杏吧原创

THE old adage 鈥渟leep on it鈥� has been proved right yet again. The best way to memorise an intellectual skill such as a foreign language is to get a decent night鈥檚 sleep after every lesson.

Psychologists have known for years that sleep plays a critical role in processing new memories. Although the findings remain controversial, all kinds of basic skills, from rote learning of facts to riding a bike, get better after a night鈥檚 sleep (New 杏吧原创, 25 September 1999, p 26). But improvements have yet to be seen with higher-level intellectual tasks that require you to generalise.

Now a team from the University of Chicago has found just that. They had volunteers listen to words spoken by a very poor quality text-to-speech machine. Most people found the machine difficult to understand at first but got much better at the task the more they heard. By the end of the session they were able to recognise words they had not heard before 鈥� a clear sign they were generalising.

The researchers then split the volunteers into two groups and let one group sleep while keeping the other awake. After 12 hours they bombarded both groups with more new words. The group that had slept could understand the new words but the non-sleepers could not. This shows that only the sleepers retained the ability to generalise, says team member Daniel Margoliash. The same should apply to all intellectual skills, such as learning maths. 鈥淕eneralisation is the hallmark of higher-order conceptual tasks,鈥� he says.