Two carrion crows, Iggy and Lemmy, identified the direction of moving dots in an experiment at the University of Tübingen. Their responses began in about 235 milliseconds--faster than the times reported in earlier comparable studies of humans and monkeys.
The birds watched dots moving across a touchscreen and pecked the direction they detected. Even when just 3% of the dots moved together, both crows performed better than chance. Researchers measured the start of each response by tracking when a bird began turning its head.
Decision signals in the crow brain
While the crows completed the task, researchers recorded activity from 248 nerve cells in the nidopallium caudolaterale, a brain region associated with planning and decision-making. Fifty-eight cells showed activity linked to the direction the birds chose. Their signals began to predict a choice about 70 milliseconds after the dots appeared.
The pattern resembles evidence-integration processes observed in mammals: as information accumulates, neural activity rises until a decision is made. The crow brain is organized differently from the mammalian brain, suggesting similar decision-making processes can emerge from distinct brain structures.
Why the crows responded so quickly remains uncertain. Compact neural wiring, birds' visual demands, and their relatively high body temperature are possible explanations, but these ideas require further testing. The study was published in the journal Science.
By comparing how different brains turn sensory information into choices, future research may broaden our understanding of cognition and inspire new approaches to efficient information processing.
