Combining Language and Ideas, Challenges for Language Learners Thinking or learning new ideas ("cognition") is hard enough for anyone, but then we add the problem of a difficult language and it makes things much harder. Your mental "computer" is "multi-tasking," working harder. The "cognitive demand" is increasing.
When language teachers add "thinking" or "learning new ideas" as part of the language class, we call this "content-based instruction" (CBI) or "content and language integrated learning" (CLIL).
Language teaching experts have divided the kinds of English skills people have into two classes, BICS (basic interpersonal communicative skills, ordinary talk between people), and CALP (cognitive academic language processing, the kind of language you need when you are learning or talking about school materials or difficult subjects (Cummins, 1979). CALP requires both higher content demand (thinking about content) and higher language demand (harder vocabulary, more advanced forms of grammar).
This description of language is true whether we are reading, listening, writing, or speaking.
As you can see in the second image, because your mental computer can only do so much (we have "cognitive limits"), as the content becomes more difficult, or we think harder about the ideas (cognitive demand), then we need to reduce how much we do with language. And the reverse is also true. If we concentrate on language (being perfectly accurate, or using vocabulary or grammar that we don't know very well), then to do our best learning, we need to decrease the other. This is the "Ideal Cognitive Load" for languge study. It's true for native-speakers as well.
If we try to concentrate (learn or use) language and content that is above our comfort zone, we feel "grief" or frustration (and get tired) and make more mistakes with the language. When learning (practicing) languge, if the language and ideas are too easy, we get bored. (These ideas are based on Csikszentmihalyi, 1997.)
Of course, if we are stressed (anxiety) or tired or have cross-cultural issues that we have to think about or get stressed about, then everything gets even harder!
R. Dickey, July 2010.