Psychology: Intelligence

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HUMAN INTELLIGENCE

Course

Nature and definition of intelligence. Types of intelligence (Spearman’s ‘g’ and ‘s’ abilities, Verbal/non-verbal abilities). Determination of intelligence (The role of heredity and environment). Measurement of intelligence (Concept of IQ, Binet and Wechsler’s test).

Question:   Describe the Concept and Nature of Intelligence.

People differ in countless ways – from purely biological term to other countless terms. Psychologists have focused on relatively small number of key dimensions and intelligence and personality are some of them. Intelligence is one of the very important aspects of individual distinctness. In the past, psychologists disagreed over whether intelligence was unitary or multifaceted in nature; today, most believe that intelligence involves both a general capacity to solve many types of problems and several specific abilities.

The term intelligence is closely related to intellect and intellect is a comprehensive term for observing, understanding, thinking, remembering and all ways of getting information. It is helpful in solving problem and reaching a goal. In other words, intelligence means intellect put to use. Today, the concept of intelligence is more pragmatic, much broader, and concerned with learning and adaptive human behavior. It is not a material fact but an abstract construct and has been defined in a number of ways.

Question:  Define Intelligence or Explain the Different Definitions of Intelligence.

Intelligence has become the prime focus of study in psychology both theoretically and practically. Intelligence is one of the most talked about subjects within psychology but there is no standard definition of what exactly constitutes 'intelligence.' Some researchers have suggested that intelligence is a single, general ability, while other believe that intelligence encompasses a range of aptitudes, skills and talents.Many psychologists have defined it according to their findings. At present, it has become a word with many meaning and used in various situations (rightly or wrongly) and thus takes various meaning depending upon situations. Various writers have focused on to particular ability as determinants of intelligence. As a result, no single definition of intelligence has dominated the field. Intelligence has been defined as an ability to learn; capacity to adapt to new situation; capacity to improve upon native tendency in the light of previous experiences; to judge well, to comprehend well, to reason well, etc. According to Torgerson and Georgia[1] the all the definitions of intelligence can be categorized into four groups.

1.       Capacity to learn

2.       Capacity to perform intellectual task

3.       Capacity to think abstractly, and

4.       Capacity to make adequate adjustment to new experiences.

Freeman[2] (1962) has stated that some definitions of intelligence state it as conglomeration of many powers. These definitions are broader than others are. Representative definitions can be cited from Wechsler and Husband. Wechsler (1944) defined intelligence as:

the aggregate or global capacity of the individual to act purposefully, to think rationally and to deal effectively with his environment.

Husband defined it as follow:

an intelligent person uses past experiences effectively, is able to concentrate and keep his attention focused for longer period of time, adjusts himself to a new and accustomed situation rapidly with less confusion with fewer falls, moves shows variability and versatility of responses, is able to see distinct relationship, can carry on abstract thinking, has a greater capacity of inhibition or delay and is capable of exercising self-criticism.

In sum, it can be said that Intelligence is defined in different ways emphasizing in one or various skills. Some have emphasized on symbols, concepts and past experiences. Some have also viewed in a narrow, one sided fashion (e.g., intelligence is innate, inborn, natural ability by Cyril Burt). Intelligence should be viewed on broad fashion. It should not be limited to certain abilities. Intelligence, thus, should be considered as less an entity and more as a process or set of process, less of a ‘thing’ and more of an abstraction.

Question:   Describe The Different Types of Intelligence or Briefly describe the Two-Factor Theory of Intelligence?

