Clockwise or counterclockwise?

Question:

Which way should the key turn in a car door to unlock it?

Clockwise or counterclockwise?

.

.

C

A

P

T

A

I

N

I

N

T

E

R

V

I

E

W

.

.

Solution: Reportedly, this vintage puzzle still pops up from time to time at Microsoft. That’s because it is so Zenlike. Right or left. Most interviewees say the answer really doesn’t matter as long as candidates defend their decision. What they are looking for are candidates who can make an essentially arbitrary decision and defend it without getting hung up about it. This puzzle actually tests a viable skill, since most of the busi-ness decisions we are called on to defend are equally arbitrary.

For some reason no one has been able to fathom, the question never asks in what direction the key should turn to lock the car. It’s always to unlock it. But there may be a clue in this (see extra credit).

If the distribution of right- and left-handed people in the world were equal, it probably really wouldn’t matter. But since most people are right-handed, a good case can be made for designing car locks to unlock by turning right. Here’s why, as explained and dramatized by a candidate, now working at Microsoft, who fielded this puzzle in the early 1990s. The candidate actually stood up, pulled put his car key, and acted out the motions:

I assume that most automobile buyers, like most people in the world, are right-handed, so let’s design this car to meet the needs of the majority of consumers. I extend my right hand, holding a car key like this, with the key between my thumb and pointer finger. Now, I turn my hand clockwise as far as it can turn without dis-comfort. I can probably turn my wrist a full 180 degrees. Now let’s try the motion counterclockwise. There is much less range of motion, maybe less than 90 degrees. I also seem to have less strength near the limit of the turn. The design of the hand, wrist, and arm thus makes it easier for a right-handed person to turn a key clockwise (that is, to the right). This analysis suggests that because it’s easier for right-handed people to turn the key clock-wise, turning the key to the right is the preferred design.

If you think about it for a moment, there’s a Zen paradox here. Since the frequency of locking a car is the same as the frequency of unlocking a car, one of these motions is going to be “easy” and the other will be “awkward.” On what basis should we decide to make the act of unlocking the car the easy motion? Is it as arbitrary as it appears? Perhaps not.

Extra credit: It makes sense to assign the easy motion to unlocking or opening the car door. There are life-and-death situations that call for being given every advantage to unlock the car. A mugger might be stalking you in the parking lot. An extra second may be the difference between being victimized and escaping. People with arthritis need every advantage to open locks. Even people with full strength in their wrists sometimes have trouble unlocking car doors when they freeze. For all these reasons, giving the majority of consumers every advantage to unlock their auto-mobiles inclines designers to open car doors by turning to the right.

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