Cognition

Cognition

Cognition can be defined as the intellectual processes ( such as perception, memory, consciousness, learning, emotions, thinking, and language ) through which information is obtained, stored, retrieved, and used.
This definition has three primary features;
1-Cognition processes information. Information is the stuff of cognition: the stuff is obtained, transformed, kept, and used. Much of this information is dealt with in the form of categories or concepts.
2-Cognition is active. The information that the world gives us is actively changed, kept, and used in process of cognition. In cognition, information is:
Obtained through the senses.
Transformed through the interpretive processes of perception and thinking.
Stored and retrieved through the processes of memory.
Used in problem solving and language.
3-Cognition is useful. It serves a purpose. We think because there is something we do not understand. We use language when we need to communicate something to others. We create when we need something that does not exist. Humans use cognition to survive physically and to live in a social world.

Thinking:

It may be defined as the mental processes of problem solving using concepts.
Concepts: They are the basic units of thinking. Concepts are general categories of things, events, and qualities that are linked by a common feature or features, in spite of their differences. According to complexity the are divided in to the following types;
Simple concept: It is based on a single common feature, such as the concept red. If a thing is red, it belongs the concept red regardless of its other characteristics. e.g. red apple, red balls, and red T- shirt. In spite of the other ways in which these objects differ.
Conjunctive concepts: Are defined by the simultaneous presence of two or more common characteristics. e.g the concept of aunt as a female and a sister of one of the parents,
Disjunctive concepts: are defined by the presence of one common characteristic or another one, or both e.g. the concepts delusions or hallucinations or both, can define the concept schizophrenic person.
Natural concepts:
The have two primary characteristics,
Being basic; In that it has a medium degree of inclusiveness. Which refers to the number of members included in the concept. It is of three levels;
superordinate concepts- are very inclusive- e.g. vehicles.
Basic concepts are of medium degree of inclusiveness e.g. cars.
Subordinate concepts are the least inclusive level of concepts .e.g. sports car
Being good prototype: They represent good examples, or category or a prototype. e.g. a sofa or a chair is a good prototype of a furniture but not a carpet. i.e. a good representative.
Problem Solving:


It is the cognitive process through which information is used to reach a goal that is blocked by some obstacle.
Cognitive Operations in Problem Solving:
There are three major types of cognitive operations involved in problem solving that apparently must be performed in sequence.
A- Formulating the problem;
Before we begin to solve the problem, we must be able to define it. We have to perceive and formulate the problem to decide what kind of problem we face. Sometimes the problem is obvious, other times it is not clear

B- Understanding and Organizing the Elements of the Problem; After formulating the problem, we must make an inventory of the elements of the problem- the information and other resources available to us. Often effective problem solving requires that we flexibly interpret the meaning and utility of these elements. The limitations most of us experience in evaluating the elements of problems is that we get stuck in mental sets. This term refers to the habitual way of approaching or perceiving a problem. Because the problems often require a novel or flexible use of their elements, a habitual way of looking at the elements of a problem can interfere with finding solution.
C-Generating and Evaluating Alternative Solutions;
Very often a problem has more than one solution. Our task is to generate a list of possible solutions, evaluate each one by attempting to foresee what effects or consequences it would produce, choose the best solution, and then develop an effective way of implementing it.

Cognitive Strategies in Problem Solving:
The cognitive strategies used to carry out the steps in the problem solving operations described above can be of three general types;
Trial- and-error approach;
In this approach we approach problems without any cognitive strategy at all, simply trying one possible solution after another. Although common, this approach to problem solving can be very time consuming and certainly does not guarantee that a solution will be discovered.
Algorithms;
These are systematic patterns that (if followed) guarantee a correct solution. Computers generally use algorithms. Indeed, computers are especially suited for them, because they can quickly consider the many alternatives required by complex algorithms. Computers do not always use algorithms.

3-Heuristic Thinking;

For extremely complex problems, computers sometimes programmed to use shortcuts known as heuristics. Heuristics are strategies that increase the probabilities of finding a correct solution. But because they do not systemically evaluate every possible solution, heuristics, do not guarantee finding the correct one. Indeed, they often lead to poor solutions.
Kahneman and Tversy- 1982, identified two heuristic that are frequently used in human problem solving;
a-The Representativeness Heuristic:
It is the strategy of making judgment about the unknown on the assumption that it is similar to what we know, e.g. in making judgments on the fitness of someone for a certain job we tend to make the judgments in such situations on the basis of similarity to our stereotypes about people in different occupations.
b-The Availability Heuristic:
It is reasoning on the basis of the information that is available in memory, e.g. if a relative, a graduate of a secondary school, asked you to help her choose a college, you would probably suggest the college that seems best for her from the ones available in your memory rather than inquiring or reading a book describing all colleges, and also on basing your recommendation on what you remember about her abilities and interests, rather than asking her a lot of questions.


