Working memory-learning condition interactions

The second experiment was designed to test for any possible interactions between working memory and learning conditions. As such, it was important to characterize the amount of experience in a given learning condition, with an especially close examination of the extent of formal training as a percentage of overall experience for the two

combined conditions. To test for interactions, a moderated regression was utilized. This procedure examines any moderating effect upon WM by a given learning context. Consequently, the moderated regression may yield results that indicate significant interactive relationships for aspects of proficiency whereas a standard logistic regression may yield no significance between WM and the same measure.

For the moderated regression only data specifically related to the three distinct learning conditions was evaluated, with tests for interaction conducted between WM and both overall experience and the extent of formal experience for the NF and FN contexts. Since the native-likeness measure represents an overall average of the two main

components tested (accuracy and fluency), and not a specific aspect of proficiency, the main proficiency measures that were considered necessary for the interaction experiment were accuracy, fluency, and fossilization. However, for the sake of comparison, an additional moderated regression was performed on NL data. Results appear to indicate a significant interaction occurring between WM and one main aspect of proficiency within the naturalistic condition, and one of the components for learners in the FN condition. Significance was also found for the additional regression conducted with NL data for the FN context. No significant interactions were found for the NF learning condition.

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For naturalistic learners, results indicate no significant interaction between WM and two of the three proficiency measures analyzed, including accuracy (F(1) = 1.290, p. = .282) and fossilization rate (F(1) = 1.080, p. = .329). A significant interaction between working memory and naturalistic experience was found for NC learners for fluency, however, with a significance of F(1) = 5.704, p. = .038. The Tukey post-hoc test further showed, however, that significance was only found between low and high levels of WM; the level of significance between low and high levels of WMC was p. = .046, whereas the level was p. = .209 between Average and high WMC learners, and .292 between low and Average-level learners (for tabulated results see Appendix D).

With respect to learners who have followed up naturalistic experiences with formal training, the results of the current study indicate no significant interaction between either the amount of naturalistic experience and WM, or the proportion of overall experience consisting of formal experience and WM. The complete lack of any statistically significant relationships between WM and any component of proficiency in the NF condition, whether in terms of either predictive or interactive relationships, is an interesting finding in this study. However, a reversal in the sequence combination of these two learning conditions, with formal training preceding naturalistic learning, appears to indicate a level of interaction between WM and formal experience: for FN learners, significance was found in the interaction between WM and accuracy. Out of curiosity the procedure was also repeated for the measure of the degree to which overall speech is native-like: results for this test demonstrated a significant interaction between WM and the overall proficiency ability or native-likeness score.

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For FN learners a significant level of interaction (F(2) = 37.436, p. = .001) was found between WMC and this learning condition in relation to accuracy. It is also interesting to note that when considered separately, the amount of formal experience as a percentage of overall learning experience also shows significance as a predictor of

accuracy via the regression analysis: F(4) = 6.401, p. = .033, whereas WM alone does not show a significant relationship (F(1) = .440, p. = .537). The post-hoc analysis was not necessary since the data for WM under the FN condition only includes two groups. A significant level of interaction was found between several levels of WM and different amounts of formal training, ranging from very low to very high percentages of formal experience: between average levels of WM and a very low amount of formal training the significance was p. = .003, between Average WM and an average amount of formal training significance was found to be p. = .045, significance was found between Average WM and very high amounts of formal training at p. = .001, and high WM and high levels of formal training showed an interaction with significance at p. = .003 (tabulated results are presented in Appendix D). The results can be interpreted to mean that the variable of WM does not work independently of formal experience (WM alone shows no significant relationship with learner accuracy, with the level of significance at p. = .537), while it does work together with formal training to affect learner accuracy. These results indicate a fairly robust interaction between working memory capacity and the extent to which overall learner experience in the FN condition is comprised of formal classroom training, a finding that fits in with the patterns observed between both accuracy and the number of potentially fossilized forms and formal experience described in Section 4.1.

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Although the measure was not included in the experimental design for the interactive analysis, for the overall measure of proficiency represented by the native- likeness score, results also appear to demonstrate an interactive relationship between WM and the amount of formal experience for the FN condition: the additional analysis

indicated a significance of F(2) = 12.088, p. = .012. For the NL measure, neither WMC nor the percentage of experience comprised of formal training indicated any independent significant relationship with the NL score (See Appendix D for tabulated results).