Crows can evaluate visual info twice as fast as mammals

What happened

Researchers at the University of Tübingen tested two carrion crows on a moving-dots task. The birds watched a cloud of dots and had to say which way most of the dots were moving. While they worked, the scientists recorded their brain activity. The crows solved the task using the same math-like logic that monkeys use, and they did it about two times faster.

Why this task matters

In the random-dot-motion task, the dots mostly move at random, with only a few moving together in one direction. Past studies in monkeys showed that certain brain cells collect evidence over time. Their firing rate rises until it crosses a threshold, and then the animal makes a choice. Bird brains do not have a neocortex, the outer layer of brain tissue found in mammals, so it was unclear whether birds used the same method.

Key facts

• Two hand-raised carrion crows took part in the study.
• The dots ranged from 81 percent moving together (very easy) to 3 percent (almost like noise).
• A 0 percent condition had no correct answer.
• Crows pecked a target to answer. Monkeys answer by moving their eyes.
• Correct answers earned the crows a mealworm treat.

Why it matters

The study shows that very different brains can solve the same problem in the same way. This suggests that the method of gathering evidence until a choice is made may be a shared tool across animals. It also shows that birds can make quick, careful decisions without a neocortex.

What to watch

• Whether other bird species show the same decision method.
• How the crows' brain cells work during the task in more detail.
• Whether the speed difference holds in other tests.