Probabalistic Watches, Tim Harford etc (which means I couldn't think of a title)

Henry Farrell writes on Crooked Timber:

Lifehacker links to an invention that I’ve thought for years would be a good idea (I’m sure that plenty of other people have had the same thought). Many people have their clocks running a few minutes fast, to encourage them to leave earlier for appointments to get there on time etc etc. The problem with this is that if you’re half-way rational, you’ll correct for the error, making it useless. So the solution is to have a probabilistic clock, where the clock is fast, but you aren’t sure how fast it is within a given and relatively short time range. Thus, you’re more likely to depart early for your appointments and get there on time (or a few minutes ahead, most probably, in many situations). This is exactly what some bloke has programmed, although it doesn’t appear that it has an alarm feature yet.

This is embarassing to say but I never thought of a probabilistically faster clock, despite my engineering degree and all. And I’ve done the same thing this past month—speeded up my wrist-watch, but ended up being late anyway because I know it’s faster! (My fellow van-poolers haven't been so pleased with my chronic lateness. But I'm trying, guys, I'm trying!)

Still, this brings up another point. My wrist-watch is of the old variety, with hands, and time-marks arranged in a circle, which means that the lowest time-interval you can accurately measure is 5 minutes. When I set it to run fast, I didn’t want to run too fast, thereby resulting in me getting there early (smart, huh?), so I set it to run faster by something less than 5 minutes. What this something is, I can’t recall—and really, no one thinks of measuring minutes except in multiples of 5. Therefore my watch does seem to be running probablistically faster, since I don’t know exactly how fast it is. No?

Has this helped? Well, not really! The rational (or procrastinating) actor proves hard to overcome. Now he simply takes out his cellphone and checks the time!

One more thought: It strikes me that the range of values that one can probabilistically speed up the watch by (1 to 4 minutes) cannot be extended. Because setting the watch faster by 11 to 14 minutes has the same effect as setting it faster by 1 to 4 (since the rational actor will cancel out the 10 minutes because it’s a multiple of 5 and thereby easily taken care of).

Commenter Maria on Henry's post brings up this typical Tim Harford gem:

Last weekend’s FT had a Dear Economist (i.e. Dear Tim Harford letter) from someone who always sets his watch fast and still manages to fool himself into being on time. ‘Mark’ wondered how this was possible, what with him being a rational actor who writes to economists asking for life hacks.

The answer was “you have a split personality, a warped view of time and are too lazy to do simple sums. Now put down this magazine: I suspect you are running late for something.”