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Read this article to learn about the definition, measurement and model of intelligence in humans.
Intelligence in Humans # Definitions:
Theories of intelligence and the practical attempts at measurement have been interwoven to a degree requiring their joint treatment. Different techniques adopted, by psychologists in measuring intelligence refer to different views as to the nature of intelligence. And the word ‘intelligence’, as it stands today, does not possess any singular definite meaning.
As Spearman says in his discussion about intelligence:
“This word in its ordinary present-day usage, does not possess any definite meaning. Neither its utterers nor its hearers appear to have behind it any clear idea whatever.”
In 1921 the British Journal of Educational Psychology published a symposium on die nature of intelligence.
Some of the definitions given are :
1. An individual is intelligent in so far as he can carry on abstract thinking—Terman.
2. An individual is intelligent in proportion as he can learn or has learned to adapt or adjust himself to environment—Colvin.
3. Intelligence is a biological mechanism by which a complexity of effect of stimuli are brought together and given a somewhat unified character—Peterson.
4. Intelligence is an acquiring capacity—Woodrow.
5. Intelligence is the general capacity of an individual to adjust his thinking to new requirements—Stem.
6. Intelligence is the completeness of understanding, inventiveness, persistence in a given task, and critical judgment—Binet.
In other words, Binet’s conception of intelligence emphasises three characteristics of the thought process:
(i) Its tendency to take and maintain a definite direction;
(ii) The capacity to make adaptation for the purpose of attaining a desired end; and
(iii) The power of auto-criticism.
7. Intelligence is “the power of re-adjustment to relatively novel situations by organising new ‘psycho-physical combinations”—Burt.
8. Spearman believes that intelligence comprises three abilities:
(i) The ability to observe one’s own mental processes
(ii) The ability to discover essential relations between items of knowledge whether perceived or thought of; and
(iii) The ability to deduce correlates. He describes these three principles as neo-genetic principles.
9. Rex and Knight defines intelligence as “the capacity for relational constructive thinking, directed towards the attainment of some end.”
10. Ebbinghaus defines intelligence as:
The essence of intelligence lies in comprehending together in a unitary meaningful whole impressions and associations which are more or less independent, heterogeneous, or even partly contradictory. “It is a combination activity.”
11. Meumman describes intelligence as the power of independent and creative elaboration of new products out of the material given by memory and the senses. From the practical point of view, it involves the ability to avoid errors, to surmount difficulties, and to adjust to environment. Most of the above definitions refer to valuable aspects of intelligence.
In general, there are threefold theories of the nature of intelligence. The conception of intelligence as a unitary entity came to psychology through the works of Herbert Spencer. But it is an obsolete idea now. Intelligence is not one ability only. There are many aspects of ability which are ignored by such unitary concept.
Intelligence in Humans # Measurement of Intelligence:
Attempts have been made to measure intelligence for many years. Differences in intelligence were correlated with differences in physical traits. Phrenology tried to look up the shape of the skull as an index of intelligence (Gall— 1810). Physiognomy tried to relate structure of faces to intelligence (Lavetor— 1777). Francis Galton (1822-1911) was the first scientist in the 19th century to undertake systematic and statistical investigations into individual differences.
Galton devised tests of sensory discrimination and also pioneered in the application of the rating scale, questionnaire method, use of free association method, which was further developed by James Mckeen Cattell. He accepted Galton’s view—the tests of sensory discrimination and reaction time could be accepted as a measure of intellectual functions. With the spread of Darwinism in the 19th century psychology become biological in its approach.
Galton, a follower of his cousin Darwin (1809-1882), tried to apply evolutionary principles of variation, selection and adaptation to the study of human individuals. Galton published in 1869 a book called Hereditary Genius and Natural Inheritance (1889). In the Enquiries of Human Faculty, in 1893, he tried to make an estimate of the individual’s intellectual level.
We owe the modem intelligence tests to efforts of Binet (1857-1911), who objected to measure intelligence by physical qualities or motor and sensory discrimination only. Galton also pointed out that we can measure intelligences only indirectly “by sinking shafts into the mind”. Spearman also pointed out that intelligence can be measured only by a number of miscellaneous problems.
The first well-known test of intelligence appeared when Binet was appointed in 1904 to study procedures for the selection of retarded children, and in collaboration with Simon produced the first Binet-Simon scale in 1905. The second revision took place at 1908.
In this scale Binet classified the test items according to age, and introduced for the first time the idea of mental age. He tried to standardize the test for children of 3 to 13 yrs. of age. If a child can pass the tests suitable for 9 yrs. old, his mental age will be 9 yrs. whatever the chronological age may be. Binet died in 1911. Third revision of the scale took place in 1916, under the direction of Lewis M Terman of Stanford University which is known as Stanford-Binet Test.
