Apple's (NASDAQ:AAPL) iPhone 5s brought two significant features that most rival phones running Google's (NASDAQ:GOOGL) Android lack: a 64-bit processor, and a fingerprint scanner. Samsung's (NASDAQOTH:SSNLF) next flagship smartphone, the Galaxy S5, could replicate both features, but not in the manner some might expect.

Rather than your finger, Samsung's next phone could scan your iris. Samsung has been slowly pushing eye-tracking technology, but with mixed results. Still, the South Korean tech giant's next flagship is shaping up to be the most technologically savvy Android-powered handset yet.

Samsung focuses on its users' eyes
According to Samsung Executive Vice President Lee Young Hee, Samsung's Galaxy S5 could feature an iris scanner. As owners of Apple's iPhone 5s can use their finger to unlock their handset, buyers of Samsung's Galaxy S5 could use their eyeballs.

On the surface, Samsung's solution just sounds much cooler than Apple's. After all, fingerprint scanners have been around for years, even on smartphones, Apple wasn't the first to include one. But iris scanners are more rare, still somewhat in the realm of science fiction.

Yet I'm skeptical that Samsung's technology will lure buyers. Samsung's Galaxy S4 included a number of eye-tracking features, including "Smart Stay" (preventing the phone from dimming when you look at it) and "Smart Scroll" (scrolling up or down a webpage using the movements of your head), but they don't always work. Reviewers have found fault with both technologies, and as an owner of a Samsung-made handset, I can attest to their flakiness.

Even Apple's fingerprint scanner, despite being well received by most critics, has drawn its fair share of complaints. Business Insider's Megan Rose Dickey notes that plenty of users have run into problems with Apple's technology.

Until Samsung can demonstrate a near-perfect iris scanner, investors should take a wait-and-see approach.

Biometrics and mobile payments
Nevertheless, biometrics remains an area of intense interest for smartphone makers, both for security and, eventually, for mobile payments. Before Apple's release of the iPhone 5s, analysts were projecting that Apple would pair its new technology with a mobile payment system.

With more than 500 million credit card numbers linked to iTunes accounts, Apple's iPhones could eventually replace their users' wallets. If merchants adopt Apple's iBeacon technology, an iPhone with a fingerprint scanner could be a better, more secure alternative to a traditional credit card.

Google has been pushing aggressively into mobile payments with its own Google Wallet initiative, though the search giant still has little to show for it. Adoption has been slow to nonexistent, and many observers have already labeled it a failure. Yet Google remains undeterred, including improvements to Google Wallet in the most recent version of Android.

Apple's closed model could give it the upper hand in mobile payments
Because Apple controls the entire iPhone -- both the hardware and the software -- it's better equipped to push features that require both. To date, Google's mobile payment problems have centered on hostile carriers and a lack of NFC technology among merchants -- but if biometrics emerge as a key component of the mobile payment experience, Apple would have the advantage.

Google would need its hardware partners, notably Samsung, to perfect their own biometric alternatives. With the talk of an iris scanner, it seems Samsung is definitely on the right track, though the South Korean tech giant's prior eye-tracking features leave much to be desired.

Biometrics -- do they matter?
Including biometrics in smartphones seems to have emerged as the next big trend. To some users, these features could prove irresistible, but until they are perfected, they seem somewhat superfluous -- anyone buying Apple's fingerprint scanner-less iPhone 5c is implying that they don't find the feature to be worth an extra $100.

Still, the push toward biometrics could matter when it comes to mobile payments. For now, Apple's superior fingerprint scanner gives it an advantage -- Google investors should hope Samsung's solution is comparable.

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Sam Mattera has no position in any stocks mentioned. The Motley Fool recommends and owns shares of Apple and Google. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.

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