A psychology professor reckons he has found a mathematical explanation for the "learning spurt" children experience while learning language.
How children learn language so quickly has long been debated. One explanation is the "grammar gene" or language instinct posited by Stephen Pinker which suggests children, for a limited period, have an inherent ability to decode the grammatical function of words which helps them memorise and use them.
From about a year and a half until five or six years kids can quickly absorb language. Children unfortunate enough to have not learnt any language by that age will struggle to ever learn any language perfectly. Similarly, adults learning a second language will struggle to ever be as accurate as a child who learnt the language before they were seven.
Bob McMurray, assistant psychology professor at the University of Iowa, says the spurt in language aquisition can be explained if two theories hold true - that children learn more than one word at a time and they learn more difficult or moderate words than easy words. McMurray found that whenever these two are true then children will experience an explosion in the number of words they pick up.
McMurray said: "Children are going to get that word spurt guaranteed, mathematically, as long as a couple of conditions hold. They have to be learning more than one word at a time, and they must be learning a greater number of difficult or moderate words than easy words. Using computer simulations and mathematical analysis, I found that if those two conditions are true, you always get a vocabulary explosion."
The average English speaker has a vocabulary of about 50,000 words but probably only uses between 5,000 and 10,000 regularly.
There's more on the language instinct here ®