This was the most widely accepted revision of the Binet Scale. It was accompanied by an extensive manual, providing a standardised technique for administration and scoring. For more than 20 years the Stanford-Binet was the standard measure of intelligence and the criterion with which all other intelligence tests—group and individual—were compared.
In 1912 William Stem proposed the idea of computing the ratio of mental age to chronological age as a measure of rate of mental growth. He called this ratio a mental quotient. Terman accepted this concept, and applied the term ‘Intelligence quotient’ or I.Q. which gained universal acceptance.
Second Stanford revision appeared in 1937, known as Terman-Merrill revision. It consisted of two equivalent forms—L and M. The 1937 tests were less verbal at the lower levels, and the earlier emphasis on rote memory at the upper levels was corrected. Earlier Binet tests call for judgement, discrimination and attention. The number of items in Binet Scale of 1916 was 54, in Stanford revision it was 90, in 1937 revision each forms had 129 test items.
The limit of mental growth in both Stanford revision and Terman- Merrill revision is 16 years. The age level after 14 years is called the average adult level, as equivalent to a mental age of XV. There are three more tests in order of difficulty, known as superior adult I, II and III, altogether there are tests for twenty levels.
Intelligence Quotient or I.Q:
The ratio between chronological age and the mental age is called the intelligence quotient or the I.Q.
The formula is I.Q. = Mental age (in months) / Chronological age (in months) ×100.
In the Terman-Merrill revision there are six tests for each six months from two years to five years. That is, each test is calculated to be one month in age. From six years to fourteen years there are six tests for each year. That is, the value of each test is two months. This is because, in case of children, the rate of growth is very rapid, so the value of each test is one month. In case of average adult level (AA) there are eight tests, each test is valued two months. In superior adult level (S.A.L.) there are six tests, each test is valued four months.
In this scale the maximum possible mental age is twenty-two years ten months. But this is a numerical score only, which shows better mental development than average only. Actually, the limit of mental age is only fifteen. In case of adults the chronological age is always accepted as fifteen for die purpose of calculating I.Q.
Below is given a calculation of mental age and I.Q. after Terman:
Let us suppose that a subject has been tested. All the 6 tests in X were given, all were passed, only 6 of the 8 in XII were given and 5 were passed; 5 of 6 in XIV were given and 3 were passed 5 of 6 in “the average adult group” were given and one was passed; 5 were given in “the superior adult” group and no credit earned.
The result will be:
The subject has a mental age of 13 yrs. 4 months. Mental age does not tell us the intelligence status of the child. Hence we want to know the ratio between his chronological age and mental age. This is the intelligence quotient or I.Q. To find it we divide the mental age (expressed in years and months) by real age (also expressed in years and months). Easier if we convert the ages in months before dividing and then multiply the result with 100, to express it in terms of percentage.
This I.Q. has now become equivalent to level of general intelligence.
A list is given below about the percentage of distribution of I.Q. after Terman-Merrill:
Feebleminded:
Degrees of feeblemindedness:
The lowest type is the idiot who cannot dress and feed himself, and fail to distinguish between common dangers like fire and water. Next in order is the imbecile who can dress himself and feed himself and avoid fire and water, but cannot be taught to earn a living, even under supervision. Imbeciles can be divided into highest and lowest imbeciles. The highest level of the imbeciles is the moron who can be taught to earn a living under supervision and can do useful work.
Grade of feeblemindedness:
Genius:
“An I.Q. above 140 does not guarantee outstanding social contribution of personal success. There must be sufficient motivation and other favourable traits besides.” Terman and Cox made an intensive study of geniuses of history. They could not be given tests of course but from their biographies, letters and other evidences.
Estimated I.Q.s of some important geniuses of history (from Terman and Cox):
A 3rd revision was published in 1960, it provided a single form (L-M) incorporating the best items from the two 1937 forms.
The 1960 scale did not involve a re-standardisation of the normative scale:
“A major innovation introduced in the 1960 Stanford-Binet scale was the substitution of deviation I.Q.’s for the ratio I.Q. used in earlier forms. These deviations I.Q.s are standard scores with a mean of 100 and an SD of 16. The principal advantages of this type of I.Q. are that it provides comparable scores at all age-levels thus eliminating the vagaries of ratio I.Q.s. Despite the care with which the 1937 scales were developed in the effort to obtain constant I.Q. variability at all ages, the SDs of ratio I.Q.s. on these scales fluctuated from a low of 13 at age VI to a high of 21 at age 11-6. Special correction tables were developed to adjust the major I.Q. variations in the 1937 scales, these difficulties were circumvented in the 1960 form through the use of deviation I.Qs. which automatically have the same SD throughout the age range.”
“The next stage was the 1972 re-standardisation of form L.M. (Terman and Merrill, 1973, Part 4). This time the test content remains unchanged, but the norms were derived from a new sample of approximately 2,100 cases tested during the 1971-1972 academic year.”
