New research at the University of Iowa shows that pigeons can discriminate the abstract concepts of space and time. The finding adds to growing recognition in the scientific community that lower-order animal species — such as birds, reptiles, and fish — are capable of high-level, abstract decision-making. Photo credit: Kathryn Gamble

New research from the University of Iowa (UI) shows that birds are smarter than we often give them credit for: it seems that pigeons have the ability to understand and discriminate between the concepts of space and time.

The experiments conducted by UI consisted of pigeons being shown a horizontal line on a computer screen, and having to judge the line’s length or the amount of time it was displayed on screen. “The interesting thing about judging the duration of an object or an event, is that the brain has to get really creative in coding this dimension that isn’t physically present in a perceptual sense,” explained Benjamin De Corte, a graduate student at UI who helped design and execute the experiments. “And [pigeon] brains are definitely capable of generating a sense of time.”

“The cognitive prowess of birds is now deemed to be ever closer to that of both human and nonhuman primates,” said Dr. Edward Wasserman, Professor of Experimental Psychology at UI, in a press release. “Those avian nervous systems are capable of far greater achievements than the pejorative term ‘bird brain’ would suggest.”

In the UI experiment, birds were shown on a computer screen a horizontal line either 6 cm or 24 cm long for either 2 seconds or 8 seconds. If they correctly reported (by pecking one of four visual symbols) the length or the duration of the line, they received food. Video credit: University of Iowa

“Basically, we had pigeons in front of a touch screen and we presented them with a line, which was a certain size and presented for a certain amount of time,” explained De Corte. “And we asked them to judge either how long the line was on the screen or how large it was.” When pigeons correctly reported the length or duration of the line by pecking visual symbols, they received food as a reward.


Importantly, the pigeons didn’t know beforehand whether they would have to judge the length of the line or the duration that it was on screen. “The task now forces pigeons to process time and space simultaneously because they cannot know on which dimension they’re going to be tested,” Wasserman explained.

Overall the pigeons were able to correctly judge the length or duration of the lines, but the researchers found that the length of the line affected the pigeons’ judgement of line duration, and that the duration of the line impacted the pigeons’ judgement of the length of the line. This sort of interplay between space and time has been found to also exist in humans and monkeys, suggesting that despite millions of years of evolutionary difference, the way birds process space and time is similar to that of mammals. “It’s weird, because the size of the line, when you’re asked to judge its duration, you’d think would be irrelevant,” explained De Corte. “It’s sort of like if I were watching TV and the volume of the television influenced how brightly I thought the TV was… and so we’re finding that there’s some sort of interplay or interaction between space and time, as there is for humans and monkeys.”


And it isn’t just space and time where birds show a similarity to humans. “Previous studies have shown that birds, including pigeons, were capable of really complex things that we thought were exclusively the domain of humans,” explained Benjamin De Corte. “Language is the main difference between us and them, but any nonverbal task that we ask them to perform they seem to do really well.”

Research has shown that pigeons can discriminate between identical and non-identical symbols, and apply this concept of sameness to other tasks. These birds have also been shown to learn and categorize images in much the same way that human babies learn words. And perhaps even more impressive, pigeons have been trained to visually identify whether biopsies of possible breast cancers were benign or malignant. Individual pigeons were able to do this task with 85% accuracy, but if you took a flock of trained pigeons and asked them to evaluate biopsy images, the group accuracy rose to 99%. “It’s amazing,” said De Corte, “if you have them all ‘vote’ on the same image, they can diagnose as well as a trained radiologist.”

And of course, it’s not just pigeons: Parrots seem to be able to understand the concept of zero; Crows have been shown to use tools (using twigs to fish out beetle larvae from dead wood, or even bending metal wires into hooks for the same purpose). And researchers have been able to show that crows can understand analogies, causal relationships and solve simple logic puzzles.


“Basically any task that we can test on humans without using language, birds can perform as well as humans,” said De Corte. “This most recent finding [of the space and time comparison] adds to that list.”