The Oral-B "powered" toothbrushes have unusual buttons for controlling the on and off functions. You have to turn it on to start it - and you have to actually start it without looking at it: while it's in your mouth. What's unusual about the button:
- The on button doesn't say "on" or "power."
There isn't enough space, really. - The on button isn't a "1"
(as it might be on a computer, on software, or electronics) - The on button isn't a symbol that is reversed by the off button.
- It doesn't light up
Normally you can tell that a button will light when on even before you see it. It wouldn't be visible when activated. - It's not a manual knob that is turned - it's a button
- It's not a toggle or a switch that rockers in its position
In the case of the toothbrush in question, they used a "+" for on(and, naturally, a "-" for off). This seems wrong to me. If you could continually press it to turn it up to a higher level, then it would make sense. But there is only 1 setting, on or off.
But it works. So the design communicates its function. It makes sense. You don't have to think about it. It's "wrong" in a pure sense, but who cares: it works.
Design of buttons and knobs (or anything that functions) is about communicating the function. This can be done with texture, shapes, symbols, and words. Even on a lowly $10 toothbrush.
