Article

No evidence that age affects different bilingual learner groups differently: Rebuttal to van der Slik, Schepens, Bongaerts, and van Hout (2021)

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Abstract

Hartshorne, Tenenbaum, and Pinker (2018, A critical period for second language acquisition: Evidence from 2/3 million English speakers. Cognition, 117, 263-277) presented the first direct estimate of how the ability to learn the morphosyntax of a second language changes with age, showing a sharp decline in late adolescence. Recently, van der Slik, Schepens, Bongaerts, and van Hout (2021, Critical period claim revisited: Reanalysis of Hartshorne, Tenenbaum, and Pinker (2018) suggests steady decline and learner-type differences. Language Learning) purport to show that in fact Hartshorne et al’s (2018) data are better explained by a gradual decline in learning with age, at least for some types of learners. However, these conclusions are based a misunderstanding of their own analyses, which in fact do not test whether the decline in learning is sharp or gradual but whether it is asymmetric, slowing with time. After correcting conceptual and mathematical errors in their analyses, the results strongly confirm the original conclusions of Hartshorne and colleagues: every type of bilingual investigated shows a sharp drop in learning rate in late adolescence.

Keywords: critical period, L2, massive online experiment