If Only They Could Talk
Who Needs Words, Anyway?
Figure That One Out
No Fools About Tools
Thinking About Thinking
ALDA: Rocky here understands groups. She knows that this is
part of one group, and that's part of a whole other group.
Not bad for a sea lion, huh? On this edition of Scientific
American Frontiers, we'll be reaching inside the minds of
ALDA: (Narration) We'll teach sign language to Hamlet the
BOYSEN: Good boy, Hamlet.
ALDA: (Narration) We'll see if ravens know what string really
means. We'll get monkeys to count, and to pick the right tool.
And we'll ask Sheeba to show us a concept.
ALDA: I'm Alan Alda. Join me now as we meet the Animal Einsteins
ALDA: There once was a horse named Clever Hans. Hans was a
genius. He could answer general knowledge questions and do
arithmetic and he'd communicate his answers by tapping his
hoof. One tap for yes, two taps for no, and he could tap out
numbers. A committee of imminent scientists studied Hans.
This was in Germany around the turn of the century. And they
concluded that there was no fraud or fakery. But they couldn't
figure out how Hans was doing this. Then, one scientist made
a crucial discovery. Clever Hans only succeeded when there
was someone in the audience who knew the answers. It turns
out the horse was picking up on tiny, unconscious nods that
people were making as they counted the hoof taps. All Hans
knew was, if I stop tapping when they stop nodding I get a
reward. We all love to know what's going on inside animal's
heads. And Clever Hans shows what a tough problem it is to
design foolproof experiments. But today, scientists believe
they are really getting somewhere in finding out what and
how animals think.
back to top
ONLY THEY COULD TALK
That looks stupid, Mom
Not as stupid as sheep, mind you, but pigs are definitely
Excuse me. No we're not.
ALDA: (Narration) It took hi-tech models and banks of computers
to make, but at its core Babe expresses an age-old human fantasy
-- talking animals.
Our mom called us all the same.
And what was that, dear?
She called us all Babe.
ALDA: (Narration) Meet Hamlet.
BOYSEN: He's a couch-potato pig, aren't ya, huh?
ALDA: (Narration) He's Hammy to his friends. And meet Hammy's
best friend, psychology professor
BOYSEN: Hammy, Hamlet, do you want a dog biscuit? Hammy, sit.
No, further down than that. Further down to sit. There is
so much lore and anecdotes around about how pigs are smart
and I don't know that we have much empirical or scientific
evidence to support that.
ALDA: (Narration) Four years ago, Sally set out to see how
smart Hamlet is. She used three different objects, each with
its own sign.
BOYSEN: Hammy -- ball! Where's the ball?...Good boy, Hamlet.
ALDA: (Narration) Eventually Hamlet learned to associate signs
with objects, but it took a laborious 8 months of training.
By the way, Sally was always careful to avoid the Clever Hans
effect -- no eye movements or nods or gestures that might
tip Hamlet off.
BOYSEN: Frisbee!... ...Frisbee!
ALDA: (Narration) Hamlet's memory's pretty good -- Sally hasn't
tested him for three years. But simple associations like these
are his limit. He can't use the signs in any way, and we can't
see his mind at work.
BOYSEN: There's a whole lot more to naming than just associating
even an abstract symbol of some sort or a gesture with an
object. He'd need to be able to use that name or that symbol
in a lot of different ways that he'd have a different understanding
that was beyond mere association.
ALDA: (Narration) We're on the California coast, at Santa
Cruz. Here the animals have a little more to say than Hamlet.
ALDA: How many tanks do you have here?
SCHUSTERMAN: Well, we have two right here, and then there
are several back there. You can use this antiseptic here,
it's a little foot bath before we go on deck. And these are
the objects she'll be working with.
ALDA: (Narration) I'm here to have a conversation with Rocky,
a very friendly sea lion.
ALDA: Oh all right give me a kiss, ha, ha, ha. That's very
nice, that feels good, Rocky.
As soon as you get the OK to start ěballî, you turn them up
ALDA: (Narration) First I have to learn Rocky's language --
about 25 signs.
ALDA: You go up and down?
ALDA: (Narration) Next the sign for ětouch with flipperî,
followed by ěgo do itî when I drop my foot.
ALDA: I almost went in!
ALDA: (Narration) Now here's ěcubeî.
All right so we're going to merge that with the action signs,
so give me a ěflipper touchî sign... okay, that's good, and
ětail touchî sign. Okay that's it, they look decent for a
ALDA: Decent, nice answer, I probably have some kind of accent.
I hope she'll recognize my accent.
ALDA: (Narration) OK -- let's talk.
Grab a couple of pieces of fish and just toss them in. She
knows you are going to feed her.
Okay, now point to your foot. All right, now we're going to
give her ěcubeî and ěflipper touchî
Okay, ěcubeîîflipper touchîshe wasn't really too sure about
ALDA: She sure looks cute.
