How Many Words Can You Acquire in a Year?

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There is an exchange in the current issue of Reading in a Foreign Language regarding papers that Paul Nation and I published on the number of words one can acquire through free reading. The original papers are here:

The exchange is here:

I will add just two brief comments:

(1) Nation agrees with Cobb that there is no “hard evidence” that second language (L2) students can acquire 1,000 words a year via free reading. If by “hard evidence” he means a longitudinal study of a group of students measuring their vocabulary growth exclusively from reading, then I agree completely. I would only add that we also lack any such evidence that direct instruction can result in a gain of 1,000 words a year. In fact, we lack long-term studies of this sort for most pedagogical interventions in the L2 field.

All estimates – mine, Nation’s, Cobb’s – extrapolate from the results of short-term studies and corpus analyses of the sort Nation carried out. Specifically, an estimate of the number of words you can acquire in a year is based on (a) how many occurrences are needed to acquire a new word family (Nation estimated 12); (b) how many words are read (the product of time spent reading and reading rate); (c) how many unknown words occur in a text; and (d) how often words at different word-family levels occur in running text. A change in any of those variables changes the final estimate.

My estimates assume that Nation’s numbers and logic are correct. If they are wrong, I am happy to revise them. But that case must first be made, and Cobb in my view does not make it.

Even better would be an affirmative case that direct instruction or some “balanced” approach would be a better use of class time than free reading. As I noted in my response, the current evidence suggests that they are not.

(2) My rebuttal fails to mention a paper by Mason and Krashen (2010) in which they make essentially the same points I do regarding the fragility of learning versus acquisition and the time inefficiency of direct instruction for vocabulary. They do in a few paragraphs what takes me several pages.

Mason, B., & Krashen, S. (2010). A reader response to File and Adam’s “The reality, robustness, and possibility superiority of incidental vocabulary acquisition.” TESOL Quarterly, 44(4), 270-293.

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