Affordances and Constraints

Note-taking for User Experience Design with June Ahn

Don Norman discusses affordances and constraints in The Design of Everyday Things, Chapter Four: Knowing What To Do.

Don Norman - The Design of Everyday Things

User experience design is easy in situations where there’s only one thing that the user can possibly do. But as the possibilities multiply, so do the challenges. We can deal with new things using information from our prior experiences, or by being instructed. The best-designed things include the instructions for their own use, like video games whose first level act as tutorials, or doors with handles that communicate how you should operate them by their shape and placement.

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User interface case study: iOS Garageband

Apple has long made a practice of giving away cool software with their computers. One of the coolest such freebies is Garageband. It’s a stripped down version of Logic aimed at beginners, and it’s a surprisingly robust tool. The software instruments and loops sound terrific, the interface is approachable, and it’s generally a great scratchpad. However, Garageband isn’t a good way to learn about music. It gives you a lot of nice sounds, but offers no indication whatsoever as to what you’re supposed to do with them. To get a decent-sounding track, you need to come pre-equipped with a fair bit of musical knowledge.

A young guitar student of mine is a good example. After only his third lesson, he jumped on Garageband and tried writing a song, mostly by throwing loops together. I admire his initiative, but the result was jagged and disjointed, lacking any kind of structural logic. It’s natural that a first effort would be a mess, but I felt a missed opportunity. At no point did the program ever suggest that the kid’s loops would sound best in groups of two, four, eight or sixteen. It didn’t suggest he organize his track into sections with symmetrical lengths. And it didn’t suggest any connection between one chord and another. Seeing enough other beginners struggle with Garageband makes me think that it isn’t really for novices after all. It seems to be pitched more toward dads in cover bands, who have some half-remembered knowledge of chord progressions and song forms and who just need a minimum of prodding to start putting together tracks on the computer.

The iPad version of Garageband is a much better experiential learning tool. Its new touch-specific interfaces encourage the playful exploration at the heart of music-making. The program isn’t trying to be particularly pedagogical, but its presets and defaults nevertheless implicitly give valuable guidance to the budding producer or songwrter. And while it’s quite a bit more limited than the desktop version, those limitations are strengths for beginner purposes.

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Tales of an Apple fanboy

I’ve now had a couple of opportunities to play around with an iPad, and to surreptitiously watch other people use it. I have strong and mixed feelings. The touchscreen interface is pretty wonderful and I have no doubt that it’s going to send the mouse the way of the floppy disk. But the walled garden aspect disturbs me. It smells a little Microsoft-y. As long Apple’s products are so delightful, I guess I don’t care that deeply what their business philosophy is. But not everything that Apple makes is equally delightful, and gorgeous though it is, the iPad gives me some qualms.

A little background. I got my first Mac exposure in 1988, eighth grade, back in the days of System 6 and Pagemaker 1.0. It was love at first use. The mouse interface is old hat now but then it was a tremendous improvement on typing arcane DOS commands.

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The desktop metaphor is, like, so five minutes ago

Update: this was written before I ever touched an iPhone or iPad. These devices are major improvements over the desktop metaphor GUIs I complain about below.

When you grow up playing video games, like I did, the primitiveness of office software user interface design comes as a shock. The desktop metaphor was a brilliant stroke back in 1970 when they thought it up at Xerox PARC, but I feel like it has outlived its usefulness.

User interfaces are the first and most immediate form of computer instruction, and for many people the only instruction they ever receive. Not every interface designer teaches their own products equally well. The problems mostly emerge from designers’ presuming implicit knowledge from the user that might not really be there. There are plenty of computer science concepts that are common knowledge to programmers and engineers, but that are esoteric or totally opaque to the population at large. For example, the general public uses the terms memory and storage interchangeably, even though they refer to different computer components that function in very different ways. Most normal people don’t have mental models of a computer program’s inner workings, and rely entirely on the interface to provide the model.

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