Google Pixel 4 and 4 XL review: The biggest upgrade Google has delivered so far

By Koh Wanzi - 24 Nov 2019

Motion Sense & Face Unlock

Motion Sense: Gimmick, or not?

Google Pixel 4 XL

The Pixel 4 comes with a tiny radar chip in its top bezel, a piece of hardware derived from Google's Project Soli, which dates all the way back to 2015. This marks the first time the technology is being implemented in a consumer device, and Google is calling the feature Motion Sense. It lets you interact with the phone without ever touching it, and is capable of detecting both gestures and presence. Unfortunately, while Motion Sense sounds really cool, it's still dangerously close to veering into gimmick territory.

That's a pity, since there's a lot of potential behind the tech. While Samsung and LG have implemented air gestures before, they didn't do so using radar. The Pixel 4 is the first phone to do this, but there still remains quite a large gap between what radar can do on a phone, and what it actually does now. At launch, Motion Sense detects three key types of interactions, comprising gestures, presence, and reach.  

I say gestures, but there are really only two, and they're both pretty basic. If you're playing a song on Spotify, you can wave your hand toward the left or right to navigate your playlist. Furthermore, it'll work even when you're not actively using the phone, so you can easily switch tracks when you're at the always-on display. 

However, for Motion Sense to work well, it also needs to know when to ignore unimportant gestures, such as when you pass a cup or some other object over your phone. It seems to do that by detecting the acceleration of your gestures, and I was only able to swipe to the next track if I performed a fast, deliberate action instead of a slow, half-hearted wave. On top of that, it doesn't seem to work too well if you start your wave in the middle of the screen. Instead, it looks like you'll need to execute the gesture a ways off from either edge of the phone. That may also be part of how the Pixel 4 avoids picking up superfluous gestures, and it needs to detect your hand moving across the entire width of the phone.

In the Settings menu, you'll be able to choose if you want to skip to the next track by using a left-to-right or right-to-left movement, so you can pick whichever feels more natural to you. In addition, there's a bright flowing line at the top of the screen that serves as a helpful visual indicator for when your gestures are detected. 

You can also choose to disable specific aspects of Motion Sense.

The most pressing question for me is whether I could actually see myself swiping at the phone instead of manually switching tracks. If I'm on a plane and listening to Spotify, which is easier to do? Fortunately, Motion Sense doesn't require some exaggerated, dramatic hand wave to work, and I was able to switch tracks by waving at the phone discreetly. Still, it's not like powering up your phone to switch tracks is a huge chore, so while Motion Sense may be cool and a tad bit more convenient, I wouldn't call it a game-changer. What's more, it's not 100 per cent reliable yet, so it's still more of a party trick in my books. 

The other gesture Motion Sense supports is a wave to snooze alarms or dismiss calls. When it comes to silencing your alarm, the phone will start to quiet down as your hand approaches it – Google says this is more "polite" – before you muffle the alarm for good with a swipe. The latter sounds rather convenient, but what happens if Motion Sense picks this moment to not work? I'm not sure you want to spend your waking moments frantically trying to air swipe your alarm to shut it up.

Gestures aside, the other capabilities of Motion Sense are a little more useful. My favourite is its presence-sensing abilities, where the phone can supposedly sense you up to roughly 0.6m away. It'll keep the always-on display on if you're around, or turn it off when you move away, a nifty feature. 

Then there's the third type of interaction, which is reach. This means it can sense when you're reaching for your phone and get the Face Unlock sensors ready to scan your face. This makes unlocking your phone quicker, and unlike on the iPhone, it sends you straight to your home screen without having to swipe up again.


There's a small treat for Pokémon fans too. You can download Pokémon Sidekick from within the Styles & Wallpapers settings, which will let you set one of five Pokémon as your wallpaper. This includes Pikachu and Eevee, in addition to Grookey, Scorbunny, and Sobble, the new starter Pokémon from Pokémon Sword and Shield. You can double-tap on the Pokémon to switch to the next one and interact with them with Motion Sense gestures. They'll wake as you approach, wave back when you wave at them, and express joy when you waggle your fingers above the screen to tickle them. And when it's night, they'll curl up for a snooze. 

Like the rest of Motion Sense's feature set, the Pokémon are fun to play with, but what you can do with them is still rather limited. Motion Sense could become a lot more useful if Google opens it up to third-party developers, but until that happens, I don't see it being the main reason for people buying the Pixel 4. 


Face Unlock

The Pixel 4 is also the first Android smartphone to offer a Face Unlock solution that is secure enough to be used for payments. It's a Face ID-style unlock, although whether it's as secure is now questionable, seeing as it can still work when your eyes are closed. In comparison, Apple requires the user to be alert and looking at the phone. I've tried this out for myself, and sure enough, the Pixel 4 unlocked for me even when I had my eyes closed. 

Pixel 4 Face Unlock

That raises obvious security issues, since someone could simply unlock your phone when you're sleeping by holding it up to your face. If you're really worried about this, it looks like you'll have to stick with a PIN unlock or enable Android's lockdown function, which disables biometric authentication and only unlocks the phone when a PIN is entered. The lockdown option can be added to the power menu, so you can quickly enable it when you need to.

Fortunately, Google has confirmed it is working on an update that will require your eyes to be open, so you won't have to put up with that forever.

That aside, face data never leaves your phone, and it's stored on the Pixel 4's Titan M security chip.

The Pixel 4 relies on an NIR flood emitter, an NIR dot projector, and two NIR cameras for Face Unlock, and it works by capturing a depth map of your face, similar to the iPhone. In practice, Motion Sense and Face Unlock worked quite well together, and I found the phone ready for me whenever I picked it up. The phone recognised me when I was wearing a cap and sunglasses too, and it didn't falter when I tried to unlock it in a dark room. Overall, I'd say it's pretty quick and reliable, and I never missed having the fingerprint sensor.

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