Crows make decisions fast, about twice as quick as humans, according to new research that suggests the birds rapidly interpret visual cues and act without losing accuracy.
Despite major differences between avian and mammalian brains, the study indicates crows and primates share similar decision-making circuitry. The findings, published October 22 in Science, add to evidence that corvids perform sophisticated computations with brain structures distinct from the mammalian neocortex.
In experiments at the University of Tübingen, animal physiologist Andreas Nieder and neuroscientist Philipp Schmidbauer trained two carrion crows, Iggy and Lemmy, to report the direction of motion in a field of moving dots on a touchscreen. Some dots moved coherently left or right while others moved randomly as distractors. The birds tapped the left or right side of the screen as quickly as possible to indicate perceived direction, receiving mealworms for correct choices.
The crows repeated the task thousands of times. Task difficulty varied, from trials with strong coherent motion to trials where only a small fraction of dots moved in the true direction.
On average, the birds selected the correct answer in 235 milliseconds, about one-fifth of a second. Prior research shows humans and monkeys take roughly twice as long on comparable motion discrimination tasks, with similar accuracy. According to the researchers, even when motion signals were weak, choices were reliably better than chance, and with clear cues, accuracy approached 100 percent.
Crows make decisions fast in lab tests
While the crows performed the task, the team recorded neuronal activity in the nidopallium caudolaterale, an avian forebrain region considered analogous in function to the primate prefrontal cortex. Neurons in this area began responding as early as 70 milliseconds after the visual stimulus appeared. Activity ramped up as evidence accumulated, reaching a decision threshold that preceded the birds’ screen taps, a pattern consistent with decision dynamics reported in primates.
The results support the view that a mammalian neocortex is not required for complex computations. External experts noted the work underscores the importance of circuit-level organization over gross brain architecture, suggesting crows and primates rely on comparable neural algorithms.
The researchers propose that rapid visual processing may reflect selective pressures unique to avian life, such as the demands of flight, fast beak movements and predator avoidance. It remains unclear how widespread this speed advantage is across bird species. Scientists say more comparative studies are needed to determine whether the effect is broadly avian or specific to corvids.
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