669,498 People Took a Grammar Quiz. Here Is What They Revealed About Age

A grammar quiz went round Facebook. It guessed your native language from the mistakes you made, people shared it to prove it wrong, and 669,498 of them finished it.

Behind the quiz were Joshua Hartshorne, Joshua Tenenbaum and Steven Pinker, who had built it to answer a question that had been argued about for decades with samples of thirty or forty people: is there an age after which you can no longer learn a language properly?

Respondents answered 132 grammar items and reported when they had started English and how they had learned it. The result, published in Cognition in 2018, is the largest dataset ever assembled on language and age — and it is more interesting than either camp wanted.

The number, and what it is not

The rate at which people absorbed English grammar held steady through childhood and all the way through adolescence. Then it fell — at around 17.4 years old.

Read that carefully, because almost every article about this study gets it wrong. The learning rate dropped. It did not go to zero. People who started English in their twenties and thirties still improved, and kept improving for decades.

That second half is the part worth owning. The thing that closes early is not learning. It is the chance of being mistaken for a native. Those are very different targets, and only one of them is any use to you.

Adults are faster at the start

There is an older finding that nobody quotes because it is inconvenient for the romance of the child prodigy. In 1978 Snow and Hoefnagel-Höhle followed English speakers of all ages learning Dutch in the Netherlands. In the first months, the adults and adolescents progressed fastest. The young children eventually caught up and overtook them on pronunciation — but the early advantage belonged to the adults.

Adults bring things a six-year-old does not: a first language to map onto, the ability to ask about a rule, strategies, and the capacity to sit through something boring on purpose. What adults usually lack is twelve unstructured hours a day of being spoken to.

What to take from it

1. If you are an adult, your constraint is the calendar, not your brain. Four honest hours a week beats a childhood you did not have.
2. Use the head start. Adults learn faster in the early months — the research has said so since 1978. Front-load the effort while that advantage is live.
3. Stop aiming at native-likeness. Target being understood without effort, which has no documented age limit at all.

Nobody in a Conversation Lab is trying to pass as a local. They are trying to say the thing they mean, at the speed the conversation is actually moving — accent included.

Sources

• Hartshorne, J. K., Tenenbaum, J. B., & Pinker, S. (2018). A critical period for second language acquisition: Evidence from 2/3 million English speakers. Cognition, 177, 263–277. doi.org/10.1016/j.cognition.2018.04.007
• van der Slik, F., Schepens, J., Bongaerts, T., & van Hout, R. (2022). Critical period claim revisited: Reanalysis of Hartshorne, Tenenbaum, and Pinker (2018) suggests steady decline and learner-type differences. Language Learning, 72(1), 87–112. doi.org/10.1111/lang.12470
• Johnson, J. S., & Newport, E. L. (1989). Critical period effects in second language learning: The influence of maturational state on the acquisition of English as a second language. Cognitive Psychology, 21(1), 60–99. doi.org/10.1016/0010-0285(89)90003-0
• Snow, C. E., & Hoefnagel-Höhle, M. (1978). The critical period for language acquisition: Evidence from second language learning. Child Development, 49(4), 1114–1128. doi.org/10.2307/1128751

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