It's how I ended up walking the ridgeline of a friend's house when I was in eighth grade:
Friend: My house has such a steep roof. I don't know how anyone could keep his balance up there.
Me: I bet I could.
Friend (dubiously): You think?
Me; Yeah.
Friend: I dare you.
Me: Get me a ladder.That I didn't break my neck was as much due to luck as skill, although it must be said that back then I did have a hell of a sense of balance, even if I didn't have much of any other kind of sense.
[Image licensed under the Creative Commons Øyvind Holmstad, A yellow house with a sheltering roof, CC BY-SA 3.0]
Reward prediction error occurs when there is a mismatch between the expected reward and the actual reward. If expected reward occurs, prediction error is low, and you get some reinforcement via neurochemical release in the putamen and right temporoparietal junction, which form an important part of the brain's reward circuit. A prediction error can go two ways: (1) the reward can be lower than the expectation, in which case you learn by changing your expectations; or (2) the reward can be higher than the expectation, in which case you get treated to a flood of endorphins.
Which explains my stupid roof-climbing behavior, and loads of other activities that begin with the words "hold my beer." I wasn't nearly as fearless as I was acting; I fully expected to lose my balance and go tumbling down the roof. When that didn't happen, and I came ambling back down the ladder afterward to the awed appreciation of my friend, I got a neurochemical bonus that nearly guaranteed that next time I heard "I dare you," I'd do the same thing again.
The structure of the researchers' experiment was interesting. Here's how it was described in a press release in EurekAlert:
[The] researchers... placed groups of five volunteers in the same computer-based decision-making experiment, where each of them was presented with two abstract symbols. Their objective was to find out which symbol would lead to more monetary rewards in the long run. In each round of the experiment, every person first made a choice between the two symbols, and then they observed which symbols the other four people had selected; next, every person could decide to stick with their initial choice or switch to the alternative symbol. Finally, a monetary outcome, either a win or a loss, was delivered to every one according to their second decision... In fact, which symbol was related to more reward was always changing. At the beginning of the experiment, one of the two symbols returned monetary rewards 70% of the time, and after a few rounds, it provided rewards only 30% of the time. These changes took place multiple times throughout the experiment... Expectedly, the volunteers switched more often when they were confronted with opposing choices from the others, but interestingly, the second choice (after considering social information) reflected the reward structure better than the first choice.So social learning -- making your decisions according to your friends' behaviors and expectations -- is actually not a bad strategy. "Direct learning is efficient in stable situations," said study co-author Jan Gläscher, "and when situations are changing and uncertain, social learning may play an important role together with direct learning to adapt to novel situations, such as deciding on the lunch menu at a new company."
Or deciding whether or not it's worth it to climb the roof of a friend's house.
We're social primates, so it's no surprise we rely a great deal on the members of our tribe for information about what we should and should not do. This works well when we're looking to older and wiser individuals, and not so well when the other members of our tribe are just as dumb as we are. (This latter bit explains a lot of the behavior we're currently seeing in the United States Senate.) But our brains are built that way, for better or for worse.
Although for what it's worth, I no longer do ridiculous stunts when someone says "I dare you." So if you were planning on trying it, don't get your hopes up.
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This week's Skeptophilia book recommendation of the week is a brilliant retrospective of how we've come to our understanding of one of the fastest-moving scientific fields: genetics.
In Siddhartha Mukherjee's wonderful book The Gene: An Intimate History, we're taken from the first bit of research that suggested how inheritance took place: Gregor Mendel's famous study of pea plants that established a "unit of heredity" (he called them "factors" rather than "genes" or "alleles," but he got the basic idea spot on). From there, he looks at how our understanding of heredity was refined -- how DNA was identified as the chemical that housed genetic information, to how that information is encoded and translated, to cutting-edge research in gene modification techniques like CRISPR-Cas9. Along each step, he paints a very human picture of researchers striving to understand, many of them with inadequate tools and resources, finally leading up to today's fine-grained picture of how heredity works.
It's wonderful reading for anyone interested in genetics and the history of science.
[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]
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