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Language: en
in popular culture the term IQ is
everywhere do IQ exams do that you
probably need 120 points of IQ don't my
IQ IQ IQ IQ low IQ individual people who
post about their IQ are
losers when people say IQ what they mean
is intelligence an objective rigorous
measurement of intellectual ability but
does it actually work well in this video
I want to find out where IQ came from
what does it actually measure what can
it predict about your life and I guess
what is my
IQ I have never taken an official IQ
test before honestly I don't think I'm
terribly smart I've always kind of
considered my IQ to be maybe just a
little above average exothermic or
endothermic I feel like that should be
exothermic good job Science Guy there
are a lot of IQ tests online but I am
very skeptical about their accuracy
still I figured some of them may be good
practice for the real thing tomorrow I'm
going to do an IQ test for real before I
do that I want to try to improve my
score and so I'm going to try to do a
whole bunch of practice tests I think
this test is trainable but tomorrow
we're going to see whether that's true
or not the idea of intelligence testing
goes back hundreds of years but the
first concrete breakthrough occurred in
1904 English psychologist just Charles
Spearman was studying students grades in
different subjects and he wondered how
their performance in one subject like
English would relate to their
performance in another like math one
option would be that the better a
student did in math the worse they would
do in English maybe because they spent
more time on their math work and so had
less time to devote to English so
performance in different subjects would
be negatively correlated another option
was that performance in one subject
would be completely unrelated to
Performance in another after all
different subjects require different
skill sets so maybe marks would be
totally
uncorrelated the third option was that
the better a student did in math the
better they would do in English in other
words their marks would be positively
correlated a correlation coefficient can
vary anywhere from negative-1 to
positive 1 a correlation coefficient of
negative 1 indicates a perfect negative
correlation meaning an increase in one
variable corresponds to a precise
predictable decrease in the other
variable similarly a correlation of
positive 1 indicates a perfect positive
correlation a correlation of zero
indicates no relationship between the
two variables and any value between 0
and one indicates a positive correlation
but the data has some random spread the
square of the correlation coefficient
tells you the amount of variation in one
variable that can be explained by
variation in the other variable for
example if the correlation coefficient
is5 then 25% of the variation in one
variable can be explained by the other
when Spearman analyzed his data he found
a clear positive correlation students
who did better in math also tended to do
better in English and the correlation
coefficient was
64 but math and English weren't the only
subjects the student studied they also
took Classics and French and when
Spearman looked at the correlations
between all of these subjects he found
the same pattern students who did well
in one subject tended to do well in them
all so how do you explain this
observation well Spearman proposed that
each person has some level of general
intelligence what he called the G Factor
this construct was meant to capture how
quickly students could could learn new
material recognize patterns and think
critically regardless of the subject
matter which explains why students
scores across subjects are correlated
those with high G score well on all
subjects and those with low G score
poorly on all subjects Spearman
published his conclusions in a paper
titled general intelligence objectively
determined and
measured but the correlations weren't
perfect so on top of the G Factor
Spearman proposed subject specific
spefic factors or S factors a student's
performance in math for example would
depend on their general intelligence
plus their subject specific factor for
math subject specific factors could
increase or decrease performance on that
particular subject Spearman believed
that specific factors could be trained
but general intelligence was fixed so he
wanted to find a way to reliably measure
general
intelligence at around the same time in
France Alfred Benet was tasked with
figuring out which kids needed more help
in school together with Theodore Simone
he developed the Benet Simone test
students were asked to name what's
missing in the drawing Define abstract
terms and repeat back sentences and
there was also this question asking
which face is prettiest there were 30
tasks in
all their performance was benchmarked
against other students of different ages
in order to to assign them a mental age
for example if a student performed about
as well as the average 8-year-old their
mental age would be eight this mental
age was then divided by their actual age
and multiplied by a 100 to arrive at a
so-called intelligence quotient and IQ
was
born so the Benet Simone test was the
world's first IQ test it was translated
by Godard into English and brought to
the US
at Stanford Lewis Turman standardized it
using a large American sample and with
some modifications it became the
Stanford banet test and for decades it
was the most widely used test in the
United States but this was just the
start many other IQ tests were developed
they all had the same goal of measuring
the G Factor the way they did this was
by assessing many different mental
abilities including memory verbal
spatial and numerical skills each one of
these areas might have a subject
specific shift but by averaging them all
together the idea was the subject
