James Bach recently blogged on the notion of intution and common sense being considered harmful. You can read his post here: http://www.satisfice.com/blog/archives/55
Merriam-Webster Online says of “intuition”:
[quote]
Etymology: Middle English intuycyon, from Late Latin intuition-, intuitio act of contemplating, from Latin intuEri to look at, contemplate, from in- + tuEri to look at
1 : quick and ready insight
2 a : immediate apprehension or cognition b : knowledge or conviction gained by intuition c : the power or faculty of attaining to direct knowledge or cognition without evident rational thought and inference
[/quote]
The word “evident” in the second definition struck me as interesting. It doesn’t say that intuition is magic, or without rational thought or inference; merely that the rational thought or inference isn’t evident.
A huge part of the mission of skilled tester, I believe, is to build credibilty by identifying and communicating our skills–which include developing rationally thoughtful inferences–to ourselves and to others. In order to do this, we need to make our thought processes visible and evident, and to identify and articulate what is common and sensible about our common sense. By the same token, when we’re fooled by a puzzle or a bug, it’s important to identify how our intuition and our sensibility could be sharpened.
Here’s an example. A colleague in Brazil gave me this puzzle to solve:
You are down the hall and around the corner from a room. The door to the room is closed, and the lights inside are off. There are three switches on the wall in front of you. One of them controls a lamp in the room. You must find out which switch controls that lamp, but you may only enter the room once (and opening the door counts as entering the room). No light leaks through the door (which closes as soon as you let go of it), and there is no other door, nor is there a window. There is no one else around to help you, and there are no tools, mirrors, or cameras available. How do you figure out which switch controls the lamp?
If you can’t solve the puzzle, the answer appears below. Hints and the answer follow, so if you don’t want to spoil the fun of solving it yourself, stop reading now!
I didn’t solve the puzzle, but as soon as my colleague began her explanation, I was able to leap to the answer without her finishing.
Hint 1: For many puzzles, it’s tempting to consider logic and tools. Logic will help here, but only to some degree, and tools are necessary.
Hint 2: The reminder that I needed was to consider more sensory modes–an important general systems principle.
Hint 3: I thought about sight and hearing, but I failed to consider the other three of the five senses.
Answer: Turn on one of the switches, and leave it on for a minute or so. Turn it off, then turn on one of the other two switches, and enter the room. If the lamp is on when you enter the room, you’ve found the right switch. If the lamp is off, touch the bulb. If it’s warm, the first switch controls the lamp. If it’s cool, the switch that has never been on controls the lamp.
I don’t feel that I’m very good at this kind of puzzle, and I’m often startled by people who can get the right answer right away. They usually explain that the answer is “obvious” to them. Obvious is my favourite one-word tautology: something is obvious to someone for whom it is obvious, and not obvious to someone for whom it is not obvious. I think that there’s a different explanation: that people who solve this puzzle without hints or help consider those different sensory modes, and those of us who don’t consider them get stuck on the puzzle. So, here’s a new puzzle solving heuristic: consider all of the senses as a means of helping find a solution to a problem.
I don’ t mind following James’ lead and banishing “intuition” and “common sense” from referring to my own thought processes, but I would like to begin using the words as trigger heuristics when I hear them from others. When I hear the words, I’d like them to prompt me to try to figure out the rational thought that people are perfoming and the inferences that they’re making, and to gather evidence that that’s what’s going on. I want to develop the skill of immediate apprehension and cognition by making invisible assumptions and heuristics as visible as possible.
That’s part of what being a tester is all about, isn’t it?
I have a perfectly legal solution that I saw as soon as I read the description of the problem:
“You are down the hall and around the corner from a room. The door to the room is closed, and the lights inside are off. There are three switches on the wall in front of you. One of them controls a lamp in the room. You must find out which switch controls that lamp, but you may only enter the room once (and opening the door counts as entering the room).”
Clearly, the thing to do is to open the door (once), and look in the room while moving the switches until you figure out which one does what. Use mirrors, cameras, or other tools if you have to.
I thought that being down the hall and around the corner would suggest that you can’t see inside the room as you flip the switches. I’ve changed the text of the puzzle to include the fact that you can’t use tools.
There might be light coming out from underneath the door and projecting a shadow into the hallway.
How far down the hall and around the corner is the room?
– If it’s a dropped ceiling i might be able to push the tiles out and see light reflecting through the dark space.
– There could be an AC vent that would let some light through.
Maybe there is no ceiling to the room at all – it could be half walls, like cubical farms. This sure would make it easier 🙂
Hah! Can’t use tools?!?!?! I quit your company! I’ll go somewhere where they appreciate efficient solutions. (exaggerated to make a point, eh?)
If it’s an LED lamp, the ‘bulb’ will not be warm after its been turned off. What do you do then?
(Find and ask the electrician.)
Nice observations. The comments here are great indications of how good testing minds can expand the set of potential solutions to a problem, just as they can expand the set of problems associated with a possible solution.
Keith’s possibility of the LEDs occurred to me too (only after my colleague led me to the answer she had in mind), but I wanted to see how long it would take for someone to suggest it–and how they would solve the refined problem. It’s interesting that delivering the puzzle as text constrains me from saying “Nope, the electrician isn’t around.” There’s another blog entry to be made on the difference between puzzles presented as text and puzzles presented as conversation–and how that’s like (and unlike) dealing with requirements.
Thanks, gents!
Chris:>Hah! Can’t use tools?!?!?! I quit your company! I’ll go somewhere where they appreciate efficient solutions. (exaggerated to make a point, eh?)
Quitting is an option. As Matisse Enzer said in the SHAPE Forum a while ago, “Everyone is self-employed; not everyone knows it.” However, I find that when there are constraints around a problem, even artificial and arbitrary ones, there may be an opportunity to learn something.
Cheers,
—Michael B.
“I want to develop the skill of immediate apprehension and cognition by making invisible assumptions and heuristics as visible as possible.
That’s part of what being a tester is all about, isn’t it?”
I would be tempted to say: “obviously” but I won’t, out of the irony.
Also, some comments regarding the puzzle:
1. A colleague asked if we could observe electricity flow since only a closed circuit will cause electricity to flow (to which I replied that good point but you don’t know what the other 2 switches control so you wouldn’t be able to reliably base your decision on electricity flow alone, and
Michael replies: Props to your colleague for the idea, and to you for thinking critically about it.
2. Do we know the (assumed) light bulb is intact? There will be no heat if the bulb has burned out and the lamp doesn’t turn on when a switch is flipped.
We don’t. Which reminds us of something else: every test procedure, every notion of coverage, every oracle—all is heuristic.
Oh, additionally:
3. Do we know which position for the switches is “ON” and which one is “OFF”? Maybe the light is already on when I go in the hallway and the suggested solution fails because instead of turning the lamp on, the second switch I flip actually turns it off. Then I enter the room and, since the lamp is not on but the bulb is still hot, I (wrongly) jump into the conclusion that the first switch must have been the one controlling the lamp when, in fact, it was the second one!
Michael replies: According to the setup for the puzzle, the lights are off when you entered the room. But, of course, you don’t know that; maybe opening the door alters the state of the lights, for example. See my previous reply!
Intuition and Common Sense
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