Psychology Magazine

The Affordances of Everyday Things

By Andrew D Wilson @PsychScientists
I ramble on about affordances quite a bit; a big chunk of those posts was dedicated to figuring out whether they are relations or dispositions (answer: they're dispositions), and then there was all that arguing with Ken Aizawa about whether they are even anything at all (answer: yes, they are).
The thing I've been a little worried about is that people might see all this and come away thinking, "Why should I care one way or another?". I wanted to spend a post reminding everyone why all this talk about affordances matters, and the reason is simply this: affordances are important because they influence our behaviour, for good and ill, all day, every day. I'd like to illustrate this with a story, and a few photos I've been accumulating recently.

The Affordances of Everyday Things

The McDonald's on O'Connell St in Dublin, with doors open for a change

Many years ago, I had come to Dublin to visit a good friend of mine, and we'd arranged to meet in town at this McDonald's; the bus from the airport stops there, so it was handy. I arrived a little early, and went inside to sit down. The doors that day were both closed, and presented me with vertical bars for handles. I then went through a routine to get in, and spent the next 20 minutes or so watching everyone else who entered the store do exactly the same routine, which went like this:
  1. Reach out with right hand to pull on the right door's handle. The door doesn't move.
  2. Think, 'you must have to push', and so push the door. The door doesn't move. This door is locked.
  3. Check that the store is open. It is.
  4. Reach out with left hand to pull on the left door's handle. The door doesn't move.
  5. Swear.
  6. Try pushing the left door, not expecting anything to happen. Door moves, letting you stumble into the store in an extremely bad mood.
I find this sequence very revealing. People tried to most obvious thing first: pulling the door closest their favoured right hands (I blame me doing this on living in a right handed world). Pulling was an attempt to effect an affordance; going right reflects a bias in design. They then pushed; people are used to dealing with stupid doors and know they often need pushing. They then went to the other door and didn't try the push, the last thing they had done; instead, they immediately tried to effect the affordance and pull again. Finally they push and get it right, but only because there was no other combination available. 
The Affordances of Everyday Things
Donald Norman and "The Psychology of Everyday Things"
If you've ever read Donald Norman's classic book, The Psychology of Everyday Things, you will be very aware of the existence of doors with handles that you have to push. Norman talks explicitly about the affordances of objects, and how the things we interact with all present a way of interacting with them to us. (Norman has read his Gibson and taken the concept from there, although he is very up front about considering them to be cognitive, mental entities. He knows this isn't what Gibson meant, though, he simply disagrees; I can respect this, because he's clearly paid attention.) The book is just a wonderful catalog of objects that have been poorly designed and solutions based in affordances for fixing them; if you've never read it, you should because it's a classic and extremely readable, and you'll never look at doors and taps the same way again.
These failures amaze me. Take that McDonald's. They had gone to some expense to present me with two doors, each with handles just begging to be grasped and pulled by a human hand. They had then gone to the trouble of making the doors work by pushing, and, for good measure, made one door into a wall by locking it. None of these actual facts about the doors were perceptually available. Quite the contrary: the affordances of the doors were the direct opposite, for pulling, and I acted accordingly (as did at least 20 people after me).
I've always thought that McDonald's (and everyone else responsible for the terrible doors in the world) should care more about this. Handles cost more than no handles; two doors cost more than one door; and making people feel like idiots because they can't operate one of the simplest devices in the world on their way to a burger they might feel a bit guilty about eating anyway is just terrible PR. And, as Norman ably describes, it just doesn't have to be this way. You can make doors whose function is clearly specified; you can make taps you only need one attempt to get water from, and oven element controls that you get right first time. These 'gulfs of expectation and execution' are not inevitable, and good design is about making these gulfs as small as possible by bringing the function of an object to where it can be perceived by the user.
I've uploaded and captioned some photos I've taken recently to a Picasa album, which you can view in full here (if you have pictures of your own, send them to me, I collect them to use in lecture!). Once you start seeing these things, you'll never go back; and the thing that you will notice the most is just how common poor design is. The vast majority of doors you will interact will suck at being doors, and everywhere you go, taps will require you to do something different to get water from them.
I highlight all this to make my point: affordances are important because they influence our behaviour, for good and ill, all day, every day, and nothing makes that more obvious than the bizarre failures of design we interact with all the time.

The Affordances of Everyday Things

This label means they did it wrong

The 'undesigned' world tells fewer lies, fortunately, because their affordances are typically grounded in anchoring properties that lead to reliable, even lawful consequences for what the object looks like. Of course, it's not perfect: the problem of perceiving the affordances for locomotion on ice reminded me quite forcefully that not all anchoring properties have consequences are specified in information, and we only perceive what there is information for. In the case of ice, the critical property (friction) doesn't exist until my foot contacts the icy surface, so there is no information ahead of time, only once I'm on the ice. And this is essentially Donald's lesson too: the key properties of the object always exist, but when poor design or no information hides these properties from perception, disaster ensues.
Donald has a simple rule for designers: "If you have to add verbal instructions, you designed it wrong"; next time you're out, count how many simple things like doors have verbal instructions, and you'll wonder how we ever let it get this way.
References
Norman, D. (1988). The Psychology of Everyday Things. Basic Books. Amazon.co.uk

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