On Apple Watch Ergonomics

Now that we’ve all had a few weeks with this new watch, it’s natural to start analyzing the interaction models: there’s been some great commentary from people I respect.

However, one area I haven’t seen discussed much is the ergonomics of this device: how efficient are we at performing tasks on the watch? The physical interactions with a device attached to our body are just as important as the mental ones.

One of the first things I noticed about using the Apple Watch was that pressing the digital crown on my left wrist required a fairly awkward position of the index finger on my right hand. While pressing on the crown without another finger to provide resistance, the strap twisted uncomfortably. When you try to get your thumb on the opposite side of the case to provide support, you either cover the face or resort to contortions.

Luckily, I had spent some time digging around in the settings in the Apple Watch app and remembered seeing some odd settings in General > Watch Orientation. The wrist selection is obvious enough, but being able to change the position of the digital crown had no obvious benefit. That is, until I tried it.

I left the wrist setting alone and changed the digital crown to be on the left (it defaulted to the right side.) This is what it looks like after the change:


I’ve been referring to this orientation as the “reverse crown”.

With any ergonomic change, you need to give yourself a few days to overcome the bias for something new and different. I gave myself three days to form an opinion.

I will say my immediate reaction was positive: I could use my thumb to activate the crown while using the side my index finger to provide stability. Also, our phones have taught us to use the thumb as a quick navigational tool.

An added benefit to this new orientation is that the speaker and microphone are directed toward your face when your wrist is raised. It’s easier to hear sounds and Siri recognition seems a little better. It will be interesting to see how much better this works when we’re wearing heavy winter jackets.

With the crown on the left side, you use your thumb to scroll. Initially, I was concerned that my hand would block the screen, but the display fits nicely in the space between your thumb and index finger:


When using your thumb on the crown, your index finger is also in a convenient location for tapping and scrolling on the display.

Apple never adds settings without a good reason. The inclusion of a preference for the crown position is a pretty clear indication that someone important knew that this was an ergonomically superior choice. But it’s also one that goes against horologic convention: Apple’s desire for this device to be visually appealing won out over ergonomics. I’ll be the first to admit that the “reverse crown” looks weird.

Luckily, Apple has given us a choice between what works best and what looks best. It’s been several weeks since I made the change and have never once considered changing back to the default setting. I encourage you to give it a try, too.


A lot can happen in fifteen years, especially on the web. At the turn of the millennium, many of us were coming to terms with the dynamic nature of a new medium that connected our world. I was honored to be a part of this collection of thoughts and reflections of that time.

I’m a firm believer of moving forward in your work and not relying on past accomplishments. The best way to find the path into the future is to look for clues from where we’ve been. A collection of thoughts from people I admire is priceless.

And before you dismiss this as information that’s only relevant for “web designers”, look at how your apps rely on web infrastructure to do something meaningful. Then think about how difficult it is to build an interface that works well on all screen sizes. These are the same things we struggled with as the web entered adolescence.

A New Way to Display

To date, Apple’s Retina displays have relied on LCD technologies. Since the iPhone 4, our mobile devices have used in-plane switching (IPS) technology to achieve high resolution with accurate color from a wide range of viewing angles. The IPS LCD panels are also present in many of the desktop monitors we use on our Macs.

Chances are good that’s about to change with an OLED display in the Apple Watch.

Unless you’ve done work on Android, you’re probably unaware how different AMOLED displays are from LCD. Let’s take a look at what lies ahead.

Physical Differences

An LCD display relies on a backlight that’s projected through three layers: one for each of the primary colors. Red, green and blue appear on screen because crystals in those layers can be aligned electrically to allow the backlight to pass through.

OLED has no backlight and has only one layer that produces light. That layer is an organic compound that emits light when subjected to an electric current. When you put them in a two dimensional matrix of transistors, you end up with an AMOLED display.

Based on these short descriptions, it’s easy to see why an OLED is thinner than its LCD counterpart: there are simply fewer layers of electronics. And it gets even better when you discover that the compounds and electronics can be fabricated on flexible plastic substrates.

LCDs have always been problematic in direct sunlight because the backlight must pass through filters which can also reflect ambient light. This has also been an issue for OLED displays where the light is emitted below a reflective metal cathode. The good news is that recent advances with the technology are producing brighter results than an LCD.

