These Clever Parrots Can Understand Probability

A kea trying to win a reward in an experiment. (Photo: Amalia Bastos)

Scientists studying kea, New Zealand’s alpine parrot, revealed that the famously mischievous birds could understand probabilities, an impressive mental feat.

The pair of researchers put six birds through a series of trials to see how they made decisions when faced with uncertainty. When prompted to choose, the kea generally opted for scenarios where they were more likely to earn a reward. This work is further evidence of some birds’ general intelligence, according to the paper published in Nature Communications.

“Kea are a species of parrot that exists only in the South Island of New Zealand. They are also the only parrot in the world to live in the alpine mountains, a cold and harsh environment where food resources can be scarce,” Amalia Bastos, the study’s first author from the University of Auckland, told Gizmodo. “This food scarcity is probably the reason why they are highly inquisitive—it is essential to their survival that they can readily assess potential new sources of food.”

The first experiment presented kea with jars containing a mixture of black and orange tokens (a black token would get them a reward; the orange would get them nothing). First, the experimenter would put one hand into a jar with 100 black tokens and 20 orange tokens and the other hand into a jar with the reverse quantities. Within 20 trials, three of the six kea immediately showed a preference for the hand that went into the jar with more black tokens.

Then, to test whether the kea were just thinking about quantities or if they were considering actual probabilities, they presented the birds with one jar containing 20 black tokens and 100 orange tokens and another with 20 black tokens and four orange tokens. Four kea immediately preferred the hand from the jar with better odds in the first 20 trials.

Finally, the kea were tested on a jar with 63 orange tokens and 57 black tokens versus another with 63 orange tokens and three black tokens—all of the kea preferred the jar with the better odds in the first 20 trials.

I’ll be taking my peanut now, thanks. (Photo: Amalia Bastos)

Then, the researchers made things a little tougher. They showed the kea two jars where a barrier had been placed halfway down. Each jar contained equal numbers of orange and black tokens, but in one jar, the region above the barrier had way more black tokens than the other. Five of the six kea preferred the jar that would give them better odds for a treat within the first 20 trials, showing that they could integrate the knowledge of the barrier into their understanding of the probability.

Finally, the researchers performed a third experiment in which two different human samplers were portrayed as “biased” or “unbiased;” the samplers would always give the kea black tokens, but the biased sampler would reach into jars with mostly orange tokens, while the unbiased sampler would reach into the jar with mostly black tokens. Three of the six kea chose the biased sampler more often than chance. As the researchers explain it: “If the kea understood that the biased sampler was indeed biased to choose a rewarding token, while the unbiased sampler had only been choosing rewarding tokens at the same frequency as the biased sampler due to the populations they were sampling from, kea should choose the biased sampler at test. This was because while the unbiased sampler would now be likely to choose a rewarding token half the time, the biased sampler should continue to choose the rewarding token in every trial.”

Importantly, you should know that the birds were named Blofeld, Bruce, Loki, Neo, Plankton, and Taz. Taz passed all the tests. You go, Taz!

Now, this doesn’t mean that parrots can count to high numbers. Instead, the team felt that the experimental results demonstrated that kea were making choices based on their understandings of probability, rather than just based on quantities (like picking the jar with the most black tokens regardless of the number of orange tokens). They also demonstrated the kea’s ability to integrate a physical barrier into their understanding of probability, and to take social cues into account, like whether a researcher was biased in their reward-giving or not.

The fact that the kea could perform as well as apes on intuitive statistic tasks is exciting, Irene Pepperberg, research associate in psychology at Harvard University who has studied probabilistic reasoning in parrots, told Gizmodo. But she argued that perhaps some of the paper’s claims about the abilities of the kea were too strong. She felt that the studies didn’t sufficiently show that the birds understood how different odds could impact their rewards.

Even still, experiments on parrots continue to demonstrate that there’s more going on between their ear holes than you might assume—and that includes at least a basic understanding of odds.

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