specific effects would cancel out
leaving a decent approximation of G of
course there would always be some error
but that's why psychologists designed IQ
tests with upwards of 7 to 10 sections
with distinct tasks to try to minimize
subject specific
distortions all the different IQ tests
differed in the number of questions and
their difficulty so to standardize the
scoring system each test was given to a
large sample of the population raw
scores were normalized usually so the
mean was 100 and the standard deviation
was 15 and that's how it's still done to
this day this is known as IQ and it's
meant to be a measure of an individuals
G factor in comparison to the rest of
the
population the way it's scaled 68% of
people have an IQ between 85 and
115 only around 2% score over 130 or
under
70 11 Lions four cats and 7 crows have a
total
of oh boy as I was studying for my IQ
test I practiced all the different types
of questions that appear on Modern tests
one section will almost certainly be on
VOC vocabulary they give you one word
like sanguin and you have to pick which
of the multiple choice options is most
similar in meaning is it gloomy asinine
recalcitrant optimistic or
reflective they might also ask you to
pick a word with the opposite meaning so
what is the opposite of perspicacious is
it canny obsequious dull fanciful or
sagacious another section tests your
ability to spot patterns with numbers so
pick the number that best completes the
pattern 3 5 8 12 what comes next
originally I was looking for complicated
patterns but as I familiarized myself
with the online tests I discovered the
patterns were usually pretty simple a
good technique is to find the difference
between adjacent terms so in this case
the first two terms are separated by two
the next by three and then four so the
logical next term should be five more
than 12 so 17 the answer is
C sometimes the numbers grow rapidly
like in the sequence 3 15 60 180 what
comes next in cases like this I look at
the ratio of one number to the one
before it in this case the second number
is five times the first the next number
is four times bigger and the next one is
three times larger so the answer should
be 2 * the fourth term which is 360
answer B one of the best known types of
IQ test questions are Ravens Progressive
matrices these involve a 3X3 grid with
symbols in each of the cells you have to
select the ninth cell which follows the
pattern I found that the bulk of these
puzzles obey one of only a few different
logical rules one is translational
motion so the symbols move from one cell
to the next in a predictable fashion the
second is rotational motion one or
several objects rotate from one cell to
the next the third is missing symbols
where in each row or column each symbol
appears once so to figure out which
symbols appear in the final cell you
just have to spot which ones are missing
and the fourth is addition where the
first cell plus the second cell equals
the third cell in this case lines that
overlap cancel out but a line plus
nothing equals a line
in most modern IQ tests all the
questions are completed under time
pressure you may have only around 10 to
30 seconds per question okay this
morning I'm taking an official IQ test
and I got to say that I'm pretty nervous
I always want to do well on tests you
know it's something I pride myself on
but at the same time you know uh who
knows how this is going to go I'm not
allowed to take you in there because
obviously people don't want the
questions getting out and they don't
even want video of what it looks like in
there you know they're very strict about
these things so I'm going to go in do
the test I'll come out and I'll let you
know how it went wish me luck what's
remarkable about IQ tests is that an
hour or two of questions on vocabulary
numbers and arbitrary shapes can predict
a surprising amount about your life for
one thing the higher your IQ the larger
your brain is likely to be a large meta
analysis from 2005 estimated a
correlation of 33 between IQ and brain
size so high IQ is literally big brain
IQ is also predictive of school Success
in 2007 Scottish psychiatrist Ian deiri
measured the IQs of 13,0 11year olds and
5 years later when these students
completed National School examinations
Deary compared their exam marks to their
IQs their performance on an IQ test when
they were 11 correlated with their
performance 5 years later on the GCS uh
about 08 that's an extremely high uh
correlation it means about 2third of the
variation in national school examination
scores could be predicted by IQ tests
taken 5 years
prior now the correlation coefficient of
this study is at the high end of the 2
to point8 Range found in similar studies
but research supports the claim that IQ
is a good predictor of school Success it
also predicts how much schooling a
person will complete maybe this
shouldn't be so surprising since some
School tests are essentially IQ tests
it's been argued that tests like the SAT
Act and the gr are basically IQ tests
they correlate with standard IQ tests at
around 8 now on my SATs I got a score of
1330 which corresponds to an IQ of
around 130 so it'll be interesting to
see if my official IQ score matches that
or if I was able to increase my score by
familiarizing myself with IQ style
questions I don't know but IQ also has
predictive power outside of school one
of the most robust findings is that IQ
can predict job success particularly in
technical or high complexity jobs how do
you measure occupational success uh you
ask people's bosses to rate them uh you
ask what people's income is you measure
productivity in ways that economists use
about you know the output
generated the correlations typically
range from. 2 to 6 and the effect is
most most notable for more complex jobs
which makes sense the highest effect is
