It's the stuff of sci-fi films: Machines that know you by your face, your voice or the touch of your finger.

Once restricted to nuclear plants, military sites and Hollywood thrillers, the technology is now going mainstream. And someday, thanks to machines that identify customers visually, credit cards and cash-machine plastic could become a thing of the past.

Banks see the systems as a possible way to cut down on costly card fraud. And while consumers may feel creepy letting machines scan an eye or a fingerprint, they also may feel safer to have the extra protection for bank accounts.

Initially, "there's a perception that this is really Big Brother," said industry analyst Erik Bowman of CardTech/SecurTech in Bethesda, Md. But in time, "the general public would see it as favorable because it adds another layer of security."

Others may be glad to stop stuffing wallets with plastic, and to stop memorizing access codes. "To consumers, the real benefit is that 'I no longer need my cards,'" said consultant Jean Woodworth of Payment Technologies Inc. in Reading, Pa.

Also, lowering the risks of fraud could let banks deliver more goodies form automated teller machines – raising withdrawal limits, for starters.

With stepped-up security and other advanced technology, "you could have mini-loan applications if you wanted, or access to investment accounts" – or even sports tickets delivered via ATMs, said Charles King of Wilmington Trust Corp.

Consumers may also be relieved to hear there's little threat of Hollywood-style horrors – notably, crooks fooling the security devices with a gouged-out eye or a lopped-off finger.

"We can tell a live eye from a dead one," said Kevin B. McQuade, chief financial officer of Sensar Inc. – though he would not explain how. The Moorestown, N.J., company's machines identify customers by examining their eyes.

Likewise, most fingerprint readers sense heat and will reject a cold, amputated finger, Bowman said – "unless you've cut it off then and there, and it still has some heat in it."

Cardless technologies may take a decade to become commonplace, Woodworth said. But even now, sales are on the upswing for machines that recognize so-called "biometric" identifiers, such as a fingerprint, the shape of a hand or face, or the patterns within a human eye.

Last year, $23.6 million worth of biometric security devices were sold, Bowman said. Most are used for sophisticated time clocks in industry, or for identifying state welfare recipients.

He forecasts sales next year of $50 million, including gadgets such as low-cost fingerprint readers for computer keyboards.

Tailored for customers without bank accounts, the $54,000 machines cash personal or payroll checks after taking a picture of the customer's face and then matching it with one on file. The company plans to enter mid-Atlantic states this year, president Mike Stinson said.

Computers such as Mr. Payroll's recognize a face by measuring its geometry, such as the distances and angles between eyes, nose and mouth.

Other biometric systems identify customers by looking directly into their eyes.

At Sensar's Moorestown office, a mock-up of an automated teller machine shows how. Sit in front of the ATM for a few seconds, and hidden cameras zoom in your iris – the colored part ringing the pupil.

The iris' tiny flecks and swirls make it more individual than a fingerprint, according to the company. From its photo of the iris, Sensar's $5,000 system creates what the company calls a "human bar code" – a digital ID that serves as a benchmark for future ATM access.

Depending on whether your iris matches the one on file, the ATM's mechanized voice intones either "identity verified" – or "impostor detected."

A spinoff of former RCA research arm Sarnoff Corp., Sensar may go public with a stock offering within a year, McQuade said. Meanwhile, the 5-year-old company is going after the banking world.

For Sensar, "1998 is a pilot year," vice president Rob Van Naarden said. He hopes to see 500 or more Sensar units being tested by more than 20 banks worldwide this year.

Van Naarden could not identify U.S. banks to be involved in the trials. But Citicorp spokeswoman Nina Das said the bank is testing Sensar's technology.

For instance, electronic fingerprint readers were built into four ATMs Diebold set up in 1996 for Standard Bank of South Africa.

Fingerprint readers also control access to MasterCard's offices in Purchase, N.Y.

"Your first reaction is you think of fingerprinting down at the police station. But it was rather simple, not messy. . . . It worked," said one MasterCard visitor, Rodney Bell of Dallas credit card processor Paymentech Inc.

Last December, Diebold unveiled an ATM that combines face recognition for an extra level of security. The system would cost well below $4,000, Diebold's Tiffini Bloniarz said.

Other types of biometrics are emerging – a scanner that traces the veins on the back of the hand, or an "electronic nose" that analyzes body odor.

"A bloodhound can tell two people apart by their scent. Why not a biometric?" said Bill Spence of Recognition Systems Inc. in Campbell, Calif.

Spence's company specializes in yet another kind of biometric – hand geometry systems, which measure finger and hand dimensions.

For instance, iris scanning promises a high degree of accuracy, Diebold's Bloniarz said. But "it still needs to be tested in the real world to find out how accurate it is."

Mr. Payroll's face-recognition cameras can be thrown off by as simple a thing as too much sunlight, Stinson said.

Besides working out technical bugs – and winning over consumers leery of fingerprinting or eye scans – biometrics vendors must sell banks on the idea.

"The PIN [personal identification number] system right now works. Everybody's gotten used to it. And it's taken the banking industry 25 years to get consumers enthusiastic about ATMs," said John Hall, spokesman for the American Banking Association.

Hall sees huge costs to overhauling ATMs for biometrics – not just for the hardware itself, but for getting consumers to embrace the new system.

Take a device that adds $4,000 to the cost of a $20,000 ATM, Hall said: "Would that machine save $4,000 in fraud? And do consumers want it?"

Biometric credit card terminals face another hurdle, Paymentech's Bell pointed out: At the point of sale, retailers don't want to give up shelf space for electronic hardware – space that could be used to sell impulse purchases.

Still, such devices "can and probably will be used," Hall said.

"The one that gets there the cheapest, and proves it will cut fraud enough to merit the expense, will be a boon."