My Reflections on Barcroft’s “Input-Based Incremental Vocabulary Instruction”

I recently read Joe Barcroft’s book, Input-Based Incremental Vocabulary Instruction. I first heard about it from this episode of the We Teach Languages podcast. I recommend listening to the episode if you want to get a quick overview of Barcroft’s ideas. And if you want to learn more about the approach, Barcroft’s book explains a lot more. The book presents some of the research findings on vocabulary learning in a way that is relatively easy to understand, and it gives a clear explanation of Barcroft’s approach to vocabulary instruction, called input-based incremental vocabulary instruction (IBI). The book explains the ten principles of IBI and gives some sample lessons to help teachers understand how to apply the principles in their own classrooms.


As you can guess from the name of the approach, Barcroft recommends providing students with a lot of input. He explains that vocabulary acquisition happens gradually over time; learners don’t hear a word one time and instantly learn it. Word meanings are complex, and it takes lots of exposure to a word before a learner fully understands all its meanings and can use the word on their own. For that reason, learners need to encounter a word numerous times through input before they can acquire it.

Barcroft says that most vocabulary acquisition happens implicitly. In other words, we acquire the meanings of words gradually, without consciously realizing we are doing so. He mentions the use of activities such as extensive reading to help students build their vocabulary implicitly. He writes: “Acquiring English or any L2 is largely an implicit process that takes place gradually over time as learners attempt to communicate in the target language” (p. 13).

However, Barcroft also recommends using some intentional vocabulary instruction—in other words, direct instruction in which students consciously study and learn new words. He cites a few of the research studies he has conducted as well as some other studies as evidence that intentional vocabulary instruction can help speed up the vocabulary learning process.

For many of us comprehension-based teachers, the phrase “intentional vocabulary instruction” is almost a dirty word; we tend to associate it with studying isolated words on flashcards or similar activities where words are learned devoid of any context and simply memorized. However, as Barcroft explains, most vocabulary learning is located somewhere along the continuum between intentional and implicit. It’s rare to find vocabulary instruction that is 100% intentional or 100% implicit. Even when a learner is focused on acquiring new words implicitly, there is often a component of intentional learning. For example, if a learner is reading a book for pleasure and sees a word that is new for them, they might stop to look up its meaning, and they might make a mental note to themselves to try to remember that word. In this case, although the overall approach is mostly implicit, there is also an element of intentional vocabulary learning.

If we consider vocabulary learning in this way, I think a lot of teachers—even those who focus on implicit acquisition of vocabulary—already do at least some intentional, explicit instruction. If a teacher pauses for a few seconds to explain the meaning of a new word or to translate it, they are making vocabulary instruction at least a little bit intentional. Even just the act of writing a word on the whiteboard often sends the signal to students that it is an important word to know, which encourages students to consciously focus on it, even if just for a few seconds.

According to Barcroft, even just a small amount of direct instruction can help students remember new words better. He says that “simply instructing learners to attempt to learn new words in a text (and telling them they will be tested on the words) can substantially increase vocabulary learning during reading (e.g., Barcroft, 2009; Hulstijn, 1992; see also Paribakht & Wesche, 1997)” (p. 23). He also found that some forms of input enhancement, such as writing target vocabulary words in bold in a text, had positive effects on vocabulary learning (p. 25). Some of the other activities he suggests have a stronger emphasis on direct learning, such as having students match target words with their definitions.

As I read Barcroft’s arguments in favor of intentional vocabulary instruction, I immediately started to wonder about the research design of these studies. How were the students tested? Were they tested over the long term? I know that many of the claims made in favor of explicit instruction often rely on studies in which students were only tested in the short term (i.e., a few hours after receiving the treatment), which is a problem since other studies have shown that explicitly learned information tends to fade over the long term.

In the studies that Barcroft conducted himself, the longest amount of time between the treatment and the delayed post-test was one week. I have to admit that I am a little skeptical of considering one week as evidence of long-term effects. In my opinion, one week is a pretty short period of time. I hope that more research can be done in this area, especially research studies that test students over the long term (longer than just one week!) to see exactly how long the effects of direct vocabulary instruction last.

There is also the question of time on task. Which approach leads to the most gains in vocabulary acquisition based on words acquired per minute? Barcroft briefly mentions this issue in his book when talking about the involvement load hypothesis. He points out that although Hulstijn & Laufer’s 2001 study found that having students write a composition using their new vocabulary words led to more vocabulary gains than simply reading a text using those words, the composition-writing activity also took more time than reading the text, which calls into question whether it was really the most efficient approach. This idea reminded me of Beniko Mason and Stephen Krashen’s 2019 study in which they found that students who simply listened to a story had greater vocabulary gains per minute than students who listened to the story and did follow-up vocabulary practice activities. On the other hand, this study from Amiryousefi and Kassaian (2010) reported the opposite finding. Clearly, there is a need for more research in this area. And it would be great to see research that focuses on the overall, long-term impacts of different conditions. For example, although the students in these studies who simply read a text didn’t remember the target vocabulary words as well as the students who consciously studied the words, the students who read the text were also exposed to more language overall. Perhaps their overall vocabulary proficiency increased more if we consider all the words they were exposed to, not only the target words being tested in the study.

