The purpose of the present quantitative meta-analysis was to examine the magnitude of the effect of text-based synchronous computer-mediated communication (SCMC) on second language acquisition (SLA). This meta-analysis synthesized eleven primary experimental and quasi-experimental journal articles and doctoral dissertations that had used SCMC as supporting tools on second language learning. The purpose of the present study was to investigate (1) the overall effect of SCMC on SLA, (2) whether SCMC has favorable effects on certain target language features (e.g., oral performance, grammatical competence, lexical development, pragmatic development, and writing performance), and (3) whether learners’ L2 proficiency level, treatment intensity, and grouping affect the effect of SCMC on SLA differently. Fifteen key words were combined with two main terms “computer-mediated communication” and “synchronous computer-mediated communication” during the literature search that was conducted in five databases: (1) Educational Resources Information Center (ERIC), (2) Linguistic and Language Behavior Abstracts (LLBA), (3) PsycINFO, (4) ProQuest Digital Dissertation Full Text (PQDT), and (5) Social Science Citation Index (SSCI).
Moreover, ten journals that have published SCMC studies were manually checked, and the reference sections of both review articles and retrieved primary studies were consulted. Besides, doctoral dissertations providing sufficient statistical data for the effect size calculation were included. After the selection of eligible primary studies with inclusion and exclusion criteria, the included primary studies were coded according to study features by two coders, and eleven primary studies with sufficient statistical data contributed to the effect size calculation. The effect size d values were calculated by contrasting data from three pairs of contrasts: (1) experimental groups and comparison groups, (2) experimental groups and true control groups, and (3) pretest and posttest. The obtained effect sizes were averaged across the primary studies to examine the overall effect of SCMC, and the effect sizes were also combined and compared based on: (1) target language features, (2) learners’ L2 proficiency levels, (3) the duration of treatments, and (4) the way of grouping in SCMC activities.
A small-sized overall effect (d = 0.25) indicates that SCMC had a small impact on SLA. Among the five target language features examined in the studies, SCMC seemed to be more effective (d = 0.40) on oral performance than on other four subgroups. As to L2 learning conditions, the results showed that SCMC had statistically significant small effects on mid-level learners (d = 0.39), long treatment duration (d = 0.42), and group work in SCMC activities (d = 0.35). However, due to the small number of study samples, the mean effect sizes for some subgroups did not reach the statistically significant level. Since SCMC generally has small effects on SLA, the arrangement of SCMC and other types of instruction in classroom becomes important. In the future, a qualitative research synthesis that addresses the effects of SCMC on second language learning could be conducted to complete the whole picture of the SCMC impact on SLA.

References
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