ALDA: (Narration) Rocky's not happy. She doesn't know what
I'm talking about.
Let's do a ball tail touch.
ALDA: Ball tail touch, OK.
ALDA: (Narration) Okay, ěballî. Looking good -- Rocky checks
for the ball -- and ětail touchî. Oh, no -- she does ěball
ALDA: Is this my accent getting her confused with the ball,
ALDA: (Narration) All right let's try again, in my best signing.
Ball ń drop tail touch.
ALDA: There she goes, whoa, far out, bravo, terrific!
ALDA: (Narration) It's an exhilarating feeling to really get
through to an animal.
Do a cube flipper, remember ěflipper touchî?
ALDA: (Narration) Cube -- flipper touch.
ALDA: OK, very good, here.
ALDA: (Narration) Now I'm going to ask a question -- ěFootball
-- is it here?î Rocky heads right for the ěyesî button.
ALDA: OK, bravo. It's great in show business, isn't it?
ALDA: (Narration) Once Rocky gets used to my accent, it's
obvious she really does get it. She knows, at some level at
least, what my signs mean, and unlike Hamlet the pig she can
use them in different ways. So with Rocky there is at least
a brief glimpse into an animal mind. In fact over the years
there have been several examples of simple communication with
ALDA: Give me a kiss.
ALDA: (Narration) This is Washoe the chimp, in the early 1960s.
Watch Washoe make a sign meaning ěopenî. Washoe was raised
from infancy by researchers at the University of Nevada..
Eventually he learned to use about 130 American Sign Language
signs. Washoe's vocabulary was impressive, but teaching animals
artificial language has its limits -- maybe we only get back
what we ourselves put in. There's no insight into what or
how the animal itself thinks.
C'mon what is it?
ALDA: (Narration) The ultimate expression of artificial language
use is Alex the parrot.
What is it?
ALDA: (Narration) Alex can distinguish and name different
Nail, that's right. You're a good birdie.
ALDA: (Narration) And different colors.
Now tell me what color?
Yellow, that's right.
ALDA: (Narration) He can identify different materials.
Yeah, that's right, very good.
ALDA: (Narration) Alex can count.
PEPPERBERG: How many? How many?
PEPPERBERG: Good parrot, good boy. One, two.
ALDA: (Narration) And he can also grasp abstract concepts.
PEPPERBERG: OK can you tell me what's different? What's different?
ALDA: (Narration) In case you're wondering, the researchers
are convinced they're not falling into any Clever Hans type
of traps that might tip Alex off. Alex can juggle concepts
in an astonishing way.
PEPPERBERG: What color bigger. You know, what color bigger?
PEPPERBERG: Good boy, good birdie.
ALDA: (Narration) And take a look at this.
PEPPERBERG: What matter four corner blue?
ALDA: (Narration) In Alex's personal language, that means
ěWhat is the four-cornered blue object made of?î He's never
been asked this question before, so this is not a circus trick.
There are several four-cornered objects, and several blue
objects, but only one that combines four corners and blue
PEPPERBERG: What matter four corner blue?
PEPPERBERG: That's right. I've got to go eat dinner, okay,
I'm going to put you in.
ALDA: (Narration) ALEX is the most successful example anywhere
of an animal using artificial language.
You be good. Bye.
ALDA: (Narration) Through that language he shows a grasp of
abstract concepts like sameness, or the idea of combining
qualities. But the big question for researchers is, do animals
think conceptually without the help of human-taught languages?
I'm sorry. You're a good boy.
ALDA: (Narration) That's what we'll explore next.
I love you.
NEEDS WORDS ANYWAY?
ALDA: (Narration) This is Rio -- the star pupil of
SCHUSTERMAN: at Santa Cruz. Ron insists Rio can understand
abstract concepts without the aid of any language. Today,
she'll show us that she gets the concept of "groups" or "classes".
Backstage they set out cards with one of either thirteen letters
or thirteen numbers. First, Rio's task is to pick just the
letters. Learning the letters was an arduous process. It took
Rio thousands of trials over more than a year.
ALDA: The first time she goes through this, she just sees
a bunch of symbols. She doesn't know which one is a letter
and which one is a number. Those are terms we use. So, she
keeps getting reinforced every time she chooses let's say
a letter. Once she's consistent at that
SCHUSTERMAN: Then she forms a class
ALDA: (Narration) To learn numbers, the reward for letters
suddenly stops. Rio doesn't like that at all.
ALDA: It sounded like a complaint.
SCHUSTERMAN: It is a complaint. You know, where is the food.
ALDA: (Narration) No number, no reward. Rio takes a swim break.
