Researchers find Grey parrots able to use inferential reasoning

Researchers find Grey parrots able to use inferential reasoning
Timneh African Grey Parrot (Psittacus erithacus timneh) - subspecies of the (Psittacus erithacus). Image: Wikipedia.
( -- A team of German and Austrian researchers has found that Grey parrots are capable of inferential reasoning on a level that is superior to virtually all other animals save great apes and humans. In lab experiments involving choosing which box contains food, the researchers describe, in their paper published in the journal Proceedings of the Royal Society B, how the birds were able to infer through auditory clues, which box contained a hidden food treat.

In this new experiment, the team built on prior research that had shown that when presented with two boxes they couldn’t see through, chose the box with the in it after finding the first empty. Such an experiment showed either that the were avoiding the empty box, or fully believed food was hidden in the second. To get a better reading, they tried a similar experiment using sound instead of sight clues.

In the second experiment, the team showed the birds two opaque boxes, one of which contained food. The researchers then shook the boxes allowing the birds to hear that something was inside just one of them. The birds then guessed correctly which box had the food in it, walked over and tipped it over and ate their treat. Next, however, the researchers tried shaking just the empty box, producing no sound. This time, the birds were able to infer that the food must be in the other box and ran to it when given the chance, accomplishing a feat the team says, humans can’t handle until the age of three. They also say that dogs and monkeys failed when given the same test and that it seems that other than the birds, only great apes and human are known to be capable of such inferential thinking.

To find out just how good the birds were at their inferential thinking, the team resorted to some trickery, they attached tiny speakers to their wrists and played recorded sounds of boxes with food being shaken instead of letting the food make the actual sound. In such cases, they found the birds could not be fooled, they picked the box with food in it only when the sound matched the boxes as they would were they to come naturally.

The researchers also found something else interesting, the birds did better when the boxes were shaken side to side, rather than up and down, likely they say, because the up and down motions of the box distracted the birds because it’s very similar to the way the birds normally bob their heads when interacting with one another.

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More information: Grey parrots use inferential reasoning based on acoustic cues alone, PNAS, Published online before print August 8, 2012, doi: 10.1098/rspb.2012.1292

Our ability to make logical inferences is considered as one of the cornerstones of human intelligence, fuelling investigations of reasoning abilities in non-human animals. Yet, the evidence to date is equivocal, with apes as the prime candidates to possess these skills. For instance, in a two-choice task, apes can identify the location of hidden food if it is indicated by a rattling noise caused by the shaking of a baited container. More importantly, they also use the absence of noise during the shaking of the empty container to infer that this container is not baited. However, since the inaugural report of apes solving this task, to the best of our knowledge, no comparable evidence could be found in any other tested species such as monkeys and dogs. Here, we report the first successful and instantaneous solution of the shaking task through logical inference by a non-ape species, the African grey parrot. Surprisingly, the performance of the birds was sensitive to the shaking movement: they were successful with containers shaken horizontally, but not with vertical shaking resembling parrot head-bobbing. Thus, grey parrots seem to possess ape-like cross-modal reasoning skills, but their reliance on these abilities is influenced by low-level interferences.

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Citation: Researchers find Grey parrots able to use inferential reasoning (2012, August 8) retrieved 17 June 2019 from
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Aug 08, 2012
It certainly diminishes the epithet "bird brain"....

Aug 08, 2012
I for one welcome our new avian overlords!

Aug 08, 2012
They couldn't do a worse job of running the place, that's for sure.

Aug 08, 2012
I am all about animal intelligence and learning that we are not the only creatures able to think. But all we have gleaned here is that auditory stimulation instigates inferential reasoning capabilities. This could be an evolutionarily learned response based on millenia of trial and error. It says nothing about the birds overall inferential skills. I'm not ready to assign them to the top of the evolutionary heap!

Aug 08, 2012
I'm not suprised to be honest,
Not to mention Alex the African grey http://www.youtub...Ogs_UlEc

Aug 08, 2012
I think that some birds are smarter than dogs. Crows, for instance.

Aug 09, 2012
Since everyone seems to be thinking, I'll try as well.

I think there are probably plenty more animals capable of complex thought like this, it's just very difficult to prove.

Aug 09, 2012
It's nice achievement, if we realize, most of PO readers can handle only downvoting and upvoting.

Aug 09, 2012
I know I'm just parroting here, but: good thinking! [/bobs head]

@ RhabbKnotte:

Unique traits are not the same as being special, since there are so many unique traits. I don't think inference is unique, but language and mentor education seems to be unique to later hominins.

The top of the evolutionary heap as measured by population size is viruses, they outnumber bacteria with a factor 10. They have even left genes in our genomes that we have exaptated to protect the human fetus from the female immune system.

I, for one, welcome our viral overlords! ... except when they bring flu.

Aug 09, 2012
What can humans do that animals can't?

Is language the only thing? Language is what allows us to leverage the intelligence and also knowledge of many brains and allows us to create greater and greater civilization and tech with the passed down knowledge.

However, when we say someone is intelligent, we're talking about them as an individual in terms of effective problem solving.

So, are we really smarter than all animals, or just better at communicating and sharing smartness?

Aug 10, 2012
What can humans do that animals can't?

Probably nothing, it's all a matter of degree. We might be a LOT better than other animals at a bunch of stuff, but nothing that happens in our brains is unique.

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