for military training in fact the US
military will not accept anyone with an
IQ under 80 they also limit to 20% the
number of recruits with IQs between 81
and '
92 during the Vietnam war in order to
increase the pool of applicants they
relaxed this last requirement but what
they found was that those below the
threshold were 1.5 to three times as
likely to fail recruit training and they
required between 3 to nine times as much
remedial training taken together this
added so much strain that the military
ran more efficiently without the extra
recruits in total
5,478 people recruited under this
initiative died at a fatality rate three
times higher than ordinary recruits so
the military reinstated their
requirements and today anyone with an IQ
less than 80 that is about 30 million
Americans would be ineligible to join
the
military even outside the military IQ
seems to play a role in how long you
live in a Scottish study scientists
uncovered IQ tests from kids when they
were 11 years old now 65 years later
they checked to see who from the sample
was still alive at age 76 they found
that on average for every 15 Point
increase on the IQ test you would be 27%
more likely to still be alive at age 76
a large meta analysis confirms that
people with higher IQs have a lower risk
of dying during the time frame
investigated in each study the last
major thing that IQ seems to predict is
income this study shows a clear tendency
for income to increase with IQ and it
found a correlation coefficient of3 but
the variance is huge in fact the top
three earners in this study all had IQs
below 100
a large meta analysis of 31 studies
found the correlation between IQ and
income to be. 21 that is significant but
small it means that only 4.4% of the
variance in income is explained by IQ
maybe one of the reasons why we don't
see as high a correlation for income is
just because economically intelligence
is not necessarily that highly rewarded
in that maybe there are jobs you know
like a just doing a real real estate
type scheme like maybe that doesn't
require a huge amount of intelligence
simultaneously you have all these very
highly intelligent people who maybe
become College professors but that
doesn't necessarily pay very well yeah a
lot of people who have very high
intelligence scores don't have the same
interest in in accumulating money the
relationship with net worth is even
weaker it hardly seems to correlate with
IQ even though people with higher IQs
are supposedly more intelligent and on
average they make more money each year
but this apparent apparently doesn't
translate into saving or accumulating
more wealth
overall but if IQ correlates with school
achievement job performance income and
Longevity why don't we hear more about
it why aren't more people tested I think
it's because IQ has a dark
history when Henry Godard brought
benet's test to America its use and
interpretation shifted dramatically in
France Benet believed intelligence could
be improved through education he
designed his tests so that struggling
students could be given more help to
catch up but in the US the modified test
was given to
adults to rank them by
intelligence and researchers like
Spearman believed that g was
unchangeable that whatever general
intelligence you were born with you
would have for the rest of your life and
many thought G was inherited passed down
from parents to children these days we
would say it has a genetic basis there
is some evidence to support these
assertions IQ appears fairly consistent
over one's lifetime so they had tests
done when people were 11 years old they
found all those tests uh in in a filing
cabinet and followed those people up and
gave them the same test when they were
90 years old U you know much much later
their scores 80 years apart were
correlated at around5 to
six there is also evidence for a genetic
basis to IQ you find for instance that
if you get two identical twins and give
them an IQ test they have a very strong
correlation it's actually about the same
as giving the same person the test you
know a few weeks
apart Henry Godard used the claims that
intelligence was inherited and
unchangeable to put IQ at the center of
the American Eugenics
movement eugenesis wanted to prevent
those with undesirable traits from
having kids in many states laws were
passed to enable forced sterilization of
people who failed to meet a certain
threshold on an IQ test the
constitutionality of these laws was
upheld by the Supreme Court in 1927 even
words that we now use as insults
idiot imbecile were used as scientific
terms in his judgment Justice Oliver
Wendel Holmes wrote it is better for all
the world if instead of waiting to
execute degenerate Offspring for crime
or to let them starve for their
imbecility Society can prevent those who
are manifestly unfit from continuing
their kind three generations of
imbeciles are
enough in total over 60,000 people were
forcibly sterilized as a result of these
laws in fact they served as a model for
Nazi Germany Hitler himself claimed to
be inspired by American eugenicists
these have been used for horrific things
in the past at the nurg trials after the
war some Nazis quoted from the American
Supreme Court
decision given this awful history I
think it's understandable that many
people completely disregard IQ today on
the science of intelligence there are a
number of things those early researchers
got wrong one is that IQ is not entirely
determined by genetics can you quantify
the effects of genetics versus
environment when you look at twin
studies on average across the whole
lifespan it's about 50 to uh uh
heritability and uh environment you
simply can't for ethical reasons
estimated in humans you know with a
reasonable degree of certainty or
accuracy given my reading of that
literature it's a pretty broad range
