The kitchen is a great place to find terrible interfaces. Who can resist taking potshots at undecipherable microwave controls? And I'm not about to dig out the manual with buttered fingers to find out how to set the power level. It's not just the new technological gizmos that complicate our cooking lives. The stove is an interface that we all take for granted — an interface that is so ingrained in us that we don't realize that it's possible to even think about making it better — but we can. There are two main stove varieties: gas and electric. Cooks generally agree that gas is preferable. Why? Because with the gas stove, the size of the flame gives immediate feedback: the larger the flame, the more quickly the food will cook. The coils of an electric stone do turn red–after a long wait–but it's hard to gauge the relative temperature from the color. Staring at a red coil tells you much less about the cooking temperature than does a quick glance at the size of the flame: the red only tells you that the stove is hot, not how hot. In interface terms, an electric stove doesn’t give a good indication of its temperature. Because of this, you’re forced to stand with your hand over the stove, just to know that turning the knob actually did something. This leads to a general rule: interfaces should always give indication that lets the user know exactly what they've just done: turning the knob makes the flame grow. And it should always give that indication immediately. It is because this rule is consistently violated that many websites disclaim "Click the 'Order' button only once" and the technically savvy wait until self-doubt sets in: "Did I actually click the button?." Nobody's sanity would be called into question if only websites provided some immediate feedback.
Take a good look at the picture of the stove above. It looks nice and innocuous, doesn't it? But which knob would you turn to start the left back burner? Knob 1, 2, 3, or 4? Is that your final answer? Did you pick knob 1? So do I every time I go to use the stove, but that's wrong. Knob 1 starts the front left burner. The answer is knob 2. Okay, how about if you want to start the right back burner? Knob 3 or 4? You’ve got the pattern now: it’s knob 4. Sorry. It’s knob 3. Frankly, it doesn’t matter which knob the controls which burner–none of the possible mappings are good. None of them are natural. You just cannot map four object arranged in a square in a unique way to four objects arranged in a line. If you pick one way, someone else will pick another. Instead, a good knob layout should mirror the burner layout:
Simple. You'd think that it would be standard–a simple change effortlessly removes the everyday mistakes of stove use: I'd never again burn the kitchen mitt I always leave on the front burner. And all because of the natural mapping between the knobs and the burners. The general interface rule we can derive is thus: controls should retain the spatial or conceptual relationship of the things they control. Now go take a look at your stove. It has the bad co-linear knob configuration. This is bad-design inertia at work. Stove designers cleverly used the same knob that controls the temperature of the stove to also control whether the burner is on or off. This is a lesson that I wish radio designers would learn. Unfortunately, this knob design this means that "off" and "simmer" are only separated by a few degrees. I don't know how much time I've wasted while uncomfortably doubled over with my eye at flame level–trying to coax the stove to burn at the lowest possible temperature. Because I never quite know where the lowest setting is, I invariably turn the burner off at least three times before getting it right. If only the stove designers had thought to put a little indent at the minimum gas flow position, then I could feel instantly–without looking–exactly where simmer is. Given that tactile feedback, I might even be able to pull off rice pudding while cooking an egg. Doubtful, but I can keep dreaming. If rethinking an interface as simple as your stove can make your life better, imagine what rethinking the fundamental interface tools of computers can do. That's what I'll be exploring through this series on interface design. [Top image by Liber]