Finally, Rio starts picking numbers -- and she'll continue
as long as she's rewarded. By the way, some letters and numbers
have extra features so they're more distinctive. Remember,
to Rio they're just shapes that belong in one abstract group
or the other. Today, Ron's going to add a new number -- it's
actually the number sign.
SCHUSTERMAN: Now this is the brand new number
ALDA: This is a number she's never seen before?
SCHUSTERMAN: She's never seen it before, and I'll tell you
why if she gets it correct.
ALDA: (Narration) Rio has to include the number sign in the
number group. Right now, Rio's getting rewarded for not picking
SCHUSTERMAN: She almost didn't get it.
ALDA: Yeah, that was really nice, you could see her mind working.
SCHUSTERMAN: She uses what we call "exclusion". She knows
all the letters. She knows the letter set. Don't go to the
letter. So whatever that novel thing is, go to that.
ALDA: It's a better bet for her.
ALDA: (Narration) To add a new letter, they first stop rewarding
for numbers. Once again, she takes a break.
ALDA: So now she's in the water, she's thinking, they're switching
them on me now.
SCHUSTERMAN: That's correct
ALDA: And if she gets the idea she might go for a.
SCHUSTERMAN: It might take a few, it's hard to know, she might
take another number.
ALDA: Okay so now she's had two wrong. She ought to get the
SCHUSTERMAN: Well, maybe.
ALDA: (Narration) On the right is a number by the way.
SCHUSTERMAN: Aha, the old lightbulb is going on.
ALDA: (Narration) Now she gets the new letter -- n. She knows
that 8 isn't a letter, so again she picks the n by exclusion.
Okay, not bad Next we're really going to challenge Rio's understanding
of the two groups. This time there's a symbol in the center
-- and Rio has to find the match from the same group. Now,
Rio must be prepared to change the group every time.
SCHUSTERMAN: So B goes with J.
ALDA: Right, B didn't go with 9. By the way, I got that and
I wasn't getting a herring.
ALDA: (Narration) Here's that new number sign she just learned.
ALDA: Wow, that was great.
SCHUSTERMAN: You can almost see her thinking.
ALDA: (Narration) Then she gets the same number sign again.
Now watch what happens.
SCHUSTERMAN: But remember she just got rewarded for this.
ALDA: This is, this is, you're starting to get to me with
this. She just got rewarded for choosing the number sign in
a different circumstance.
SCHUSTERMAN: That's right.
ALDA: It is now not in the right class.
SCHUSTERMAN: That's right.
ALDA: And she doesn't go for it even though she just got a
reward for it.
SCHUSTERMAN: Yeah, Bob.
ALDA: Okay, okay, this is really making an impression on me
ALDA: (Narration) Ron's research has left little doubt that
Rio can work with the abstract concept of "class" or "groups"
-- and there's no language involved.
ALDA: Are you saying, therefore, that in some way these animals
SCHUSTERMAN: Yes, I'm saying they're reasoning, and they're
reasoning without language.
ALDA: I mean that seems like an extraordinary conclusion to
come to. I mean, I can see how you came to it. But doesn't
that strike you sometimes? Don't you say to yourself, "gee,
I'm operating on the idea that these animals are thinking
SCHUSTERMAN: Oh, I didn't always believe that.
ALDA: Well it must have, when you finally realized you believed
it, you must have said to yourself, what an extraordinary
thing to think.
SCHUSTERMAN: That's correct. I did.
ALDA: (Narration) We can only speculate how sea lions in the
wild might use this ability to form abstract groups. Ron suspects
that classifying helps sea lions sort out the many individuals
they encounter, labeling them as friend or foe, family or
non-family, and so on. In other words, it's an essential part
of being a sea lion.
BOYSEN: Hi sweetie.
ALDA: (Narration) Here's
BOYSEN:, whom we first met with her pig Hamlet. Sally's main
work is with chimpanzees, and she thinks they can handle abstract
concepts with ease. We're going to run a "hide and seek" experiment
using a scale model room and a matching real room that's just
a few feet away. Sally says that chimps can get the connection
between the two -- that one can be a symbol for the other.
BOYSEN: Here's our little miniature room. And we have a replica
of that cupboard. And a little chair right here, blue tub.
We have a miniature tree here.
ALDA: And this little can here?
BOYSEN: That's the item we're going to hide. They'll watch
as we hide this, like under the blue tub. Then I go into the
real room and hide a real can of soda. And then the chimp
has to pay attention to where we hid it here and then find
it in the same place inside there.
ALDA: What's the real room look like compared to this?
ALDA: (Narration) Everything in the model has its full scale
ALDA: That doesn't open?
BOYSEN: Yeah. The chimps know how to open it.
ALDA: I guess you have to be a chimp.
BOYSEN: You just go like this. It's kind of an IQ test.
ALDA: Oh, I see.
