WORKING MEMORY CAPACITY AND LEXICAL DENSITY IN L2 SPEECH PRODUCTION

Weissheimer, Janaina; Mota, Mailce Borges · 2011 · Crossref

DOI: 10.22456/2238-8915.28843

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Summary

This study investigates the relationship between working memory capacity and lexical density in second language (L2) speech production, specifically addressing how these factors influence oral performance and development. Motivated by conflicting findings in prior research regarding the correlation between memory resources and speech complexity, the authors aimed to determine if working memory capacity predicts lexical density and if it influences the development of this skill over time. The research questions focused on whether working memory and lexical density are related and whether individuals with higher or lower memory spans experience different gains in lexical density across testing phases. The study employed a longitudinal, experimental design involving 45 intermediate-level undergraduate English learners in Brazil. Participants underwent two data collection phases separated by a twelve-week interval. In each phase, participants completed a Speaking Span Test (SSPAN), adapted from Daneman (1991), to assess working memory capacity, followed by a Speech Generation Task (SGT) where they narrated picture-cued stories. Lexical density was measured using "weighted lexical density," which calculates the proportion of lexical items to total linguistic items, assigning half weight to high-frequency (repeated) items and full weight to low-frequency (unique) items. This method aimed to capture the trade-offs between using novel vocabulary and relying on formulaic language. The results revealed a negative relationship between working memory capacity and lexical density, contrary to the initial hypothesis that higher capacity would yield more diverse vocabulary. Participants with higher working memory spans produced speech with lower lexical density, characterized by a greater use of high-frequency, repeated lexical items and formulaic chunks. Conversely, lower-span participants produced speech with higher lexical density, utilizing more low-frequency items. Regarding development, only the lower-span group demonstrated a statistically significant increase in lexical density between the two phases. Higher-span individuals did not show significant gains in lexical density, maintaining their reliance on high-frequency items. The authors conclude that L2 speech production involves competing goals, such as fluency, accuracy, complexity, and lexical density, leading to trade-offs. Higher-span speakers appear to prioritize fluency and accuracy by reusing activated, high-frequency lexical items ("islands of reliability"), which reduces cognitive load and allows for faster speech rates with fewer pauses. Lower-span speakers, lacking these resources, produce more lexically dense but less fluent speech. The study implies that working memory capacity inversely predicts lexical density development, suggesting that higher capacity facilitates fluency at the expense of lexical variety. These findings contribute to theories of working memory and L2 acquisition by highlighting the strategic allocation of cognitive resources in speech production.

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• working memory