By now everyone has read Don Norman’s seminal book The Design of Everyday Things. If you haven’t read it yet, don’t worry, it’s like Knut’s books, everyone talks about it, but no one has ever read it.

No, seriously. If you haven’t already, do yourself a favor, stop reading this right now and order yourself a copy. Your future self will thank you.

I’ll not provide another summary to Norman’s book. I would be doing a disservice to you, and I’m sure that by now there are lots and lots of presentations, blog posts and what not resuming that book. What I want to focus instead, is on a word that he uses in his book - “Affordance”. One little detail is that Norman did not invent the word nor the concept. In his book he cites J.J Gibson’s “The Theory of Affordances” (1977). Norman just did two things: brought that term to the HCI field, and due to the success of his book, popularized it.

So, what does it mean?

Affordances are the physical properties between two entities. A paper (entity 1) affords you (entity 2) to write, but also to:

  • draw;
  • tear;
  • fold;
  • crease;

You get what I mean...

The concept of “entity” here is relevant because while water affords you to swim, it does not afford you to walk. But water affords some species to walk on it (e.g. mosquitoes and water striders). If you want to dig some more, check its wikipedia article.

If it sounds simple, it is simple

If you read this far, congratulations, you just graduated in affordanciology.

I’m not sure why, but the problem seems to be that many people don’t really understand what an affordance is, or have different ideas about it. This means that you can be in a room with two other people all arguing and everyone has a different mental model. This means that at some point:

  • The discussion is not productive since everyone has a different mental model
  • They realize it, and start debating what “affordance” means. At this point the discussion turns into something like discussing religion, sports, or politics.
  • Some people are humble enough to say: “I don’t care about that as long as it’s easy for the end-user"

But it is not uncommon to hear someone saying, “That button has no affordances”, or “You should keep the links underlined to give it a stronger affordance”.

Physical properties, not visual cues

If its dark and you can’t see the water, does it stop to afford you to swim? If we mix Tang into the water, and it does not look like water anymore, does it stop to afford you to swim? You need to change to water to an extreme, like freeze it, so that is stops to afford you to swim. But if you do so, it is no longer water, but ice. you can consider it as a different entity, since its physical properties are not the same as water.

What as water mixed with Tang has to do with buttons and links, you ask. This means that you can visually change a button or link however you want, as long as you don’t change their “physical” properties, they will still afford clicking.

So it only makes sense to say, “the button has no affordances” if you changed the button and it no longer allows you to click, drag, push, or interact with it in any way. Question for five star points. Does it make sense to say “the link is underlined to give it a stronger affordance”? Hint: Adding more Tang to the water will strongly afford you to swim? Whatever this means.

So why do people say it?

Because people often mistake affordances with signifiers. Yes, I know. I’m way ahead in the bullshit bingo.

So, affordances are the physical properties between two entities. Signifiers are literally cues to those physical properties. You don’t need to get yourself immersed in water to understand that it affords swimming. You have a mental model for how things work, so if you see something visually similar with water (say Tang), you immediately know that it affords swimming, even though you have never been immerse in Tang. I’m being highly inaccurate here, but you get the point.

The interesting part here is trying to understand how the hell did you know it afforded swimming if you never experienced it before.

So, before regurgitating some random words that you have heard in a meeting or blog post, be sure everyone is on the same page. It might sound silly, but might save you some time in useless discussions.