Studies show that vocabulary size is the most significant individual factor contributing to language proficiency.
The number of words you know accounts for anywhere from 50% to 70% of proficiency gains depending on the language and the skill being studied.
But what does it mean to really know a word? You have to consider vocabulary depth in addition to breadth.
Vocabulary breadth is quite simple to measure objectively: how many words do you know? Depth, on the other hand, is much more nuanced: how well do you know those words? We’re not just talking about spelling, pronouncing, or defining a word. A native speaker’s depth of knowledge about any given word goes much, well, deeper than that. It includes and understanding multiple meaning senses, implied connotations, and a range of collocations and expressions associated with that word.
Consider, for example, the dictionary entry for a common verb like break, shown below. While the spelling, pronunciation, part of speech, and primary meaning sense are covered in the first three lines, this accounts for less than 2% of the information contained in the entire entry.
The beginning learner will learn that break means to separate, or cause to separate, into pieces as the result of a blow, shock, or strain. But there are 33 other meaning senses listed in this entry (some dictionaries list even more!), most of which are known to virtually all adult native speakers of English. You can break the law, break someone’s heart, break a strike, or break a horse; a wound can break the skin, and if the microwave stops working we will say that it is broken, even though it remains completely intact.
And this doesn’t even begin to cover the many idioms and expressions used with break: to break bread, to break the mold, or even “Break a leg!” All of this, and more, is what it really means to know a word, and this is the difference between vocabulary breadth and vocabulary depth.
For beginning language learners, learning as many useful and frequently occurring words as possible is the greatest driver of proficiency. Learning materials are often designed with this in mind — textbooks use word lists to help beginners memorize basic, essential vocabulary without introducing any additional meanings, expressions, or slang.
It’s a logical approach: “the word knowledge aspects that are more amenable to explicit study are likely to be mastered before those word knowledge aspects that require exposure to numerous diverse contexts.”1 But as learners progress into intermediate and advanced levels of proficiency they encounter more and more of these “diverse contexts”, and the depth of their knowledge is tested.
Beginning around CEFR level B1, as learners begin reading a broader range of authentic materials (written by native speakers, for native speakers), and as they are increasingly capable of engaging in more meaningful interactions with native speakers, they will begin to encounter the extended meaning senses, implied connotations, and idiomatic expressions that are typical of both written and spoken communication between native speakers.
It’s at these levels that, as learners continue to expand the breadth of their vocabulary knowledge, they should begin to consciously think about circling back around to the core vocabulary they’ve already “learned” and adding to the depth of their knowledge about those words.
Learn words in context. Read short stories, news articles, novels, or poetry in the target language. Listen to music and search for the lyrics. When you see a familiar word used in an unfamiliar expression or with a meaning sense that you haven’t encountered before, ask a native speaker about it; this can be a great way to engage in meaningful conversation and to learn more about the cultural contexts associated with these extended meaning senses, expressions, and idioms. Or look it up in the dictionary and take note of the many different meanings and uses. The first few additional meaning senses listed in dictionary entries are usually presented in order of frequency from the more frequent to the less frequent.
Use authentic materials. You don’t know what you don’t know, but greater exposure to authentic language use will introduce you to new meaning senses of words you already “know”, new expressions, slang, abbreviated speech, and other facets of language that you won’t find in textbooks or word lists. Listen to the radio, read song lyrics, watch TV shows or even commercials—they are all rich in new, deep knowledge of the language.
Engage in conversations. Depth is not just about understanding, but also production. You may understand a certain collocation or expression when you read it, but do you know when it’s appropriate to use it in conversation? This comes with practice hearing and producing the language with a teacher, Skype conversation partner, or other native speakers.
Works Cited:
1 Schmitt, Norbert (2014). Size and Depth of Vocabulary Knowledge: What the Research Shows