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Today, we talk about intelligence. All of you probably had an intelligence
test at least once in your life. And today we're going to talk about,
first, what is intelligence? What do we mean by the word intelligence?
How it's measured. And to what extent is it inherited?
Is it something we're born with or is it something that we acquire?
Now, intelligence has been interested by psychologists for a long time because we
have an interest in measuring mental abilities.
and in fact. We'll find out it's still debated about
what intelligence is and how it's measured.
Because it's such a complex term people differ in whta they think it really is
and the best way to measure it. Sternberg, Robert Sternberg, called
intelligence a measurement map. Measurement based map of the mind.
Because it is very much tied in to how it's measured and what we measure.
And Spearman was the first to talk about that we could give a lot of tests but as
of, there's something that all these tests have in common.
And that he called general intelligence or g.
In other words, if we had this test of intelligence and this test of
intelligence, there was some common measurement that we could see in the fact
that they were correlated with each other.
John Horn and Ray Cattell took that further in say, well yeah, there's
general intelligence but we, it's best if we sort of separate.
Crystalized intelligence from fluid intelligence.
it's a GC and a GF. Fluid intelligence is those cognitive
abilities that allow us to interpret the world around us, to reason, to solve
problems and crystalized intelligence are those, the results of those fluid
abilities. In other words, what we have acquired.
So, things like verbal ability, vocabulary, and world knowledge.
That's a part of crystallized intelligence.
But, the idea was, we were trying to measure some general ability that allows
us to interact with the enironment around us.
Now, Thurstone actually came up with what he called the primary mental abilities.
And he used some statistical techniques called factor analysis to group together
those abilities that seemed to group together well.
In other words, by using correlations, he would come up with empirically based
factors that seem to cling together, and he came up with his primary mental
abilities. He decided there was seven of those
distinct mental abilities that we measure when we measure intelligence in an
intelligence test. Those primary mental abilities are Verbal
comprehension, which we measure from things like a vocabulary test.
Verbal fluency. How many words can you come up with with
a given letter, like C, in a specific period of time.
Fluency. And number, the ability to do simple
arith, arithmetic problems, mathematical problems.
Space, the ability to rotate things in space.
Memory, the ability to remember words and remember pictures.
Inductive reasoning, things like an analogy test or a test where you complete
a series, two, four, six, eight and then you say ten.
Inductive reasoning and then perceptual speed.
How quickly can you perceive things and make decisions.
Things like being able to look, cross out all the a's in a big long matrix of, of
letters. The, he believed these were the primary
mental abilities that were captured in intelligence tests.
And remember, intelligence tests often have many different kinds of tasks that
you have to perform. Now the most common intelligence test for
children is the Stanford-Binet. One that's been around a very long time.
For adults, we, typically use the Wechsler Adult Intelligence Scale or WAIS
and you are probably familiar with the Scholastic Assessment Test.
It's called Scholastic Assessment Test. It used to be called, The Scholastic
Aptitude Test. But then the College Board realized that
it meas, really measures both aptitude and achievement.
So it's fluid intelligence and crystallized intelligence.
So now it's called the Scholastic Assessment Test.
Now, there's certain things that all intelligence tests have in common.
First, psychometric quality. If you take a test and then take the test
again a week later you should pretty much get the same score.
That's called reliability. How reliable is that measure of
intelligence? We also have validity.
Is it really measuring what we say it's measuring?
Now there's several kinds of validity. You can have construct validity or
content validity, which says it's measuring the same thing that other
commonly use intelligence test measures. So if I develop an intelligence test and
it correlates highly. With the waste of a stanford Binet, then
I would say it has content of[INAUDIBLE] validity .
It could also have predictive ability, for example the SAT that you take as an
admission requirement for colleges, correlates well with performance in the
first year of college. So it has predictive validity.
It predicts well how you're going to do in your fresh one year.
And then there's face validity. That is, is it, you really understand
what it's measuring while it's measuring it.
Intelligence tests are pretty face valid, but some personality tests are not.
Because they don't want you to really know what it's measuring.
They also, most intelligence tests are standardized, that is we give the tests
to lots of people so we know what is an average seven year old do on the Stanford
Binet? What does an average ten year old do on
the Stanford Binet? So it's standardized.
By knowing what the average score is and so we have norms based on samples of the
population. For example, IQ which is a measure, is
determined by the middle, your mental age divided by your chronological age times
100. Middle age is what your score is in the
standardization norms. You might be a 9 year old, but in fact
your middle age is of a 12 year old according to the standardization norms.
If we, if you're middle age is the same as your chronological age, then your
score is going to be 100. So the average score on intelligence
tests like the Weiss, for example, is 100, because the mental age divided by
the chronological age gives you one, and times 100 gives that.
If your mental age is higher than your chronological age, then your IQ is
going to be higher than 100. So this is a measure of intelligence
that's based on standardization norms. Now this is a bell shaped curve or a
normal distribution, which you find if you give the intelligents test to lots of
people. And it has, it shows first what the
average is, in this case the average according to the IQ is 100.
Which means your middle age and your chronological age are the same, and if
your middle age is higher than your chronological age then you are going to
be distributed with a higher IQ score, and if it's lower than the chronological
age you will have a IQ score that is lower.
It also measures this distribution. Only shows the average but it also shows
how distributed the scores are around the average.
If the scores are very close to the mean then this would be a very narrow
distribution and if the scores are very widely around the mean then it'll be
distributed in a larger one but this particular distribution, has a, a score
that is a distribution of 15. And that's called a standard deviation.
Now one standard deviation in IQ score, standard deviation is 15, is 34% of the
distribution. That means that 68% of distribution is
around the mean. 68% is one standard deviation below and
above the mean. If you go between one and two standard
deviations it's another 14%. That means that 96, 96% of their variants
occurs between two standard deviations above and below the mean.
This just tells you what the score is. So if you score 130, that means that you
are in the 96% and are at the high end of that.
