Recently a psychology student posted a copy of the “Four Card Problem” which is a logic puzzle where players must flip over the minimum number of cards to possibly prove or disprove a rule. The way to play is quite simple, yet fewer than 10% of university students have been able to successfully answer it. Ready to step up and give it a whirl?!

Not you, psych students and graduates who have probably already seen this! Back off for a sec and give the rest of us a try first.

Tweet: This problem that came up in my psychology class was interesting. Only 5 percent of university students got it. I was fairly stuck too.

Here is a translation of that logic puzzle.

When British psychologist Peter Wason presented a similar problem to 128 university students, “A and 3” was the most popular answer from 46 percent of them. The second most popular answer was simply “A” which 33 percent (and I myself) answered.

Now you can probably deduce from the intro that these answers are not correct. But as other psychologists have pointed out about this test, the reason that this is so hard to answer has more to do with the abstract relation between letters and numbers.

For example if we were to phrase the question this way:

Then there’s a better chance you will say “10 and beer” are the correct answers since they are the only two that have restrictions. To lay it out completely.

If the other side of “10” says “beer” then it breaks the rule.

If the other side of “25” has any drink it doesn’t break the rule.

If the other side of the coke says any age it doesn’t break the rule.

If the other side of the beer says anything under 18 then it breaks the rule.

Therefore only the first two cards would have any impact on proving or disproving the rule. The other two have no effect. So, going back to the original question.

If the other side of “A” says anything but “3” then it breaks the rule.

If the other side of “K” says anything it doesn’t breaks the rule.

If the other side of “3” says anything it doesn’t break the rule.

If the other side of “7” says “A” then it breaks the rule.

 Therefore only “A” and ‘7” would have any impact on proving or disproving the rule. The reason most people get it wrong is that they mistakenly assume “3” has a restriction placed on it. That’s not true though since only “A” must say “3” not the other way around.

And even more people forget about “7” because rather than setting out to disprove the rule, most of them are focused on confirming whether it’s true or not. See, the bulk of humanity isn’t a bunch of negative-nancies after all…probably to our detriment.

Interestingly enough the number of correct answers in the comments was pretty much in line with Wason’s results. Actually, there were more people who were annoyed that this version of the puzzle didn’t use “AK47” than who answered correctly.

Source: Twitter via My Game News Flash (Japanese), Social Psychology Network, The Adapted Mind: Evolutionary Psychology and the Generation of Culture – Chapter 3 (English) 
Beer Image: Amazon
Cola Image: Amazon