Measuring of Intelligence

Intelligence is a person’s capacity to (1) acquire knowledge (i.e. learn and understand), (2) apply knowledge (solve problems), and (3) engage in abstract reasoning.  It is the power of one’s intellect, and as such is clearly a very important aspect of one’s overall well-being.  Psychologists have attempted to measure it for well over a century.

The attempt to measure human intelligence had begun in the 19th century itself. Alfred Binet in collaboration with Theodore Simon developed the first intelligence test in 1905. The Binet-Simon Scale contained 30 items. The scale was revised many times by Binet. In 1916, the scale was revised by Lewis M. Terman of Stanford University and is known as Stanford Binet Intelligence Scale.

Another important event in the development of intelligence test was the formation of the Wechsler Adult Intelligence Scale (WAIS) published in 1955 and Wechsler Intelligence Scale for Children (WISC). During the First World War time A.S. Otis developed a group test of intelligence known as Army Alpha Intelligence Examination.

Intelligence being only a concept or an abstraction can’t be measured in physical units like a length of cloth or temperature of the body rather we measure an individual’s intelligence by means of what we call Intelligence Tests.

The most commonly known intelligence tests fall into three categories. Namely: 1. Individual Tests, 2. Group Tests, and 3. Performance Tests of Intelligence.

Intelligence tests may also be classified as Verbal Tests and Non-verbal tests. In verbal tests, the person is asked to read or write. In Non-verbal tests, the person is required to perform some acts or to do some practical work.

The Concept of C.A, M.A and I.Q:

Some of the basic expressions for the measurement of Intelligence are i) Chronological Age (C.A), ii) Mental Age (M.A) and iii) Intelligence Quotient (I.Q).

1. Chronological Age (C.A):

This is the physical age of a person counted from the date and time of his birth. It is counted in terms of years, months and hours etc.

2. Mental Age (M.A):

Binet conceived the idea of Mental Age (M.A.) to measure intelligence. Tests were made for different age levels. This is an index of intelligence rank. A child’s mental age can be measured from his performance on an intelligence test. If a test was passed by 60-90% of children of given age, Binet accepted it for that age level. A child who successfully perform all the tasks thus accepted for the five year old child is taken to have a mental age of five, whatever his Chronological Age (C.A.) may be. If he is five years old chronologically too he is rated as normal or average. A seven year old child having a M.A. of six is considered as mental deficient; but if he has a M.A. of eight then he is said to be above average in intelligence.

3. Intelligence Quotient (IQ) is the score you get on an intelligence test. Originally, it was a quotient (a ratio):  IQ= MA/CA x 100 [MA is mental age, CA is chronological age]. Today, scores are calibrated against norms of actual population scores.


IQ Classification
Below 70 (2.2%) Mentally Retarded or Feeble Minded (50-69: Morons, 25-49: Imbeciles, Below 25: Idiots)
70 – 79 (6.7%) Borderline
80 – 89 (16.1%) Dull – low average
90 – 109 (50%) Average
110 – 119 (16.1%) Superior
120 – 139 (6.7%) Very Superior
140 and above Genius

Verbal and Non-verbal Tests

i. Verbal tests. This denotes tests in which questions are asked or oral or in written form of a given language, for which answers also have to be given in oral or written language. These tests are not intended for, and cannot be used in the case of illiterates and small children, since such people lack linguistic ability.

ii. Non-verbal tests. These include tests that do not require the use of language, but could be manipulated using figures, pictures, blocks or even other objects. Examples of it are Army Beta Intelligence Test, Pidgon’s non-verbal tests and Raven’s Progressive Matrices. Their advantage is that they can be used for testing subjects who lack language ability.

