Cheat a raven just once and they'll recall your misdoing for at least a month, a new study finds.
You know how you can fake out a dog with a pretend toss of a ball when playing fetch and the eager pup will happily come back for more and more? Given the results of a recent study out of Austria, I'm guessing we wouldn't expect the same from a raven.
Corvids in general, and ravens, Corvus corax, specifically, have been shown to have some pretty fancy memory tricks up their sleeves, "sophisticated cognitive mechanisms involved in memory," as the researchers put it. So the team wanted to put those to test in an experiment looking at memory and reciprocal interaction.
Working with a team of nine ravens, the scientists trained the birds in the fine art of exchange – specifically that the birds could trade up a piece of bread for a more coveted piece of cheese. Once they all knew the drill, the team conducted single-session series of interactions in which there was a "fair" human – one who followed through on the deal – and an "unfair" human. Once the bread was delivered to the unfair human, the tester ate the piece of cheese right in front of the expectant bird.
And unlike the ever-pleasing pooch who might patiently await another reward, the birds appeared to react "in a ‘frustrated’ way to the behaviour of the unfair experimenter," notes the paper. "They started vocalizing, showed increased activity and cached or ate the remaining pieces of the low-quality reward. We assumed these behavioural expressions were confirmation of an unfair experience." And who can blame them?
In the next leg of the experiment, the birds had a choice of whom to exchange with; after two days, most of the birds chose the fair human. At 30 days they were given the choice again, and again they shunned the unfair human in favor of the fair one.
The study authors conclude, "we could show that ravens can remember from a single interaction sequence who acted cooperatively in the past and that they subsequently prefer to exchange reciprocally with this person, rather than with someone who acted uncooperatively in the past. Moreover, we showed that this memory can last at least 1 month."
And while eating the poor things' cheese right in front of them seems a tad cruel, the authors make it clear that the birds were never forced to participate and were not tested if they did not want to come into the test compartment. "Moreover, when they showed distress or unwillingness during a test, we terminated the test." While ethical treatment kept the researchers in compliance with animal behavior guidelines and Austrian law (and is obviously the right thing to so), maybe there was an added intention as well – don't cross the ravens, they likely won't forget.
The paper, "Ravens remember the nature of a single reciprocal interaction sequence over 2 days and even after a month," was published in the journal Animal Behaviour.