Dynamic assessment (henceforth DA) understood as a subset of interactive assessment has been prolifically utilized by the interested scholars in L2 context (Aljaafreh & Lantolf, 1994; Lantolf, 2001; Ableeva, 2008; Anton, 2009) to revitalize Vygotsky's enamored notion of the Zone of Proximal Development (ZPD) and shed a more nuanced light on the learners' underlying abilities encompassing the present abilities as well as the future-in-the-making. The focus of this study is to measure the effects of delivering textual and visual scaffolding in a computerized fashion on L2 readers' comprehension processes and, in this way, bring to surface the hidden ‘floor effects’ (Caffery et al. (2008). The study relied upon Vygotsky's (1978) notion of ZPD, Brown's (Brown & Ferrara, 1985) Graduated Prompt Approach and Guthke's (2000) recently developed computerized model of dynamic assessment (C-DA). The cohort consisted of 50 intermediate students of English major who took a dynamic test of reading comprehension. The reading text was a short description of an event given to students to identify their zone of actual development (ZAD). Upon their failure to find the correct answer, the manipulated version characterized by highlighting and underlining was offered and finally closed by the visual prompts so as to find the learners' zone of proximal development (ZPD). The results indicated that through computerized dynamic assessment one can more vividly diagnose the students' underlying abilities in terms of both independent (ZAD) and assisted (ZPD) performance abilities. From didactic standpoint, it is recommended that the C-DA be used as a complementary and more valid procedure to assess the reading ability of L2 learners. The procedure is also assumed to be useful for standardized, high-stakes testing as it lends itself to a large group of testees.