2023-06-24 14:02:15
What do great apes, pigeons and parrots have in common? Not much you might think at first glance, but they do share one important thing in common: they can categorize. And we didn’t know that about those parrots yet.
Categorization means that animals – or humans, if you like – can distinguish between two objects: for example, they always know how to point to the oranges when they have to choose between oranges and bananas. In this case, kea, a New Zealand parrot species, managed to choose from two pictures the picture of the face they knew or did not know. A skill that has so far only been demonstrated in very few animal species. “There are still very few studies that have tested this in lab animals and none looked at parrots,” Austrian researcher Elisabeth Suwandschieff explains in conversation with Scientias.nl.
Grab a photo
The scientist of the University of Veterinary Medicine Vienna explains how the research was done: “For this experiment, we trained 12 kea parrots to peck at one of the two pictures they were shown on a touchscreen with their beak. For each correct answer, they received a piece of peanut. The photos of the people were taken from different angles, sometimes from above, sometimes from the side. One photo was always of someone with whom the kea had close contact over the past five years, while the other photo was of someone completely unknown.” Half of the animals were rewarded for choosing a known person, the other half for choosing an unknown person. Both groups probably used the famous person as the deciding factor.
The control group also had an important task this time. “They were shown the same photos of human faces and were rewarded for choosing specific photos.” However, it was not about known versus unknown people, but about a mix of both. “It was therefore impossible for the control group to apply the concept of familiarity to make a choice between the faces they saw.”
More and more photos
But the experiment did not end there. “By adding more and more photos of new known and unknown people to the test, we were able to see whether the test group was able to apply this concept. And guess what: that group was indeed faster in solving the task if more photos were added. This indicates that the parrots were able to use the concept of familiar versus unfamiliar faces. The test group could immediately make the right choice, because they could immediately link the new photos to the familiar versus unfamiliar faces. The control group again had to learn the new individuals specifically, but remarkable: in the second session these birds also managed to choose the right photos, which shows that the control group already understood the task so well that it was sufficient to see the photos once.
Same test, different reward
“We did the same thing in the last test: we added a number of new photos and the parrots had to distinguish between familiar and unfamiliar faces,” adds researcher Raoul Schwing of Vienna University. “Everything remained the same for the control group, but we changed the reward for the test group. If one half was first rewarded for picking out the unfamiliar face, they now received a reward for choosing the familiar face correctly. And the opposite was true for the other half. Not many birds managed to understand this, but some could. And that’s very clever, because most animals in general are not able to apply more than one rule at a time. The parrots succeeded: for the new photos they were shown, they applied the new rule – they were rewarded for selecting the known photo – and for the old photos they used the old rule – they chose the unknown photo. ”
The New Zealand parrot species Kea. Photo: Brad Grove
It was not made easy for the parrots. “To make sure the photos were as similar as possible, all people had a white sheet around their neck and torso. They were also asked to look neutral. This was so that the kea could not use other signals to complete their task, such as a pattern on a T-shirt. They only had the facial information to make their choice,” said Suwandschieff.
Handsome heads
The fact that the parrots managed to do this is a major achievement. This means that of all the signals the animals use to distinguish between individuals, facial information alone is enough. They can thus use this concept of familiarity to solve a task where there are two categories. This puts parrots in the same league as great apes and pigeons who have already proven that they can do this. “The parrots are showing that they are capable of the same things as our closest relatives. That is remarkable given the phylogenetic distance between the two animal species,” he says admiringly.
Free as a bird
Finally, there is also a practical application for the animals themselves. “The results make it clear that parrots in a lab situation can flexibly adapt to their environment, developing the ability to distinguish between humans. A skill that was never needed and therefore never developed in the wild. On the other hand, this ability also has implications for the welfare of the animals and must therefore be taken into account when trading and breeding parrots,” explains Suwandschieff. The parrots were not locked up in cages in a laboratory during the experiment, but were able to fly freely outside in an aviary of more than 500 square meters.
Kea. Photo: Osting
But why did the researchers actually choose kea parrots? “They are very exceptional birds. They have complex social structures, are opportunistic foragers of food, and are very fond of new things. All these properties make them a very suitable species to test flexible behaviour, technical and social intelligence and problem solving ability.”
Not recognizing
The researchers want to emphasize that they have not investigated whether the animals actually recognize people they know as being that one caretaker, for example. They only tested whether or not the animals could distinguish between familiar and unfamiliar faces. “We are basically testing parrots’ ability to categorize at a higher level. The fact that we used photos of known and unknown people is actually not the most important thing. We could also have used pictures of different fruits that are yellow or orange,” said researcher Raoul Schwing.
He explains: “Our choice of face photos only made it more complex. We showed that the parrots are able to group different photos of the same person.” So the animals could match photos taken from different angles to the same person. “But we have to be careful when we talk about recognizing. They did recognize the familiar faces, but it’s not technically what we showed. What we showed is that they could use the pictures of the familiar faces as a way to categorize them. Nevertheless, we do see evidence in the way the kea interacted with certain people and responded to those who approached them that they did recognize different people.”
Quick learner
“But the fact that the animals were able to categorize is already enormously fascinating,” says Suwandschieff. And the last test was of course extra special: the animals had to understand that it was not choosing the familiar face that resulted in a peanut, but the unknown photo. “The animals could apply the same concept, while reversing the reward. It was very surprising that this worked, especially considering the speed with which the kea parrots learned the trick.”
Now that the parrots have shown what they can do, the researchers want to do much more testing. “It is interesting to really see if the animals recognize people. This requires a different test setup with multiple stimuli, such as photos of people combined with their voices. But now I’m researching the social learning skills of the kea, another fascinating field of research. In the end, we still know very little about many species, so there is still plenty to research.”
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