Crow family make memories like we do

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Eurasian jays - members of the crow family - are able to remember incidental details of past events. The findings - which have just been published in PLOS ONE - suggest that these brainy birds have memories not dissimilar to our own. To find out more, Chris Smith went to Clare College to meet Nicky Clayton, professor of comparative cognition at the University of Cambridge…

Nicky - A long time ago now, I showed that jays are able to experience the past. That is, they don't just remember information about what's happened, they're able to project themselves - in self and time - to remember what happened, where and when. That was the first demonstration of what scientists called episodic memory. You could think about it as experiential memory. You don't just know a fact about Clare College, the second oldest college in Cambridge, you will have an experiential memory of our conversation sitting in the SCR, in Clare, on this gorgeous sunny day. That's an experiential or episodic memory.

Chris - That would be like, every time I come to Clare College, the sun shines. So, next time I go to Clare College, I won't take my raincoat and I'll wear a T-shirt. That would be an example of that kind of associated planning for the future based on an experience in the past.

Nicky - Absolutely. That's exactly what it's about. If you think about it, as Lewis Carroll said in the series, Alice in Wonderland and Alice Through the Looking Glass, it's a poor sort of memory that only works backwards. If you think about it, it is. What's the point in remembering things if you're never going to need to use those memories again. But really, experiential memories, not facts about the world, these experiences evolve with the future in mind because you use them in the here and now to think about the past in order to plan for the future. Hence your example of the sunny day and no need for an umbrella and just wear a T-shirt.

Chris - So what have you done to push that further?

Nicky - So what the recent experiment is on is about jays memories of the past, their experiences. The first author on the paper is my PhD student, James Davies. The idea was to think about whether they could remember other aspects about the event, because one of the hallmarks of experiential memory in people is that we don't set out with an agenda of things to remember: we just experienced an event and then we remember things about it. And so the idea was that maybe we shouldn't just be asking 'can they remember what, where and when,' but can they remember other incidental features about the event?

Chris - I came to Clare College to see Nicky Clayton, I remember that, but I also remember I was wearing a red jumper at the time.

Nicky - Exactly that. Or that you were sitting on a red sofa, and there was no reason to remember that. It doesn't really help your memory of the event in any particular way, but it's just these unexpected things that you just happen to remember.

Chris - And you wanted to know, do the birds do that like we do?

Nicky - Yes. We wanted to know whether they could incidentally encode these features, not features that they deliberately needed, but whether they just happened to remember them by chance. And when I say we, I mean my PhD student, James Davies, my former PhD student who's now a professor at the National University of Singapore, Elias Garcia Pellegrin, and myself. I just want to make sure that they get credit, I don't want you to think it's all Nicky Clayton and nobody else is important. And of course I must give credit to the gorgeous Eurasian Jays because, without them, none of this would've happened.

Chris - How do you do that then? How do you get a bird to remember the red jumper as well as where I hid my lunch?

Nicky - Well, what we do is we give them various little pots that they can hide food in, or the experimenter can hide food in, but the pots have different patterns or colours or shapes on them. Those features are incidental to the task. They've just got to remember which cup had food, where, and how long ago. But these features are irrelevant during training, they're nothing to do with it. Then we ask them afterwards: but did you remember? So you might imagine rather than a jumper, there's a tray with particular patterns on it and the cups are on those. Can they remember the pattern on the table where the cup was?

Chris - And do they? Do they store that incidental information alongside the other things they were trying to remember?

Nicky - Yes, they do. So it's often called the unexpected question because they're not being trained that this is the question. They're being trained that they need to remember what, where and when, they're not being trained about your red jumper or the patterns on the cups or trays and they just happen to remember it. So that shows that this is another feature of experiential memory that they share with us. They seem to remember their personal past experiences in the same way as we do, and that's why it's important.

Chris - And apart from the fact that they appear to share that memory trait. What else does this tell us about how the birds are thinking?

Nicky - Well, it's just one more thing in this clever cognitive toolkit that these members of the crow family have. Their brains relative to body size are as large as those of chimpanzees, and they seem to be able to do all the same kind of cognitive feats; experientially remembering the past, waiting for a better future award, being able to imagine the future, and think about what others are thinking. That's why we call members of the crow family, including these jays and ravens and magpies and crows, feathered apes, because when it comes to their cognitive abilities, although they have feathers and not hands, they seem to be as smart as chimpanzees.