The Transylvania Times -

By Alice Wellborn
Everyday Education 

IQ Tests Are Just One Measurement


We can thank the French government for IQ tests! Early in the 1900s, when universal education was mandated in France, Alfred Binet was commissioned to develop a test to identify children in need of special assistance in school. He came up with the concept of “mental age,” measuring intelligence by comparing individual children to those with average abilities in their age group. Binet defined intelligence as “judgment, otherwise called good sense, practical sense, initiative, the faculty of adapting one’s self to circumstances.”

The numerical “intelligence quotient,” or IQ, was developed by William Stern, a German psychologist, and Lewis Terman, an American psychologist. IQ is the ratio of mental age over chronological age, times 100. For example, an 8-year-old child with skills like an average 10 year old would have a mental age of 10 and an IQ of 125 (10/8 = 1.25 x 100 = 125).

The first IQ test, the Binet-Simon Scale, was introduced in 1905. The first American IQ test, a revision of the original Binet-Simon, was introduced in 1916. It was called the Stanford-Binet Intelligence Scale and, in its latest revision, is still in use today.

In 1955, David Wechsler, an American psychologist, developed the Wechsler Adult Intelligence Scale (WAIS), followed by the Wechsler Intelligence Scale for Children (WISC) and the Wechsler Preschool and Primary Scale of Intelligence (WPPSI). He defined intelligence as “the global capacity of a person to act purposefully, think rationally, and deal effectively with his environment.” The Wechsler tests are the most commonly used in the United States today.

But what does IQ mean? IQ is an ill-defined human construct: something we have made up to help understand the world and how people fit into it. Really, IQ is best defined as the score someone gets on an IQ test! As one would guess given the origin of IQ testing, IQ tests generally measure those skills that are most closely allied with success in academic learning: logical, sequential reasoning skills and a good memory.

IQ scores are designed to mirror the normal curve - also called the “bell curve.” The normal curve illustrates how, theoretically, different traits and abilities are distributed through the human population. Here’s what it looks like:

The big middle part of the curve, which covers 68 percent of the population, shows what we can call “within normal limits” – the range that would describe most people for that characteristic. For example, if you took everyone in your town and stacked them up by height, the stack would look like the bell curve – 68 percent of people are of average height, 14 percent of people are tall, 2 percent of people are very tall, 14 percent of people are short, and 2 percent of people are very short.

IQ scores work the same way. If you took everyone in your town and stacked them up by their IQ score, 68 percent of the people would have an average IQ, 14 percent would be smart, 14 percent would be slow learners, 2 percent would be intellectually gifted, and 2 percent would be intellectually disabled.

Anytime your child is given a “standardized test” – including an IQ test – that test is meant to describe where your child stacks up on the bell curve when compared to other children his age. And your child really is being compared to other children his age. Standardized test scores come from giving the test to lots and lots of real children. The good, well-standardized tests (for example, the Wechsler Intelligence Scale for Children or the Stanford-Binet Intelligence Scales) are based on thousands and thousands of children, with the population of children matching the latest U.S. Census data for socio-economic status, racial diversity, urban/rural, etc. Another name for standardized tests is “norm-referenced tests” because the scores are based on what’s “normal” for a certain population of real people.

Standard scores are the number that describes where your child stacks up on the bell curve. IQ scores are standard scores. Percentile rank is another way of describing how a particular person ranks within a group. Percentile ranks should not be confused with percentages – they are very different, but very easily confused. If a child gets 60 percent on a test, that means she got 60 percent of the questions right and 40 percent of the questions wrong (not so good!). If a child is at the 60th percentile on a test, that means that she performed better than 60 percent of the children in the comparison group, and only 40 percent of the children in that group performed better than her (well-done!). Percentile ranks go with standard scores. A perfectly average standard score is 100, and that is at the 50th percentile.

On the Wechsler Intelligence Scale for Children (WISC) – the most widely used IQ test for children – IQ’s in the 70s are considered “borderline” (slow learner), IQ’s in the 80s are low average, IQ’s from 90-109 are average, IQ’s from 110-119 are high average, IQ’s in the 120’s are superior, and IQ’s 130 and above are very superior.

IQ tests are still used in schools today to help make decisions about eligibility for special education programs. The tests are given to children who are referred through the special education system. The tests are individually administered, scored, and interpreted by a school psychologist. The psychologist writes a report to explain the results, and this report is given to parents. In Transylvania County Schools, we have three excellent school psychologists on staff.

IQ tests are valid and reliable, but the scores are not written in stone. All kinds of things can lower a child’s score: illness, anxiety, language skills, fatigue, hunger, attention deficit disorder, behavior problems. The school psychologist gives parents a range (called a “confidence interval”) within which the “true score” should fall.

There are lots of different ways of being smart, and IQ tests measure just one of those ways: school smart, or book smart. IQ scores do not measure, for example, creativity, physical prowess, social intelligence, compassion, mech-anical skills, spirituality, emotional intelligence, or intuition.

IQ tests do a great job of indicating who will have difficulty in school – which, after all, is what they were intended to do. They do not measure the value of a child and they do not predict success in life. IQ is just one way of looking at a person – an important way, but not the only way.

(Wellborn now retired, but formerly a school psychologist in Transylvania County schools.)


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