Of all the biometric systems, such as fingerprint, voice and face recognition, iris scanning is one of the more reliable ways of identifying individuals. Every iris has over 250 characteristics, which make up a unique pattern. No two irises are ever alike. In their details and even identical twins have different irises. Neither does your iris change over time, unlike your fingerprint or voice. Compared to fingerprints, which only have around 25 characteristics and can get scratched and scarred, it is a far more reliable way of identifying yourself.

In practice, iris scanning is relatively quick and non-intrusive. A monochrome video camera with a close-up lens takes a picture of the iris. It takes less than tree seconds to capture the image which can be taken from up to a metre away. Systems should be able to cope with such circumstances as different light conditions and users wearing spectacles and even sunglasses, although there is a problem with people wearing mirrored sunglasses. They will also be able to tell if the user is trying is trying to defraud the system with a photograph of an iris by looking for natural contraction and dilation in the pupil.

It may not be long before you have the chance to try it out yourself. NCR, which makes cashpoints for many of the high-street banks, has been looking at the idea for some time, and the Nationwide building society is currently running the first trial scheme in Swindon. BT has also been looking at the idea, mostly for building security.

The six-month Nationwide trial will place iris scanners on counters and on one cash machine in the branch under its head office. To use it you will have to take a few minutes to register with an initial iris scan, but after that you can choose to use the iris scanner instead of signing documents at the counter or keying-in your PIN number at the cashpoint. If the pilot scheme is successful, it could still be 18 months to two years before the technology is deployed in the high street.

NCR developed the prototype cashpoint used by Nationwide at its research laboratories in Dundee. Richard Lander of NCR says the company has been looking at various biometric systems including eye, hand, face and voice recognition, and points out that iris scanning does not suffer from the problems inherent in other biometric systems like the weather, noise and ageing.

Lander predicts it will not be the new technology itself that attracts, but the advantages it offers:"There will probably be the usual objections there are with any new technology. People feel that a little bit of their soul is being eaten up.It will make consumers more secure, but the services that can be offered are the most important draw." New cashpoints will be able to offer everything from ordering cinema tickets to printing out share certificates and organising bank loans.

The list of uses for iris scanning goes way beyond cash points. It could be used with SmartCards, which have memory onboard to store personal details, to perform any number of different functions, letting you access your personal details, to perform any number of different functions, letting you access your personal and company files from any PC, authorising access to pay-per-view TV ore replacing your passport when crossing borders. You could even dispense with credit cards: your SmartCard has your bank details and your iris acts as your signature.