probably somewhere between 40% and
70% okay and since education can improve
IQ it is not completely fixed over a
lifetime plus intelligence might not be
a single construct as initially imagined
these days scientists recognize two
forms of intelligence fluid and
crystallized fluid intelligence is your
ability to learn process information and
solve novel problems whereas
crystallized intelligence involves the
knowledge you've accumulated over your
lifetime both types of intelligence
increase throughout childhood
but fluid intelligence peaks in early
adulthood and then declines whereas
crystallized intelligence remains more
stable but IQ has been further misused
to promote the idea of racial
differences in intelligence there is for
example an observed gap between the
average IQ of black and white Americans
articles have also been published on the
IQs of different nations around the
world many of these nations are
purported to have average IQs below 70
that's the cut off for intellectual
disability how could this be the
conclusion that some draw is that there
are genetic differences between races or
nations in intelligence but I think
that's a gross misrepresentation of the
data the problem I'd argue is that IQ
tests don't necessarily measure what you
think they're measuring and the proof is
that there's a representative sample of
white Americans whose average IQ is
70 who are these people just ordinary
Americans who lived around a 100 years
ago researcher James Flynn studied the
average results of IQ tests over the
past Century and every so often the
tests get updated and renormalized to
keep their average at 100 now what Flynn
noticed was that each time they got
renormalized the scores had to be
shifted down a bit more by about two or
three IQ points per decade and if they
didn't do this what we would see is that
the average IQ of the whole population
was increasing at a steady rate for the
last 100 years adding up to around a 30
point increase this is known as the Flyn
effect we're our immediate ancestors on
the verge of mental
retardation because 70 is normally the
score for mental retardation or are we
on the verge of all being gifted because
130 is the cutting line for giftedness
now the genetics of the population
haven't really changed over 100 years so
what caused the increase well there is
some debate about the true causes but
one of them is probably improving
childhood nutrition and health you know
height also increased across that time
period right people got taller and
taller and taller another cause is
better education there's lots of
evidence that school makes you more
intelligent you become better at problem
solving if you have more knowledge
because it's easier for you to make
associations if you have more things to
make the associations with a third
proposed cause is a shift in the types
of work that most people do from Mostly
manual labor 100 years ago to much more
abstract thinking these days and that
shift may have made us better at
answering the types of questions that
are asked on IQ
tests rotate again the point is that IQ
tests appear to objectively measure
intelligence but they don't even in the
same same country separated only by time
cultural changes can affect the average
scores on IQ tests so why shouldn't we
expect cultural differences between
groups at the same time to have the same
effect some tests go so far as to label
themselves culture Fair meaning the
questions should be equally valid for
all cultures but the truth is it's
impossible to construct such a test does
that work no okay no I mean that's just
a title right that's just a marketing
term I don't think there is such a thing
as a completely culture-free or culture
Fair uh test culture Fair tests assess
visual relations geometric shapes and
patterns ignoring the fact that cultures
differ in for example whether they have
words for shapes or spatial relations
these differences influence how people
think about and use categories it's also
debatable whether cultures without
printed materials even perceive them in
the same way that we do what culture
Fair tests don't SS is ethnobotanical
knowledge or training dogs to hunt or
surviving alone in the rainforest
arguably these forms of intelligence are
more important for survival than knowing
say the next number in the sequence but
since they are less common in our
culture and we don't have good ways of
measuring them we see IQ puzzles as the
definitive way to quantify intelligence
and the people who make these tests
agree there are stringent requirements
before a test validated for one
population can be used with a very
different population even in the limited
forms of intelligence that IQ attempts
to assess there are factors other than G
which affect the final
IQ like motivation how much someone is
incentivized to complete the test can
have a marked impact on their score many
Studies have tried paying subjects to
complete an IQ test in some studies
they're offered a little say around a
dollar other studies offer between $1
and $10 and the real high rollers offer
more than $10 a large meta analysis
showed that motivating people in this
way increased IQ and the larger the
dollar amount the greater the average
increase at the high end IQ increased by
up to 20 points the effect is largest
for those with below average IQs so in
addition to G IQ tests also measure
motivation but it doesn't stop
there they do rotate training and
coaching for an IQ test can boost scores
by up to eight points I just completed
the test in uh some random notice n
barely talk after that it seemed pretty
fair there were lots of different
sections the math section in particular
I feel like I killed those questions
were easy I would say having done the
test I feel like that should be
trainable like you should be able to
train someone to do that well test