‘To achieve national representatives, the test publishers took advantage of a sample of approximately 20,000 children at each age level employed in the standardisation of a group test (Cognitive Abilities test). This sample was chosen from communities stratified in terms of size, geographical region and economic status, and included Black, Mexican-American, and Puerto Rican children.”
The children to be tested with the Stanford-Binet were identified through their scores on the verbal battery of the Cognitive Abilities Test; so that distribution of scores in this sub-sample corresponded to the national distribution of the entire sample (The only cases excluded were where language spoken at home was not English).
To cover ages 2 to 8, the investigators located siblings of the group tested children, choosing each child on the basis of the Cognitive Abilities Test score obtained by his or her older sibling. Additional cases at the upper ages were recruited in the same way. The Stanford-Binet sample included approximately 100 cases in each half- year age group from 2 to 5½ years, and 100 at each year group from 6 to 18.
In comparison with the 1937 norms, the 1972 norms are based on a more representative sample, as well as being updated, and, hence, reflecting effects of intervening sample as well as cultural changes on test performance. It is interesting to note that the later norms show some improvement in test performance at all ages. (This is attributed to the impact of mass media on young children, and the increasing literacy and educational level of parents, among other cultural changes).
“On the basis of both cross-sectional and longitudinal comparisons, Thorndike (1977) explored these normative changes further and proposed still other contributing factors including the introduction of special television programmes designated to stimulate intellectual development in pre-school age children.”
Characteristics of Binet-Simon test and an estimate thereof:
(1) Binet was the first to use age standards.
(2) It is an efficient test to provide a single score describing the child’s present level and general intellectual ability.
(3) He abandoned faculty psychology, and tested general intelligence, as a sum-total of mental processes, like memory, attention, imagination etc. and nor as separate faculties.
(4) It is primarily a measure of scholastic aptitude, and heavily loaded with verbal ability, especially at higher levels.
(5) Early tests call for judgement, discrimination and attention. Verbal tests and reasoning play a much greater part in later years.
(6) It is an excellent test for identifying children of abnormally slow development.
(7) It is therefore unsuited for measurement of differential aptitudes. It is constructed to maximise the measurement of a general factor and minimise the influence of group factors or separate abilities.’
Intelligence in Humans # Guilford’s Structure of Intellect Model:
Guilford’s structure of SI model is not hierarchical in nature. It is a cross- classification of the abilities. “That is to say, it classifies the abilities in three different ways, and the categories of one way intersect with those of the other ways of classification.”
He proposed that performance on any cognitive task can best be understood by analysing it into the kind of the mental operation or process is performed, and the type of content or test material on which the mental operation is performed, and the resulting product of performing a particular operation on a certain type of test content.
In Guilford’s model there are five possible kinds of operation (memory, cognition, divergent thinking, convergent thinking, and evaluation), four types of content (figural, symbolic, semantic, and behavioural), and six products (units, classes, relations, systems, transformations and implications).
It implies 5x4x6= 120 possible factors, comprising the structure of intellect. In the words of Guilford “It must not be supposed that although the abilities are separate and distinct logically and they can be segregated by factor-analysis, they function in isolation in the mental activities of the individual. Two or more of the abilities are commonly involved in solving the same problem.”
Cognition:
Immediate awareness.
Divergent production:
Deduction of logical alternatives from given information.
Convergent production:
Generation of logical conclusions from given information where emphasis is upon achieving unique or conventionally best outcomes.
Content:
Figural-figure and ground perceptral organisation, semantic pertaining to information in the form of conceptions or mental constructs to which often words are applied.
Behavioural:
Pertaining to information, essentially non-figural and nonverbal, involved in human interactions, e.g. attitudes, needs, designs, moods, intentions, perceptions, thoughts etc. and others and ourselves involved.
Units:
Things, character—close to Gestalt figure and ground conception.
Classes:
Conceptions underlying sets of items of information grouped by virtue of their common properties.
Relation:
Connections between items of information based upon variables.
System:
organised aggregates of items of information.
Transformation:
Changes of various kinds (re-definitions, shifts, transition or modifications) in existing information.
Implications:
Circumstantial connections between items of information by virtue of contiguity, or any conditions that promotes ‘belongingness’. The second way of classification is in terms of content, or areas of information within which the operations are performed, figural (concrete, perceived), symbolic (signs, code elements such as numbers or letters), semantic (thoughts, conceptions or constructs), and behavioural (psychological). Each set of abilities distinguished as to content includes 30 abilities that are parallel to those in every other content category.
The product categories describe the formal kinds of information. Information takes the form of units (segregated chunks), classes (common properties within sets), relations (meaningful connections), systems (organised patterns), transformations (changes, transitions), and implications (information suggested by other information).
Within each product category there is a set of 20 abilities which are parallel to those in each of the five other product categories. The structure of intellect model is basically an extension of Thurstone’s theory of primary mental abilities restricted to orthogonal factors.