- [Lecturer] You've probably heard of IQ,
which means intelligence quotient,
and you may even have taken an intelligence test,
which is supposed to measure how intelligent you are,
but what does intelligence mean?
For a term that's used so widely
we have kind of a hard time defining it.
Does it mean street smarts, book smarts, creativity?
Psychologists, even though they still
have some disagreements, tend to define intelligence
as a mental quality, allowing you to learn from experience,
solve problems and use your knowledge
to adapt to new situations.
Intelligence tests use numerical scores
to measure your aptitude for those types of tasks
and compare them to how well other people do.
So if intelligence is made up of different aptitudes,
then is it multiple abilities or is it just one?
One theory is that there's just one general intelligence.
Evidence to support this theory comes from the fact
that people who score really well on one type of test,
such as verbal ability, also tend to score really well
in other types of tests, such as math.
Now, you might be better at one of these categories
than the other, relative to yourself,
but relative to other people you probably
have about the same level of skills in both areas.
The factor underlying these consistent abilities
is referred to as the g factor.
You can think of g for general intelligence.
Although there's some good evidence for g,
there's also some support for theories
of multiple intelligences.
A psychologist named Robert Sternberg
proposed a theory of three main types of intelligence,
analytical intelligence, what we might think of
as academic abilities or the ability
to solve well-defined problems,
creative intelligence, the ability to react adaptively
to new situations and to generate novel ideas,
and practical intelligence, the ability
to solve ill-defined problems,
such as how to get that bookcase
up the curvy staircase into your apartment.
When someone tells you their IQ score
what they're really telling you
is their analytical intelligence.
The scores are scaled so that an average person scores 100,
so depending on where you are in relation to 100
you can tell how you compare to the population at large.
You may be wondering how intelligence
affects people's lives.
Obviously, people with high analytical intelligence
tend to do well in school,
however, people who score high on any
of the intelligence scales we've mentioned so far
don't really tend to have better marriages,
raise their kids better or achieve greater mental
and physical well-being than people who score lower.
For this reason, another psychologist proposed
that there is another type of intelligence
called emotional intelligence.
This ability helps you perceive, understand,
manage and use emotions in your interactions with others.
Yet another way of thinking about intelligence
is in terms of two major categories,
fluid intelligence and crystallized intelligence.
Fluid intelligence is our ability
to reason quickly and abstractly,
such as when we're solving novel logic problems.
Crystallized intelligence, on the other hand,
refers to our accumulated knowledge and verbal skills.
The main difference here is that fluid intelligence
tends to decrease as we move into older adulthood,
whereas crystallized intelligence tends to increase
or stay the same.
With all this talk about different definitions
of intelligence, you're probably wondering
how it ever gets measured.
Interestingly, the first person
to develop an intelligence test
actually didn't even mean for it to be an intelligence test,
Alfred Binet was just trying to establish
a child's mental age in order
to measure children's intellectual development
and predict how well they would do in school.
Later on, a psychologist at Stanford University
modified Binet's original test
and extended it to teenagers and adults.
One thing that the Stanford psychologist noticed
was that Binet's original test items,
which were originally designed for French children,
didn't seem very predictive
of California children's abilities.
After he modified the test,
unfortunately people forgot about that difference
and started using the new version
to judge how generally intelligent immigrants
coming into the US were.
Now, you can probably see the problem with that,
even from just a language perspective.
If a test is trying to measure verbal ability,
then you might be able to do just fine
in your native language, but it's a lot harder
in a language you don't know.
Since then, more pains have been taken
to try to make intelligence tests more applicable
to people from all different cultures,
but it's an ongoing issue.
One last consideration that's inherent
in any question of traits or talents,
but particularly popular with intelligence,
is the question of nature versus nurture,
that is, how much is intelligence due to your genes
and how much is due to your environment
and other experience?
We study this question by looking at heritability,
which is the proportion of variability in a trait
that's due to genes.
Specifically, we usually study heritability with twin
and adoption studies, meaning we look at the corelation
between intelligence scores in identical twins,
two people with the exact same genes,
who grew up in different environments.
We also look at the corelation and scores
between identical twins raised together,
as well as the corelation and scores
between fraternal twins raised together.
Since we have a mix of same and different genes
and environment, we compare those correlations
and try to determine what proportion
of the variability in those scores
we can attribute to genes
and what proportion is attributable to the environment.
What we know from these studies
is that of those three groups
there's the strongest corelation and IQ scores
between identical twins raised together.
That alone doesn't really tell us about any differences
between nature and nurture, though, so let's keep going.
Identical twins raised apart
still have a high corelation, but not as high,
suggesting some environmental influence on intelligence.
Fraternal twins raised together
have an even lower corelation, though,
suggesting that there is also a genetic component.
So the short answer is both nature and nurture
contribute to intelligence.
Since we tend to have more control over the nurture aspect
than the nature aspect, there's been a lot of research
into what types of environments promote intelligence,
especially for children.
Interestingly, although we know
some environmental situations
that impair normal cognitive functioning,
there's no recipe for structuring an environment
to make a genius, when children are deprived
of exposure to language or interaction with people,
their intellectual development is impaired.
However, there's not a direct relationship,
tons and tons of language exposure helps a child,
compared to no exposure,
but it doesn't necessarily make that child a genius.
Perhaps even more important than just intelligence score
is your attitude toward intelligence.
Some people have what's called a fixed mindset,
they think that intelligence is biologically set
and unchanging, others have what's called a growth mindset,
meaning that they think intelligence is changeable
if you learn more.
People with a growth mindset tend to be more motivated
and able to accomplish more in their careers,
than people with a fixed mindset.
So, whatever your IQ score is or isn't, try to keep in mind
that you can always grow and always learn.