Rats Learn To Hide And Seek

17:36 minutes

a rat peeking around a corner
A rat playing hide and seek. Credit: Reinhold, Sanguinetti-Scheck, Hartmann & Brecht

One of the most wonderful things about the internet is how you could spend years watching videos of animals at play. There’s the classic cat-playing-with-a-box genre. You can also watch a dog playing jenga. And you can type in pretty much any combination of animals, along with the word “playing,” and find adorable videos—like a baby deer, rough-housing with a lemur. Incredible stuff. 

Neuroscientist Juan Ignacio Sanguinetti of the Humboldt University of Berlin gets inspiration for his work by watching home videos like that. And in his latest work, in the journal Science, he describes playing hide-and-seek—with rats.

Watch Sanguinetti’s masters student, Annika Reinhold, play with the rats below.

Credit: Juan Ignacio Sanguinetti

Our question for listeners this week was: “What games do you play with your pets? And how do you know when your pet is having fun?” Here’s what you said on the Science Friday VoxPop app:

Kevin Charpentier from Reno, NV: So I have a little Boston Terrier named Pablo and this dog loves fetch. When he sees the ball his eyes dilate, he’s obsessive. Every 10 or 12 throws I have to hide the ball just so he can catch his breath. And I’m assuming he’s having fun while doing it because as long as you’re willing to keep throwing the ball, he’s willing to fetch it. 

Steve from King Of Prussia, PA: When I do a partial water change in my aquarium, the Harlequin rasboras, there are three of them, will swim alternately up into the stream going against the current of the incoming water and then they’ll stop and get washed back down into the tank and then they’ll come back up again kind of in rotation it sure does look like they’re playing.

Tamara from Loveland, CO: I have fun with my cat when she brings me toys and looks at me… like she really really wants me to throw them and I throw them and she gets all excited and bolts after it. Like, well, we call her “NASCAT” as in NASCAR. NASCAT.

Further Reading

  • Check out the study in the journal Science.

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Segment Guests

Juan Ignacio Sanguinetti

Juan Ignacio Sanguinetti is a neuroscientist at Humboldt University of Berlin.

Segment Transcript

IRA FLATOW: This is Science Friday. I’m Ira Flatow. One of the most popular things about the internet is spending hours, days, maybe even years watching videos of animals at play. You know how many videos of animals there are and you have watched? Just amazing.

You’ve got the classic cat-playing-with-a-box genre, but you can also watch a dog playing Jenga. Seriously, Google it. And you can type in pretty much any combination of animals and the word playing, and you’ll find adorable little videos like a baby deer roughhousing with a lemur. Incredible stuff out there.

Well, so why am I telling you this? Well, because my next guest, a neuroscientist, actually gets inspiration for his work by watching those home videos, ideas about how to study animals interacting and playing with other animals and humans. And in his latest work out this week in the journal Science, he describes playing hide-and-seek with rats. Yes, we have that for you.

My question for you, our audience, is, what games do you play with your pets? And how do you know when your pet is having fun? Here’s what you told us on Science Friday VoxPop app.

KEVIN: So I have a little Boston Terrier named Pablo, and this dog loves fetch. When he sees the ball, his eyes dilate. He’s obsessive. Every 10 or 12 throws, I have to hide the ball just so he can catch his breath. And I’m assuming he’s having fun while doing it because as long as you’re willing to keep throwing the ball, he’s willing to fetch it.

STEVE: When I do a partial water change in my aquarium, the harlequin rasboras, there are three of them, will swim alternately up into the stream going against the current of the incoming water, and then they’ll stop and get washed back down into the tank, and then they’ll come back up again kind of in rotation. It sure does look like they’re playing.

TAMARA: I have fun with my cat when she brings me toys and looks at me like she really, really wants me to throw them. And I throw them, and she gets all excited and bolts after it like, well, we call her NASCAT, as in NASCAR. NASCAT.

IRA FLATOW: NASCAT. Sound familiar to you? Do you play with your pets? So that was Kevin from Nevada, Steve from Pennsylvania, Tamara from Colorado. Tell us your stories– Science Friday VoxPop app or give us a call 844-724-8255. 844-724-8255 or you can tweet us @scifri.