Types of intelligence

The question of what is intelligence and what it is composed of has been considered along with the problem of how it operates. This concern arise not only form a desire to obtain a better theoretical understanding of intelligence and its operation but also from the composition and nature of intelligence. Researchers have developed various types of models of intelligence.  Some of the models of intelligence are as given below:

1.  Two-factor theory of intelligence (developed by Spearman in 1904)

2.  Group factor theory of intelligence (developed by Thurston in 1938)

3.  Multi factor theory of intelligence (developed by Thorndike in 1927)

4.  Guildford’s structure of intellect (developed in 1956)

5.  Cattell’s (1971) alternative theory to Spearman

6.  Piaget’s developmental theory of intelligence

An example of intelligence test can be drawn from  Thurston's group factor theory of intelligence which was developed in 1938. Louis L. Thurstone (1887-1955) was a psychologist who offered a different theory of intelligence than Spearman theory of intelligence which was developed in 1904. Instead of viewing intelligence as a single, general ability, Thurstone's theory focused on seven different "primary mental abilities" (Thurstone, 1938). The abilities that he described were:

·         Verbal comprehension

·         Reasoning

·         Perceptual speed

·         Numerical ability

·         Word fluency

·         Associative memory

·         Spatial visualization

Focus on multiple abilities as the basis of intelligence is also emphasized by other psychologists e.g., Guildford (1956). We will focus more on Spearman's Two Factor Theory of Intelligence. 

Spearman's Two-Factor Theory of Intelligence

Charles Spearman (1868-1945) in 1904 used factor analysis and developed the theory of intelligence. Book entitled The Abilities of Man was published later. The theory was published before the development of Binet’s Intelligence Test. Charles Spearman’s model of intelligence state that there are two types of intelligence – General intelligence (or ability/factor) and specific intelligence. His theory is known as two-factor theory of intelligence.

Spearman was a British psychologist who described the concept of General and Specific ability (intelligence). General ability is also referred as 'g' factor and specific ability as 's' factor. He used factor analysis to examine a number of mental aptitude tests and concluded that scores on those tests tests were remarkably similar. He found that people who performed well on one cognitive test tended to perform well on other tests, while those who scored badly on one test tended to score badly on other. He concluded that intelligence is general cognitive ability that could be measured and numerically expressed (Spearman, 1904). He proposed that theory that performance on an intelligence test was a product of two factors – the ‘g’ and ‘s’.

According to Spearman all intellectual activity was dependent primarily upon ‘g’ factors, which is common to all so called mental activity. This ‘g’ factors are possessed by all individual but in various amounts and amount was to be measured in determining of intelligence. Spearman used ‘g’ to identify the quality of all round general superiority or inferiority which shows up in most test correlation. He also found in each test he applied a smaller, more specific ability associated with them. And, to these smaller factors he named as ‘Ss’ or specific abilities, each of which is specific to a particular type of activity. The specific factor called ‘s’ of his system can be influenced by number of factors such as training, innate specialized abilities or result of environment. The 's' factor was introduced because Spearman found that some people had some specific abilities that did not match with 'g' factor so he indicated that the ‘g’ involves in all mental ability and found in all person in different degree while ‘s’ factor involves in varying degrees in different activities and found some persons only (not in all persons). Psychologists who have developed measurement tests of intelligence largely focused on ‘g’ factor. This is because 'g' is possessed by all people and is the primary and most important factor in various activities. The difference in intelligent among people is also the due to ‘g’ factor. People also differ in specific abilities but this is due to many causes and in many ways this 's' factor is also under the control of ‘g’ factor.

Cattell (1971) has proposed an alternative to Spearman’s ‘g’ and ‘s’ factors. Actually, Cattell split ‘g’ into two parts – fluid intelligence or ‘gf’ which according to Cattell is the major measurable outcome of the influence of biological factors on intellectual development. It is comparable to inherited ability. It is free from influence of the culture and education and experience. Other is crystallized intelligence or ‘gc’ (which is a measure of outcome of cultural and educational experiences).

     

Question:  What are the Major Determinants of Intelligence ?

