Author Archives: Hal Finney

What percentage of the world’s airports are in the USA? (Answer below the fold.)

Take a guess. Now, take another guess, different from the first one, and average them. According to research reported on in The Economist, averaging the 2nd guess improves accuracy by 6.5%. Better still, wait 3 weeks before taking a second guess. Averaging now improves accuracy by 16%. (Story found via Slashdot.)

Here is the full report from Pschological Science.  Some excerpts:

It is important that neither group knew they would be required to furnish a second guess, as this precluded subjects from misinterpreting their task as being to specify the two endpoints of a range.

That could make it a little tricky to do this on your own; you have to try to make your first guess as good as you can, and then start fresh for the second guess.

This benefit of averaging cannot be attributed to subjects’ finding more information between guesses, because second guesses were less accurate than first guesses

Hmmm, how can second guesses be less accurate than first guesses, yet averaging them is more accurate than either? I suppose it means that the two guesses tend (on average) to bracket the correct answer, with the second guess farther away than the first one. That means that your first instinct to improve your guess is more likely than not to be in the correct direction, but go too far. Knowing this might allow you to improve your guesses even more.

Oh, and as for the airports? According to the CIA World Factbook, there are 14,947 airports in the U.S., and 49,024 in the whole world, so 30% of the world’s airports are in the U.S. For the record, I guessed 25%, and then 15%, so averaging didn’t help me. But in general this might be a useful trick to easily improve guesses.

Rolf Nelson points out that we don’t have good terminology to call “beliefs we would have had if we didn’t choose to be persuaded by the fact that everyone else believes differently”. It’s an important distinction because this kind of belief is arguably more helpful to know, for both majoritarians and others.

In classic group-decision experiments like “guess how many beans in the jar”, you get less accurate answers if people call out their guesses one after the other, because they are revealing their adjusted beliefs, that take into account the social consensus (perhaps without realizing it). If people write their answers down, we get Rolf’s kind of beliefs, uninfluenced by the consensus view, and those have been shown to be more accurate on average.

So Rolf’s point is very relevant about the lack of terminology. Devil’s Advocacy is about as close as I can come, but that doesn’t capture it. What do you suggest would be a good way to describe these kinds of beliefs? Once more people start making a conscious distinction between the two modes of believing, how should we talk about it?

Follow-up to: Conformity Myths

Robin posted earlier about a NYT Magazine article on conformity. I was able to find an online copy of the scientific paper here: http://psr.sagepub.com/cgi/reprint/10/1/2.

The synopsis from the NYT is not complete. Of the 12 times that people were challenged to disagree with the social consensus, the most popular choice was to agree 0 times. 25% of the subjects did this. The second most common was to agree 3 times, done by 14%. Third most common was agreeing 8 times, 11%. Only 5% went along with the crowd all 12 times.

I think it’s quite significant that 25% of subjects never went along with the crowd and stuck to their own perceptions. In total, only 32% of the answers were wrong.

I’m not sure I follow Robin’s comments on this. It seems to me that this re-interpretation of the classic experiment suggests that people are not as conformist as generally thought. That would mean that we do more than merely give lip service to celebrating independence, that culturally we are quite effective at following the ideal of independent thinking.

The key question is, what is the right thing to do here? Should one conform when presented with 8 people denying the evidence of one’s own senses? I argue that it is the right thing to do.

Now of course, if you know you’re in a psychological experiment, maybe you can’t help but be suspicious that something fishy is going on. But in general, in real life, if 8 people come in and tell you that your perceptions are completely wrong, you should take it very seriously. I imagine that in the history of the world, in the great majority of such situations, the 8 were right and the one was wrong. As an example that some may be familiar with, if a bunch of friends come in and tell you you’re drinking too much, while your perception is that you can easily handle the alcohol, you should probably listen to them.

I would suggest that conformity is the right thing to do in these situations, and to that extent I am rather dismayed that the subjects were as non-conformist as this data shows.

de gustibus non disputandum
(there’s no accounting for taste)

Can Eliezer’s reasoning about lotteries be extended to something like sexuality? The goal of our sex drives is reproduction of the fittest members of the species. But today we have interrupted this process so that most sexuality does not lead to reproduction. The underlying logic of the drive is no longer functional. Does this mean that our sex desires are irrational, and that we should consider sex to be as pernicious and harmful as lotteries?

Another example is our love of sweet and fatty foods, which are harmful to our health in today’s environment. The fundamental reasons we seek these foods no longer apply today. In a sense, this kind of hunger is irrational, in that satisfying the drive is actually harmful to us.

Where do we draw the line in judging whether our desires are rational?

Continue reading "Irrationality or Gustibus?" »