September 8, 2004

User Interfaces

Posted in General at 11:18 am by Ian

The task of designing a logical and elegant user interface to what may be a complicated system is one that I’ve gained a great deal of appreciation for over the past few weeks, due to a combination of writing software that requires such controls, reading about some alternate controls to common interfaces, and trying to clean myself.

Let’s begin with cars. A few weeks ago, I was reading a thread about the possibility of controlling cars with a joystick. Apart from the fact that we’ve always done things another way, why not? Obviously, the controls originated because they were different mechanical systems with different requirements. The wheel was large because it gave the driver leverage over unpowered wheels. The brake and gas were separate pedals because acceleration and deceleration are controlled by different mechanisms, even though they both control the speed of the car. However, the strange organically grown combination of levers and a wheel operated by hands and feet is, if not necessarily optimal, very effective because it both isolated different aspects of control (there’s no reason for the controls for acceleration to be tied to those that change the heading of the wheels), and because it offered very precise control over steering.

A joystick wouldn’t have any of those properties, because it gives up precise control for a simple and abstract interface. Neither one is inherently better than the other, one is just a further abstraction. The design of most controls is a tradeoff between direct control of systems and a simpler model of controlling outcomes.

Except my shower.

There are basically two things to control for a shower: pressure and temperature. But of course you rarely (never?) see a shower that has independent controls of each. Usually, there’s either two dials, one each for cold and hot water, or a single dial, that quickly puts pressure to the maximum, and only affects the temperature through most of its range. My bathroom also has two dials, on the same axis, and they affect temperature and pressure in some way or another. The back dial has the following helpfully printed on it: “” The fore dial has “->OFF->”. It’s like they tried to go for direct temperature/pressure control but didn’t actually wire it correctly. Neither seems to independently control anything. My current method is to turn the dials at random until the water stops being really cold or really hot.



  1. Nikhil said,

    You’ve never seen the single shower dials that you twist to change temperature and pull/push (or tilt) to change the pressure?

    That’s independent control for you. They’re my favorite. If you ever visited my home, you could check out mine. 😮

  2. Ian said,

    Oh… yeah. I have! Yet another good design.

  3. Liza said,

    Well, the Brits manage with completely different faucets for hot and cold water…and with driving on the other side of the road and all…they’re such survivors.

  4. Ian said,

    Like, they have a hot shower and a cold shower? Do they just stand in the middle of the shower stall and spin rapidly to keep temperature-regulated?

  5. Adam said,

    hehehe that’s a pretty funny image… Tony Blair spinning madly in his shower to maintain optimal temperature.

  6. Liza said,

    The showers don’t have different faucets but according to friends that studied in London, the hot and cold water don’t really come out at the same time to provide one with warm water…it’s more sporadic, and hence, more fun.

  7. JT said,

    Sounds like the showers at my college…

  8. Liza said,

    Do you go to college in England, by chance?

  9. JT said,

    No, I went to college in Nebraska. But the dorm I lived in for 3 years was about 85 years old, so we just attributed the adventures in showering ot the building’s age.

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