Juan Ignacio Nacho Sanguinetti is a neuroscientist at the Humboldt University of Berlin and one of the authors on that research published in Science. And we have a link to that and videos. You want to see the video rat hide-and-seek and what animals are playing? Well, it’s up there on our website, ScienceFriday.com/animalgames. ScienceFriday.com/animalgames. Welcome to Science Friday, Dr. Sanguinetti.

JUAN IGNACIO NACHO SANGUINETTI: Thank you. Thank you, Ira. It’s a pleasure talking to you.

IRA FLATOW: Were you really inspired to study animal play by the videos on the internet?

JUAN IGNACIO NACHO SANGUINETTI: Well, so in the lab, we’d been looking into play behavior for a couple of years. A few years ago, our lab published research about tickling rats and how rats vocalize and create this joy laughters when they are tickled by a human experimenter. So we’ve been looking for different ways of study play behavior in animals.

And it is true that anybody who’s had a pet before knows that you can play different things with your animals. As some of your audience has described, fetch is a classic game you play with a dog. And if you teach a dog how to play fetch, then you’ll need to hide from him because he will come with the ball to you, like, all the time.

So we’ve been looking into a different place and, luckily, YouTube is a treasure trove of animal behavior. The fact that anybody has a cell phone and a camera in their cell phone allows us to see so many different animals and so many different animal behaviors just by going into YouTube, you know?

IRA FLATOW: I want to get right to the rats playing the game. You mentioned that you could tickle them, they make certain sounds. We have a sample of these sounds modified so humans can hear them.


Wow. What was that, Dr. Sanguinetti? What were we hearing there?

JUAN IGNACIO NACHO SANGUINETTI: That is a rat being tickled and having this joy vocalizations, which are these vocalizations in the ultrasound range, so humans can hear them, and that are associated with positive emotions with playful behaviors and playful encounter between rats.

And that was part of the things that we found in our study when we tried to put now rats to play a more sophisticated form of play, the game known as hide-and-seek, a very old game, a game that is shared by many different cultures in the world.

IRA FLATOW: You know, I didn’t really, until I looked at the video– it’s up on our website at ScienceFriday.com/animalgames– I could not believe that anybody could play hide-and-seek with a rat until I saw this. It’s amazing. How did you get the rat to learn how to play this?

JUAN IGNACIO NACHO SANGUINETTI: So the first thing to point out is that you cannot grab any random rat in the lab and teach it how to play hide-and-seek. As you know, all dogs don’t learn new tricks. So you have to use rats that are very young, for example, because we know that play is something that animals do more when they’re young and do less when they are adults, right?

So the first thing you need to do is to really habituate the rat, both to the experimenter and to the room where it’s going to play. And then slowly but surely, you can teach the rats how to play the game. For example, in a game of seek what we did, we had a starting box where the animal was placed to start the game.

And then what Annika Reinhold, who was the master student running these experiments, did, she would get far away from the rat. And then the rat would come close, and whenever the rat came close, she would tickle the rat, and play with the rat, and made the rat chase around her hand and, in some way, giving the rat a social reward.

And then what she would do was to increase, slowly, the complexity and start hiding better and better from the rat until the point where we were able to close the starting box and then open the box remotely, and the rat would have to search in this 30-square meter room for Annika.

IRA FLATOW: So the reward for the rat is not a pellet of food, it’s getting tickled?

JUAN IGNACIO NACHO SANGUINETTI: Yes, exactly. There is no food reward, no water reward. It’s just the social interaction with the experimenter. And we know that social interaction is a very rewarding thing, like when you deal with children, they like to be cuddled. They like to be played with. So this is the same for our pets and for our rats in our study.

IRA FLATOW: And so that’s what you’re really studying, then, is the social interaction feature. What do we learn about humans from that?

JUAN IGNACIO NACHO SANGUINETTI: Well, it’s very important to study social interactions. We’re still trying to figure out the social brain and how the brain conducts social interactions between animals. So the play is one critical example of a type of interaction. There is this thing called social play when an animal plays with another animal. And from studying these kind of things, we will get closer to understanding social interactions in human and how the brain controls social interactions in humans.

