Carrion Crows Match Primate Decision Logic at Double the Speed

Andreas Nieder and Philipp Schmidbauer of the University of Tübingen demonstrated that carrion crows process visual evidence with the same mathematical logic as primates, but at twice the speed. The study, published in 2026, resolves a long-standing question about how brains without a neocortex handle complex decision-making.

The researchers used the random-dot-motion task, a standard benchmark in neuroscience. In this test, a cloud of flickering specks drifts weakly in a specific direction. Subjects must identify the motion and report their answer. In primates, neurons in the neocortex accumulate this visual evidence over time. Their firing rates rise until they cross a threshold, triggering a committed choice.

Nieder noted that birds lack a neocortex, which left the mechanism for their decisions unclear. He described this as the central question of the study. The team sought to determine how a differently organized avian brain encodes decisions. To ensure a direct comparison, the team kept the experimental setup identical to the monkey version. The only difference was the output method: crows pecked a touch-sensitive monitor to indicate direction, while monkeys used eye movements.

The team tested two hand-raised carrion crows. The birds faced a display showing white dots on a black background. A fraction of the dots moved coherently in one of four directions. The crows earned a mealworm for correct answers. The researchers varied difficulty by changing the percentage of coherent motion, ranging from 81 percent at the easy end to 3 percent at the hardest level. They also included a zero percent condition with no correct answer.

The results showed that the crows solved the task using the same accumulation process as primates. Despite the structural differences in their brains, the birds reached decisions in half the time required by monkeys. This finding indicates that a brain without a neocortex can arrive at comparable decisions through a similar process. The study provides direct evidence on the speed of avian cognitive processing in complex visual tasks.

The experiment was conducted in a controlled laboratory setting. The crows were trained to interact with the touch-sensitive display. The researchers recorded brain activity throughout the trials to track the accumulation of evidence. The data confirmed that the birds' decision-making was not merely faster, but structurally analogous to the primate model.

The study contributes to the understanding of cognitive efficiency in different brain architectures. It shows that the absence of a neocortex does not prevent the use of standard mathematical decision-making processes. The findings offer a new data point for comparing cognitive speeds across species.