Comment by sopooneo | Hacker News Reader

Comment by sopooneo | Hacker News Reader

Just posting this here for anyone like me that had read some of Don Norman's work, but not The Design of Everyday Things, and was confused by a certain differing use of vocabulary.

In his original coining of the term, Normal used "affordance" to mean a thing an object allowed to be done, but some user, usually a human, sometimes another object. For instance, a chair affords sitting by a person. A door handle affords opening.

But in the design world "affordance" is now almost ubuiquitously used to mean some visual hint added to a design element to indicate what can be done with it. For instance, in a UI, you might say that you added an "affordance" in the form of a drop shadow to show a button is clickable (probably a crappy example, me being a non-ui person).

In the later editions of Design of Everyday Things, Norman addresses this difference (perhaps we could say evolution) of his idea and term. If I remember correctly, he does not love this conflation of ideas, but has come to terms with it.

> A door handle affords opening.

It's a bit more subtle than that. From my copy of the 2002 edition (p.9):

> Affordances provide strong clues to the operations of things. Plates are for pushing. Knobs are for turning. Slots are for inserting things into. Balls are for throwing or bouncing. When affordances are taken advantage of, the user knows what to do just by looking: no picture, label, or instruction is required.

Then on p.88

> Consider the hardware for an unlocked door. It need not have any moving parts: it can be a fixed knob, plate, handle, or groove. Not only will the proper hardware operate the door smoothly, but it will also indicate just how the door is to be operated: it will exhibit the proper affordances. Suppose the door opens by being pushed. The easiest way to indicate this is to have a plate at the spot where the pushing should be done. A plate, if large enough for the hand, clearly and unambiguously marks the proper action.

It's not just that handles afford opening, it's that they afford pulling.

I've had a quick flick through the pages on affordances, and can't see anything that stands out about the drift of the word "affordance", so that might be in a later edition than the 2002 one. (The original edition is from 1998).

Yes, in a later version of the book, Norman differentiates between signifiers (which we might now call perceived affordances) and affordances. However, the HCI field and UX field has by and large not adopted signifier as part of its vocabulary, and most people use affordance to mean the perceived relationship rather than Norman's original definition.

It's also worth pointing about that the original definition of affordances, by Gibson, is about animals and their relationship to their environment, which can be quite broad in its totality.

Feels like there needs to be more intuitive terminology and for it to only be used when it's helpful to the discussion because most of the time I see the word "affordance" used, it's dropped in unnecessarily into the conversation where the poster should know the other commenters aren't going to know what it means, or it devolves into a discussion about the definition (see here). I've don't hear it used outside UX circles.

During UX work on projects, it's simple enough and comes naturally to most for everyone involved to phrase it something like "we should add X so it's more obvious you can Y". I'm don't see the gain in breaking it down more outside of more academic discussions, and introducing unnecessary terminology creates a barrier for communication.

A while back someone, replying to one of my comments, mentioned affordances in C#. He simply meant procedure or function, but chose to use a fancier sanding, more abstract word which really confused me. There is too much misuse of pompous language happening where simpler, plainer descriptions work better (yes, language is also a user interface of sorts).

Right. "visual hint" is self-explanatory and cannot be misinterpreted, and seems to be a more common term. As a non-UX person I've never heard the UX jargon "affordance", but I've heard "visual hint" tons.

I don't believe this was in the original edition, but someone can correct me if I am wrong: he proposed the concept of "signifiers" to fill the definition that people were increasingly giving to "affordances".

A signifier helps to indicate the presence of an affordance that might not be immediately apparent.

I recently had occasion to reside, temporarily, and for unremarkable reasons, in a rented apartment in the Scottish town of Dundee. The lobby of the apartment building was accessed through a single door, with handles on both sides.

Adjacent to the handles, there was also, on each side of this door, a hand-scribbled sign reading “Push”.

Needless to say, I pulled.

The door did not open.

I pushed.

The door did not open.

I pulled again.

The door opened.

In the friendly pubs of Glasgow, they'd tell me: "Pick a window. You're leaving!"

“Perceived affordance” is the term I believe.

I don't understand the distinction? Just that it isn't physical?

(Also, affordance isn't mentioned in the article anyway?)

The distinction is that in the original meaning, it meant "to make the action possible." In the new meaning, it means "to suggest the action is possible visually." The original meaning had to do with actual usability, as opposed to just visual design.

Huh, ok. If Norman said that himself then fair enough, but it surprises me. I learnt it from Bob Spence, I recall he used the example of door handles and push plates: you can pull or push the handle, but it visually invites pulling, especially in contradistinction to the plate, which clearly says 'push me' - that's essentially suggesting the action by what's not possible visually.

I thought (not necessarily, but probably visual) design (to tell you how to use the thing) was the whole point. The original meaning as you say seems pretty redundant, that's just the same as the thing's function?

He wrote that in the book: "Affordances determine what actions are possible. Signifiers communicate where the action should take place."

A doorknob tells you the door will open, but doesn't tell you which way it will open, so you have to add something (a signifier) to the door if you want that.

Whereas a pushbar both tells you the door will open and how to do it and it's all tied together without a sign.

Yes, that's exactly how I understand affordance. I just didn't get the distinction between original & current meaning other commenter described.

It sounds like someone described a real problem (ambiguous interactions with everyday things) and someone else stole that term and said "we can apply it to the thing we add to fix the problem we created with our bad design".

Sadly, this kind if linguistic trick is quite common.

Well, with the distinction being made it seems that a door push plate with barbed wire welded to it would be a current/changed meaning affordance that it can't be pushed (or anti-affordance if you will) but in the original meaning.. it's either neutral or an affordance that it can be pushed because it physically can be.

Or a pull handle on a door that should actually push open - I think that was an example given when I studied it, I think there was another term for it but I can't recall, a 'misleading affordance', say. But in the supposed original meaning it's just still an affordance for pushing, because it does physically allow that, even if it looks like it should pull?

If it's correct, the original meaning just seems redundant to me, the changed one seems to make more sense and be more useful, but perhaps I still haven't understood the top level comment.

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