taking strategy is also important some
people are just better at taking tests
under time pressure than others I think
the hardest thing about the test was the
time limits looking for the patterns in
a series of shapes and it just normally
takes me a little while and so I feel
like I didn't finish those you have to
know when to skip questions how to
eliminate clearly wrong answers and when
to guess anxiety also plays a role
apparently a small amount of anxiety is
good but past a certain point it
negatively impacts
performance uh I guess the overall
review
is I think I think I did okay um and I
think the training actually really
really helped that's my prediction let
us fast forward to the future and see
how I actually did I actually got my
results from the author of the IQ test I
took are three areas uh three specific
areas for the math one for the numbers
ones I think that's where where I felt
really comfortable and I you know got
there before the time was done and then
I could go back and look at a few things
uh you blew the roof off the
quantitative one on the quantitative it
was 43 course on the crystallized
intelligence index it was 132 the uh
fluid intelligence index was
118 which still is a higher score than
88.5% uh if it's not it's not bad but
that's it's interesting that that one is
is uh you know significantly lower I
guess and that's not an unusual
difference around that concept of G
people have strengths and weaknesses if
we were to look at the best estimate of
G for you uh on this set of tests and
it'd be different if you took a
different test was at
134 which uh is higher than 98.8% of the
population
wow hopefully you're not disappointed
with any of that no you know I I wanted
to do well I you know I feel like my
motivation was was high possibly higher
than the the average person so what is
IQ good for my clinical practice now is
forensic nurse science and about 90% of
my cases are death penalty one of the
most common issues is what's referred to
the Atkins defense after the name of the
US Supreme Court case that eliminated a
death penalty for people with
intellectual disability can't the
criminal just throw the IQ test can't
they just intentionally answer every
question wrong we know that I mean we
include just like in the test that that
you took there are embedded uh measures
of invalidity it's detected using
various mathematical algorithms we're
better than 95% accurate in detecting
people who are attempting to fake poor
performance oh wow one thing that we
might be interested in doing is to boost
people's con ability early in life so
that it takes them if even if they go
into con of
decline uh it takes them longer to reach
the point uh where they'll have sort of
functional actual everyday problems
where they where they lose Independence
whether it comes to you know dealing
with their money or whether it comes to
dealing with um you know reading labels
whatever it is that that that people
struggle with when they get into kind of
later stages of cognitive decline if we
could discover a way to lastingly boost
people's intelligence that would be
massively helpful maybe its best use is
in identifying individuals with strong
intellectual abilities who haven't
otherwise been able to demonstrate them
teachers would recommend that a kid gets
put in the gifted and talented program
because generally they they'd observed
them uh doing well in the classroom but
if you replace that with a standardized
test an IQ test you find um higher
proportion of of poorer kids and kids
from from uh minority ethnic backgrounds
in the gifted and talented program when
you use an IQ test and the reason is
that you're using an objective measure
you're not just relying on some
teacher's opinion getting into a good
school was about who you knew uh or who
your parents knew or how much money your
parents had not so much about how you
were doing the idea that you could try
to develop an objective is measure that
would try and iron out all those social
biases was clearly a well-meaning
idea IQ is something that um not only
psychology but the general public has a
LoveHate relationship with tell me about
that psychologist hate to talk about you
know intelligence and people's
intelligence test scores and that kind
of stuff and I've had Parents you know
when I've included intelligence as part
of a neuropsychological evaluation of
their kid they say well
yeah yeah I'd I'd like to know his IQ
but you know we don't really care about
that what was
it and then I also think you have the
debate about IQ extremes on both sides
which I think doesn't help um you have
the extreme of people who say this is
the most important thing ever people's
IQ is the is is a majorly important
factor that we must know about them and
we can classify them into particular
schools or particular ways of Education
or whatever that's on one extreme and I
think that's totally unpr unproductive
but there's another extreme The Other
Extreme is the kind of blank slate view
which is that these tests are completely
useless they don't tell us anything that
they're only a tool of racism and uh
Prejudice and so on I think that's wrong
as well and there's just this massive
Firestorm on both sides happening around
them and the people in the middle just
get just get forgotten the people have
more moderate views on these on these
sort of topics so you know I'd recommend
that people um look for the more
moderate views on this I think the big
mistake is thinking that IQ in some way
determines someone's worth what's much
more important in my opinion is how you
interact with and help the people around
you which is why I think Steph Hawkings
said people who brag about their IQ are
losers while IQ tells us something it
doesn't tell us how our lives will turn
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