Note from Jan Dawson: I’m honored and grateful to announce that Aaron Miller, my co-host on the Beyond Devices Podcast, will be authoring some posts on the Beyond Devices blog going forward as well. This is the first of what I hope will become a series of posts over time. These posts will have a slightly different tone from the rest of the blog, and will be educational in nature, and frequently tied to research concepts – a concession to Aaron’s day job as a business school professor. To reflect that, these posts will be tagged “Studying Apple“. For more about Aaron, check out the About the Authors page.

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Walt Mossberg and others seem to love Apple’s new Music service, but Mossberg’s (and others like David Pogue’s) complaint has been that the applications delivering it are too complex. The criticism applies to both Music on iOS and iTunes on the computer. There is a lot going on in Apple Music; there’s no denying it.

Complexity isn’t the problem, though. Friction is. You might call it a semantic difference, but if you do you’re missing out on an essential aspect of everything human beings make. It’s worth understanding the difference between something that’s complex and something that’s frictional.

User Interface Friction

These three points explain something called User Interface Friction (UIF):

1. Attention is a scarce resource. Mental effort falls under a concept known as executive function. Simplified, executive function describes the many ways we focus our attention on things. We have a limited store of attention. We can only pay attention to a few things at a time. We can also use up our attention, our ability to focus. Time and rest restore it.
2. Friction is wasted energy (and wasted attention). Although physical friction has its uses, in most situations friction is wasted energy. It’s a great analogy for users’ attention and software. All of your attention spent on an app should help toward your goal. Wasted attention is User Interface Friction. As excellently described in this article from Coding Horror, low UIF is a goal but some UIF is inevitable.
3. UIF is affected by both users and the interface. Just like physical friction is a measure of how two surfaces interact, UIF is a measure of how users and interfaces interact. And as app interfaces can be metaphorically “smooth” or “bumpy”, users can also be smooth (expert) or bumpy (novice). Expert users can handle bumpier interfaces, because they’ve learned how to use them.

Obviously, software designers should try to minimize UIF as much as possible. Low friction makes an app more useful and more enjoyable, even if it’s something boring like a banking app. Software designers can even measure cognitive load while users interact with the app, and pinpoint where attention is overspent. (Here’s a 2006 article [PDF] describing ways to measure cognitive load for testing website usability. The Sternberg Memory Test is especially easy to use.) The idea is that if users have to overspend attention to accomplish something, then the interface needs improvement.

I’m not a user interface expert, so I can’t go very deep into the principles of good UI design that have developed over the years. (This Quora discussion is a good place to start.) But I know when I’m experiencing friction. A lot of the time it’s from bad design, but not always.

Some apps are necessarily “bumpy” because of how much they do. Final Cut Pro, for example, is a massively complex video editing application. It does things editors could only dream about a few decades ago. Because of this complexity, Final Cut Pro relies on expert users to reduce UIF. (This is part of the reason Final Cut X, a huge interface revamp, was so controversial.) To be sure, Apple shouldn’t waste editors attention, but it has the benefit of editors knowing how Final Cut Pro works.

Any app, no matter how bad, can be learned with time. That means we can become experts in poorly designed interfaces if we just stick with them. Lazy or poor app designers demand more expertise from users than necessary. Users generally abandon an app if the expertise cost is too high for them.

Apple Music and Friction

Generally, Apple users are not computing experts. That’s not an insult. It’s just the reality of having hundreds of millions of users. Apple’s success fundamentally comes from its ability to make low friction interfaces for very useful products.

Like any company, Apple runs into problems when its novice users are presented with complex products. This encounter puts Apple’s design chops to the test. But some things are just too complex to simplify for novices, and Apple requires users to develop some expertise.

There’s a lot of depth and complexity to Apple Music. Consider all that it does:

1. Integrates a streaming music library with your owned music library.
2. Helps you purchase music to make it part of your owned library.
3. Provides extensive music recommendations—through curated playlists and suggested artists—based on your (complex) tastes.
4. Brings new music to your attention, organized by multiple criteria.
5. Plays multiple radio stations.
6. Gives you a way to organize streaming and owned music in playlists.
7. Allows you to search for music by multiple criteria.
8. Gives you control over the play order of the music you’re listening to.
9. Connects artists and fans, giving artists a way to share their work and lives through multiple media.

This list gets dramatically longer in the case of iTunes on the computer, because it includes movies, TV shows, podcasts, iTunes U, audiobooks, iOS apps, even more radio, and ringtones, along with all the different aspects of organizing, using, and purchasing those things. And let’s not forget all the device syncing, with multiple generations of iPods, iPhones, iPads, and even legacy MP3 players.

How do you keep all of that simple? I’m not convinced you can. Siri commands help some, but don’t get you all the way there. In the end, even the venerable Apple can only get the interface to a certain level of smoothness.

That doesn’t mean we should excuse Apple for bad UI design. iTunes 12 was a big change that introduced a lot of friction. (The money quote for our purposes: “But for now, iTunes 12’s most basic operation—finding and playing media—requires a lot more thought than it should” [emphasis added].)

So what has Apple decided to do with its Music apps? It apparently expects us to develop some expertise. Walt Mossberg and everyone else complaining about the friction in Apple Music also seem to love the value it provides. Apple designers, intentionally or not, are banking on our willingness to stick with it and get better at it.

That doesn’t mean we can’t complain about the friction, though. For me, the worst offender is the mysterious ellipsis button. (Who knows what combination of commands it reveals every time I tap on it? It’s like the UI equivalent of a slot machine.) Over time, we can all hope that Apple reduces the friction for its fundamentally complex Music service. In the end, making complex things frictionless is how Apple pays the bills.