Zahra Rezaee - English Language Research Center, South Tehran Branch, Islamic Azad University, Tehran, Iran
Parisa Daftarifard - English Language Research Center, South Tehran Branch, Islamic Azad University, Tehran, Iran
Morvarid Lavasani - Department of English Language, Yadegar-e- Imam Khomeini (RAH) Shahre Rey Branch, Islamic Azad University, Tehran, Iran

Dynamic assessment (DA) has been recently used to dominate the realm of pragmatic research. This study investigated the effect of dynamic assessment on EFL learners’ complaint speech act performance, as the most face-threatening one.  Thirty-three participants were selected using the convenience method of sampling. They formed two groups of NDA (non-dynamic assessment) (n = ۱۵) and DA (dynamic assessment) (n =۱۸) and the participants were all lower-intermediate on the Oxford Placement Test. The learners in both groups took a discourse completion test (DCT) as the pretest and posttest. At intervals, the participants in the experimental group took an intervention within the DCT test over five sessions. The gradually constructed hints which were constructed using both literature and experts’ view were given upon the participants’ response. The results of the study using the Rasch model and Classical True Score Theory revealed that DA groups significantly outperformed NDA groups. Furthermore, most of the participants in DA group made considerable changes from the pretest to the posttest. Rasch model reveals that the learners had idiosyncratic zigzagged changes as was predicted by Vygotsky. The findings of the study can shed light on language teaching and materials development for the complaint speech act.

Complaint speech act, Developmental Trajectories, Dynamic Assessment, Pragmatic, Rasch model