Israeli researchers have developed a computer game that gives people the strength to keep negative thoughts in check and stay happy.

Noga Cohen, a research student at the Psychology Department at Ben Gurion University, was determined to find a way to help people stop repeatedly turning over negative or "ruminative" thoughts in their minds.

She decided to develop a computer game that forces players to exercise strict control over what their minds focus on, and then see if they can apply this discipline to unhappy thoughts.

In a joint project with Hebrew University, she found that a half hour "training session" on the game could reduce ruminative thoughts that were triggered by a memory of an unpleasant personal experience. She reached this conclusion by comparing the players of the game with a control group that did not play it.

The tasks in the game were simple: identifying the direction of one arrow from among many, and deciding on the colour of a square.

Dr Cohen's original research only dealt with the very short-term effects of the game, but she now wants to test the lasting effects of repeated play.