Left of the blue wall.

CHARLES FERNYHOUGH: I'm Charles Fernyhough. I'm a psychologist at Durham University in the UK.

ROBERT: Fernyhough.

JAD: And when I first read about this experiment in Charles's book ...

CHARLES FERNYHOUGH: Called A Thousand Days of Wonder.

JAD: It blew my mind out of my nose and onto the book.

ROBERT: [laughs]

JAD: It was a little messy.

ROBERT: I never want to be with you in a library.

JAD: [laughs] It takes a little journey to get to the mind-blowing part, but luckily—I'll let Charles explain it. The whole thing happens in a room.

CHARLES FERNYHOUGH: Yeah, you're put into this room which is colored completely white. The walls are white. The ceiling's white. The floor's white.

ROBERT: So it's all white.

JAD: All white.

CHARLES FERNYHOUGH: Everything's white. And you can tell where you are to the extent that some of the walls are longer than others. So on your left hand side ...

JAD: Are we in a rectangle, is what you're describing?

CHARLES FERNYHOUGH: Yeah, it's a rectangular room.

JAD: Are you with me so far?

ROBERT: I'm with you so far.

JAD: Okay, just to give you a sense of the baseline conditions here: imagine you are a rat in this room. Okay?

CHARLES FERNYHOUGH: And somebody comes along and hides an object in one corner of the room.

JAD: What?

CHARLES FERNYHOUGH: It can be anything. I mean, for rats you could use food.

JAD: Like a biscuit or something?

CHARLES FERNYHOUGH: Yeah.

JAD: You hide a biscuit in one of the four corners.

CHARLES FERNYHOUGH: In one corner.

JAD: You see it.

ROBERT: Okay.

JAD: But before you can get to it, they pick you up by your tail, spin you around a bunch of times ...

CHARLES FERNYHOUGH: So you don't know where you are. You don't know which direction you are facing in. And then they say, "Right, now go find the biscuit."

JAD: So if you do this with a rat, what will happen is it will say "All right, let me go find the biscuit." And it will ...

CHARLES FERNYHOUGH: Go to one corner which looks right. But of course, the room also looks like that if you turn around through 180 degrees and face exactly the opposite direction.

JAD: Because it's a rectangle.

CHARLES FERNYHOUGH: So they get it right about 50 percent of the time.

ROBERT: Because corners of rectangles, two of them are identical.

JAD: Yeah.

ROBERT: All right, so should we get on with this? Because I'm well aware of rectangles.

JAD: I just needed to get that out of the way because the cool part is coming up now.

ROBERT: I hope so.

JAD: So what the experimenters did next is they took one of the four white walls and they turned it blue. So imagine this scenario: you're in this room, you've got these four white walls, or rather three white walls.

ROBERT: One of them is blue.

JAD: Right. Well, now you're not confused anymore. You can relate everything to the blue wall. You can be like, "Oh, the corner with the biscuit was left of the blue wall or right of the blue wall."

ROBERT: I like it to the left.

JAD: You now have the blue wall as a ...

ROBERT: Navigational clue.

JAD: Yes!

CHARLES FERNYHOUGH: That makes sense. You know, we would all be able to do that. That's not going to be difficult for us.

ROBERT: All right. Have we got to the good part yet?

JAD: Yeah, it's coming. It's coming.

CHARLES FERNYHOUGH: Turns out though ...

JAD: The rats, he says ...

CHARLES FERNYHOUGH: They're still scoring 50-50.

ROBERT: What?

CHARLES FERNYHOUGH: It's as if they can't take any notice of the blue wall.

JAD: Even with the blue wall they're only finding the biscuit 50 percent of the time!

ROBERT: Wait a second, can a rat see color?

CHARLES FERNYHOUGH: Yeah, rats can do color.

JAD: They do color pretty well.

ROBERT: Okay.

JAD: They also do left, right just fine.

CHARLES FERNYHOUGH: But what they can't do is connect those two bits of information together.

JAD: In other words, they can only—well, they can do left. That they can do. They can do blue. But they're both separate. They can't do left of blue.

CHARLES FERNYHOUGH: These different kinds of knowledge can't talk to each other.

ROBERT: How does anyone know that? I mean, what rats have been interviewed for this survey?

JAD: What? They infer this based on studying the rats.

ROBERT: So the rat doesn't have what? Doesn't have the neurons? Doesn't have the—what doesn't he have?

JAD: The rat can't do it, that's all they need to know. And I'm gonna make it weirder now—neither can some humans.

ELIZABETH SPELKE: I spent the first 10 or 15 years of my scientific life studying creatures who don't talk yet.

JAD: That's Elizabeth Spelke. She's a psychologist at Harvard. Quite famous for her work with ...

ELIZABETH SPELKE: Kai.
JAD: As you can hear ...

ELIZABETH SPELKE: Babies. And I was interested in their abilities in relation to the abilities of other animals.

LAB ASSISTANT: Come on, get up. We're gonna go to the monkey room.

JAD: So she began the baby development lab, which is filled with toys and on any given day five or six really tiny kids.

LULU MILLER: How old is she?

WOMAN: She's six months.

LULU: And who's this?

CHILD: I'm a big kid.

JAD: Toddlers too.

LULU: How old are you?

CHILD: Three and a half.

LULU: Three and a half. Big time.

JAD: So at a certain point, Elizabeth Spelke decided to build a version of the white room in this lab because she wondered: if rats have so much trouble connecting the idea of left to blue, what about ...

ELIZABETH SPELKE: Surely ...

JAD: ... baby humans?

ELIZABETH SPELKE: ... a self-respecting 18-month-old human child will succeed in putting them together. But ...

CHILD: No.

ELIZABETH SPELKE: ... what we find is that children behave just like the rats.

JAD: Just like the rats.

ELIZABETH SPELKE: Just like the rats.

ROBERT: Really?

JAD: Just like the rats or almost just like the rats?

ELIZABETH SPELKE: Well, we don't test them with food, we don't test them with digging.

ROBERT: [laughs]

ELIZABETH SPELKE: So in superficial ways, superficial features of the studies are different.

JAD: But she says kids, like the rats, cannot connect the idea of left to the idea of blue. They just can't do it. And they can't do it at ...

CHILD: One.

JAD: They can't do it at ...

CHILD: Two.

JAD: They can't do it at three.

CHILD: Four, five.

ELIZABETH SPELKE: And we find that those children start performing like adults around six years of age.