Well, I did choose A.

But I still think it’s an interesting question as to why many people chose C: It suggests some ideas about how people think.

You can learn something about a system from its failures, as well as from its successes…

I got it (option C) wrong too, and like some of the above I looked at the answer too soon!!!

Also, I suspect Jack’s marriage is in trouble.

This is obviously because of my training at recognizing and overanalyzing logic problems when I know I’ll feel particularly stupid if I get it wrong. What I wonder is: Would I have gotten the problem without training in tricky logic questions of this sort otherwise? Was the crucial thing about my past experience the training itself or the capacity to realize I needed to think longer?

since when is a canary a person??

and for exactly this reason C is the correct answer – sorry SciAm.

(my math teacher in school had trick questions like this to teach us never to assume things that were not given. the canonical example goes like this: there are 4 children and 3 lollies. Anne, Bernard and Chris each ave one lolly. Does David have one? of course you can’t tell, since noone specified David was one of the four.)

http://xkcd.com/660/

I admit to getting it “very wrong”: I was thinking about separating mother/child pairs.

I got the A answer after about 2 seconds of thinking about it, but I paused for awhile thinking there must be a catch somewhere (something along the lines of ‘what could Ann be’). Its a typical problem with overanalyzing a question that often plague IQ test results.

This problem only works if you know beforehand that you are *always* going to be offered the chance to change doors. If this isn’t stated beforehand, then its easy to imagine a scenario where changing doors is not in your favour, i.e. if the host only offers you the chance to change when he knows you’ve picked the winning door. The failure to say that you will always have the option to change your door before the door-picking has started, means that any probability calculations are meaningless.

Hence as Ann can only have these 2 polarisations , I said myself the answer is A .

I think that more than anything this kind of puzzle/article shows the importance of reflecting on your own thinking habits and trying to improve them, rather than trying to get the right answer first up. In the past I have made a lot of silly mistakes on tests etc when trying to go too quickly – only by realizing this problem and directing conscious effort towards recognizing when to slow down did I stop myself making these mistakes (as much). I think that learning when to control your thinking more carefully is a crucial skill to work on.

Yes, as you’ve shown, there IS a correct line of reasoning.

But you’ve also shown two other lines of reasoning that are wrong, but which look just as plausible.

The only way that I could be sure of the right answer was to look into & count the very specific cases: Then one can identify the correct way of looking at it.

And, further to the point that I raised: according to the wiki article on the Monty Hall problem, it seems to stump people universally. No mention is made of any special error-rate for higher-IQers.