All the human traits in which psychologists are interested are the result of interaction between heredity and environment but how far is intelligence is the result of inheritance and how far is the product of environment is still riddled with complexity. Eysenck (1980) believed that in western country at present in a rough numerical 80 per cent of all the factors contributing to individual differences of intelligence are heredity, 20 per cent environment. Jensen (1969) whose hypothesis is known as Jensenism also insists heredity as the major determinant of intelligence. Cyril Burt (1956) attributed 88% of intelligence to heredity and 12% to environmental influences. One of the arguments is that despite the same environment in the orphanage, children bear different IQ due to heredity. Environmentalist (those who support nurture as the major determinant of intelligence), on the other hand argue that despite the same chromosomes and genes of identical twins, when separated and reared in different environment their IQ can vary by 15 to 20 per cent. Studies also indicated that child's IQ is correlated with social class and the education of the parents, family size, birth order, rural-urban difference, etc.

The importance of heredity and environment cannot be denied in intelligence. They are the two sides of a coin – the existence of one cannot be imagined in absence of other. Individual is the product of 46 chromosomes, which contains specific characteristics handed from both parents. The development of these characteristics must take in social environment where these characteristics are expressed. The heredity factors probably set the upper limit in development yet much depend on factors operating in the environment in deciding (1) the direction of development, and (2) the level finally reached. Heredity provides the potential for a person’s IQ and environment interacts with this potential to create the final product.

The below are some of the factors that affect the intelligence:

1. Prenatal and postnatal conditions (the age of mother, the use of drugs during pregnancy, diet of mother during pregnancy and after the birth, brain injury during and after the birth, etc.)
2. Sex and intelligence: Male was found achieving higher IQ than female. But during young age and adolescent age female was seen more or slightly intelligent than male. The difference in IQ in later period is regarded as due to cultural expectation, motivation and opportunity provided.
3. Intelligence and race: It is found that white people generally superior in average IQ than the black one especially in those countries where white culture is dominant. It is argued that white people get richer environment than black people. Some have blamed that IQ test is developed by the whites who are socialized in cultural values and norms of white people.
4. Urban-rural areas and intelligence: some distinct patterns of IQ score were also obtained between children of rural and urban areas. The urban children obtained higher score in IQ test than rural children. Rich industrial, educational, social, economical conditions of the urban areas were attributed as the cause of difference between IQ level of rural and urban children.
5. Socioeconomic status and intelligence: the IQ level of socially, economically middle or higher-class children were found higher than lower, unprivileged, unskilled, and labor class. The deprived environment was considered as leading to lower achievement in intellectual performance.
6. Age and intelligence: Age is considered one of the crucial factors that affect the intelligence. As the age increases the child does better in IQ test. The intellectual capacities keep on increasing well into early adulthood. Slowly the rate of growth declines after the certain age level and motor as well as verbal skills slowly tends to decay. Age affects the intellectual level and performance.
7. Education and intelligence: Education is the process of acquiring skills and developing inner potentialities. Intellectual functions are susceptible to improvement by education. Generally, the greater the exercises the higher chance of increasing the intellectual ability. Studies have found a significant increase in mean score between educated and non-educated group.

Question:  Describe the History of Measurement of Intelligence 

In 1904, when psychology was just emerging as an independent field, work on developing tools to measure intelligence was already in work. Alfred Binet was assigned along with Theodore Simon to develop a test of intelligence. The first version of intelligence test was published in 1905. Since then Binet test has been revised several times. During First World War concept of group test and non-verbal tests were also widely used. By the time 1940s, tests of general intelligence for adult were developed. With passing of time, the meaning of IQ and measurement of it has also considerably changed. Basic requirement of intelligence test – reliability, validity, development of norm, etc. were also objectively tests. Attempts to make intelligence test culture-free were also made. There are hundreds of intelligence tests today used in educational, clinical and other settings. The development of intelligence test has made considerable progress in understanding individual differences.

Alfred Binet and the First IQ Test

At the beginning of 1900s, the French government had problems with the placement of children at the specific classes and their performance so in order to systematized the process placement of children the government asked psychologist Alfred Binet to help decide which students were mostly likely to experience difficulty in schools. The government had passed laws requiring that all French children attend school, so it was important to find a way to identify children who would need specialized assistance.

