Harald Clahsen

Lexical processing and the mental lexicon

An adult native speaker of English with a normal speech rate produces more than 150 words per minute – on average, more than one word every half second. Indeed, under time pressure, for example, when you are calling your friend in New Zealand from a public telephone in Britain or the United States, a native speaker can produce one word every 200 ms, which is less than a quarter of a second, and your friend can still understand what you are saying. The lexicon of an average native speaker of English contains about 30,000 words. This means that in fluent speech you have to choose continuously from these 30,000 alternatives, not just once, but two to five times per second, and there is no clear limit on how long you can indulge in this process. Furthermore, your friend is recognising your words at the same rate at the other end of the telephone line. If you wanted to, and had enough money, you could make the telephone companies happy by talking to your New Zealand friend for hours, with a decision rate of one word every 200–400 ms. Incredibly, despite the high speed of lexical processing, errors in the production and comprehension of words are very rare. Research has revealed that in a corpus of 200,000 words, getting on for twice the length of this book, only 86 lexical errors were found, i.e., fewer than 1 in every 2,000 words.