Wednesday, April 29, 2009

Grad school does strange things to your mind.

Now that I'm between semesters (school starts back up again on Monday), I have a bit more free time. I've been using some of it to read non-ABA research as, frankly, I'm getting sick and tired of certain tendencies in the ABA literature.

To this end, I picked up a 1982 paper by Kahneman and Tversky which was published in Cognition. The paper is entitled On the study of statistical intuitions, and is the earliest academic citation I could find for conjunction fallacy... although the usual "original experiment" is another paper.

In my reading, however, I came across the following:

Errors and biases in judgement under uncertainty are the major source of data for the mapping of the boundaries of people's statistical intuitions. In this context it is instructive to distinguish between errors of application and errors of comprehension. A failure in a particular problem is called an error of application if there is evidence that people know and accept a rule that they did not apply. A failure is called an error of comprehension if people do not recognize the validity of the rule that they violated.

An error of application is most convincingly demonstrated when a person, spontaneously or with minimal prompting, clutches his head and exclaims: 'How could I have missed that?'

I laughed.

Then I realized that I'd been finding a peer-reviewed journal article humorous. Gyah, does grad school ever mess with your brain...


  1. Welcome to grad school. :)

    As for the T&K conjunction fallacy paper... I remember primarily finding fault with some of their methods, even though the conjunction fallacy appeared to be so strong. Basically - to illustrate a bit of what was going on up there - it seemed like T&K went out of their way to make sure the subjects DIDN'T view it as a probability test. I always wondered what the results would be if T&K set up tests that actually looked like probability tests.

  2. The results would be completely different, of course. The entire point of the study was to assess intuitive judgement... and most people (I'm an exception) take probability tests as an cue to use formal, mathematical reasoning.

  3. Nicholas LeifkerMay 1, 2009 at 9:26 AM

    That's what you call a 'Well, duh...' If people instinctively understood probability correctly, casinos would be out of business.

    Here's the fun question, though. Even if people understood it was a probability game, would they get the conjunction fallacy right? I'm not sure they would. As T&K pointed out, people tend to use a kind of heuristic (confirming information increases perceived probability, discouraging information decreases perceived probability) to determine probabilities. Unless the subjects have had some education in probability theory, I'm not sure if it would make a difference.

  4. They actually discuss that in the 1982 paper I cite above. Good stuff. :-)