[BRIEF NOTE] On the intelligent crows of Aesop's Fables

[rfmcdonald]

The Aesop's Fable of The Crow and the Pitcher was proven by science. In the paper "Using the Aesop's Fable Paradigm to Investigate Causal Understanding of Water Displacement by New Caledonian Crows", investigators determined that the famously intelligent New Caledonian crow can interrogate questions of volume as well as young humans.

Understanding causal regularities in the world is a key feature of human cognition. However, the extent to which non-human animals are capable of causal understanding is not well understood. Here, we used the Aesop's fable paradigm – in which subjects drop stones into water to raise the water level and obtain an out of reach reward – to assess New Caledonian crows' causal understanding of water displacement. We found that crows preferentially dropped stones into a water-filled tube instead of a sand-filled tube; they dropped sinking objects rather than floating objects; solid objects rather than hollow objects, and they dropped objects into a tube with a high water level rather than a low one. However, they failed two more challenging tasks which required them to attend to the width of the tube, and to counter-intuitive causal cues in a U-shaped apparatus. Our results indicate that New Caledonian crows possess a sophisticated, but incomplete, understanding of the causal properties of displacement, rivalling that of 5–7 year old children.

Virginia Morell interviewed one of these researchers, Sarah Jelbert, for National Geographic News. An excerpt:

How did you come up with your idea to give the Aesop's Fable test to the crows?

Our study was based on the fantastic work of two other researchers, Christopher Bird and Nathan Emery. [They showed that rooks would use stones to raise the water level in a tube so that they could reach a worm.] Dropping stones into water isn't something New Caledonian crows do in the wild; no animal does. But it is also a completely natural thing, and so is a fair test of animals' cognition.

We trained six crows to drop small stones into tubes. And then we gave them different tests to see how much they understand or can learn about the cause and effect of water displacement. Would they understand that dropping stones into water in a tube [to get a piece of meat to float to the top] is different from dropping them into sand in a tube? Or that hollow objects have a different effect from solid ones?

They did very well at four of the six tests, where they were able to apply their natural understanding of cause and effect and the properties of objects. They understood that solid objects sink and hollow ones float, for instance, and that it doesn't make any sense to drop stones into sand. But they were incredibly poor at the counterintuitive test, which involved a U-[shaped] tube; they had to infer that there was a connection between the two tubes, but none of them could do this.

And what do their successes and failures at these tests tell us about the cognitive abilities of New Caledonian crows?

We're trying to understand the cognitive mechanisms of animal minds, and to do that you need to look at tests that animals can pass and those that they fail. In human psychology, researchers have discovered that the way people make mistakes is often most informative about how they think. The errors give away how they are solving problems. Is this true for animals, too? Or do they have a completely different way of conceptualizing problems? By looking at the errors the crows make, we may get a better understanding of how they successfully solve problems.

Jelbert reserved judgement as to whether or not the crows took the tricks they learned into the wild.