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.