From one of of our bathrooms at home, the shower/tub controls are pictured at left.
The handle pointing to five o’clock regulates the water flow. The knob pointing to one o’clock sets the temperature. But how do you activate the shower?
Look at the picture again. What do you think?
The answer is, you pull down on the tub spout’s ring, where the water comes out. This plugs the tub spout and directs the water up to the shower head.
Functionally it makes sense, but the only thing obvious about this feature is its need for a better affordance: a design element that shows the user what to do.
The computer-user-interface expert Don Norman popularized the term affordance in his book The Design of Everyday Things. One of his classic examples was the door that you pull, only to find that you need to push it. Why did you pull? Probably because it had a pull-style handle, when it should have had a flat plate. The latter can only be pushed. (A rule of thumb: If a door needs a sign to tell you “push” or “pull,” it could use a better affordance.)
Although the term sounds jargony, affordance provides a shorthand for thinking and talking about what would otherwise be referred to as, “something that shows you what to do with it.” The term is used primarily by certain types of designers. We would all benefit if a wider array of professionals understood and internalized the term. Spread the word.