In my post yesterday, When is a Chimp Smarter Than a Child?, I introduced a curious result from a recent comparative psychology study. To recap: both children and chimps were shown an extremely simple, transparent Puzzle Box, and then watched as an adult retrieved a prize from inside it. Rather than getting the prize out in the obvious direct way though, the adult first performed a number of superfluous actions such as tapping on the top of the box and unnecessarily removing a sliding bolt. When the chimps and kids later had an opportunity to get a prize out for themselves, only the kids wound up copying those irrelevant actions; the chimps, contrastingly, succeeded in ignoring the unnecessary steps and just going straight for the prize. On the surface then, it’s the chimps who seem to have unexpectedly come out on top in this task.

So what does this mean? The dissertation work that I’m currently completing at Yale began with this exact question. What does this odd situation, in which kids suddenly seem to be less clever than chimps, have to tell us about childhood cognition?

One possibility, as scientists and parents alike have pointed out, is that it may not tell us very much at all. That is, there are a number of plausible, deflationary explanations for children’s behavior in this task, none of which would be any great shakes scientifically. For example:

• The children may have assumed that they were “supposed” to copy the adult; they may have thought that they were playing an imitation game in which the whole point was to copy what the observed.
• They may have been reluctant to contradict an adult authority figure by ignoring her actions and choosing a more efficient route to the prize.
• They may have wanted to please the adult by copying her actions.
• They may have felt that the adult understood something non-obvious about the structure of the Puzzle Box, and thus that she had a reason for performing the seemingly unnecessary actions, even if it was not obvious.
• Since children learn so much from imitation, it may have been less effortful for them to simply copy what was observed rather than critically analyzing each step.

Unfortunately, Horner and Whiten’s original study didn’t rule out any of these reasonable explanations. Because of this, many psychologists assumed that there wasn’t much to the chimp/child contrast in this case. It was assumed that children overimitated, or copied the adult’s unnecessary actions, not for deep cognitive reasons, but instead because for one or more of the comparatively uninteresting social reasons outlined above.

It seemed to me though that while these deflationary explanations were indeed plausible, more interesting alternatives also existed. In particular, I wondered if perhaps observing the adult’s actions was changing the child’s understanding of the object in a more concrete, cognitively significant way. Perhaps somehow after watching the adult retrieve the prize inefficiently, children were really getting stuck thinking that one had to perform all of the observed actions to open the Puzzle Box? Essentially I wondered if children might be copying the adult’s unnecessary actions because of a “causal illusion” not unlike an optical illusion such as the Muller-Lyer effect illustrated below:

Consider the two horizontal line segments in the image. Excluding the arrow points on their ends, which horizontal segment seems to be longer? For most of us, it’s hard to resist the strong intuition that the bottom line segment is slightly longer than the top. In fact though, they are exactly the same length. (See later in this post for a link to a possible explanation). However, even once you’ve measured the line segments for yourself, it’s still impossible to look at the image without feeling as though the bottom segment is definitely longer.

I wondered if the children in the original Horner and Whiten study might be experiencing a similar kind of cognitive illusion, this one of the causal variety. That is, perhaps after observing the adult, they were left with the strong (false) intuition that all of the adult’s actions - even the ones that the chimps identified as unnecessary - were really somehow important for getting the prize out. Just as the visual system is tricked by the Muller-Lyer illusion, I wondered if children might be being misled by the way their brains processed and encoded the adult’s actions on the Puzzle Box.

Working with my colleague Andrew Young (now in the PhD program at the University of Wisconsin-Madison) I set out to answer this question by running a new study, this one involving more than 100 preschool-aged children from all over Connecticut. As in the Horner and Whiten study, the basic structure of the experiment was pretty simple: the kids watched as an adult retrieved a prize from a simple puzzle object, and then later had a chance to retrieve a prize for themselves. However, our study also included an important twist, one that was critical for addressing the deflationary explanations that I discussed above. Specifically, Andrew and I deliberately structured the task to make it as clear as possible to children that they were not supposed to exactly copy what the adult did. Instead, our task biased them to be on the lookout for “silly” unnecessary actions, and then to avoid reproducing them when acting on the puzzle objects themselves. In psychology jargon, we introduced implicit task demands that would encourage children to ignore what the adult did, and instead to operate the puzzle object in the most efficient way possible.

In my next blog post, I’ll talk about the methods that we used in more detail, and then introduce our initial results as New York Times science journalist Carl Zimmer described them. Mr. Zimmer’s article on what we discovered is extremely informative and entertaining, so stay tuned!

In the meantime, here’s a link to some more information on the Muller-Lyer illusion that I discussed above.

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This entry was posted on Thursday, November 22nd, 2007 at 10:50 am and is filed under Comparative Psychology, Imitation, Overimitation. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.