Faced with this task, Binet and his colleague Theodore Simon developed question not taught in the school such as attention, memory and problem-solving skills that can best predict school success. While testing the children he realized that some children were able to answer questions that were more advanced than older children were generally able to answer, while other children of the same age were only able to answer questions that younger children could typically answer. Based on this observation, Binet suggested the concept of a mental age, or a measure of intelligence based on the average abilities of children of a certain age group.

Thus, the first intelligence test known as Binet-Simon Scale became the basis for the intelligence tests still in use today. However, Binet also stressed the limitations of the test, suggesting that intelligence is far too broad a concept to quantify with a single number. He stated that intelligence is influenced by a number of factors and changes over time. He also said that the level of intelligence test can only be compared among children with similar backgrounds (Siegler, 1992).

The Stanford-Binet Intelligence Test

The Bint-Simon Test was brought to the United States where it generated considerable interest. Stanford University psychologist Lewis Terman took Binet's original test and standardized it using a sample of American participants. This adapted test, first published in 1916, was called the Stanford-Binet Intelligence Scale and soon became the standard intelligence test used in the U.S. The Stanford-Binet intelligence test used a single number, known as the intelligence quotient (or IQ), to represent an individual's score on the test. This score was calculated by dividing the test taker's mental age by their chronological age, and then multiplying this number by 100. For example, a child with a mental age of 12 and a chronological age of 10 would have an IQ of 120 (12 /10 x 100). The Stanford-Binet remains a popular assessment tool today, despite going through a number of revisions over the years since its inception.

What is IQ and how IQ score are calculated?

IQ stands for ‘Intelligence Quotient’ and is a numerical score based on standardised tests which attempt to measure intelligence. Originally the concept of intelligence scale was developed by Bint-Simon, the term ‘intelligence quotient’ was first coined in 1912 by German psychologist, William Stern based on the test developed by Bint-Simon. The original formula for calculating IQ was:
(mental age divided by chronological age) x 100

In other words, a person’s intelligence level was measured as a quotient of their estimated mental age and chronological age. A 10-year-old child that had the mental age of a 12-year-old was considered to have an above average IQ of 120 [(12/10) x 100]. The score of an intelligence test that is a number derived from standardized psychological tests of an individual’s capacity to learn. The test results provide a score which is compared to the same age group. For instance, a score of 100 means that half of the population scores higher than you and half scores lower than you. A score of 100 is about average. A score of 130 means that 97.5% of the population of your ages scores lower than you. 2.5% of the population have an IQ under 70. (It is said that Einstein's IQ is about 160.)

The score of the IQ tells the level of intelligence. The following is a rough breakdown of various IQ score ranges. However, it is important to remember that IQ tests are only one measure of intelligence. Many experts suggest that other important elements contribute to intelligence, including social and emotional factors.

·         115 to 129 - Above average; bright

·         130 to 144 - Moderately gifted

·         145 to 159 - Highly gifted

·         160 to 179 - Exceptionally gifted

·         180 and up - Profoundly gifted

There are slight difference in the score number obtained through the test and its category level in Wechsler and Standford Intelligence test they consistently indicate the Bell-shaped curve in intelligence distribution in the population.

Intelligence Testing During World War I

When WW I started U.S. Army officials faced a monumental task of screening a large number of army recruits. In 1917, as president of the APA and chair of the Committee on the Psychological Examination of Recruits, psychologist Robert Yerkes developed two tests known as the Army Alpha and Beta tests. The Army Alpha was designed as a written test, while the Army Beta was administered orally in cases where recruits were unable to read. The tests were administered to over two million soldiers in an effort to help the army determine which men were well suited to specific positions and leadership roles (McGuire, 1994).

