Sports shoes that work out whether their owner has done enough exercise to warrant(保证；授权) time in front of the television have been invented in the UK.

    The shoes — named Square Eyes — contain an electronic pressure sensor and a tiny computer chip to record how many steps the wearer has taken in a day. A wireless transmitter(传话器) passes the information to a receiver connected to a television, and this decides how much evening viewing time the wearer deserves, based on the day's efforts.

    The design was inspired by a desire to fight against the rapidly ballooning waistlines among British teenagers, says Gillian Swan, who developed Square Eyes as a final year design project at Brunel University to London, UK. “We looked at current issues and childhood overweight really stood out,” she says. “And I wanted to deal with that with my design.”

    Once a child has used up their daily allowance gained through exercise, the television automatically switches off. And further time in front of the TV can only be earned through more steps.

    Swan calculated how exercise should translate to television time using the recommended daily amounts of both. Health experts suggest that a child take 12,000 steps each day and watch no more than two hours of television. So, every 100 steps recorded by the Square Eyes shoes equals exactly one minute of TV time.

    Existing pedometers(计步器) normally clip(夹在) onto a belt or slip into a pocket and keep count of steps by measuring sudden movement. Swan says these can be easily tricked into recording steps through shaking. But her shoe has been built to be harder for lazy teenagers to cheat. “It is possible, but it would be a lot of effort,” she says. “That was one of my main design considerations.”