ALDA: (Narration) We're going to be working with strong, full
BOYSEN: You stay out here.
ALDA: Right. You're going to be in there?
ALDA: Now, you're safe in there?
BOYSEN: Sure. Now don't try this at home.
ALDA: I haven't got a chimp at home.
BOYSEN: Miss Sheeba
BOYSEN: Very nice, okay, she has to get a little rowdy here.
This is so much fun isn't it?
ALDA: (Narration) Sheeba is 13 years old -- raised from age
two by Sally.
ALDA: That was cute.
BOYSEN: That was very impressive.
ALDA: You know, I've worked with actors like this before.
ALDA: (Narration) I have to admit, she's not striking me as
much of an intellectual yet.
BOYSEN: Okay, I've got some real Pepsi for you. All right,
where should we hide it? Let's see. I'm going to take this
little one. Are you watching me? And I'm going to put it in
here. Okay, watch. I'm going to put it right in here. So we
put it in here. Should I show you again. Look. I put it right
in here. Isn't that cool. I know I have makeup on. See my
lips? I know I have different makeup on. Now, see that? We're
going to keep on going. Now you stay right here. I'll be right
back. I'm going to hide this real one for you. Okay, stay
right there. Stay there. Where is it? Where did we put it?
In here, right. There's the little one. Okay, go find the
real one for me. Hurry. Hurry. See if you can find it.
ALDA: She gets it opened, too.
DELOACHE: Here's Big Snoopy and this is his little friend,
ALDA: (Narration) Now look at how a two and a half year old
human does in the same experiment.
DELOACHE: Look I'm hiding little Snoopy
ALDA: (Narration) This experiment has been tried with hundreds
DELOACHE: You wait here while I hide Big Snoopy. I'm going
to hide him in the same place in his room.
And I'll go find him.
DELOACHE: Okay, Amos, Big Snoopy is ready, can you come find
him? Remember he's hiding in the same place in his room that
Little Snoopy is hiding. Remember Big Snoopy's hiding in the
ALDA: (Narration) Until about age three kids never get that
the model symbolizes the real room.
BOYSEN: Sheeb, that's where I put the little can, see it?
Now I'm going to go hide the real one.
ALDA: (Narration) So in one way Sheeba is sharper than the
average two and a half year old human.
BOYSEN: Don't cheat, I'll be right back.
ALDA: (Narration) There's no doubt Sheeba sees the model as
representing the real room. And if that isn't abstract thinking,
I don't know what is.
BOYSEN: Okay, I hid it, where is it? Where'd I hide it? Remind
me where I put it. Right there! Okay, now go get it for me,
hurry, go on. Go hide it, or find it, whatever. Oh, you found
it, all right, good work, good work.
back to top
ALDA: So what kind of monkeys are we going to be working with?
CAREY: These are rhesus.
ALDA: (Narration) We're in Puerto Rico to investigate the
amazing counting skills recently discovered in monkeys. I'm
with psychologist Sue Carey, and she's taking me out to a
small island just offshore. Called Cayo Santiago, it's home
to about 1,000 rhesus monkeys.
ALDA: These monkeys have been here isolated on this island
CAREY: The 30s. They were brought over interestingly enough
for behavioral research.
ALDA: (Narration) Sue's background is studying how young children
think. But lately she's begun looking for the roots of human
thinking in monkeys.
CAREY: See them playing in the water? Shall we go up this
ALDA: (Narration) We're going to conduct a simple counting
experiment with apples and boxes -- if we can find a monkey
that will pay attention.
CAREY: Okay, what we've done here is we've tried to find a
monkey that was all by himself. There are no other monkeys
around as far as we can see. Then we're going to show him
that the boxes are empty. Then we're going to kneel down and
I'm going to put two apples in one box and Laurie will put
three in the other. And then we'll step back and see which
one he chooses. If he chooses the one with three, then he
knows that three is more than two. Simple as that. Okay.
ALDA: (Narration) Laurie shows that her box is empty while
the monkey looks on. Sue makes it clear that her box is empty
CAREY: Okay, don't look at him anybody.
ALDA: (Narration) Slowly and deliberately, Sue places 2 chunks
of apple in her box. Next, Laurie puts 3 chunks of apple in
CAREY: Okay, walk away.
ALDA: (Narration) Which box will the monkey go to?
CAREY: Okay, now you see what happened. He went to the one
ALDA: I suppose this is meaningful if you do it many times.
CAREY: We have done this very experiment -- three versus two
-- with 15 monkeys, and 14 out of the 15 went with three.
ALDA: (Narration) To assure their results were solid, trials
were run with several variations.
SANTOS: Sit. Go back. Good. Watch. Ready.
ALDA: (Narration) As Laurie is doing here, sometimes she put
her apples in first instead of Sue. And they changed who put
in three versus who puts in two. Regardless of the variations,
the monkeys went for the box with three. So the monkeys must
be counting what goes into each box. And that's not all.
