Weschler, why the?

There are several psychological tests

Many websites or magazines display evidence presented as "psychological evidence." The term flourished and spread happily in the press without the fundamentals of the true psychological test being respected. Above all, a psychological test aims to be an objective measure of cognitive or affective aspects, in the form of a measure of operationalizing variables of these aspects, in relation to a reference population, and respecting the characteristics of validity, fidelity and sensitivity. You can see our video on the subject here

Definition of a test

A test is any technique that allows a quantitative or typological description of an individual placed in a defined situation, with reference to the behavior of a set of individuals placed in the same conditions, the same situations. A psychological test is a test that allows to measure the values of the psychological dimensions (affective, cognitive, behavioral).

The history of intelligence tests

The idea of an orderly measure of intelligence was first inspired by Alfred Binet, when French education asked him in 1904 to establish a means of discerning between young pupils, those who could follow a normal program of study and those whose weakness of the faculties would force them to resort to a specialized education.

Alfred Binet then had the idea of a measuring instrument that establishes an index of intelligence, a numerical estimate of the mental level of a student. While building his test, he realized that some of the proposed items were specific to a given age: some items (later classified as "5-year-old mental age items") were thus approved by 50% of the 5-year-olds. years, by almost all of the 6-year-old students, and not served by the majority of the 4-year-old students. The same thing happened with other articles of other ages.

This finding led him to evoke the idea of a mental age: although mental age generally corresponded to actual physical age, some students, called "gifted", passed tests of a mental age greater than their physical age. On the other hand, other students, called "retarded", were mentally old than their physical age. Binet constructed a test composed of several tests and numerous items, which allows to establish a raw score of mental age, which could be compared with the expected level of mental age for a given physical age. The comparison (the relationship) between the mental age determined by passing the test with the expected mental age (for a given physical age) thus constituted an index from which students could be classified, as, for example, retarded deep, light, normal, gifted, gifted ...

This test was very successful not only in school education, but also in clinical practice, and it kicked off the manufacturing of tests and tests to measure intelligence.

Modern tests

David Weschler builds a test battery, the Weschler Adult Intelligence Scale ( WAIS , formerly Weschler-Bellevue scale, 1939, 1955), dedicated to the measurement of IQ for adults, as well as the Weschler Intelligence Scale for children ( WISC ) that offers the opportunity to compare IQ at different ages.

Weschler's IQ was very successful, and is now called standard IQ, although this notion of IQ has nothing to do with calculating a quotient. The interest of the calculated quotient is to be able to place a subject in his age group, that is, in relation to individuals of his age.

Weschler's intelligence battery consists of 11 subtests. To construct this test, Weschler performed a distribution of raw results on different individuals, at different ages. The mean of the scores obtained is around 23, the maximum towards 50, the minimum is 0. This distribution was then normalized so that its average became 100: the standard deviation was then 15 (This standard deviation is a value that is regularly used to interpret the result: for example, a score below the mean, minus one standard deviation, indicates mild weakness).

Wechsler IQ is now used regularly, and is considered one of the most important evidence in the estimation of the (global) general intelligence.

Today, which exists as evidence

Wechsler scales come in three forms, depending on the age of the subject:

- WPPSI , which is the pre-school form of the test. It is aimed at children from the age of 2 years & 6 months, to 7 years & 3 months

- WISC , for children from 6 years to 16 years and 11 months. Currently WISC-V. The tees are updated every 10 years to avoid the Flynn effect.

- WAIS , for youth and adults, from 16 to 79 years and 11 months

The distribution of the results is made according to a normal distribution curve of intelligence, also called Gaussian curve. The average is set to 100, with a standard deviation of 15 points :)

Scores that are two standard deviations below or above the mean will be considered out of the ordinary. Therefore, the threshold of 130 to start talking about distrust is not chosen arbitrarily, as it can sometimes be read or heard. It is explained by the statistical construction, this normal distribution that is always characterized by this bell-shaped appearance, with a great majority of the subjects in the center, & two extremes that thin very quickly on either side of this central swelling.

The exact distribution is as follows:

- from 2.2% to 2.3% of the population has a Total IQ 70 and therefore a delay

mental (of which 0.13% have a Total IQ 55)

- 95% of the population has a total IQ between 70 and 130 (of intelligence

low to higher intelligence, passing through the norm, a norm that can be medium low or

High average)

- between 2.2 and 2.3% of the population has a total IQ 130 and therefore a high

intellectual potential (of which 0.13% have a Total IQ 145, which can be classified

Very High IQ. That is, just more than 1. This rate drops

then to 0.025% for a score from 150, that is, just a little more

of 1 in 5,000!)

The Gaussian curve according to the Wechsler scale, the Cattell scale or also the percentile scale:

Conclusions

Something very important: like all psychometric tests, you must go face to face with the psychologist (always without parents), especially in ONE SESSION! The Wechsler scales are scientifically valid tests, particularly because they are standardized. That is, they are based on an adjudication under identical conditions, whatever the child or the psychologist.

The (neuro) psychologist will observe the child during this transition: it is essential (a psychometric test is not a CCM!). Their fatigability is, therefore, very important in this type of exercise, as are their reactions to boredom, difficulty or, on the contrary, ease.
Therefore, if the test is divided into 2, 3 sessions, or more ... (which is often done by school psychologists), this transfer rhythm is totally broken: -?

Therefore it is important that the subject who passes the test does so under normal conditions & according to the instructions in the manual. This rigor of a standardized procedure, common to all, guarantees the reliability of these tests.

It is important to note that this Total IQ is a composite note, totally different from the sum of the standard notes! Therefore, it does not make sense to add the five tracks in the hope of obtaining a total IQ, if the psychologist considered that it was not representative.

Privilege interpretation and clinical observation, and do not give the score (s) full power as was the case until Wisc-IV. Thus, it can be expected, in the long term, not to hear more from the mouth of psychologists that at 129 IQ a child is in the norm, but at 130 it is excessive.

It is the whole idea of Wisc: to get rid of the Total IQ, from the single and heavy figure, not always very talking. And allow the practitioner to explore a wide range of skills, including children with Dys disorder (s), non-verbal (or dysphasic) children, children with intellectual disabilities, children with depression, or even children with ADD / H, or a form of autism.

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