Framing and Emotional Factors in Decision Making:

Framing questions in positive versus negative terms can have dramatic effects on the decision making of even highly intelligent persons. Emotion and logic are intimately intertwined and not independent. Moreover, persons in negative moods were more influenced by differences in the way that decisions were framed (as opportunities or threats) than persons in positive moods. In other situations, cognitive and emotional factors work together to determine our perceptions of risk, e.g. in evaluating the risk in traveling by air in comparison with automobiles travel.

Artificial Intelligence:

In 1956, john McCarthy first used the term artificial intelligence to describe computers that were programmed to think like human brains. Computers and human brains share many processes. They encode, store, and retrieve data. They perform logical functions, and they frequently use heuristics. However, there are significant differences. Computers perform some functions, such as rapid computation, much better than human brains but perform others much worse, e.g. it is difficult to program computers to read handwritten messages (such as dresses or letters). A focus of research on artificial intelligence is the design of expert systems, or problem solving computer programs that operate in a very narrow area. MYCIN was one of the first programs designed to help physicians diagnose and treat blood diseases and meningitis. In general, the use of computers in problem solving is most effective when the problem area is well defined.

Experts and expertise:

After reviewing many studies on different types of expertise, Glaser and Chi (1988) summarized the major characteristics of human experts;
Experts excel in a limited number of areas.
Experts are fast.
Experts spend enough time analyzing a problem.
Experts recognize more ''patterns'' than novices.
Experts uses their memories more effectively.
Experts use a deeper level of analysis.
Experts use self-monitoring.

Creative Problem Solving:

Creativity- can be defined as the ability to produce ''products'' (such as plays, solutions to social problems, poems, sources of energy, symphonies) that are both novel and socially valued (useful, aesthetically beautiful, informative, and so on).
Guilford has used the concepts of divergent and convergent thinking to evaluate creative ability.
Convergent thinking;
It is logical, factual, conventional, and focused on a problem until a solution is found. When you asked to solve an algebra problem, you use your convergent thinking skills to provide the answer. Most formal education emphasizes the teaching and assessment of convergent thinking.
Divergent thinking:
It is unconventional, loosely organized, and only partially directed. It produces answers that must be evaluated subjectively. Divergent thinkers, more easily break out of mental sets that limit our thinking.
An individual's creativity might also be a result of intelligence. However, most researchers believe that creative thinking is to some extent separate from general intelligence. There is an evidence that people who successfully solve novel problems are different from unsuccessful problem solvers in the amount of effort they make, rather thah basic intelligence. Successful problem solvers attempts more solutions to the problem before giving up, they have the willingness to work hard. It is possible to be highly creative without being highly intelligent, and vice versa.
Steps of the creative process:
Wallas (1926) suggested that creative problem solving typically proceeds in four steps;
Preparation: Includes initial attempts to formulate the problem, recall relevant facts, and think about possible solutions.
Incubation: It is a period of rest. Wallas used the term- incubation- to compare the creative solution to an egg that needed to be incubated for a while before it is ''hatched''. People trying to solve difficult problems that require creative solutions generally feel the need to set the problem aside for a while after the initial preparation period. Wallas believed that creative solution needed this time to ''incubate''.
Illumination: Refers to the sudden insight pertaining the solution.
Verification: Involves the necessary but sometimes anticlimactic step of testing the solution.
A creative solution to important human problems does not always emerge in this way, but many anecdotes in history show how difficult problems have been creatively solved in bursts of insight following periods of preparation and incubation, e.g. the story of the ancient Greek scientist Archimedes when he was challenged by the king, on his ability to determine the gold content of his crown.
Hayes (1978) proposes three ways of making creative thinking more likely;
Individuals must have a knowledge base. Most creative geniuses appear to build their best work on a firm foundation of knowledge of their field. Learning as much as you can about your problem will increase your chances of solving it creativity.
They require the right atmosphere for creativity. People require time to let their ideas incubate. Working with a group of people (brainstorming) provides an effective atmosphere for developing creative solutions.
People can develop creative solutions to problems by considering analogies, or similarities to other problems that have been solved in the past.

