Introduction: Under the influence of Vygotsky, dynamic assessment (DA) has recently crept into the realm of L2 testing to assess learners' cognitive modification through the concept of mediation and zone of proximal development (ZPD) (Ableeva, The Effects of Dynamic Assessment on L2 Listening Comprehension 2008; Lantolf, Sociocultural theory and the pedagogical imperative 2010). Computerized dynamic assessment (C-DA) is introduced as a technological offshoot of DA which has the applicability to provide a more vivid picture of learners cognitive functioning (Poehner, 2008). DA proponents proposed that the presentation of mediations is the only option to assess and assist learners' ZPD and cognitive functioning. Result: In this study, response latency (RL), with the potentiality to analyze on-going information processing of mind, is employed as a measurement tool in assessing learners' cognitive functioning via C-DA form of an L2 reading comprehension task borrowed from Philips (Longman complete course for the TOEFL Test: preparation for the computer and paper tests, 2001). A software was programmed based on Campione and Brown's (Dynamic assessment: one approach and some initial data, 1985; Dynamic assessment: an international approach to evaluating learning potential, 1987). Graduated Prompt Approach, an adapted version of Guthke and Beckmann's (Dynamic assessment: prevailing models and applications, 2000), and Aljaafreh and Lantolf's (Mod. Lang. J 78:465-483, 1994) hierarchical presentation of mediations to record the learners' passive RL. Conclusion: The results reveal that learners' with larger ZPD not only reached the answer with implicit mediations but also reflected shorter RL in reaching the correct answer. The learners' information processing also expedited through presentation of mediations.