Another bad interface: Clock hands

Take your standard everyday analog clock. You wouldn’t think that a device that’s been around this long would have bugs in it, would you? I never really thought about it until I started teaching my son how to tell time.

Telling time is easy. You look at the hour hand. See what number it points to. That’s what o’clock it is. If it points to 7, it’s 7:00 o’clock. If it’s between two numbers, it’s between o’clocks. Halfway between 4 and 5? It’s half-past 4 o’clock. Almost at 11, but not quite? It’s almost 11 o’clock, but not quite. The hour hand tells you the time to within 10 or 15 minutes. Almost all the information on the clock is in the hour hand.

So which hand is more prominent? Not the hour hand, the minute hand. The minute hand is always the long one, which means it draws the eye more, and is easier to read. This is an interface bug. The most important information should be the most prominent.

I guess it’s just one of those things you don’t think about once you internalize it, like the way we Americans use a fork and knife. (Ever think about how often you have to change hands? Watch your own hands the next time you eat, you’ll be amazed how much time you spend moving forks and knives from hand A to hand B.)

5 thoughts on “Another bad interface: Clock hands”

  1. You’d think that would be on Wikipedia or something already. All I’ve been able to determine is that the hour hand predated the minute hand (duh).

    Perhaps precision of measurement is part of the issue. As you said, the hour hand is “about halfway between” the 3 and the 4, and that’s good enough. The minute hand is on the 27 minute mark. Therefore, the minute hand needs to touch the border where the tick marks are located, but the hour hand can point vaguely in that direction.

    That’s my 2 minute analysis, anyways.

  2. (Oh, almost forgot — if I’m using a knife, the fork never leaves my left hand. And I’m still the slowest eater at the table, probably a result of the old Fiske School training where we didn’t want to go out in the cold after lunchtime.)

  3. You raise an interesting point. But I disagree (naturally). Knowing it’s about 27 minutes past something is mostly useless. Knowing it is quarter- or half-past 3 o’clock is almost always good enough. (Andwhen you figure in how many clocks are off by 5 minutes or more, the minute hand becomes less and less important.)

    It’s a bit of a dodge anyhow, there are plenty of ways to design it so both hands actually intersect the circle of numbers and tickmarks. For example, the whole circle could be moved inwards so both hands contact it. Or you could have two circles, one marked 1-12, another 0-60. Or have both hands equal length, but the hour hand significantly wider. Hm, I like that one.

  4. Obfuscation. Assuming that the clock is not set properly is beside the argument.

    Again, you can see if the hour hand is between the 3 and the 4 without the hand reaching the edge. If you are going to have a minute (or second) hand, it has to reach the ring.

    If you move the ring closer to the center of the ring, the tick marks get closer together, and therefore become harder to read. And just try to legibly add 60 numbers around the ring.

    And, any ‘old’ clock will have a thicker hour hand, either all the way along the length, or as a bulb on the end; check out Big Ben, for instance. ( http://www.k5kj.net/SkyFire/TEMP/Big-Ben-04.jpg ) It is only those newfangled modern analog clocks that have the hands the same width.

  5. In the face of the awesome firepower Michael is strafing me with, maybe I’ll drop back to “reasonable people can disagree”. Even though I still think I’m right.

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