CAREY: Each monkey only sees one trial. That monkey has never
been in this experiment before. So I mean that's extremely
interesting. He's spontaneously counting the apples. How is
he gonna know that one of us in going to put three and the
other is going to put two. But he sees apple, he spontaneously
counts how many times they go in there.
ALDA: (Narration) Using a portable "magic stage", Laurie and
Sue are now investigating whether the monkeys can also do
basic addition. The experiment works like this. A lime is
placed on the stage and a barrier put down to block the view.
After a brief pause, another lime is added.
SANTOS: Monkey, monkey, look, look.
ALDA: (Narration) One plus one is two -- no magic there. The
monkey quickly loses interest. It's videotaped to measure
later how long the monkey looked. Now here's another show.
It's identical to the first, except for the surprise ending.
SANTOS: Watch. Ready.
ALDA: (Narration) One plus one equals, one? The monkey stares
for a long time -- many seconds more than before. Sue believes
this means the monkey was surprised -- that it must have known
something was wrong. Such îLooking time experiments" as they're
called were actually developed to figure out what's going
on inside the minds of human babies. When shown non-magical
events like this one, 3 month old babies get bored rapidly.
But show them an impossible or magical event like this The
infants stare and stare. Their fascination with magical events
suggests they know the world doesn't work this way. So based
on looking time, the monkey was surprised. He must have added
the second lime to the first and realized he was shown something
impossible. The chimpanzee named "Aye" is a famous example
of an animal's awareness of numbers. After years of working
with psychologist Tetsuro Matsusawa, Aye can quickly count
the dots flashed on a computer screen and indicate with near-perfect
accuracy how many he saw. If we freeze this video, you can
see there are nine dots on the screen. An instant later, Aye
presses the number 9. Aye also can arrange numbers in ascending
order. He's faster than any human who's ever done these tests.
Sally Boysen's chimpanzees have shown they can solve math
problems that would delight a kindergarten teacher. Here,
the problem is three plus three. Seven years ago, Frontiers
recorded the first-ever attempt at addition by a chimp.
BOYSEN: How many? Show me. Yeah, six. That's the right answer.
Good girl, there are six peaches out there.
ALDA: (Narration) Watch what happened when numbers were used
instead of peaches.
BOYSEN: Here's another one.
ALDA: (Narration) This is Sheeba, by the way -- the same chimp
we did the model room experiment with.
BOYSEN: Okay, how many was that? Can you pick? Show me. Four!
ALDA: (Narration) Eventually, this chimp could add up to nine.
She really seemed to understand what numbers were all about.
BOYSEN: How many of these do I have? Two bananas. Right, there's
two bananas here.
ALDA: (Narration) That's not all Sally's chimps understood
BOYSEN: First I cut this. One more time. And now I have this
little weensy piece. It's a fourth of a banana. Right.
ALDA: (Narration) Sally discovered that her chimps could even
grasp the sophisticated concept of fractions.
BOYSEN: I've got another fourth, that's right, there it is.
ALDA: (Narration) So the overall conclusion is, humans just
don't have a monopoly on the world of numbers.
ALDA: We are accustomed to thinking of ourselves as being
so far removed from the other animals in tasks like that.
It's shocking to realize that we're much closer cousins than
BOYSEN: Yeah, and for years we've thought about ourselves
that way. Even Aristotle said, "man is rational because he
THAT ONE OUT
HEINRICH: has a passion for birds. When he's not teaching,
you'll find him out behind his house -- where he keeps an
aviary filled with ravens, the largest type of crow. When
it comes to brains, crows have an A-plus reputation.
HEINRICH: The crow family has always been thought to be extremely
intelligent. Although the interesting part is, why do people
think they're so intelligent when in fact there aren't even
any real tests that have examined that. And so that's the
challenging part to find out, you know, how intelligent are
they? And how do you know that they're intelligent?
ALDA: (Narration) One of the best ways to test an animal's
intelligence is to see how it handles a difficult situation
for the first time. And today, this 10 month old raven is
in for a surprise. What will the bird do when dinner is tied
onto a string, and the string tied onto a branch? String is
something the raven has never seen before -- and at first
the bird is too scared to go near it. Bernd lures the raven
up to the branch to get it focused on the meat. The fact that
the raven tries to fly away with the meat shows it doesn't
understand that string joins things together. But once it's
had a taste, it's determined to get another bite.
HEINRICH: Well, now that we've seen that you tried to fly
off with it. Well, that doesn't get the meat. So now what?
