It is often essential to measure the human intelligence so as to provide special attention to the deficient ones. Being an abstract concept it is absurd to think of expressing its magnitude in numbers. However, expressing in terms of imaginary units psychologists could visualize to accord ranks and quantify the intelligence. The intention of measuring intelligence originated ever since the era of Chinese emperors during 2200 BC when it was attempted to measure the differentiations in the cognitive abilities among humans through the large scale aptitude tests. The work of Francis Galton during late 19th Century was considered as the first modern attempt to test the intelligence. During the first part of 20th century the Binet-Simon scale is devised after the names of Alfred Binet and Theodore Simon. In the later part of 1930s David Wechsler propounded the concept of Wechsler Intelligence Scale for Children (WISC) and later Wechsler Adult Intelligence Scale.
During the 1960s Vernon and Caroll accepted the theorems of Spearman and Thrustone prescribing intelligence to be narration of abilities at different levels of generalities and devised a theory as hierarchical expression of intelligence. Later Robert Sternberg and Richard Wagner devised a test of practical significance. The validity of the test indicates the magnitude to which the test succeeds in accomplishing the object. The potentiality of the test to accord consistent results is known as its reliability. The tests of validity and reliability of the tests associated with measurement of intelligence are to be resorted to in relation to the objectives behind the tests involved. The SAT was shown to be a measurement of the magnitude of IQ to a greater extent. The practice of psychometrics is opposed to vehemently on various grounds. The validity and reliability of online IQ testing measures are also not free from suspicion.
The intelligence tests strive to quantify the level of human intelligence, the basic ability to be aware of the world around, incorporating its functioning and application of the acquired knowledge to increase the quality of the life. In the words of Whitehead 'intelligence enables the individual to profit by error without being slaughtered by it'. Intelligence, therefore, is the quantification of the potentiality not a measure of what is learnt. It is therefore free from culture. The parents of most of the children require them to be aware of the law and their rights. However most are unaware that they should also be aware of the facts. The 'facts' pertaining to their child is brought out by means of various tests and evaluations applied on them. The variations in the test records over a definite period is resorted to evaluate the educational benefit or regression, to undertake significant educational decisions ranging from qualifying to the strength of educational services extended. This is the reason behind the evolution of the concept of the intelligence testing. However, this involved the problem of quantifying an abstract concept of intelligence. But it is advocated that 'if something exists, it exists in some amount. If it exists in some amount, then it is capable of being measured.' (Tests and Measurements for the Parent, Teacher, Advocate & Attorney)
The modern test for intelligence was perceived to have been conceived out of the necessity to devise a method for differentiating between the children those were intellectually normal and those were inferior. The objective was to admit the inferior children into special schools so as to provide them with more personal attention. With this objective in view the French Government commissioned the renowned psychologist Alfred Binet in 1904 that led to the formulation of the Binet scale and the concept of the Intelligent Quotient. (IQ Test: Where Does It Come From?)
History & Development
The search for an effective and correct method measuring the differentiation in cognitive abilities among the humans traces back to 2200 BC, when the Chinese emperors were resorting to large-scale 'aptitude testing for deployment of high officials. It is evident from the stories like Wild Boy of Averyon that even during 18th century, efforts were concentrated on bringing out the differentiation between the normal and abnormal thinking. (Individually Administered Intelligence Tests: Brief History of the Measurement of Intelligence) The work of Francis Galton during the late 19th Century is considered as the first ever modern attempt on intelligence testing. Galton is even considered to be the father of the analysis of individual differences. He propounded the measurement of intelligence to be as direct as possible and therefore recommended the reaction time as a viable strategy and resorted to different sensori-motor motor measurement. In line with Galton contemporary approaches have been advanced by the psychologists like Arthur Jensen and Mike Andersen those reveal that they are evaluating the integrity of central nervous system-inherent capabilities against the demonstration of intelligence in everyday life. (Key Players in the History & Development of Intelligence & Testing)
Alfred Binet, the French psychologist adopted a different approach and concentrated on the study of normal mind instead of the pathology of mental ailment. He attempted to search out the methods of measuring the capability to think and reason along with study in any specific discipline. He devised a method of testing intelligence in 1905 in which the children were asked to do tasks like pursue instructions, copy designs, name objects and required the children to arrange them properly. He offered the test to french school students and generated a paradigm along with Theodore Simon, known as Binet-Simon scale. (Binet pioneers intelligence testing: 1905) This is based on the criteria of average level of performance. Wilhelm Stern and Lewis Terman in 1912 and 1916 attempted to apply Binet's test and showed that the Paris-developed age norms are not applicable appropriately to the school children of California. They attempted to reformulate the test in the name of Stanford-Binet revision in 1916 where in the upper age limit is extended to 'superior adults'. For the first time the concept of Intelligent Quotient or IQ evolved taking into consideration the relationship between the mental age of the individual age and the chronological age. (Key Players in the History & Development of Intelligence & Testing)
This test is presently considered to be the most popular standard of measuring Intelligence in terms of IQ as a relationship between Chronological Age and Mental Age. The IQ is expressed as 100 x MA / CA. Some problems with such measure have been pointed out. Firstly, the quotient provides the inconsistency of equal level of intellectual superiority, even they are at different age groups, when there is variations in the mental age is apparent. This test fails to measure correctly the intelligence of adults since there is no steady enhancement in the mental age through out the life span. Moreover it is noticed that the IQ do not fall strictly along a bell-shaped curve. Besides, it is quite difficult in converting the IQ scores from other achievements and ability tests. (History of Intelligence Testing & Ways of Calculating IQ)
The Stanford Binet test was considered time consuming and costly for its large scale application to assess the new recruits to U.S. army at the beginning of the World War I and also required highly trained personnel. Robert Yerkes was appointed to head the committee set up for the purpose in 1917 that incorporating the contributions of 40 psychologists developed the Army Alpha and Army Beta tests. Charles Spearman in 1920s studies the relations among experimental intelligence tests and applying the 'factor analyses'. He advocated a 'two factor' theory of intelligence-General Ability (g) and Special Abilities. Spearman's analysis was mainly concentrated on general intellectual capacity that laid the foundation for development of subsequent strategies. He was so enthusiastic about 'g' that he went to the extent of advocating allowing people with a certain level of 'g' to have offspring. David Wechsler in 1939 found the Binet scales to be too verbose for its application on the adults and propounded an instrument with sub-tests to quantify both verbal and non-verbal abilities. In 1949 he generated Wechsler Intelligence Scale for Children - WISC and in 1955 the Wechsler Adult Intelligence Scale. (Key Players in the History & Development of Intelligence & Testing)
In 1930s Thurston accepted the Spearman hypothesis of a general factor however, not in agreement with its importance. He put forth that the g is only a second order factor which arises out of the relation of seven first order facts like, verbal comprehension, word fluency, number, space, associative memory, perceptual speed and reasoning. Thus the strategy of Thurstone was considered to be first multifactor approach to intelligence. Raymond Cattell in 1960s propounded the two related but differentiated elements of 'g' such as fluid and crystallized intelligence. The fluid is the ability to visualize relationships i.e. The primary reasoning ability and crystallized means the acquired knowledge and skills i.e. factual knowledge. There is a negative correlation between the age and the fluid intelligence and positive correlation between the age and crystallized intelligence. Guliford in 1960s isolated himself from…