Fred Genesee

Exposure vs Comprehensible Input

One of the central concepts in second language acquisition research is that learners must understand the language they encounter to learn it. Krashen’s classic work, Principles and Practice in Second Language Acquisition, called this “comprehensible input.” (I consider this essential reading for ELT practitioners and students so I’m hosting a free copy here.)

“Comprehensible input” is different from “exposure.” “Exposure” simply means that the learner has contact with a language. It’s essential, but it’s not enough.

If learners have comprehensible input, then they, necessarily, have exposure. But exposure without comprehensible input will result in very little learning.
It’s important that educators recognize this distinction because it can have a profound influence on the design of educational programs and materials. I’ve seen programs that made no effort to choose materials that their students could understand and that just doesn’t work.

One of the reasons that there is confusion on this point is that we see misleading headlines like this one from the New York Times: “Language Acquisition is a Matter of Exposure.” Articles like this could lead educators and administrators to believe that learners only need to have contact with a language to learn it – that immersion, alone, will result in learning, when, in reality, students must understand a large percentage of what they are exposed to in order to acquire language.


We can better understand why an article like “Language Acquisition is a Matter of Exposure” seems to overemphasize the role of exposure if we recognize the agenda of the writer and researcher. One of the main goals of this research, by Fred Genesee, was to promote immersion programs by relieving the fears of monolingual audiences that mistakenly believe bilingual programs could be harmful to young learners. But, read Genesee’s work carefully, and you will see that Genesee, too, recognizes that learners must understand and use the language in order to acquire it. Genesee has done a great deal of work in bilingual and dual language instruction.

But in this NY Times article, notice that Genesee says…

“Parents or caregivers must ensure that children get a certain amount of exposure to the language, and that this exposure is consistent, continuous and rich.”
Here Genesee is making it clear that the children are receiving language from “parents and caregivers” and that the exposure must be of a certain quality. The fact that the children are receiving language from “parent and caregivers” assumes the presence of interactions typical of adult caregivers with children…

We have a long history of scientific evidence showing that this type of caregiver interaction is essential to the development of infants. In short, this type of interaction cannot be separated from the apparent ability of infants to so easily learn language. This type of interaction is clearly designed to make the language comprehensible to the child.

In other work, Genesee explicitly states that the programs he has researched, immersion programs, meet Krashen’s requirement:

“Krashen and other researchers have argued that comprehensible input is important for second language acquisition. That is to say, students can only acquire language that they can understand. In this regard, immersion programs provide extensive comprehensible input. This is evident from the impressive performance of immersion students on tests of comprehension.”
So, Genesee’s work centers on exposure, but he clearly recognizes and promotes the idea that learning also requires comprehensible input. This is an important distinction for educators to make when choosing and designing language programs and materials.

Genesee and several others have published a very useful synthesis of research done on the development of English language learners in the U.S. schools. A Kindle version of the book-length report, “Educating English Language Learners: A Synthesis of Research Evidence”, has been released very inexpensively and would make an excellent source for any research scholar writing on the issues surrounding multilingual education.

The printed version is also available in India.

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