With this new strategy, the meat's moving below, but it's
not getting any closer to the Raven's mouth. Now there's a
breakthrough. It's a totally creative solution -- raise the
meat step by step -- but still not perfect... The raven knows
it's on the right track. Then as a test, Bernd shoos the Raven
HEINRICH: He's not going to fly off with it now, he knows
ALDA: (Narration) Only seven of the ten ravens Bernd has tested
could solve this problem. So it's unlikely that the solution
is genetically programmed into the birds. Bernd concludes
that the successful birds had to be thinking the problem through.
HEINRICH: There wasn't any very long trial and error learning.
If there was any learning it was extremely quickly. And I
could only explain that that he had some concept of what was
happening, of what he was doing.
ALDA: (Narration) Next stop Harvard, where before we can film,
the animals have to get used to me and the camera. They're
little South American monkeys called cotton topped tamarins.
ALDA: Are they getting used to me here?
HAUSER: The animals started off when you walked in the room
giving what we think of as alarm chirps. They're chirps that
are evocative of being a little bit afraid, curious, investigative.
And now they're giving basically sort of low level chirps.
They're just curious now. So they've really gotten used to
the fact that you're in the room.
ALDA: My ratings have gone down in just a minute or two.
ALDA: (Narration) Marc Hauser, like Bernd Heinrich with his
ravens, also dreams up ingenious experiments to probe how
ALDA: This is the gravity experiment? How does this work?
HAUSER: That's right. This is an experiment which is going
to determine what kinds of expectations the animals form when
something drops. And the way we're going to test that is we're
going to show them that these ending pipes are empty -- there's
nothing inside of them. And then we're going to close the
doors. And then we're going to insert an opaque tube up here.
And we're going to take a piece of food. And we're going to
wave it in front of them so that they track it. And then we're
going to drop it and we're going to let them search.
ALDA: (Narration) Which door the tamarins open up first should
reveal where they expected the food to drop. Here's our subject.
First he gets a chance to look behind all the doors.
ALDA: He's checking to see that they're empty?
HAUSER: Exactly. So we're making sure he knows they're empty.
We're going to close the doors. And now we're going to give
him a track.
ALDA: (Narration) The monkeys love fruit loops, and "giving
him a track" means waving a piece in front so the tamarin
follows it. That was quick. Let's see it again. The tamarin
goes for the door directly below where the fruit loop was
dropped. So he expected gravity to apply.
HAUSER: Let's try this again now. Same configuration.
ALDA: (Narration) Even after 20 trials, the tamarin still
makes the same error.
ALDA: He doesn't learn anything about the tube.
HAUSER: Absolutely nothing. And this reinforces the view that
he's got such a strong idea in his head that this is where
it's got to fall that even though he's never getting reinforced
there he's not going to switch his strategy.
ALDA: (Narration) Now Marc tries to teach the tamarin about
the tube by using a transparent one. This time when the fruit
loop falls, it's path will be obvious. This time he gets it.
HAUSER: Now, the critical question is, having had that experience,
and being reinforced correctly now on the first go, will he
now take that experience and generalize that to this new experience?
ALDA: (Narration) The new experience is actually the original
setup with the opaque tube. The tamarin fails again. He's
learned nothing. But take a look at what happens with another
variation of the experiment. This time the whole tube apparatus
is on its side. The tamarin gets the correct answer on the
first try. Without the distraction of gravity, it was able
to think about the tube.
ALDA: When we say thinking, do we mean thinking almost fully
HAUSER: Showing that they can track objects and either fail
in that task or pass that task shows they can make an estimation
of what happens when something disappears out of sight. Now
in one sense, that shows that they're able to maintain an
object that's gone in their mind. So on some level, that means
they're forming some kind of representation. Some kind of
image of what that object's like in their head.
ALDA: (Narration) Marc's experiment is a fascinating one,
because it shows the limits of tamarin thinking. When gravity's
involved, they get overwhelmed by how they know it works.
But strip gravity away and underneath lies logical thinking.
Just like the ravens.
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FOOLS ABOUT TOOLS
ALDA: (Narration) It's well known that chimpanzees can use
simple tools. In the wild, for example, they've been observed
cracking open nuts with rocks. And here in captivity, they
use sticks to get at honey.
ALDA: Do you want a stick?
ALDA: (Narration) This use of tools seems very human -- kind
of smart like us. It's even led to speculation that apes learn
skills and pass them on, just as we do.
ALDA: How did they learn to do this? Do they learn the same
way we do?
TOMASELLO: Well, there are a couple of different theories
about how they might go about learning it. On the one hand,
I would say that they do go about learning in it very much
the same way that a child would. They are exposed to the tool.
They have a problem in front of them and they, either some
combination of trial and error or insightful problem solving.
And in many cases, I do believe they employ insightful problem
solving in the sense that they don't have to try out ever
possible solution. They can look at the problem and see which
one might work better.