Language

Language is a symbolic code used in communication. Language is one of the most significant cognitive achievements of the human species. Without language, human beings and human civilization would be a pale shadow of what they are.
Semantics:
It is the meaning of what is said. The function of language is to say something to someone. The ''something'' is the meaning (the semantic content) that is communicated through language.
Two language structures can be identified, a- surface structure- referred to superficial spoken or written structure of a statement. And b- deep structure- referred to the underlying structure of a statement that holds its meaning.

Generative Property of Language- Elements and Rules:
Here we generate language from a set of elements and a set of rules for combining them in to speech. When we say that language is generative we mean we mean that an infinite set of utterances can be made using a finite set of elements and rules.
The following are the elements and rules;
Phonemes:
These are elements and are the smallest units of sounds in language. English languish is made up of only 44 phonemes (there are more phonemes than letters of the alphabet in English, because some letters combinations such as ch and th stand for separates phonemes). Different languages have different numbers of phonemes, but the principle is the same in every language: Every utterance is generated from a surprisingly small numbers of sounds.
Morphemes:
They are the other elements, and the smallest units of meaning in language. Morphemes are closely related to but are not the same as words. Some morphemes stand alone as words. Word, stand, and fast are each single freestanding morphemes. Other morphemes can exist only if they are bound to other morphemes. Examples are the morphemes for past tense in pushed, the plural in cars. And the prefix morphemes anti meaning ''against'' in the word antibiotic. The average person knows thousands of morphemes but can speak an infinite number of utterances using a finite set of morphemes and rules for combining them.
Syntax:
The rules of a language that allow an infinite number of understandable utterances to be generated are called syntax. There are rules for the ways in which phonemic sounds can be combined in morphemes and rules for how morphemes can be combined in utterances , e.g. in English, we learn that the suffix-ed communicates past tense and that the s suffix denotes a plural. These rules of syntax are the heart of generative language, for, without them, only a finite number of things could be said with the finite set of morphemes. These rules, allow us to make new sentences that will immediately and effortlessly be understood by all speakers who speak normally in the same language.
Language and Thought:

Language and thinking are closely related phenomena. Although we often think in visual images, sounds, and images of movements- and some thought may involve no conscious images at all- much of our thinking takes place in the form of silent conversations with ourselves. If this is true, does language exert any influence on our thinking? If so, it is possible that people who speak different languages might think somewhat differently. This hypothesis was stated by Benjamin Whorf (1956) and is known as the Whorfian hypothesis, or linguistic relativity hypothesis, e.g. each language contains terms referring to ''personality types'' that are important in each culture, as in using the term artistic type which may have different meaning in different languages and this can affect thinking in each language user. In the same way, the language usage, as in using the term chairperson instead of chairman might affect the way we think about the capabilities of females to serve leadership roles.


Animal Languages:

Although humans have the most flexible and symbolic language for communicating propositions, we are not the only species that can communicate. Animals can use different movements, rituals or gestures in communications, e.g. bees, use a simple but elegant system to communicate messages such as discovering flowers containing a nectar supply, the bee who discovers the nectar tells the other bees about it through a symbolic dance, which is of different pattern according to the distance of the nectar. Using these dances, bees can communicate rather complex messages very efficiently. Unlike humans, however, they have a limited vocabulary and can only communicate in a way that is firmly limited by inheritance. Human language, in contrast, must be learned through interactions with fluent speakers. In addition, human languages are more flexible. Animal communication can varied little, whereas humans can generate an infinite number of unique and novel utterances. These differences between human and animal languages have some psychologists to assume that only humans can ever acquire a human language because we alone have the mental abilities needed for generative language. This assumption appears to be true, however, in some experiments it was possible to teach chimpanzees human language on a limited basis. The linguistic accomplishments of even the most advanced adult chimpanzees and apes is limited compared with that of human 3-year-olds.

