The development of formal tests of intelligence assessment is quite modern. The formal intelligence tests were developed in the early 1900s. Sir Francis Galton (1885) is considered as the father of the mental tests. In 1884, in an International Health Exhibition at London’s South Kensington Museum, he tested more than 9000 men and women visitors without their knowledge.

The term “test” was not known until then. Galton measured such characteristics as head size, visual acuity, and strength of handgrip, breathing capacity, reaction time, visual acuity, and memory for visual form. He was a naturalist and mathematician. He attempted to discover individual differences. He was keen to know how and why people differ in their abilities, and why some are gifted and others are below average.

Galton believed that intelligence could be measured by objective tests. Galton raised many important issues concerning intelligence – the degree to which it is inherited, how it can be measured, and what are its components. Intelligence theorists are still studying these issues today.

The American psychologist, J. McKeen Cattel also studied the nature of individual differences. Like Galton, Cattel believed that sensory, perceptual, and motor processes constitute the core of intelligence. He developed the label mental test


Being requested by the French Ministry of Education in 1904, Alfred Binet devised a method to identify the mentally disabled children from the normal school children. The Ministry asked him to determine why a number of children were not profiting from the standard school curriculum, and to develop means to teach these weak children in public schools. Binet and his disciple Theophil Simon developed an intelligence test as requested.

The test was called 1905 scale having 30 different kinds of items. The items ranged from the simple ability of touching one’s nose or ear to the more complex abilities of defining abstract concepts.

The concept of Mental Age (M.A.) was first developed by Binet. K age is the average age at which normal individuals achieve a particular on a measure of intelligence. Mental age is separate from the Chronolc Age (C.A.), which is the number of years or months since the child is Binet is credited with devising age-appropriate test items so that num children’s responses could be compared. The items were chosen object without being influenced by differences in their varied environment, impulsive judgment, and rote memory. The items were based on rational judgment reasoning.

Normal children of different ages were tested, and then the average for each age was determined. Then each child’s performance was com to the average of all other children of the same age.


Test findings were interpreted in terms of the average age at which normal children achieved a particular score. This measure was called Mental Age (M.A.). For example, when a child’s scores on various item test add to the average score of a group of 5 year olds, the child is said to have a mental age of 5 irrespective of his/her actual chronological age (C.A.) Binet defined retardation as being two mental age years below the chronological age. A bright child’s M.A. will be more than his/her C.A. A dull child’s M„ fall below his/her C.A.