ALDA: (Narration) Can animals really think about tools? That
was the question which
HAUSER: set out to explore back at Harvard -- working with
his cotton top tamarins. Both of these blue canes are tools
-- but if you could only pick one to hook a marshmallow, which
would it be? This tamarin knows the right answer. After getting
a chance to look from above it goes for the cane with the
marshmallow inside the hook. After weeks of practice, the
Tamarin is used to using thin blue canes. But here comes something
new A blue cane that's too fat to grasp versus a thin cane
that's red -- a color the tamarin's never seen in a tool.
The Tamarin went straight for the easy one despite the strange
color. The point of the experiment is to find out whether
Tamarins understand which features of a tool are important
to its function. The nobbly green triangle is certainly weird
looking -- but it's set up to use more easily than the familiar
blue cane. The Tamarin sized things up right away.
HAUSER: The only thing we were looking at was the first time
they experience that change in a feature. The reason for that
was we didn't want to teach them to pick the right thing.
We wanted to see what they would spontaneously do.
ALDA: (Narration) No matter what new tools are presented,
on the first try the Tamarin always picks the one that would
get the reward most effectively. Here's another tool brain
teaser. You can use cloth to pull in a marshmallow -- if you
choose the correct one. It took the Tamarin a few days of
practice before it was consistently going for the continuous
cloth. Now Marc wants to know what it learned. It might have
just learned to avoid the cloth with the "visual stripe",
so Marc tries confusing things by adding an extra band of
color to each cloth. On the first try -- after a moment of
thought -- the tamarin spots the continuous one. Here's the
toughest case of all -- where the break in the cloth is wavy
not straight. It's not easy to see which cloth is continuous.
But for the tamarin, no problem.
HAUSER: You're a genius. They seem to be able to attend to
those aspects of the problem that really matter in terms of
solving the problem, excluding changes that we try to throw
at them that really don't make any difference whatsoever.
ALDA: (Narration) So once again, there's a surprising depth
of thought inside an animal mind.
back to top
BOYSEN: Okay, we're going to try and suit you up here.
ALDA: Why am I putting this on?
BOYSEN: Well, we're going to try and turn you into a little
bit of a scary person.
ALDA: It's going to be pretty scary to the fashion police
when I put this on over my sweater
BOYSEN: That's true, well, this way you're going to look a
little bit more like one of the veterinarians who might be
coming in to do, say, the chimp's annual physical. And they
really don't look forward to that too much.
ALDA: (Narration) Sally Boysen and I are about to play an
elaborate mind game with some chimpanzees.
BOYSEN: So now you've got the scrub, the mask and then we're
going to give you the ultimate frightening weapon.
ALDA: Which is?
BOYSEN: The tranquilizing gun.
BOYSEN: And look, it matches your scrub.
ALDA: I like to be accessorized.
BOYSEN: Okay now, as we come out
ALDA: (Narration) The subject of our experiment is a chimp
named Daryl. That's him up on the walkway -- and right now
he thinks I've come for him.
BOYSEN: We're gonna hide. So come on in here, over by that
ALDA: (Narration) Actually, we're going to make Daryl think
I'm after another chimp named Kermit -- who's still indoors,
and therefore doesn't know the vet's here.
BOYSEN: We've got to let him calm down a little so that he's
sure that it's not gonna be him. He's got to get used to this.
Because we want him to calm down enough so that he's not distressed.
ALDA: (Narration) We're going to observe how Daryl reacts
when Kermit's let out -- to see if Daryl warns his friend
that I'm here.
BOYSEN: Daryl, Daryl. It's all right. Come here. Daryl, Daryl,
ALDA: (Narration) The big question we're asking is whether
chimps are aware of what other chimps know or don't know.
If they have this awareness, it would mean they "think about
thinking" -- something most scientists believe only humans
BOYSEN: So, we're going to kind of pretend that we're like
right here, and you want to kind of crouch a little. As though
you're going to get this guy next door.
ALDA: (Narration) As the door to Kermit's cage is opened,
Daryl cries out -- and Kermit stops dead in his tracks. Minutes
later we run the experiment again. This time Kermit is already
outside and can see for himself that I'm coming to get him.
He's clearly upset. But now, up above, Daryl is silent --
a big difference from before.
ALDA: He doesn't let out a call
BOYSEN: He doesn't have to because they both know and in this
case it's every man for himself. They both have knowledge
of the situation. So it's not necessary. And if you will,
maybe he's aware that Kermit already knows so I don't have
to tell him anything.
ALDA: You know, when you put it in high class terms like that,
that he's aware of the state of mind of the other chimp, it
really sounds extraordinary. It sounds like big news. And
I can imagine people being very reluctant to take that without
a lot of testing. Because it means they're more like us than
we thought they were.
BOYSEN: I think the chimps are capable of showing us much
more. And our limitations are our own inadequacies as humans
to design an experiment that will show that.
