Last weekend, I drove to NYC to deposit my oldest son and his girlfriend back in Brooklyn after they had spent a nice weekend with us. Up and back through three of the five boroughs: Staten Island, Brooklyn, and Manhattan. I’ve driven through NYC dozens, maybe 100’s of times, and even before they lived there, I was already a hardened veteran of NYC driving. As soon as I cross the Goethals Bridge or emerge from the Holland Tunnel into the canyons of lower Manhattan, I’m in NYC driver mode. Like flicking a switch.
I’m a freakin pro. And truth be told, I love it.
U-turn in the middle of the street? Yup. Turn left from the right lane? Of course. Just stop in the middle and double park? You betcha.
I’ve not (yet) had an accident, and I know why. Because when I’m driving around there, I expect any and all things all the time. Just as I don’t think twice about disregarding all traffic decorum, I expect all of those around me to do the same.
Of course you can cut me off. Oh, you want to stick your bumper into the 8-inch space separating me and the guy in front of me? Sure, go ahead. Going around me on the sidewalk to the right? Be my guest.
It’s all good because none of it is astonishing to me in this context. I expect it, I’m ready for it, I adjust, and it’s no big deal. And yeah, I do it also.
But what happens on the roads in the small rural community in eastern Pennsylvania in which I live? Nothing like that. It’s all slower, orderly, and calm. I don’t expect any of that.
But then someone gets cut off, and what happens? Boom. Accident. Or, at the very least, “You idiot! Where’d you learn to drive!” It might bother me for the rest of the day.
This is the Principle of Least Astonishment — minimizing confusion and unexpected behaviors while maximizing intuitive understanding.
We in the software development world use the Priniciple of Least Astonishment (also called the Law of Least Surprise) all the time.
If we’re doing our job and using this principle, you (the user) can figure out how to do things on your phone or computer that nobody has taught you explicitly. For example, nobody taught you how to find the settings on your phone. You know they’re in the “Settings” app. We use this principle under the covers as well, even in the nitty-gritty interworkings of the technology. We argue vehemently about how this API should work or what should data it requires.
Least astonishment changes with the intuition of the culture and its people. Which means it changes over time and with context. If you handed an iPhone to George Washington, he wouldn’t be able to find the settings, nor even understand how to turn it on because he doesn’t have any context or intuitive build-up for the technology.
He would be very astonished.
Next time you’re organizing your closet, developing a set of guidelines for your Church committee, or driving around your town, make sure you’re applying the Principle of Least Astonishment. It will serve you well.
