Hi, my name is Jennifer Nagel. I teach philosophy at the University of Toronto,
and today I want to talk to you about mindreading.
You could think of mindreading as a power to detect something hidden.
A person’s feelings or goals aren’t visible on the surface
in the way that their hair color is.
Still, if a person has tears streaming down
their face, one glance tells you they're sad;
if a kid is on tiptoes trying to get the cookie jar,
it’s not a mystery what they’re after.
Let’s say you can detect the mental state right away from what you’re seeing.
You can infer it from outwardly visible features
like whether someone’s standing on tiptoes;
the inner state causes outward effects that you can see and hear.
You can also pick up on clues from the situation
about what somebody must be feeling inside.
Mindreading is subtle, because a single mental state can have many different
visible causes and effects over time, and it can interact with other mental states.
If we detect mental states from their outward signs,
this doesn’t mean we make a checklist of those
signs and review it to deduce the mental state;
usually our mental state inferences are unconscious and automatic.
We see someone smile and just automatically judge they're happy.
We might not make the same automatic move if we learn that this smiling
person has been kidnapped and is being forced to pretend that he’s okay.
The upcoming video on the problem of other minds gets into skeptical
worries about how we can know whether someone who's smiling really feels happy,
or feels anything at all.
For now, we’ll just assume we’re looking at situations
where the inner mental state lines up with the outward signs.
Even in these straightforward cases, there is a real puzzle about
when we actually start thinking in terms of mental states at all.
For example, let's take an ability that's shared by humans and several other animals:
we notice when others are looking at something, and
we turn and follow their gaze, to see what it is.
Michael Tomasello and colleagues explored this ability
in the 1990s in experiments with chimpanzees.
Here’s one of their experiments: a trainer stands at the edge of the enclosure,
and she waits until there is a chimp in front of
her who has his back turned so he can’t see her.
Then she waves a nice treat, like an orange, behind his back
and waits for ten seconds, to see if he’ll turn around and look.
There's two conditions: in the control condition, the chimp's
alone there, so he might just turn and look by chance.
In the experimental condition, the chimp with his back to us isn't alone;
he is facing another chimp, who can see the treat when the trainer waves it.
Does the subject turn around to look more when he sees
that the other chimp has spotted something behind him?
For chimpanzees and for other apes and monkeys, the answer is: yes
Some other animals can follow gaze too, including
ravens and goats, and humans are really great at it.
Does this gaze-following behaviour show that chimps, ravens and goats are
mindreaders, tuned into the visual perceptions of their fellow animals?
Before we say yes, we have to think about other possible explanations.
What if chimps don’t really get the idea of seeing?
Maybe they've just learned that when other chimps turn their heads in some direction,
there is value to turning your head the same way:
aligning your gaze often leads to positive outcomes like gaining a food reward,
or being tipped off to a predator’s approach.
The direction of other faces could be just a
shallow pointer towards features of interest.
Animals who follow gaze like this are really responding
to the outer effects of the mental state of seeing,
they're not representing that underlying mental state at all.
Some birds are shallow like this.
For example, the northern bald ibis isn’t as smart as a
raven, but it will turn its head to align with others.
When an ibis looks up at something behind a barrier, however,
other ibises will just point their beaks up to face the same way,
stupidly looking at their side of the barrier, rather than moving
around it to check out what the other bird can actually see.
It looks like these birds don’t really track seeing:
they just have shallow gaze-following abilities.
By contrast, socially smarter animals like chimps go around
the barrier to check out what the other animal is looking at.
We can still wonder how much the chimps understand, though: maybe they
are just better at reading face direction as a pointer, having learned
that it makes a difference whether there is a clear line of sight,
still without really understanding seeing itself as a mental state.
You might be wondering how we can ever tell that a creature is
responding to mental states rather than just their outward signs.
Here’s one test: Imagine getting a chance to play
with two weird new sets of goggles which look the same
from the outside, like dark sunglasses, except that
one pair has red rims and the other has blue rims.
From the inside, however, you soon discover that the red goggles are opaque,
so wearing them is like wearing a blindfold.
The blue goggles let you see the world normally.
Then, for the first time, you get a chance to watch
other agents put on either the red or the blue goggles.
Now, do you expect the red-goggled agents to know what is in front of them?
How about the blue-goggled agents?
Notice that your expectation here can’t be based on memories of watching
the outer effects of the different mental states,
like seeing red-goggled agents bump into stuff
You’ve got to remember how it was for you yourself to wear those different goggles.
Grasping how others will act based on your own
first-person experience is a sign of deeper mindreading.
It takes genuine social intelligence to recognize that
your own experiences of the world can be shared by others,
to switch from your first-person perspective
to thinking about another agent.
In the next two videos, we will talk about how
mindreading capacities develop in human beings.