Working memory and second language comprehension and production: A meta-analysis

Headnote

Published online: 24 December 2013

© Psychonomic Society, Inc. 2013

Abstract Although working memory (WM) figures centrally in many theories of second language (L2) proficiency development and processing, some have argued that the importance of WM is overstated (e.g., Juffs, Transactions of the Philological Society, 102,199-225, 2004). Despite many studies over the past two decades, the literature lacks a quantitative synthesis of the extant results. In this article, we report a meta-analysis of data from 79 samples involving 3,707 participants providing 748 effect sizes. The results indicate that WM is positively associated with both L2 processing and proficiency outcomes, with an estimated population effect size (ρ) of .255. In additional analyses, we assessed whether the WM-criterion relationship was modulated by potential covariates identified in the literature search (i.e., participant characteristics, WM measure features, criterion measure factors, and publication status). The results of the covariate analyses indicated larger effect sizes for the executive control (vs. storage) component of WM, and for verbal (vs. nonverbal) measures of WM. Minimal publication bias was detected, suggesting that WM has a robust, positive relationship with L2 outcomes. We discuss the implications of these results for models of WM and theories of L2 processing and L2 proficiency development.

Keywords Working memory · L2 processing · L2 comprehension · L2 production · Second language acquisition · Meta-analysis

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Introduction

Robust working memory (WM) effects have been found across a range of complex cognitive processes, including reasoning, problem solving, planning, abstraction, mental ar- ithmetic, and first language (L1) comprehension (Engle, 2002; for a meta-analysis addressing the role of WM in L1 compre- hension, see Daneman & Merikle, 1996). Although theoretical positions vary, there is little argument that these complex cognitive behaviors at least partially rely on the attentional and executive control processes that underlie WM perfor- mance. Second language (L2) processing places demands on these WM resources, too, especially for less-proficient speakers, and growing evidence indicates that executive func- tions support the various cognitive control mechanisms nec- essary for L2 use (e.g., Abutalebi & Green, 2008;Hernandez &Meschyan,2006). It should thus come as no surprise that WM has been implicated in studies of L2 processing (see, e.g., Michael & Gollan, 2005; Tokowicz, Michael, & Kroll, 2004) and learning (e.g.,...