People regularly using handheld computer controllers such as gamepads and mobile phones are becoming ambidextrous, according to a study released this weekend by Dr Sadie Plant of Warwick University's Cybernetic Culture Research Unit.

The research, conducted across nine cities throughout the world including London and Tokyo, revealed that the thumbs of under 25-year-olds have overtaken their fingers as the most muscled and dextrous digit.

"Discovering that the younger generation has taken to using thumbs in a completely different way and are instinctively using thumbs where the rest of us are using our index fingers is particularly interesting," said Dr Plant. "The relationship between technology and the users of technology is mutual. We are changing each other."

Regular mobile phone users had become accustomed to using several fingers to operate the keypad, while youngsters used minimal movement, adapting to using both thumbs.

But along with the benefits of increased thumb use and improved hand-eye co-ordination come the physical problems associated with such technology, such as Hand Arm Vibration Syndrome from 'rumbling' gamepads and RSI (repetitive strain injury, otherwise known as work-related upper body limb disorder) from mouse and keyboard use.

"Although there are advantages to using equipment, what is important, especially for children, is to use it in moderation and hopefully prevent medical problems," said a spokesman at the RSI Association.

The RSIA said out that one in 50 workers already suffers from RSI, costing industry around £3bn a year.

Plant's research also showed that children were now using their thumbs for other tasks where they would have traditionally used their index finger, such as ringing doorbells. "Thumbs are the new fingers," he said.