The biggest challenge for OLED is with the organic material where light is emitted. Basically, byproducts of the chemical reaction that produces light accumulate over time and reduce the efficiency of the output. Again, this is an area where manufacturers are focusing their efforts. In just a few years the lifespan of these devices have increased by several orders of magnitude, but is still limited to tens of thousands of hours. Don’t expect your Apple Watch to become a family heirloom.

How Not to Do It

OLED displays have gotten a bad rap on mobile devices primarily because of a thing called PenTile.

PenTile mimics how our eye works: 72% of the luminance we perceive is determined by the green wavelengths of the electromagnetic spectrum. The RGBG arrangement of sub-pixels lets a display get brighter without increasing the overall number of transistors needed. This, of course, keeps manufacturing costs down.

Unfortunately this physical layout of the light emitters also makes colors grainy and text hard to read. Color accuracy also suffers. PenTile is also a trademark of Samsung. I can’t see Apple using this approach in their Retina displays.

It’s much more likely that Apple’s industrial designers have been working hard to find a new and better way to use OLED technology without losing fidelity. I can’t wait for someone to look at the Apple Watch’s display under a microscope.

Black is Best

From Apple’s point-of-view, one of the most important things about OLED is how it consumes power. A transistor on the display only uses energy when it’s producing light. Compare this with an LCD backlight which must be lit in order to see any pixel.

Folks with OLED displays on their Android devices have figured out that a lot of black pixels makes their battery last longer. So too Apple.

It’s also important to remember that each pixel on the display has a limited lifetime. The less time the OLED spends producing light, the longer it lasts.

One of my first impressions of the Apple Watch user interface was that it used a lot of black. This makes the face of the device feel more expansive because you can’t see the edges. But more importantly, those black pixels are saving power and extending the life of the display. It’s rare that engineering and design goals can align so perfectly.

And from what we’ve seen so far of the watch, that black is really really black. We’ve become accustomed to blacks on LCD displays that aren’t really dark: that’s because the crystals that are blocking light let a small amount pass through. Total darkness lets the edgeless illusion work.

Flat Black

I’ve always felt that the flattening of Apple’s user interface that began in iOS 7 was as much a strategic move as an aesthetic one. Our first reaction was to realize that an unadorned interface makes it easier to focus on content.

But with this new display technology, it’s clear that interfaces with fewer pixels have another advantage. A richly detailed button from iOS 6 would need more of that precious juice strapped to our wrists. Never underestimate the long-term benefits of simplification.

The Future

Apple is a company that likes to leverage its technologies across a wide range of products. Look at how many of their devices are using IPS LCD displays now, then imagine a move to an OLED display pioneered by the Apple Watch.

When Jony Ive taps the home button on his iPhone and says, “The whole of the display comes on. That, to me, feels very, very old.” it’s a sign that individually addressable sources of light are the wave of the future.

Of course it will take time for this to happen, but you know it’s going to look awesome when they’re done. And along the way, we’ll learn to think about pixels differently.


Think about how much we’re talking about the Apple Watch, especially the gold editions. Then read this.

Aspiration is a powerful force. Both for Apple and its customers.

Xcode Compromised

There’s a very good chance that Xcode has been compromised.

The article refers to “Xcode” generically, but as we all know, there are a lot of pieces to this puzzle: I’m going to examine a few of them below. It’s your job to think about how these things might affect your own products.

Code without a source

Any libwhatever.dylib in your project contains code you’re not compiling from source. You don’t really know what that code is doing, do you?

To get an idea of the extent of this problem, try this:

$ find /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS.sdk/usr/lib/ \
  -name "*.dylib" -or -name "*.a"

I count 190 libraries available to iOS in the current version of Xcode.

Of course, open source code is easy to review. But even there, if you miss a simple goto, it can have serious consequences.

Third party build phases

Do you use something like Crashlytics? Every time you do a build the Crashlytics.framework/run binary is executed on your behalf. Does this code do anything beside process your .dSYM files?

Who knows? I sure don’t.

Chain of trust

As we’ve recently seen, breaking the chain of trust is remarkably easy given the right amount of privilege and malice.

We have all seen Xcode verify before launching. There are even simple ways to disable that check.

Unfortunately, these checks only verify the delivery of the binary code. There’s no check of the package’s origin or the toolchain used to create it.

Trusting trust

You can’t even trust your compiler. If LLVM is somehow compromised, even clean source code can become an attack vector.

Now think about the other problems above and how a compromised compiler can make them much more likely and pernicious.


Updated March 10th, 2015: More details on the specifics of the attack can be seen here.