| The purpose of this investigation was to synthesize (by means of a meta-analysis) the results of primary research studies, which examined the relationship between Universal Grammar and Second Language Acquisition, in order to discern whether second language learners do have full access to Universal Grammar.;In order to proceed with this investigation, primary research studies were retrieved through a multiple channel approach: a combination of manual and computer searches. A set of criteria was established to determine which of the retrieved studies would be included in this meta-analysis. Using these criteria, fifteen primary research studies could be included in this meta-analysis.;The unit of analysis for this study is the sample unit of analysis. These fifteen studies yielded 22 independent samples, on which the subsequent analyses were performed.;Using effect sizes (Cohen's d-index) as the measure of the outcome of the primary study's sample(s), 70 effect sizes were generated. Each of these effect sizes was weighted and averaged to produce an overall effect size for this meta-analysis. The overall mean effect size produced was 1.25 with a standard deviation 0.68, a very large effect size. In addition, a confidence interval was calculated on this mean effect size. The lower limit was 1.17, and the upper was 1.31.;Based on the premise that the mean effect size would approach zero if second language learners do have full access to Universal Grammar, the above results indicate that they do not. Moreover, the confidence interval test does not contain zero, which confirms that second language learners do not have full access to Universal Grammar.;Sixteen variables associated with the Publication, Participant and Design characteristics were analyzed to determine if any of these variables had an influence on the effect size generated for each sample. This examination shows that the Target Language being tested does have an influence on the effect size associated with each particular sample.;Overall, the results of this investigation contribute to a better understanding of the relationship of Universal Grammar to Second Language Acquisition. Implications for future research are discussed. In addition, implications for teaching of a Second Language are discussed. |
