Why Can You Understand English but Not Speak It?

By Dr. Jeff McQuillan, Ph.D. in Applied Linguistics and Education, University of Southern California

You can understand more of a language than you can speak or write. This is normal. It is true for everyone who learns a second language. We linguists sometimes call this the "receptive-productive gap" (Webb, 2008, and Shin, Chon, & Kim, 2011).

Several researchers, such as Webb (2008) and Shin, Chon, and Kim (2011), have shown that learners recognize far more words than they can actually use. This is one reason you understand English in many cases but you cannot speak it.

What is the receptive-productive gap?

The receptive-productive gap is the difference between the words you can recognize and the words you can use. Listening and reading are receptive skills. Speaking and writing are productive skills.

In 2008, researcher Stuart Webb tested 83 Japanese university students of English on 180 words. The words were divided into three different levels or "bands," depending on how frequently they were used in everyday English. For the most commonly used words, the students scored 28.4 out of 30 in terms of understanding the words (receptive vocabulary), and 25.1 in terms of using the words (productive vocabulary).

But for the less common words, the two scores were much further apart. Students recognized 18.7 of the 30 less frequently used words, but could produce only 12.1 of them. In Webb's 2008 study, about a third of the less commonly used words learners recognized could not yet be used.

How large can the gap get?

The difference between the words you can understand and the words you can use gets bigger as the words become less frequently used. But at least one study has shown that it can be large even for common words.

In 2011, Shin, Chon, and Kim tested 403 Korean high school English students on the first nine groups of 1,000 words, going from the most commonly used English words to the least commonly used.

In Shin, Chon, and Kim's 2011 study, students scored 9.35 out of 10 receptively and 8.04 productively on the first 1,000 most common words. On the 2,000-level words, their scores continued to be high for receptive vocabulary (9.01 out of 10), but their productive vocabulary was only 4.67 words, less than half. So even for words used in conversational English (roughly, the first 3,000 word families), students had a large gap between what they could understand and what they could say.

Why does the gap exist?

The gap exists because learning a word well enough to understand it takes far fewer encounters than learning it well enough to use it. Research on word knowledge has found that you learn the meaning of a word a little more each time you read or hear it (Frishkoff, Collins-Thompson, Perfetti, & Callan, 2008, and McQuillan & Ediger, 2018).

To know it well enough to understand it typically takes 10 to 15 encounters listening to or reading the word (Pellicer-Sánchez & Schmitt, 2010). But to be able to produce the word takes a lot more than that (Webb, 2007). Since recognizing a word takes fewer encounters than producing it, you can always understand more words than you can say. See more information on our page about how words are learned.

How do you make the gap smaller?

You make the gap smaller by getting more comprehensible input, meaning English you hear or read and mostly understand. Comprehensible input gives you repeated encounters with words in different contexts, and those repeated encounters increase the number of words you can actually say. The number of words you can say is what in part predicts speaking fluency (Uchihara & Saito, 2019, and Tong, Hasim, & Abdul Halim, 2022). Note that speaking "practice" can't create knowledge that isn't in your brain yet (Krashen, 1998). You do not learn to speak from speaking. You learn to speak from listening and reading.

Select listening material you understand at 85 to 95 percent. Do lots of listening and reading of similar material. Over time, you will read or hear words repeated in different sentences, in different contexts, and your brain will automatically learn them.

~ Dr. Jeff McQuillan, from beautiful Los Angeles, California