Many children (and adults) have heard Aesop's fable about the crow and the pitcher. A thirsty crow comes across a pitcher partly filled with water but can't reach the water with his beak. So he keeps dropping pebbles into the pitcher until the water level rises high enough. A new study finds that both young children and members of the crow family are good at solving this problem, but children appear to learn it in a very different ways from birds.
Recent studies, particularly ones conducted by Nicola Clayton's experimental psychology group at the University of Cambridge in the United Kingdom have shown that members of the crow family are no birdbrains when it comes to cognitive abilities. They can make and use tools, plan for the future, and possibly even figure out what other birds are thinking, although that last claim is currently being debated. A few years ago, two members of Clayton's group showed that rooks can learn to drop stones into a water-filled tube to get at a worm floating on the surface. And last year, a team led by Clayton's graduate student Lucy Cheke reported similar experiments with Eurasian jays: Using three different experimental setups, Cheke and her colleagues found that the jays could solve the puzzle as long as the basic mechanism responsible for raising the water level was clear to the birds.
To explore how learning in children might differ from rooks, jays, and other members of the highly intelligent crow family, Cheke teamed up with a fellow Clayton lab member, psychologist Elsa Loissel, to try the same three experiments on local schoolchildren aged 4 to 10 years. Eighty children were recruited for the experiments, which took place at their school with the permission of their parents.
In all three experiments, instead of worms, the children tried to retrieve red tokens that they could exchange for colorful stickers depicting animals, pirates, and other images. (The team found that both younger and older children were keenly interested in having the stickers.)
In the first experiment, the children were presented with two tubes, one filled with water and the other with sawdust, and had to decide which one to drop marbles into to get a token from inside.
The second experiment featured just one tube filled with water, but the children had to choose between two different objects to put into it—a cork ball that floated, or a marble that sunk.
The third task was the toughest. Cheke and her co-workers presented the children with an apparatus with three different water-filled tubes: two wide ones on either side of a narrow tube, which held a token. The bottoms of the tubes were hidden, concealing the fact that one of the wide tubes was in fact connected at the bottom to the narrow center tube, whereas the other wide tube stood alone. And since the middle tube was too narrow to drop a marble into, the child could choose to put the marble into only one of the two wide tubes. The only way to get the token was to drop a marble into the wide tube connected to the narrow one. Thus in this third case, the apparatus worked in a way that was mysterious to the children.
The children were allowed five trials per experiment lasting 2 minutes each to learn the tasks. As might be expected, the older children did better than the younger children: By age 8, most children were able to successfully perform all three tasks during the first trial, and younger children required more trials, the researchers report today in PLoS ONE. But their performance contrasted in an important way with that of the birds. While the jays were able to learn the first two tasks by trial and error, they could not master the third experiment, in which the solution was not obvious and even counterintuitive.
Cheke and her colleagues conclude that this suggests a fundamentally different learning process between the birds and the children. Whereas the birds were put off by a seemingly physically impossible setup and couldn't learn the third task, children weren't stymied by the apparent impossibility of the task, but forged ahead and learned to raise the tokens anyway—even if it wasn't obvious how it was happening or the solution didn't seem to make intuitive sense.
"Children start off with no idea of what is possible and what is not possible," Cheke says. "If they did, they would never be able to learn. This is why children like magic, and why they will believe you when you tell them all kinds of fanciful things."
Alison Gopnik, an expert in child developmental psychology at the University of California, Berkeley, calls the study "fascinating and illuminating." The main difference between the birds and the children, Gopnik says, is that members of the crow family "have sophisticated but specific knowledge about how physical causal relationships work in the world," whereas children "seem to have broader and more wide-ranging causal learning abilities."
As a result, Gopnik adds, the birds "are beautifully adapted to learn about this world," but "children are beautifully adapted to learn about many possible worlds."