The task used is called dual n-back. N-back is a memory test where n refers on how many previous stimuli must be remembered. Dual means that verbal auditory stimulus and spatial visual stimulus are presented at the same time. Two memory tests are ran simultaneously and n previous auditory and spatial targets must be remembered separately.

For example, in 2-back series, target sounds are marked red in the following sequence:

s-d-f- d -s-g- g -d- g -t-d-s-g- s

Visual stimuli are green boxes in one of eight positions around the center box. Here are shown a sample sequence and target stimuli are colored red:

You can play the game yourself. Try first single 1-back, spatial or auditory. The main task, which is claimed to raise IQ, is dual 2-back. For most people it is quite a difficult, so try easy ones first. Do simple task until you get continuously over 90% scores and then move on to harder ones.

PLAY!

If you have very old browser with no html5 support, try old version.

For further information, see Jaeggi,Buschkuehl, Jonides, Perrig, "Improving fluid intelligence with training on working memory"

Update 2009-11-28

I noticed there is a commercial dual-n-back software, which is much more convenient to use than this free web applet. You can download it on your computer or use it with iPhone. It got "Top Ten Tech Gifts Under $50" from PC Mag online, so check it out:

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