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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For example, take a look at this Puzzle Box that my colleague Andrew Young and I built, based on Horner and Whiten’s model.

There’s not too much to it – it’s basically just a Plexiglas cube with a divider in the middle. Now imagine that you’ve been told that there is a prize inside the box; where is it and how would you get it out? Since there’s only one place in the box that is opaque (the blue tube in the lower compartment) it seems pretty clear that that is exactly where the prize has to be. And that big red door on the front just begs to be pulled off, so that seems like an immediately obvious and expedient way of finding out what’s inside.

All of that is true, but when Horner and Whiten showed a Puzzle Box just like this one to both chimpanzees and preschool-aged children, they added a twist. Before the chimps or kids could retrieve a prize, they saw an adult get one out for herself. Rather than just getting the prize out directly though, the adult did it in a very circuitous, roundabout way. Take a look at this picture and you’ll see what I mean:

The adult began by using a small wand to (1) tap on the bolt on top of the box, (2) push the bolt out of its frame, and then (3) tap on the floor of the empty upper compartment. Only after all of this rigmarole did the adult do the thing she actually had to do to get the prize, namely moving the door and sticking the wand inside the opaque compartment.

After the adult had her prize, both the kids and the chimps both had a chance to get a prize out for themselves. How did they choose to go about it?

The chimps, it turns out, weren’t impressed with the adults roundabout technique. Rather than imitating what the adult did , the chimps just cut right to the chase – they skipped over the unnecessary steps (the ones shown in yellow) and instead just did the necessary things to get the prize out (the steps shown in blue). Score one for our chimps relatives.

Based on what the chimps did, I think most people would expect – as I certainly did – that kids would take a similarly smart approach. But that’s not what happened at all. Instead, fully 80% of the children copied all of the adult’s actions, including the unnecessary steps that the chimps couldn’t be bothered to reproduce. The kids, in other words, approached the task in a way that was a lot less clever than the chimps.

Now to be sure, there are a number of simple explanations for this result. For example, maybe the kids just thought it would be fun to use all the parts of the box. Maybe they thought that they were supposed to copy the adult, and felt sheepish about ‘contradicting’ an authority figure by ignoring part of the display. Or maybe the kids are just in the habit of imitating, and simply copying all of the steps seemed like less work to them than thinking it through.

All of these are possible, and even plausible, explanations. They are pretty much what Dr. Horner and Professor Whiten themselves said about this curious result. But when I first came across this work, I wondered: might something deeper be going on? Is it possible that the kids aren’t copying the adult because the want to or think that they should, but instead because they are confused in some interesting way about how the Puzzle Box works? I’ll return to this question tomorrow as I begin describing the first in a series of experiments I did to get to the bottom of this mystery.

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