 ic.