Intelligence

Intelligence is the some total of cognition. It refers to the cognitive abilities of an individual to learn from experience, to reason well, and to cope effectively with the demands of daily living. In short, intelligence has to do with how well a person is able to use cognition in coping with the world.
The term intelligence was not in widespread use until it was popularized in the late 1800s by the writings of Sir Francis Galton. Galton was the cousin of Charles Darwin, the scientist credited for developing the theory of evolution. Galton believed that intellectual ability was inherited, and he tried unsuccessfully to develop an intelligence test to use in his research, Although he was unsuccessful in his own research, Galton gave psychology the concept of intelligence.
Basic components of intelligence:

General factor intelligence,

In Galton's view, intelligence is a single general factor that provides the basis for the more specific abilities that each of us possesses. According to this conception, if we are generally intelligent, we are more likely to develop strong mechanical, musical, artistic, and other kinds of abilities. This view that a general factor of intelligence underlies each of our more specific abilities has been advocated in more modern times by psychologist Charles Spearman, who used the term- g to refer to the general factor of intelligence. Spearman based his opinion on complex mathematical analyses of intelligence test scores that support, but do not prove, his theory of general intelligence. This concept of a g factor of intelligence is held by David Wechsler, who is the author of the most widely used intelligence tests for children and adults in the United States today.
Specific abilities- intelligence,
Other psychologists have argued that intelligence is not a single general factor but a collection of many separate specific abilities. These psychologists make a great deal of the fact most of us are much better in some cognitive skills than others, rather than being generally good at everything. Louis Thurstone (1938), for example, developed an alternative to tests of general intelligence, called the Primary Mental Abilities Tests, that measures seven intellectual abilities. J.P. Guilford (1982), taking an even more extreme position than Thurstone, suggested that some 150 different abilities make up what we call intelligence.
Theories of Intelligence:

Until the 1960s, research on intelligence was dominated by the factorial approach. However, with the development of cognitive psychology and its emphasis on information-processing models, a new approach emerged, the basic idea is to try to understand intelligence in terms of cognitive processes that operate when we engage in intellectual activities.

Gardner's Theory of Multiple Intelligence:

Howard Gardner (1983) also argued that there are multiple types of intelligence. Gardner became convinced that there are many separate kinds of intelligence partly by studying patients who had suffered brain damage to only some parts of the cerebral cortex. He found that these individuals lost some kinds of intellectual abilities while other kinds of intelligence were left intact. This suggested to him that different types of intelligence are mediated by different parts of the brain. Gardner also studied the fascinating abilities of rare individuals with savant syndromes. These individuals have low general intelligence but show extraordinary splinter skills in arts, music or arithmetic computation. As a result of his investigations, Gardner has suggested that there are seven independent types of intelligence;
Linguistic (verbal).
Logical- mathematical.
Musical.
Spatial (artistic).
Kinesthetic (athletic).
Interpersonal (social skills).
Intrapersonal (personal adjustment).
Gardner's definition of intelligence is much broader than the traditional one, Gardner believes that great skills in music and good emotional adjustment should be said to reflect intelligence just as much as skill in mathematics. Most tests of intelligence focus on just verbal and logical-mathematical areas of intelligence.
The issue of one versus many types of intelligence remains unsettled today, but most authorities believed that there is truth to both approaches. That is, it is probably correct that a general factor underlies all intelligence, but people can be strong in one specific area of intelligence and weak in another. Interestingly, people with higher than average intelligence show more peaks and valleys in specific facets of their intelligence than people with below average intelligence.


B-Sternberg's Triarchic Theory (of Cognitive Components):
The theory stresses on the Cognitive Components of Intelligent Behavior.
This approach suggests that the basic nature of intelligence can be illuminated by applying what we have learned in research on cognition. Sternberg has proposed a tentative theory of intelligence that specifies the cognitive steps that a person must use in reasoning and solving some kinds of problem, i.e. the cognitive components of intelligence, using ,mainly, an information-processing model of cognition as the use of encoding all the relevant information about the problem, organizing the elements of the problem and finding alternative solutions.
Sternberg suggests that this way of looking at intelligence gives us a framework for discovering which components are most important in determining whether one person is ''more intelligent'' than another, e.g. there is an evidence that better reasoners take more time to complete the encoding component than poor reasoners, but they are faster at all of the other stages.

