Crows are intelligent animals that can use tools, hold a grudge And even organize funerals. New research suggests that these birds can make certain decisions more quickly than humans and monkeys – another potential sign of their intelligence, researchers say.
In a study published Thursday October 22 in the journal Scienceresearchers discovered that two carrion crows (Corvus crown) could distinguish the direction of moving dots on a screen in 235 milliseconds on average, or less than a quarter of a second. On the other hand, historical studies of humans suggest they make decisions in similar tasks six seconds faster.
The birds were very precise, and recordings of their brain activity suggested that their decision-making process resembled that seen in primates and humans.
Latest videos fromLive Science
Since birds and mammals have evolved along distinct paths for over 310 million years“This suggests that evolution could have independently developed similar solutions to the same computing problem,” co-author of the study. Andreas Niederprofessor of animal physiology and director of the Institute of Neurobiology at the University of Tübingen in Germany, told Live Science in an email.
In a raven’s split-second decision
To understand how crows make decisions using cues in their environment, researchers trained two carrion crows to complete a visual task on a touch screen. The birds observed a cloud of white dots moving on a black background. Some dots moved left or right while others moved randomly. The crows had to determine the predominant direction of movement of the dots and peck the corresponding target on the screen to earn a mealworm reward.
By changing the proportion of dots moving together, researchers could make the decision easier or more difficult for the crow. When most of the dots were moving in the same direction, the answer was pretty obvious to the birds. But when only a small percentage moved together, the birds had weaker visual evidence on which to base their decisions.
One of the carrion crows used in the study performs a decision-making task.
(Image credit: Andreas Nieder)
Crows achieved nearly 100% accuracy when many points were involved and movement was clear. But even when just 3 percent of the dots moved in concert, the two birds performed much better than simple guessing, getting the answer right 50 percent of the time.
Get the world’s most fascinating discoveries delivered straight to your inbox.
The birds maintained high accuracy during different phases of the experiment, suggesting that they were not sacrificing judgment for speed.
The study did not directly compare crows to humans and monkeys performing the exact same task. However, previous studies suggest that humans and monkeys take approximately twice as long to perform comparable visual motion tasks and at their own pace.
What’s going on inside the raven brain?
To understand how the birds made their decision so quickly, the researchers recorded the activity of 248 neurons in the nidopallium caudolaterale (NCL) – a region of the bird brain considered functionally comparable to the prefrontal cortex in humans and primates. Birds lack the layered cerebral cortex found in mammalian brains, but the NCL performs equally advanced functions.
In primates, neurons accumulate sensory information and their activity increases until it reaches a critical threshold and the brain makes a decision. The new results suggest that crows use a comparable process, the researchers concluded.
“The main implication is that a brain does not need a mammalian neocortex to perform sophisticated calculations,” Nieder said.
The team was able to use neural activity to predict the crows’ eventual choice “as early as 70 milliseconds after” the dots appeared, Nieder said. This was about 170 milliseconds before the crows’ behavioral responses, i.e., their pecking at the screen.
The speed of crows’ decision-making may reflect the demands of the birds’ daily lives.
“Flight places enormous demands on visual processing and sensorimotor (sensation and movement) coordination,” Nieder said. “Birds must navigate three-dimensional environments, avoid obstacles, and respond quickly to moving objects. Finding food and capturing prey may also require rapid and precise decisions. These pressures may have promoted rapid information processing.”
But for now, scientists don’t know why crows seem to outpace primates in this particular type of decision-making. The study included only two birds and no direct comparisons with primates. Further work could therefore be carried out to confirm the results and explore this question further.
For Nieder, observing the faster decision-making process in crows raises a broader question about how scientists define intelligence.
“Rather than assuming that the mammalian brain is the model for intelligent behavior,” he said, “we can study different species to discover which computational principles are shared among animals and which reflect adaptations to their particular environments.”
Are you a bird enthusiast? Find out with our bird quiz!