And humans are an incredible case of social interaction. They are basically a species that has this incredible social network. We’ve evolved to have, like, these big families, these big groups, and to have these big social networks around us.

So to navigate those social networks, we need a brain that allows us to go from one place to another and to understand the people around us and how they behave, what the other people can do and what you can do with them. So this is a very important topic to understand our brain and how our brain evolved.

IRA FLATOW: A lot of reaction from asking people how they play with their animals. I have Clare who writes, “I play find it with my doggos. You hide the treats throughout the house while they wait in the bathroom. Afterwards, you let them out and say, find it.

They then search, sniff for the treats. We had to be more obvious with the treats after we got a Beagle to give the Lab a chance. So I had a couple of dogs.” Let me go for a reaction to Melissa in State College, PA. Hi, Melissa.

MELISSA: Hi, Ira. Pleasure to talk to you.

IRA FLATOW: Thank you. Go ahead.

MELISSA: OK. I was saying earlier that my definition of play for an animal is when they initiate it– then you know they’re into it– but when they return to it voluntarily. Like a dog bringing you a ball and saying, play with me, play with me now, that’s not very ambiguous.

Or you’re paying tug-of-war, the animal will tug. If you let go, and they hand it back to you. So that’s one– those are two clues. And the other is the body tension. If it’s a stiff tension and they’re defensive, they’re not having fun. But if it’s a bouncy tension, they’re full of, well, bounce, then I think they’re playing.

IRA FLATOW: Yeah, I’ve seen that with dogs I play with also. It’s the same kind of thing. You can really tell one and when an animal is playing, can’t you?

JUAN IGNACIO NACHO SANGUINETTI: Yeah, I think those things that the audience member mentioned are critical things. For example, we know that rats, when they are in this playful state, she said something about this bouncy nature. So we described a type of behavior the rats do when they’re playing that is called, in German, Freudensprung, which translates into “joy jumps,” which is the rats are jumping in place, basically, like, with their four legs. So this is one kind of way to tell when the animal has some positive response.

The other thing that the audience member mentioned, which is very interesting, is the willingness to continue the game, to continue playing. And that is something that we found in our paper that is that we found that rats not only cared about the social reward at the end of the game, but that sometimes they would even try to evade this reward so that they could continue playing. So sometimes if the rat was hiding and the experimenter would find the rat and would try to introduce this social reward, the rat would leave and hide somewhere else again. So they would really try to extend the game.

IRA FLATOW: Did you ever tried to trick the rat, like play a joke on the rat?

JUAN IGNACIO NACHO SANGUINETTI: No. So that is something that I’ve been thinking about for many years since I’m also an amateur improviser and comedian, but is how to try to surprise a rat into something that would be funny. So I’ve been thinking, like very unprofessionally, but many years–

IRA FLATOW: You can share it with us. It’s OK.

JUAN IGNACIO NACHO SANGUINETTI: So my idea of a joke for a rat is that– so you train the rat to always run a maze, a normal maze, where the objective is to find cheese, let’s say, right?


JUAN IGNACIO NACHO SANGUINETTI: So then you train the rat, and the rat is focused. It gets into the maze. It smells cheese and tries to find it. And then again, and again, and again until, at some point, what you do is– you do the same thing, but then suddenly all the walls are made out of cheese.

So then I imagine myself in the position of the rat just running around, like, trying to find the cheese, and then that moment when you realize, ah, that Eureka moment, like, so that’s what I envision myself. But this is, of course, just my fantasy into one day trying to understand some of the basis of humor and surprise.

IRA FLATOW: Well, you say you’re into the theater, you’re into doing impromptu. Do you think you could have an act with your rat on stage doing hide-and-seek? People would love to see that, I’ll bet you.

JUAN IGNACIO NACHO SANGUINETTI: No. No, but I’m going to tell you something. I know some improvisers in New York that have shows for dogs. So they pretend to be dogs, and dogs are the audience. So it’s not that far away that you could try to do performance with animals themselves.