At the end of WWI, the tests remained in use in a wide variety of situations outside of the military with individuals of all ages, backgrounds and nationalities. For example, IQ tests were used to screen new immigrants as they entered the United States at Ellis Island. The results of these mental tests were inappropriately used to make sweeping and inaccurate generalizations about entire populations, which led some intelligence "experts" to exhort Congress to enact immigration restrictions (Kamin, 1995).

Major tests of intelligence

Intelligence test can be divided into individual and group test. Some tests are verbal and some are non-verbal or performance. Individual test can be applied to one individual at a time while group test can be applied to a large group in a single setting. Similarly, verbal test is applied to education population while non-verbal test is used for the illiterate, children, and foreigners. Intelligence tests are also divided into standardized test and non-standardized test. Standardized tests are well tested in the large and varied population and used with the help of the norm. Unstandardized test are those tests developed in the school (by teachers) to measure the immediate capabilities of the students. Such tests are not based on norms or not tested on large population thus lack external validity.

Some of the major IQ tests are standardized tests of intelligence and are also regarded culture-free. Stanford Binet Test and Wechsler’s Intelligence Scale are the most popular standardized tests of general intelligence.

• Binet Simon Test of Intelligence (Read from the book)
• Wechsler Intelligence Scales

The Wechsler Intelligence Scales

David Wechsler of Bellevue Hospital in New York in 1939 published the Wechsler-Bellevue Intelligence Scale, which combined verbal with non-verbal­ or performance sub-tests. Wechsler test is an individual test. In 1949, he developed Wechsler Intelligence Scale for Children (WISE) and revised it in 1974. The WISC-R is for children aged six to sixteen years eleven months. The Wechsler Adult Intelligence Scale (WAIS) was published in 1955 and was designed for the adult population. Wechsler also published Wechsler Pre-primary Scale of Intelligence (WPPSI) in 1967 for use with children aged four to six and a half years.

All three scales have essentially the same format and organization but the level of difficulty differ with the age level. The main characteristics of Wechsler’s scale are as follow:

The scales fall into two major categories: the verbal scale and the performance scale. These are comprised of number of sub-tests. The verbal scale tests measure levels of functioning using previously learned verbal material. It consists of :

Verbal Scale

1. Information,
2. Comprehension,
3. Arithmetic, 
4. Similarities, 
5. Vocabulary and, 
6. Digit span.

The performance scale tests how the testee fares with relatively new and novel material practically rather than verbally. Most of the items are times, with bonus points for quick and successful performance. The tests include –

Performance Scale

1. Picture completion, 
2. Picture arrangement, 
3. Block design, 
4. Object assembly and, 
5. Coding.

The results from these tests are presented as a verbal IQ, a performance IQ, and a full-scale IQ. In addition, for each area there is a profile of five or six sub-tests. Score of each test and variation in sub-tests reveals important meaning to the psychologists (e.g., In picture arrangement test - which is like comic-strip-type pictures that must be arranged from a standard presentation to tell a story – tests sequential thinking and the understanding of social situation). Psychologists use sub-test result (also full scale test result) as an exceptional opportunity to observe behavior and thought processes of the testee.

Wechsler discarded the original IQ equation and brought in the new idea of ‘deviation’ Iqs based upon scaled scores.

Wechsler has looked at a broad spectrum of mental ability and provide profiles based upon deviation IQ, and scaled scores. He regarded intelligence in a unitary manner but preferred to think in terms of a whole array of abilities. Wechsler scale is widely used in education and clinical sector. In clinical setting, the test is also used to identify the part of brain dysfunction. 

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[1] Torgerson, T.L. and Georgia S.A. (1954). Measurement and Evaluation. Professional Book in Education. Dryden Perss, New York. p.75.

[2] Freeman, F.S.(1963). Theory and Practice of Psychological Testing. 3^rd Edition. Oxford & IBH Publishing Cs. New Delhi. Pp. 149-154.