- [Instructor] A long time ago, people used to think
that children were just miniature versions of adults,
and that they thought in pretty much the same way.
But then this guy Piaget came along and he figured out
that children actually reason quite differently.
In fact, he believed that children are actively constructing
their understanding of the world as they grow,
so that as their bodies grow, their minds grow as well.
He thought that this happened generally in different stages.
So, I want to tell you about Piaget's four stages
of cognitive development.
First, we start out with zero to two years.
At this point, children are said to be
in the sensorimotor stage.
This word kind of makes sense.
Sensori just comes from the senses.
So he said children gather information about their world
with their eyes, so through sight, smell, taste,
hearing, and touch.
So that's why whenever you see a baby zero to two years,
they're always touching stuff and putting it in their mouth.
Then the motor part is that they are very active.
As they discover how to use their senses,
they also discover how to move their bodies around.
This helps them explore the world and learn
what they're capable of.
The main task or awareness that develops during this time
is object permanence.
This just means that infants don't recognize
that objects still exist even though they can't see them.
For example, if you give an infant a toy or something,
say you have a nice ball for them,
and you take it away, they won't look for it
because they don't understand that it still exists.
The next stage occurs from about age two
to right around six or seven years.
The reason I'm being a little wishy-washy on the years
is because these are really just general guidelines.
It's not really hard and fast rules
of when these stages happen.
The next stage is the preoperational stage.
The operational part just means mental operation,
so imagining things or mentally reversing actions,
things like that.
The thing to notice about this phase is that
this is really when children start to develop
and engage in pretend play,
and they'll begin to be able to use symbols
to represent things.
What you might notice is that around age two is also
when children learn to talk.
As they learn that words symbolize objects,
that starts to help them into the preoperational stage,
and understand the idea of symbols.
Children of this age are very egocentric.
That's not a bad thing.
They're not just arrogant and bragging all the time.
They just don't understand that other people have
a different point of view than they do.
If you're ever watching TV with a child,
like a five-year-old, they might sit down
right in front of you and not understand
that you can't see through them, because they can see.
Also, sometimes kids will try to hide from you at this stage
by covering their eyes.
The whole, I can't see you, you can't see me idea.
Then once they get to about age seven
to about age 11 years old,
then they are in the concrete operational stage.
Again, remember operational means mental operations,
and now they can do concrete operations.
So this is where children learn the idea of conservation.
If you know a little kid and want to see what stage
of development they're in, then you can do this little test.
It's pretty fun.
It's easy.
You take two identical glasses and pour the same amount
of water in them, and show them to the child
and say, "Which one has more?"
And kids will tell you they all have the same amount.
Then, right in front of the child, so that she sees you,
you take one of those glasses and pour it
into a short, fat glass.
Then you take the other one and pour it
into a tall, skinny glass.
Then right away, ask the child again,
"Which one has more?"
Up until concrete operational, the child's going to say
the tall, skinny glass has more because the water's higher.
But once they reach the concrete operational stage,
and understand that the amount of water doesn't change
just because the glasses are different sizes,
then they'll tell you that they both still have
the same amount of water, even though they look different.
So that's a fun little test.
At this stage, children can also begin
to reason about mathematics.
They'll be able to understand that 8 + 4 = 12,
and then that must mean that 12 - 4 = 8.
Moving on up, children from about age 12 and up
are in what Piaget called the formal operational stage.
That's when children are able to reason
about abstract concepts and think about consequences
of potential actions.
They're able to reason out what might occur.
Also, Piaget thought that this is
where really sophisticated moral reasoning
began to take place.
At this point, children are reasoning more like adults,
and they continue to develop that over time.
Later developmentalists have come along and figured out
that these stages aren't quite so discreet as Piaget
may have originally thought.
Children don't always develop these abilities
within the certain age brackets,
but they do tend to progress in a predictable fashion.
Thanks to Piaget, now we know that children are more
than just miniature adults.
So, go find a child and see what stage they're in.
Test Piaget's theory yourself.