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"Donald A. Norman" <[log in to unmask]>
Reply To:
Thu, 15 Aug 2002 12:20:16 -0500
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Gerard Torenvliet just posted a note, correctly concerned that the term
"Affordances" has strayed very far from its original definition, both by
J.J. Gibson (who invented the word and introduced it to the study of
perception) and by me (who expanded the concept and introduced it into
the world of design).

Gerard  said:
> Just this morning, reading my chi-web mail, I came across a
> reference to an interface that had great 'visual affordances'.
> Now, I understand exactly what this author was trying to get
> across -- that the graphic design of the interface increased
> the likelihood that users would know what to do with
> different screen elements.  What I disagree with is
> summarizing this down to the term 'visual affordances'.
Well, Gerard, although you are absolutely correct, the world has decided
that "affordance" should have anew meaning. I think we have no choice
but to follow. And you know what? The new meaning isn't bad: it
certainly is very much needed.

When I first detected the misuse of the word, I tried to correct the
(mis)users. I tried to point out that affordances exist independently of
whether or not anyone knows about them. In the book that introduced the
term to design (The design of everyday things) I explicitly discussed
invisible, hidden affordances as useful design tricks. So I tried to
tell people that affordances didn't have to be visible. I tried to
explain that the correct term for what designers were doing would be
"Perceived affordances."

I would now officially like to give up. Change my mind.

Language changes with the times. No word remains static. Language
purists have complained for hundreds of years, but foo on them: language
has to change with the times to reflect the needs of the times.

It is clear that we need some word to describe the things we add to
designs to make controls perceptible. Hence, we add ridges, depressions,
different textures, labels, and lines. We have invented conventions in
interface design, such as drawings of buttons, underlines, colors to
indicate unvisited and visited items, and scroll bars. Lines that
demarcate areas to be clicked.

There is no word to describe this: Affordances is technically
inappropriate, but very closely related to the intended concept. And so,
the meaning of affordances has transformed itself

"I put an affordance in the interface," says the visual designer,
meaning that a box was drawn around a clickable region. Now,
technically, in the original sense of affordance, that is wrong. The
region was always clickable. The box is a "sign" that this is the
appropriate region. The semiotic community understands the distinction.
But, alas, the average designer knows even less about semiotics than
about linguistic origins.

People talk the way they talk. You can't hold back changes in language.
It is a mistake to try. Moreover, my entire design philosophy is based
around the concept of learning from users.  When people use a word
inappropriately, but consistently, it means that there is a gap that
needs to be filled, that no word exists to describe the concept needed
and the old word has been expanded to cover the gap. So I have given in:
Affordances covers the concept of perceptible signs about the meanings
of interface elements.

(I use the word "perceptible" rather than "visual" because I include
sounds, tactile feelings (touch), sight, and any other sensory element
that might be useful.)

Sorry about that: I'd like to be a language purist: but language is no
different than any design field: respect the way people really behave,
not the way you wish they would behave.  In this case, the people have
spoken, and the word they speak is "Affordance."

Don Norman

Donald A. Norman
Prof. Computer Science,  Northwestern University
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Nielsen Norman Group
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