The dark history of IQ tests - Stefan C. Dombrowski

View full lesson: https://ed.ted.com/lessons/the-dark-history-of-iq-tests-stefan-c-dombrowski

In 1905, psychologists Alfred Binet and Théodore Simon designed a test for children who were struggling in school in France. Designed to determine which children required individualized attention, their method formed the basis of the modern IQ test. So how do IQ tests work, and are they a true reflection of intelligence? Stefan C. Dombrowski explores how the tests have been used throughout history.

Lesson by Stefan C. Dombrowski, directed by Kozmonot Animation Studios.

In 1905, psychologists
Alfred Binet and Théodore Simon

designed a test for children
who were struggling in school in France.

Designed to determine which children
required individualized attention,

their method formed
the basis of the IQ test.

Beginning in the late 19th century,

researchers hypothesized that cognitive
abilities like verbal reasoning,

working memory, and visual-spatial skills

reflected an underlying
general intelligence, or g factor.

Simon and Binet designed a battery of
tests to measure each of these abilities

and combine the results
into a single score.

Questions were adjusted
for each age group,

and a child’s score reflected how they
performed relative to others their age.

Dividing someone’s score by their age
and multiplying the result by 100

yielded the intelligence quotient, or IQ.

Today, a score of 100 represents
the average of a sample population,

with 68% of the population
scoring within 15 points of 100.

Simon and Binet thought the skills
their test assessed

would reflect general intelligence.

But both then and now,

there’s no single agreed upon
definition of general intelligence.

And that left the door open
for people to use the test

in service of their own preconceived
assumptions about intelligence.

What started as a way to identify
those who needed academic help

quickly became used to sort
people in other ways,

often in service of deeply flawed
ideologies.

One of the first large-scale
implementations

occurred in the United States during WWI,
when the military used an IQ test

to sort recruits and screen
them for officer training.

At that time, many people
believed in eugenics,

the idea that desirable
and undesirable genetic traits

could and should be controlled
in humans through selective breeding.

There were many problems
with this line of thinking,

among them the idea that intelligence
was not only fixed and inherited,

but also linked to a person’s race.

Under the influence of eugenics,

scientists used the results
of the military initiative

to make erroneous claims
that certain racial groups

were intellectually superior to others.

Without taking into account
that many of the recruits tested

were new immigrants to the United States

who lacked formal education
or English language exposure,

they created an erroneous
intelligence hierarchy of ethnic groups.

The intersection of eugenics and IQ
testing influenced not only science,

but policy as well.

In 1924, the state of Virginia
created policy

allowing for the forced sterilization
of people with low IQ scores—

a decision the United States
Supreme Court upheld.

In Nazi Germany, the government
authorized the murder of children

based on low IQ.

Following the Holocaust
and the Civil Rights Movement,

the discriminatory uses of IQ tests

were challenged on both
moral and scientific grounds.

Scientists began to gather evidence
of environmental impacts on IQ.

For example, as IQ tests were periodically
recalibrated over the 20th century,

new generations scored consistently
higher on old tests

than each previous generation.

This phenomenon,
known as the Flynn Effect,

happened much too fast to be caused
by inherited evolutionary traits.

Instead, the cause was likely
environmental—

improved education,
better healthcare, and better nutrition.

In the mid-twentieth century,

psychologists also attempted
to use IQ tests

to evaluate things other than
general intelligence,

particularly schizophrenia, depression,
and other psychiatric conditions.

These diagnoses relied in part on
the clinical judgment of the evaluators,

and used a subset of the tests
used to determine IQ—

a practice later research found does
not yield clinically useful information.

Today, IQ tests employ many similar
design elements and types of questions

as the early tests,

though we have better techniques for
identifying potential bias in the test.

They’re no longer used to diagnose
psychiatric conditions.

But a similarly problematic practice
using subtest scores

is still sometimes used to diagnose
learning disabilities,

against the advice of many experts.

Psychologists around the world
still use IQ tests

to identify intellectual disability,

and the results can be used
to determine

appropriate educational support,
job training, and assisted living.

IQ test results have been used
to justify horrific policies

and scientifically baseless ideologies.

That doesn’t mean the test itself
is worthless—

in fact, it does a good job of measuring
the reasoning and problem-solving skills

it sets out to.

But that isn’t the same thing
as measuring a person’s potential.

Though there are many complicated
political, historical, scientific,

and cultural issues wrapped up
in IQ testing,

more and more researchers
agree on this point,

and reject the notion that individuals
can be categorized

by a single numerical score.