Longer words tend to carry more information, according to research by a team of cognitive scientists. It's a suggestion that might sound intuitively obvious, until you start to think about it. Why, then, the difference in length between 'now' and 'immediately'? For many years, linguists have tended to believe that the length of a word was associated with how often it was used, and that short words are used more frequently than long ones. This association was first proposed in the 1930s by the Harvard linguist George Kingsley Zipf1.
Zipf believed that the relationship between word length and frequency of use stemmed from an impulse to minimize the time and effort needed for speaking and writing, as it means we use more short words than long ones. But Steven Piantadosi and colleagues at the Massachusetts Institute of Technology in Cambridge say that, to convey a given amount of information, it is more efficient to shorten the least informative — and therefore the most predictable — words, rather than the most frequent ones. Zipf's original association is roughly correct, as implied by how much more often 'a', 'the' and 'is' are used in English than, say, 'extraordinarily'. And this relationship of length to use seems to hold up in many languages. Because written and spoken length are generally similar, it applies to both speech and text.