“When I use a word,’ Humpty Dumpty said, in rather a scornful tone, ‘it means just what I choose it to mean – neither more nor less.
Needles to say, many factors appear to play a role in vocabulary development, though the exact nature of the role is not always clearly understood and the findings of some research studies seem to contradict to the received wisdom of the ELT profession and what has been standard practice in the classroom. Some factors are to do with input; in other words, the way in which vocabulary presents itself to learners, for example through teacher presentation, reading words in text, learning words during peer exchange, or through self-access work of some kind. Other factors are to do with storing, organizing, and building vocabulary in the mental lexicon and being able to retrieve or recall it when it is needed.
The mental lexicon has been characterized variously as a storehouse, a library, an encyclopedia, and a computer. All of these are legitimate to a degree in describing its many capacities, but it is at present unclear exactly how learners store and organize words in the mental lexicon and what kinds of relationships are built among words as they are stored. In order to learn words learners use a range of strategies. Some of these can be called cognitive: they are direct mental operations which are concerned with working on new words in order to understand, categorize, and store them in the mental lexicon. Examples are making associations, learning words in groups, and exploring a range of meaning, and using keywords. It is therefore useful for the teacher to be aware of the variety of methods used by learners to cope with words, to encourage learners in effective strategies, and to introduce some of these through teaching.