Until recently, researchers thought intelligence was genetically hard-wired, but a new study from Switzerland suggests that healthy adults and children can improve their mental ability by playing a simple memory game.

The game, called Dual-n-Back, tests memory with visual and audio prompts. Players start by having to remember if an audio or visual cue is the same as the one previous. If there is a match, players press a button. As player proficiency improves, the task changes from having to remember the previous one back to going back two prompts and then three. Some players are able to work their way up to remembering 20 back.

Swiss researchers had participants play Dual n-Back for 25 minutes a day for 19 days. The game engages fluid intelligence: attention span, how many pieces of information a person can keep track of, as well as the ability to adapt to new situations and solve new problems. Researchers found that over time, performance improved by 40 percent.

But game performance wasn't the only thing that improved. IQ scores increased as well. Before beginning the n-back exercise, participants were given an IQ test. The average participant scored 10 correct answers. After 19 days of playing Dual n-Back, however, the average number of correct answers increased to 14.7.

"The most important point of our work is that we can show that it is possible to improve fluid intelligence," said Martin Bushkuehl, a psychology researcher based at the University of Bern, Switzerland, in an interview with Wired. "It was assumed that fluid intelligence was immutable."

Play Dual-n-Back.