BOYSEN: Kermit, Daryl
ALDA: (Narration) By the way right after the experiment, we
let Daryl and Kermit know that we were only playing.
BOYSEN: See, you got the response and now he wants to play.
ALDA: (Narration) In the future, Sally wants to find out when
chimps develop an awareness of the mind.
ASTINGTON: We're going to have a little snack now.
ALDA: (Narration) Humans don't become aware of what's going
on in the mind until around age three -- as this demonstration
illustrates with two and a half year old Jacob and a juice
ASTINGTON: What's in the box?
ASTINGTON: Look at that. What are they?
ALDA: (Narration) Jacob calls the ribbons ropes, which is
fine because it's the next question which counts.
ASTINGTON: What did you think was inside the box before I
turned it over?
ASTINGTON: Ropes, okay.
ALDA: (Narration) Jacob is unaware that just seconds ago he
was sure it was juice. And, unlike the chimp Daryl, Jacob
also believes that if he knows something, so will everyone
ASTINGTON: Jesse hasn't seen inside this box. What would Jesse
think was inside before I turn it over?
ALDA: (Narration) So it seems that adult chimps can think
more about the mind than young humans. And based on our next
experiment, so might tamarin monkeys.
HAUSER: Okay, so here's how it runs. A tamarin will be sitting
in that box over there and an experimenter will be standing
over here. An actor will come in eating an apple.
ALDA: That's me?
HAUSER: That's you, ah, eating an apple.
ALDA: I can do that.
HAUSER: You can do that.
ALDA: I actually got a lot of good reviews for eating an apple.
HAUSER: You've got credentials, yeah, I want to see the CV.
So you come in eating an apple, and then you give the tamarin
a little piece.
ALDA: (Narration) As the play develops, we'll be closely watching
the reactions of our audience -- the tamarin -- to see if
ALDA: I'll see you opening night
ALDA: (Narration) The play opens while I'm offstage. Marc
shows the tamarin that both of the boxes are empty. And now
it's time for my entrance.
ALDA: Howdy Bub. Uhm, good. Good apple. Want some.
ALDA: (Narration) Right away my audience is hooked.
ALDA: I'm going to put this away in here; cover it up. See
ALDA: (Narration) Now, while I'm offstage again, Marc does
a little switcheroo with the apple. This is one of those looking
time experiments, so the animal's surprise will be gauged
by how long it looks.
ALDA: Hmm. Where's that apple. I'd sure like some more of
that apple. I think I'll go in here.
ALDA: (Narration) When I look in the empty box, the tamarin
pays no attention -- there's no surprise in what I've done.
ALDA: The tamarin saw me leave the room after putting it in
this box. If it's a really smart tamarin, it would expect
me to come back and look for it in this box. If the tamarin
only has a sense of what he or she believes or knows, then
they'll expect me to look where they know the apple is.
ALDA: (Narration) So let's try that now.
ALDA: Ymm, good apple. Want some? I'm going to put it in here
and I go.
ALDA: (Narration) This time when I come back, I do something
ALDA: Ymmm. Sure could use another bite of that apple.
ALDA: (Narration) I shouldn't know this, and the tamarin stares
three times longer than before.
ALDA: That was a big reaction. He stood up. How do you know
they're not looking longer because their mind wanders at that
moment or something or there's a noise over there or something
HAUSER: What we try to do is test a number of animals in exactly
the same conditions. And so what we're hoping for is convergence.
That all the animals will show very similar patterns given
the manipulations we do.
ALDA: So I guess I'll put this apple in the box and cover
ALDA: (Narration) Now a third variation of the show. This
time I stay in my seat while Marc switches the apple -- so
if the tamarin's thinking about what I'm thinking it should
know that I know the apple's been moved.
ALDA: Hmm. Sure would like some apple.
ALDA: (Narration) Now when I reach into the second box, the
tamarin isn't very surprised. Here's the last variation of
ALDA: Okay, putting this in here.
ALDA: (Narration) Once again, I witness Marc switching the
apple. But this time I do something surprising when I go back
for another bite -- as if I didn't know what Marc had done
right before my very eyes. The tamarin looks for a long time
-- so it must be thinking about what I know and what's in
ALDA: How different are we from these other animals. Are we
just vastly, radically different? Are we a total innovation
in evolution? Or does this show connections, threads that
HAUSER: No animal is doing calculus. No animal is writing
Shakespeare and so forth. Those are vast differences. But
what I think seems to be revealing itself now over time is
that at the core, we share many of the same principles of
thought and knowing.
ALDA: (Narration) Researchers like Mark Hauser and Sally Boysen
represent a new era of investigating animal minds. Their approach
depends on exquisitely designed experiments that tease out
exactly what the animal thinks. And yes -- they do think --
they are Einsteins in their own way.