Difference between Verbal test and Non-verbal test

Sl.No. Verbal Test Non-verbal Test
1. It makes use of language It makes use of pictures and designs
The abilities measured are verbal reasoning, memory and numerical reasoning The abilities measured are spatial ability, speed and induction
It cannot be used for testing individuals who lack language ability Individuals who lack language ability also can be tests by it.
It is less expensive It is more expensive
The results of the tests are much affected by schooling The results of the tests are less affected by schooling
Standardization is easy Standardization is difficult
7. Administration and scoring are easy Administration and scoring are difficult

Individual and Group Tests

i) Individual Tests. These tests are administered to one individual at a time. They include performance tests as well as tests that require linguistic ability. Some examples of these are: Stanford Binet Intelligence Tests, Wechsler Bellevue Intelligence Test, Koh’s Block Design Tests, etc. These tests are particularly appropriate for testing individuals, but they are not financially feasible as they are expensive. In addition to this they are time consuming. Administration of such tests require more expert training also.

ii) Group Tests. In this category the tests are administered upon a large number of examinees simultaneously. The group Intelligence test of the State Bureau of Psychology is an example. Such tests are more objective and less expensive. But in these tests no rapport between the subject and the examiner is established. Hence compared to individual tests, they are less useful for solving problems of individuals. Nevertheless, they have proved really useful for the purpose of educational and vocational guidance.

Difference between Individual and Group Tests

No. Individual Test Group Test
1. Tests intelligence of an individual at a time Tests intelligence of a group at a time
2. Useful for children of every age Not useful for children of lower age groups
3. Time consuming Time saving
4. Uneconomic in terms of money and labour Economic in terms of money and labour
5. Administration is not easy Administration is easy
6. Interest of the individual is assured Interest of the individual is not assured
7. Results can be judged then and there Results cannot be judged them and there

Performance Tests of Intelligence.

These tests measure intelligence through some sort of performance of the individual. The performances are in the form of concrete activities that demand for the ability to see relations and solve problems. For measuring intelligence of persons with language handicap arising out of deafness or speech defect or cultural variations, this type of tests are widely used. Obviously, this is a non-verbal test. Some of these are described below.

  1. The Pinter-Paterson Performance Scale. This has been the first major attempt to develop a standardized series of performance tests. Items in the test were taken from the work of Seguin Form Board, Healy Picture Completion Test, Knox Form Board, Ship test, Cube Test etc. The scale consists of fifteen sub-tests. For most purposes a short scale consisting of ten tests are being employed.
  2. The Arthur Performance Scale. This consists of five tests. They are Know Cube, Seguin Form Board, Porteus Mazes, Healy Picture Completion Test and Arthur Stencil Design Test. This scale is intended for young children.
  3. Bhatia’s Performance Test. Koh’s Black Design Test, Alexander Pass Along Test, Pattern Drawing Test, Immediate Memory of Sounds and Picture Completion Test are four sub-tests included in this battery. In the first among these, designs printed in 10 cards in increasing difficulty are to be arranged using coloured cubes. Speed is the factor contributing to high score. In the second, graded problems are presented. The coloured boxes are arranged in the reverse order and the individual is to rearrange it to give the shape given in the card. Time is one important factor here also. In the pattern drawing test eight diagrams of increasing order of difficulty are to be drawn without lifting the pencil and repeating the lines. In the memory test, consonants or digits are to be repeated in the same order first and then backwards. Five pictures cut out into 2,4,6 or 12 parts are to be assembled in the shortest possible time to gain maximum scores. The total score on the whole test is then determined and it is converted into IQ’s using the tables provided in the test manual.
  4. Raven’s Progressive Matrices Test. It is a non-verbal test and was developed in the U.K. The test has been designed to evaluate the subject’s ability to see the relationship between Geometric figures/designs. It can be administered individually as well as in a group. The test has three forms:

a) Raven’s Standard Progressive Matrices: It consists of 60 matrices divided into 5 sets a, b, c, d, e of 12 problems each. These problems are arranged in progressively increasing order of difficulty. The test can be used for persons in the age group of 6 years and 65 years.

b) Raven’s Advanced Progressive Matrices: It consists of 36 matrices. It can be administered to one who is average in intellectual capacities. It can be used for person between 111/2 years to 40 years.

c) Raven’s Coloured progressive Matrices: It has 3 sets A, AB, B consisting of 12 matrices in each set (36). It can be used in the age group of 5 ½ yrs. to 11 years and beyond 65 years of age.

Raven’s Progressive Matrices Test is most popular and widely used for measuring intelligence. Perceptual and reasoning ability are mainly measured in this type of test.