Sternberg has identified three types of components;

Metacomponents- which deal with thought processes. And used to plan, control, monitor, and evaluate processes during problem solving.
Performance components- which deal with the effects of experience on intelligence, and carry out problem-solving strategies. These are creative abilities.
Knowledge- acquisition components- which consider the effects of the individual's environment and culture. They encode, combine and compare information during the course of problem solving. These are practical abilities.
These components are intertwined. Each comes into play during problem-solving process, and non of them can operate independently. Sternberg illustrates the functioning of these components with analogy problems of the following kind:
Lawyer is to client as doctor is to ------------- a- medicine b- patient
C-Anderson's Theory of Intelligence And Cognitive Development:
This theory holds that individual differences in intelligence and developmental changes in intellectual competence are explained by different mechanisms.
Differences in intelligence result from differences in the ''basic processing mechanism'' that implements thinking, which in turn yields knowledge. Individuals vary in the speed at which basic processing occurs. A person with a slower basic processing mechanism is likely to have more difficulty acquiring knowledge than a person with a faster processing mechanism. This is to saying that low speed processing mechanism produces low general intelligence.
D-Ceci's Bioechological Theory:
This theory proposes that there are ''multiple cognitive potentials,' 'rather than a single underlying general intelligence or g. These multiple abilities, or intelligences, are biologically based and place limits on mental processes. Their emergence, however, is shaped by the challenges and opportunities in the individual's environment, or context. In Ceci's view, context is essential to the demonstration of cognitive abilities. By ''context,'' he means domains of knowledge as well as factors such as personality, motivation, and education. Context can be mental, social, or physical. A particular individual or population may appear to lack certain mental abilities, but if given a more interesting and motivating context, the same individual or population can demonstrate a higher level pf performance.
Varieties of Intelligence:
Fluid and Crystallized Intelligence;
Fluid intelligence: Is the ability to learn or invent new strategies for dealing with new kinds of problems.
Crystallized intelligence: Is the ability to use previously learned skills to solve familiar problems.
The distinction between fluid and crystallized intelligence is supported by research on how intelligence changes with age. Crystallized intelligence- the ability to use familiar skills- improves throughout the years that adults work. That is one reason that most leadership jobs are held by persons over 40. In contrast, fluid intelligence- the ability to learn new skills for new problems- declines from middle age on.
Tacit intelligence;
Tacit intelligence is the practical knowledge and skills needed to deal with everyday problems that are usually not taught in school including skills in fishing, growing vegetables, maintaining cars, talking photographs, painting with water colors, shopping for food within a budget and so on. General intelligence tests are not useful in predicting competence in these specific areas that are generally not taught at school. A useful test of tacit intelligence must assess practical knowledge and skills in getting things done. Sternberg and Wagner(1993) developed a measure of tacit intelligence consisting of scenarios describing work-related situations in particular areas of employment. Persons taking the test are asked to rate the quality of a number of different solutions to the problems. Because different areas of employment- from plumbing to selling insurance- pose different kinds of problems, tests of tacit intelligence that are specific to a given area are most useful in predicting who will perform well in that domain.
Measures of Intelligence { Intelligence Tests }:


