Part of the fun of unleashing a new technology on the world is seeing how people react and use it.
Who would have thought that the introduction of the smartphone would lead to a decline in phone calls? Who would have imagined that the proliferation of Internet-connected mobile devices would correspond with an increase in printing? Who would foresee that social media would become a primary mode of media consumption?
You can test as many use cases as you can think of in the laboratory before you introduce a new technology, but naturally, you can’t prepare for the ones you can’t imagine.
So it’s with great fascination that the world watches the rollout of Apple’s iPhone X, which includes Face ID, a facial recognition security feature that allows you to use your face, rather than your thumbprint or passcode, to log into your mobile device.
Early reviewers are already putting Face ID through its paces, and the applications are, how should we say, interesting. Here’s a look at some of the most notable.
Identical twins could pose a problem.
Both the Wall Street Journal and Business Insider tapped twins (and in one case, triplets) to see if Face ID could pass muster. Results were mixed. The Journal‘s 8-year-old triplets foiled the facial recognition system while Business Insider’s twins did not.
“The three seemed far more excited about defeating the system than afraid their brothers might one day break into their iPhones,” the Journal’s Joanna Stern writes. Still, “FaceID is secure, fast, reliable and very easy to use.”
It may not work as well in extreme light.
As Fortune’s own Don Reisinger notes, Face ID appears to work better than expected in very bright environments, according to various early reviews of Apple’s iPhone X, but direct sunlight or changing conditions could trip it up.
It’s nothing to worry about, biometric technology expert Kevin Bowyer tells Reisinger. “Sure, there is probably something in some extreme conditions—maybe high noon in Death Valley or something,” he says. “But I will be surprised if anyone had documented any large problem in normal sunny conditions.”
…but it thrives in extreme dark.
You might be surprised that facial recognition technology works in almost complete darkness—until, that is, you learn that Face ID uses infrared light to function.
“Face ID worked perfectly in an almost completely dark room, too, lit only by the iPhone’s screen,” CNET’s Scott Stein wrote in his review, before adding: “We’ll still need to do a lot more testing to see what Face ID’s limits are.”
It may not be scarf or hat-friendly.
Much like the DMV for a driver’s license photo, Face ID isn’t too keen on foreign objects blocking your face. “Face ID demands you lose the scarf over your nose or the hat pulled down past your eyebrows,” Alex Cranz writes at Gizmodo, noting that people in winter climates may find this to be a (necessary) inconvenience.
…and there are mixed reviews about eyeglasses.
Both CNET and Gizmodo tested Face ID for eyeglasses. The results were mixed: Gizmodo’s Cranz writes that the system took mere hours “for the Face ID module to understand the big planes of plastic in front of my face,” noting that it learns over time. CNET’s Stein was more succinct: “Face ID didn’t mind my sunglasses.”
It doesn’t automatically unlock your phone.
Don’t expect that Face ID will simply unlock your phone automatically the way Apple’s Touch ID did—that’s a bit aggressive. To prevent misuse, “The phone ‘readies for unlock’ when it recognizes my face,” CNET’s Stein notes. “The iPhone still needs my finger-swipe to finish the unlock. It’s fast, but that extra step means it’s not instantaneous.”
And sometimes, you can get locked out of facial recognition entirely.
Like Apple’s Touch ID, Face ID falls back on the passcode in the event facial recognition fails, muting the allure of the new technology. “The iPhone X occasionally asked me to re-enter the passcode after a failed Face ID attempt, then locked out further Face ID efforts until I entered the passcode again,” CNET’s Stein writes. “If you’ve used Touch ID, this will remind you of trying to use an iPhone with wet fingers.”
Still, early reviews are positive.
Though reviewers have only had Apple’s iPhone X for one day, most have come to the conclusion that Face ID delivers in almost every reasonable real-world situation.
“Face ID recognized me quickly whether I was in a brightly lit office, in a completely dark room, or wearing sunglasses,” Time’s Lisa Eadicicco writes in her hands-on early review. “That wasn’t so with Samsung’s Galaxy S8+.”
The Verge‘s Nilay Patel put it another way: “The good news is that Face ID mostly works great. The bad news is that sometimes it doesn’t.”