The introduction of Vygotsky's sociocultural theory (SCT) into the second language (L2) domain provides a potential site to explore the mechanisms underlying L2 learners' cognitive modification and the transformation of social understanding into the personal one. This study provided a picture of L2 personalization in two groups of advanced and intermediate English Language (EL) learners. Software was designed to present 25 consecutive statements and capture two groups of EL learners' intra-psychological process by asking them to present their perspective toward a social event in two ways: a) giving punishment and blame scores to the main character; and b) provide oral comment for each episode. The software also recorded the two groups of learners' response latency. The findings brought to surface L2 sociogenetic mental functioning in internalization/externalization process and presented the evidence of individualistic personalization in EL learners. The learners transformed the presented contexts through internalizing/externalizing their intra-mental operations by interpolating and integrating their personal beliefs and knowledge.