The intelligence of an individual is manifested through an intelligence test. Paul Broca and Sir Francis Galton were one of the first scientists to initiate the idea of measuring intelligence. They determined intelligence by measuring the size of the human skull, and they assumed that the size of the skull depicts smartness. Wilhelm Wundt, on the other hand, used introspection (the human ability to reflect on their thoughts) as the measure of intelligence. In 1904, Alfred Binet and Theodore Simon developed the modern intelligence test in IQ history.
To measure the human intelligence, following are some of the significant tests −
Alfred Binet and Theodore Simon developed the first real test when the French Ministry of Education asked to develop a test to distinguish mentally disabled children from normal, intelligent lazy children. This Binet - Simon scale became the basis for many further intelligence tests. In the US, Stanford University psychologist Lewis Terman took Binet's original test and standardized it using a sample of American participants, now known as Stanford– Binet Intelligence Scales. The adapted test was first published in 1916. The test measures five factors - knowledge, quantitative reasoning, visual-spatial processing, working memory, and fluid reasoning. It consists of both verbal and nonverbal subtests. The Stanford-Binet intelligence test uses a single number, known as the intelligence quotient, to represent an individual's score on the test.
Binet devised his test by age levels as developmentally disabled students seemed to think like non-retarded children at younger ages. Within these scales, the tasks that average children of a specific age should find moderately difficult are kept. Children are given only the levels in their range. The lowest level at which a given child passes all items is the child's basal age. The scores are computed based on the number of items passed correctly. For each correct answer, two months' credit for MA is received. The test is continued till the child reaches a ceiling age, the highest level at which all items within the level are failed. The scale was constructed so that the mean mental age (MA) of a normal population at a particular age is equal to the chronological age (CA). In the test, the items become less concrete and more verbal as one goes up the age scale. After the test, an individual's score is expressed as a mental age. The IQ is calculated by the formula −
IQ = MA/CA
Where MA is the Mental age calculated by the test, and CA is the Chronological age.
This scale is used in school placements to determine the presence of learning disability or developmental delay. While tracking, intellectual development included in neuropsychological testing to assess the brain function of individuals with neurological impairment.
David Wechsler developed a scale for measuring the intelligence of 1939, known as the Wechsler– Bellevue Intelligence Scale. Later, it was revised as Wechsler Adult Intelligence Scale (WAIS), published in 1955. Wechsler felt that the popular Binet scale was not accurate as it did not incorporate non-intellective factors into the scale. WAIS is an individual test. The test consists of two parts, the verbal part has six tests, and the non-verbal or performance part has five tests that require a minimum of language. It has been used for 16 to 64 years and takes one hour.
Raven's Progressive Matrices are culture-fair non-verbal intelligence tests developed by John C. Raven in 1936 to research how genetic and environmental aspects influence intelligence. The Raven's Test is intended to be culturally and ethnically unbiased, measuring the hereditary component of intelligence without regard for the environment. The exam consists of 60 matrices (or abstract patterns) from which a portion has been deleted, and the subjects must select the missing portion from six to eight alternatives. Each group of items becomes increasingly difficult to encode and understand, demanding increased cognitive ability. There is no time limit, and it can be administered in a group. It measures general intelligence, educative ability, and reproductive ability. They are offered in three different forms for different ability levels and age ranges from five years through adulthood −
Coloured Progressive Matrices − It was designed for younger children, the elderly, and people with moderate or severe learning difficulties. Sets A and B from the standard matrices are used in this exam, with a set of 12 items placed between the two as set AB. Except for a few pieces in Set B, which are portrayed in black-and-white, most items are placed on a colored backdrop. If participants outperform the tester's expectations, the transition to standard matrix sets C, D, and E is accelerated.
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Standard Progressive Matrices − This form contains a total of 60 matrices divided into five sets (A to E), each containing 12 items (e.g., A1 through to A12). As one only initial problems and moves up in the progression, a set becomes more difficult, requiring an even greater cognitive capacity to encode and analyze information. The items are presented in the black-on-white form.
Advanced Progressive Matrices − The advanced form of the matrices comprises 48 entries, divided into two sets of 12 (set I) and 36 (set II) (set II). Items are again displayed in black-on-white format and get progressively tough as the set progresses. These items are appropriate for both older individuals and adolescents with above-average intelligence.
There are various intelligence tests used to measure the intellect of a person. Each of these tests targets a different aspect of intelligence testing, following different definitions of the concept. Some tests are better at measuring academic skills, while others are better at measuring creativity or problem-solving skills. Different intelligence tests measure different things, so it is hard to say which one is the best. Some tests focus on cognitive abilities, while others measure more practical skills. Each of them has its own strengths and weakness.