But it’s a very interesting topic because how one plays a role and how animals play roles in their natural lives in the animal kingdom, whether they’re in the role of a prey or a predator– accidentally– or if they’re in other kind of social situations that there is a relationship of status and hierarchy, these are very interesting questions that neuroscience is starting to tackle.

IRA FLATOW: You’re about 30 years too late for Ed Sullivan. You could have done it. I’m Ira Flatow. This is Science Friday from WNYC Studios. Ah, that was an old– you have to be of a certain age to remember the Ed Sullivan Show.

JUAN IGNACIO NACHO SANGUINETTI: No, no, no, no. I got it. I didn’t know if I was allowed to laugh.

IRA FLATOW: Oh, wait. I never laugh on this show, you’ll notice. So where do you go from here? What else can you do? Do you want to teach the rat to do other things, or another game, or something else to further study it? Or you just keep following this maze, so to speak?

JUAN IGNACIO NACHO SANGUINETTI: So there are several things. The first thing that we like to point out is that we think this paradigm of playing with the rats and playing hide-and-seek with the rats allows us to probe some of the rat’s cognitive capabilities. Like, we want to figure out, like, when the rat is making decisions and when the rat is choosing to hide in a certain location, or in another location or, for example, where is the rat choosing to search for the experimenter?

So these are very interesting– it’s a very interesting paradigm to tackle questions like decision making, motivation, when is the rat motivated truly to play, for example. So that on one hand. And on the other hand, of course, we’re still looking for inspiration and games to try to teach animals to use those games as a way to, in a very naturalistic way, probe for understanding the brain at play.

IRA FLATOW: Right. We’ve talked a lot about birds recently and how intelligent birds are. I have a tweet coming from Skip who says, “I lived for a time with a crow named Hugan. If I was on the phone too long, she would go to the modular plug at the baseboard and unplug the phone.” Now, birds would seem– we’ve talked about birds recently, how smart they are. You say you’re looking for other animals to play with? How about a bird? Think about working with birds.

JUAN IGNACIO NACHO SANGUINETTI: Oh, crows are also known to play. In fact, I will challenge the audience to go to YouTube and try to find videos of crows playing in the snow. There are some videos where crows use the snow on a windshield of a car to slide down. And then they would just go up and slide down again. And they also use roofs for things like this. So crows are very interesting animals, indeed.

IRA FLATOW: But you’re sticking with your rats for now? Or are you branching out?

JUAN IGNACIO NACHO SANGUINETTI: We will see. We will see. I still have to decide what my future holds in neuroscience. I just finished my PhD here, and I’m trying to find new topics. So I’m very excited about that.

IRA FLATOW: So improv is not a day job yet? I can’t fall back–


IRA FLATOW: –on an improv career.

JUAN IGNACIO NACHO SANGUINETTI: No, no, no. I have a serious science career with a side of improv addiction.

IRA FLATOW: But does it actually– but it must help you think creatively, I would think, you know?

JUAN IGNACIO NACHO SANGUINETTI: Oh, absolutely. Absolutely. I think like it’s a very creative endeavor. And I treat it, in some ways, in a very similar way as I do all my other work because I do take it seriously. And I think it’s incredibly interesting, and it’s a very, very interesting way of also figuring out things about the brain, I think.

Because it’s, in a way, the social brain, the human brain gone wild. It’s taking all the skills that we have to navigate social situations and using them in make-believe social situations. And starting in a set from nothing and just looking to your partner and going into a story is unbelievable–

IRA FLATOW: Well, we wish–

JUAN IGNACIO NACHO SANGUINETTI: –and humans can do that.

IRA FLATOW: Yes. We wish you great luck, Dr. Sanguinetti. Juan Ignacio Nacho Sanguinetti, neuroscientist at the Humboldt University of Berlin. Thanks for joining us. We have a link to his paper, and I’ll tell you, the video of the rats playing hide-and-seek will make your day. ScienceFriday.com/animalgames. We’re going to take a break. We’ll be right back after this break.

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