Stanford-Binet Intelligent Scale:
The first person who developed a useful measure of intelligence was Alfred Binet. In 1903, he began working on developing a test that he hoped would distinguished intellectually normal from subnormal Parisian schoolchildren.
In the United States, the test was refined by Lewis Terman of Stanford University, as the still widely used Stanford-Binet Scale. Terman retained Binet's concept of mental age. Each test item was age- graded at the level at which a substantial majority of children pass it. A child's mental age could be obtained by summing the number of items passed at each level. In addition, Terman adopted a convenient index of intelligence suggested by the German psychologist William Stern. This index is the-Intelligence Quotient ( IQ ), which expresses intelligence as a ratio of mental age to chronological age:
IQ = MA / CA x 100. The number 100 is used as a multiplier so that the IQ will have a value of 100 when MA is equal to CA.If MA is lower than CA, the IQ will be less than 100; If MA is higher than CA, the IQ is more than 100.
The most recent revision of the Stanford-Binet uses standard age scores instead of IQ scores. These can be interpreted in terms of percentiles, which show the percentage of individuals in the standardization group falling above or below a given score. IQ scores tend to fall in the form of a bell-shaped curve, with the most people's scores hovering around 100. It represents a Normal Distribution Curve.
This means that most people will obtain the average score , or scores that are close to the average, on the test. As the scores deviate from the average in either direction ( either higher or lower than average), the scores become progressively less common.
Most people have a IQ range between 90 to 110. Intelligence testing provides one of the main criteria for diagnosing mental retardation. The usual line of demarcation is an IQ of 70 or below, degrees of retardation range from mild to profound: individuals with IQs from 50 to 70 are said to be mildly retarded: 35 to 49, moderately retarded; 20 to 34, severely retarded; and under 20, profoundly retarded. People with IQ above 120 are considered to be of high intelligence. Approximately 90 percent of people who have retardation fall in the mild range, the vast majority of people with retardation can lead satisfying and productive lives.
In line with the current view of intelligence as a composite of different abilities, the 1986 revision of the Stanford-Binet groups its tests into four broad areas: verbal reasoning, abstract/visual reasoning, quantitative reasoning, and short-term memory. A separate score is obtained for each area.
Wechsler Intelligence Scales:
In 1939, David Wechsler developed a new test because he thought the Stanford-Binet depended too heavily on language ability and not appropriate for adults. The Wechsler Adult intelligence Scale, or WAIS, is divided into two parts- a verbal scale and a performance scale- that yield separate scores as well as a full-scale IQ. Wechsler later developed a similar test for children, the Wechsler Intelligence Scale for Children (WISC).
Items on the performance scale require the manipulation or arrangement of blocks, pictures, or other materials. The Wechsler scales also provide scores for each subtest, so the examiner has a clearer picture of the individual's intellectual strengths and weaknesses. For example, a discrepancy between verbal and performance scores prompts the examiner to look for specific learning problems such as reading disabilities or language handicaps.
Both the Stanford-Binet and the Wechsler scales are fairly valid predictors of achievement in school.
Group Ability Tests:
The Stanford-Binet and the Wechsler scales are individual ability tests. They are administered to a single individual by a specially trained tester. Group ability tests, in contrast, can be administered to a large number of people by a single examiner and are usually in pencil-and-paper form.
The Scholastic Assessment Test (SAT) and the American College Test (ACT) are examples of group- administer general-ability tests that are familiar to most college students in the United States. Virtually all 4-year colleges require applicants to take one of these tests as a way of setting a common standard for students from high schools with different curricula and grading standards D- Raven Progressive Matrices (RPM)- Test:
This test provides a trusted, non-verbal assessment if intelligence. Because these scales minimize the impact of language, skills and culture bias, they are particularly well suited to measuring the intelligence of individuals with reading problems or hearing impairment as those whose native language is not English. RPM test is appropriate for both children and adults. It measures two complimentary components of general intelligence: The capacity to think clearly and makes sense of complex data (educative ability) and the capacity to store and reproduce information (reproductive ability). The test offers three progressive, more difficult forms intended for different problems. Items on all forms ask the examinee to identify the missing component in a series of figural patterns. Grouped in sets, the items require increasingly greater skills and analyzing information.
The three forms are summarized below:
Colored Progressive Matrices (CPM);
For use with children 5 through 11 year age, elderly people, and individuals of any age who are mentally impaired. Easiest of the three forms CPM is used to assess the degree to which examinee can think clearly, or in the case of older or impaired individuals, the extent to which the intellectual abilities have deteriorated.
Standard Progressive Matrices (SPM);
It is the most widely used of the three forms, was designed to assess non-verbal reasoning in general population. In educational setting, used as a language free measures of Intelligence. In organized setting, it is used to determine potentials for success in technical or mid-level managerial position.
Advanced Progressive Matrices (APM);
Used for individuals from 12 year and up whose intellectual abilities above average. The most difficult of the three versions, APM can be used to assess professional placement and assessment of intellectual efficiency: - of speed and accuracy of higher level cognitive work.
Each of these forms can be group or individually administered.


Are people Becoming More Intelligent?
There is a clear evidence supported by psychological tests particularly the progressive matrices, that in many countries around the world, there is strong evidence that intelligence scores have risen dramatically over the past few generations. When tested at the same age using the same test, people born in earlier years answered fewer questions correctly than persons born more recently and having higher average IQs . The rate of increase in scores on tests of general adult intelligence (that measure both fluid and crystallized intelligence) like the Stanford Binet and Wechsler intelligence scales are surprisingly large, but data on tests that measure only fluid intelligence show even larger gains of about 20 points per generation (every 30 years). The strongest evidence of changes in fluid intelligence come from the Raven progressive matrices test.
There are many explanations for this dramatic increase including: 1-Improvement in nutrition and health particularly obstetric care. 2-Increases in level of education. 3- Decrease in number of children per family. 4- Stimulation and challenges of children born in the latter part of the twenties century by a degree of environmental complexity that was unknown in 1930, as educational TV, computers learning toys and so on.
However we should be cautious in concluding that genuine increases in intelligence have occurred.