The crows are thinking*

*what are they thinking about?

“I think it demonstrates convincingly that crows and probably other advanced birds have sensory awareness, in the sense that they have specific subjective experiences that they can communicate,” he said. “Besides crows, this kind of neurobiological evidence for sensory consciousness only exists in humans and macaque monkeys.”

To test whether crows know and can analyze the contents of their brains, neurobiologist Andreas Nieder of the University of Tübingen in Germany trained two birds to peck a red or a blue target on a panel, depending whether they saw a faint light. Nieder kept varying the “rule,” with the birds told which color meant what — red = saw it, or blue = saw it — only after the flash. That required the crows, Glenn and Ozzy, to keep monitoring their brains; they had a second or two to figure out what they had seen and tell Nieder by choosing the corresponding target.

While the crows were solving these tasks, the researchers were tracking the activity of hundreds of their neurons. (Crows’ brains have 1.5 billion neurons, as many as some monkey species.)

When the crows reported having seen a faint light, sensory neurons were active between the flash and the birds pecking the color that meant, yes, I saw that. If the crows did not perceive the very same faint stimulus, the nerve cells remained silent, and the bird pecked, no, I didn’t see anything. Ozzy and Glenn’s brain activity systematically changed depending on whether or not they had perceived the dim flash.

During the delay, many neurons responded according to the crows’ impending report, rather than to the brightness of the light. “A population of neurons contained information about the crows’ subjective experience throughout the trial,” the scientists wrote.

The birds were aware of what they subjectively perceived, flash or no flash, correctly reporting what their sensory neurons recorded, Nieder told STAT. “I think it demonstrates convincingly that crows and probably other advanced birds have sensory awareness, in the sense that they have specific subjective experiences that they can communicate,” he said. “Besides crows, this kind of neurobiological evidence for sensory consciousness only exists in humans and macaque monkeys.”

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