I think it’s also important to consider learner motivation. Many students find intentional vocabulary learning activities such as using flashcards or doing matching activities boring. That’s not to say that these activities should never be used, but it is something to consider when deciding how much time to spend on direct vocabulary instruction in class.

While reading this book, I also started thinking a lot about why intentional vocabulary instruction might be helpful. Is it helpful in and of itself? Or is it helpful because it makes the input learners receive more comprehensible? In some cases, intentional vocabulary instruction is simply a way of making the input more comprehensible. If a learner uses a completely implicit approach to language acquisition, there’s a lot of language they hear or read but don’t understand. On the other hand, someone who uses a mostly implicit approach but also takes a moment periodically to look up the meaning of words or even occasionally study words using flashcards is making those words more comprehensible to themself. Having a clearer understanding of the word meanings then speeds up the acquisition process.

In the book, Barcroft also busts some of the common myths of vocabulary teaching. For example, a common vocabulary practice activity in language classes is to have students write sentences using their new vocabulary words. But Barcroft cites research evidence showing that this activity negatively affects students’ learning of new words if done in the early learning stages. Some teachers will also probably be surprised to learn about the possible negative effects of having students copy down new vocabulary words. One of Barcroft’s research studies showed that having students copy new vocabulary words made them less likely to remember those words later when compared with words that students simply saw displayed on a screen with a picture but didn’t copy.

However, Barcroft does not think that students should never produce output using new vocabulary words in class. In fact, he cites research studies showing that producing output using the target words increases students’ ability to remember and use them. He explains that there is a difference between producing output “without access to meaning” and “with access to meaning.” He defines output without access to meaning as “repeating what one hears in a ‘parroting’ manner instead of attempting to retrieve and produce a target word or phrase on one’s own” (p. 26). Having students copy down new words or doing “repeat after me” activities are clear examples of vocabulary activities without access to meaning. On the other hand, having students produce output with access to meaning refers to activities that require students to retrieve target words on their own, such as having them do a cloze activity where they need to write the correct target vocabulary words in the blanks. Barcroft says: “Research findings suggest that only output with access to meaning is going to have a positive effect” (p. 27).

The terms “with access to meaning” and “without access to meaning” were new to me, but I think this distinction aligns with the same principles as other types of communicative approaches to language learning. It provides further evidence that students develop competency in a language not by breaking the language into pieces and repeating those pieces over and over but instead by interpreting and expressing real messages for real purposes.

Barcroft also emphasizes that learners should always receive input before producing output when learning new vocabulary words. He writes: “If students are required to use new words in activities before they have had sufficient opportunities to process them as input, the students may struggle to perform the activities and not learn the target words as well” (p. 19). That’s why Barcroft argues against using activities like sentence writing in the early stages of vocabulary learning. At later stages, though, Barcroft says it is important “to create conditions that allow learners to produce the target vocabulary in an increasingly fluent manner in different communicative contexts” (p. 38).

Of course, my main question as a teacher is: How do we know when students have processed the target vocabulary words as input enough times and are ready to produce them in output? Unfortunately, the book doesn’t really answer this question, though I don’t think anyone can answer the question definitively right now. Hopefully future research can shed more light on this question. And, of course, we can do some experimenting in our own classes to try to find the optimal time to start expecting output from our students.

In the meantime, though, I do plan to implement some of the ideas that Barcroft mentions in his book. I think his overall approach is a good one: that we should focus on providing students with a lot of meaning-based comprehensible input while occasionally sneaking in a little bit of intentional, direct instruction to complement the implicit process and that we should give students opportunities to produce output after they have had sufficient exposure to input. As always, finding the appropriate balance is the key. We’re probably never going to know for sure the exact proportion of time to spend in each area (90% input and 10% output? 75% input and 25% output?), but we can try our best to find the combination that works for our students.


Barcroft, J. (2009). Effects of synonym generation on incidental and intentional vocabulary learning during second language reading. TESOL Quarterly, 43, 79-103.

Hulstijn, J.H. (1992). Retention of inferred and given word meanings: Experiments in incidental learning. In P.J.L. Arnaud & H. Béjoint (Eds.), Vocabulary and Applied Linguistics (pp. 113-125). London, England: Macmillan.

Hulstijn, J.H. & Laufer, B. (2001). Some empirical evidence for the involvement load hypothesis in vocabulary acquisition. Language Learning, 51, 539-558.

Paribakht, T.S., & Wesche, M. (1997). Vocabulary enhancement activities and reading for meaning in second language vocabulary acquisition. In J. Coady & T. Huckin (Eds.), Second language vocabulary acquisition (pp. 174-200). Amsterdam, Netherlands: John Benjamins.

3 thoughts on “My Reflections on Barcroft’s “Input-Based Incremental Vocabulary Instruction”

  1. Tracy

    Thank you so much for this thorough review. I read his routledge book on the same topic but found it difficult to understand, so I want to read his original book. I like your analysis. I don’t agree with him on several points and share your skepticism about some other points.


    1. Thanks for the comment, Tracy! Yes, I found the book interesting, even though I was a little skeptical about some things and wish he had gone into more detail to explain them. I haven’t read the Routledge book, so I don’t know how similar the two books are.


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