Memory sticks: Can I learn subliminally?

• 09:57 08 April 2011 by David Robson

The idea that we could learn while asleep was once the stuff of dystopian science fiction. In both Aldous Huxley's Brave New World and Anthony Burgess's A Clockwork Orange, authoritarian regimes use sleep learning to brainwash the lead characters. For a while it also became the mainstay of numerous teach-yourself courses that claimed you could learn a foreign language while you napped. Experiments to test this idea produced some promising results initially, though critics wondered whether the subjects might be feigning sleep as the recordings played. Sure enough, when researchers started measuring participants' brainwaves to make sure they were truly in the land of nod, the effects all but disappeared (Journal of Experimental Psychology, vol 51, p 89).

The hope of effortless learning has not completely vanished, however. Now there is a suggestion that you don't always have to actively pay attention to remember something. Last year, Beverly Wright at Northwestern University in Evanston, Illinois, trained volunteers to discriminate between two sounds of nearly identical pitch. Some groups slaved away at the task for the whole study period. Others trained actively for half the time, then listened passively to the sounds for the rest of the period while performing an unrelated written task.

The result? Both achieved pretty much the same level of accuracy on the subsequent test - provided that passive listening came soon after active learning (Journal of Neuroscience, vol 30, p 12868). "Within half an hour the effect begins to go away and by 4 hours it's definitely gone," says Wright. Intriguingly, the outcome was the same when the passive stimulation came first. You cannot skip active practice completely, however: passive stimulation on its own held absolutely no benefits.

Although Wright's study involved a highly specific task, she believes students learning a language, or musicians learning a tune, should benefit from a similar mix of active study and passive listening. You could spend 30 minutes speaking a language and then 30 minutes listening to a podcast in that language while playing on the Wii, for example.

Read more: The other six secrets of memory mastery

Memory sticks: Seven ways to remember anything
Want to remember pi to 67,890 digits? Learn Swahili? Or just ace that midterm exam? David Robson reveals the secrets of the memory masters

Memory sticks: How do the champions do it?
Mnemonics helped one man recite pi to 67,890 places. Another could recite a 50-number list backwards after just 3 minutes' study, thanks to synaesthesia

Memory sticks: Do mnemonics work?
Memory champions swear by them – now two psychologists have found out if mnemonics are useful in day-to-day life

Memory sticks: How should I bone up for a test?
Come exam time, which method provides the biggest pay-off from hours of hard study?

Memory sticks: Does it matter when I study?
Helps your brain reinforce its memory traces by pacing your study and matching it to your sleep patterns

Memory sticks: Can I expand my short-term memory?
New techniques have increased memory span by around 15 per cent over a training course of five weeks

Memory sticks: When is it too late to bother?
A septuagenarian who started training his memory at the age of 58 can now recite all 60,000 words of Paradise Lost with amazing accuracy

David Robson is a feature editor with New Scientist