  1. Wechsler Bellevue Intelligence Scale (WBIS). This scale, published in 1939, was developed and standardized by David Wechsler of Bellevue Psychiatric Hospital. The test was first revised in 1955 and three different scales come into existence. They are:

i) Wechsler Pre-schools and Primary School Scale of Intelligence (WPPSI) – designed for the children belonging to the age group 4 to 6.

ii) Wechsler Intelligence Scale for Children (WISC) – designed for school children in the age group of 6 to 16 years.

iii) Wechsler Adult Intelligence Scale (WAIS) – designed for adults in the age group of 16 to 64 years.

Wechsler Adult Intelligence Scale is an individual test which has the unique quality of being simultaneously a verbal as well as a performance scale. The scale consists of eleven sub-tests. Six sub-tests make up the verbal scale and remaining five comprise the performance scale. These tests are listed below in the order in which they are administered.

  1. Verbal Scale:

a) Test of general information

b) Test of general comprehension

c) Test of arithmetic reasoning

d) Test of distinction between similarities

e) Test of digit span

f) Test of vocabulary

  1. Performance Scale:

a) Block Design Test

b) Digit Symbol Test

c) Object Assembling Test

d) Picture Arrangement Test

e) Picture Completion Test

The scores on these sub-tests are added together to assess the subject’s intelligence.

Advantages of Intelligence Tests

  1. Intelligence tests are used for the purpose of making selection of suitable candidate for admission to courses that demand different levels of intelligence.
  2. Intelligence tests help the teacher to classify students into homogeneous groups for providing individualized instruction.
  3. Scores obtained in intelligence tests can motivate individuals to reach higher levels in the ladder.
  4. Intelligence tests help in revealing the potentialities of an individual and in this way make possible the prediction of one’s success in a particular field.
  5. Intelligence tests help to detect the exceptional children such as gifted, backward and mentally retarded. This in turn helps the teacher organize appropriate compensatory services.
  6. Intelligence tests help in the diagnosis of problematic behavior of the child.
  7. Intelligence testing has been proved to be very useful in psychological, sociological and educational research.

Limitations of Intelligence Tests

  1. Intelligence tests label some students as superior and the others as inferior. This type of knowledge may create so many psychological problems.
  2. A teachers’ knowledge of the intelligence of his pupils may result in slackness on his part. He may put the entire responsibility of a pupil’s failure on his inferior intelligence, while an intelligent student may be left to work for himself.
  3. Intelligence tests results have been misused to uphold the theory of royal blood, segregation and sectarian outlook.

Abilities measured by intelligence tests

  1. Numerical reasoning
  2. Analogies
  3. Classification
  4. Spatial relations
  5. Logical selection
  6. Synonyms
  7. Practical judgement
  8. Verbal comprehension
  9. Memory
  10. Problem solving


Conclusion. Thus, Intelligence Tests have been and or even now being used in education. Intelligence tests are psychological techniques of measurement and their interpretation helps in guidance and intellectual capacities of children.

About John Parankimalil

John Parankimalil, SDB, M.A. (English), M.Ed, Ph.D (Education), popularly known as P.D. Johny is a member of the Salesians of Don Bosco. He is presently the Rector and Principal of Don Bosco College, Tura, Meghalaya and Director of Don Bosco College of Teacher Education, Tura. He received the 1st Computer Literacy Excellence Award from Dr APJ Abdul Kalam, the President of India in August 2002 and the Guruvar Best Teacher Award from Shri Kapil Sibal, HRD Union Minister in 2009. He was formerly Principal of St Anthony's Higher Secondary School, Shillong and National President of All India Association of Catholic Schools (AINACS), New Delhi and the Charter President of Rotary Club of Orchid City, Shillong. He has authored several books. He is an Eduationist, Story-Teller and Leadership Trainer. He conducts seminars for Principals, Teachers, Students and Parents. His popular books include, He Can Who Thinks He Can (Macmillan), An Elocution Manual (Orient Longman), Progressive Parenting (Unicorn), Inspirational Stories for Purposeful Living (Babhani) The Way to Success and Happiness (Savio), How to Win Over Your Problems (Babhani), The Secrets of High Achievers (Babhani).
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One Response to Measuring of Intelligence

  1. Nice Blog, thanks for sharing this kind of information.

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