Intelligence Quotient

History Noteworthy Contributors about IQ

1. Sir Francis Galton - The first scientist to aim to build a modern IQ

The first scientist to aim to build a modern IQ test in 1884 was Sir Francis Galton (the cousin of Charles Darwin). By measuring the size of the human skull he believed he might estimate intellect. And he assumed that the bigger the cranium, the cleverer the individual.

Galton was interested in the concept of a talented individual. Therefore, he organized a laboratory to evaluate reaction times and other physical characteristics to prove his idea that intelligence is a generic mental capacity which is a product of organic development.  The sharpness of your eyesight and hearing as well as your reaction times to diverse stimuli may be tested in his open laboratory.

Galton's study of intelligence in his lab environment and his theoretical understanding of the heredity of intelligence, which was one of the fathers of contemporary intelligence research, prepared the stage for decades of subsequent research and discussion in this subject.

2. James McKeen Cattell - Father of mental test

James Mc Keen Cattell devised the first mental exam in the world in 1890 and comprised identical activities which measured nearly all speed and perceptual accuracy. However, it quickly turned out that academic performance cannot be predicted; consequently, it is probably a flawless measure for whatever we would call intelligence.

3. Alfred Binet & Theodore Simon - Carried out the first contemporary intelligence test

In 1904, Alfred Binet (1857-1911) and Theodore Simon carried out the first contemporary intelligence test in IQ history (1873-1961). During the beginning of the 1900s, the French government engaged psychologist Alfred Binet's support in the realization of which youngsters would be more sluggish students (Binet et al., 1912). At the beginning, Binet's practical consequences were extremely important: to be able to detect children who could not keep up to their classmates in the recently mandated system of education for everyone.

He and his partner, Theodore Simon, as a result, proceeded to work up a series of particular questions focusing on areas such as memory and problem solving. 

The test by Binet consisted of questions of knowledge as well as questions needing basic thinking. Binet as well had to use an external validity criteria, as he discovered in age, besides test elements. In fact, while the speed of development varies considerably, older children are far more intellectually mature than younger children. And thereby, Binet found the average age at which the kids could on average solve each question and classify objects properly.

 Thus he would be able to assess the position of the children in relation to their fellows. For example, if the kid could answer problems that were solved on average only by children two years younger, the child would have a mental development two years ahead. 

Intelligence testing, currently called the Intelligence Quotient Test (IQ), is most well known and utilized following the introduction of the Binet-Simon scale in the early 1900s.

4. Lewis Terman  - who brought IQ test to over the world

In 1916, Stanford psychologist Lewis Terman modified the exam to the American pupils when the Binet-Simon scale moved into the United States and the Stanford-Binet intelligence scale was released (Cherry, 2020). 

After Lewis Terman reviewed the Binet test and created a far more suitable standard than the original, IQ tests in the USA became a true success story. It was published as the Stanford-Binet exam (Terman was a psychologist at Stanford University).

He wanted to multiply the outcome by 100, so the final equation for IQ is X 100 / mental age. A 130 IQ sounds a lot cooler than a 1.3 IQ. 

However, this approach works only successfully in kids. If the parents of a kid were informed that their 6-year-olds had an average of 9-year-old mental capacity and consequently had an IQ of 150. But if it was informed the grandpa of the child that, despite him being just 60, he couldn't praise him on his cognitive skills as he was the typical 90-year-old.

Clearly, the quotient works only if the initial criteria of Binet is functional; – for example if indeed the greater age is usually much better. In other words, if mental development is no longer taking place, the technique is unsuitable.

5. David Wechsler - complete the IQ test until now

The same as Thurstone, Gardner and Sternberg, Wechsler believed that many distinct intellectual ability skills were involved and considered that Stanford-scale Binet's was too closely a reflection of a whole notion of intelligence. 

Intelligence tests do as intelligence theories build one another. Following the Stanford-Binet test by Terman, American psychologist David Wechsler produced a new technique because of his unhappiness about the limits of the Stanford-Binet exam (Cherry, 2020). 

Because of that, in 1955, Wechsler established the Wechsler Intelligence Scale for Children (WISC)  and the Wechsler Adult Intelligence Scale (WAIS) as the most up-to-date version being the WAIS-IV (Cherry, 2020).

The calculation of adult IQ by David Wechsler simply compares performance to a normal distribution of the measured values. The IQ of individuals with a score equivalent to the mean age of 100 in his system. The average adult IQ is 100, as is the average kid IQ of the original system. He employed the statistical properties of the normal distribution to allocate IQ scores depending on contemporary extent. For instance, if one of his contemporaries scored a standard deviation over the average, and so surpassed 86 per cent, the IQ would be 115, and so on.