In this article, we will give you an answer to the question of what Is Intelligence in psychology according to the fact that the brain is a flexible organ? From birth, the use of acquired knowledge, challenges to overcome, etc., shape it. This is the phenomenon known as neuroplasticity.

Neurogenesis – formation of new neurons – is positively influenced by neurotransmitters, growth factors, neurotrophic factors, hormones, a culturally rich and stimulating environment, physical activity, social interaction, and learning. Psychological stress, psychiatric disorders (depression), social isolation, or lack of sleep negatively affect the formation of new neurons—similar effect cause of drug abuse.

It is now clearly demonstrated that there is active neurogenesis throughout life in humans.

I – Intelligence in Psychology. Intelligence in Psychology According to the Intellectual Quotient

IQ (Intellectual Quotient) is the generic term used since 1912 to designate the different psychometric tests of intelligence or to designate the result obtained in one of these tests.

The intelligence quotient, also known as IQ or CI, consists of a score obtained by a person who performs a series of tests to measure his intelligence and who receives 100 as a central value of mean intelligence. Those who score above 100 are above average, and those who are scoreless do not reach average intelligence.

There are several types of IQs, which give different ratings. However, all are psychometric tests: standardized tests that compare an individual’s performance to specific questions in relation to the responses of the general population to the same questions.

The intelligence quotient would be an intrinsic datum to an individual; that is to say, it would be immutable over time and characterize the intelligence of the individual.

In general, it is believed that IQ is a genetic attribute with which we are born and remains for life, such as eye color or height. In fact, it is more like other attributes of our body and mind, such as body weight, mood, energy levels, and blood pressure, all of which can fluctuate throughout our lives.

II – Measuring the Intellectual Quotient

IQ is one of the means of measuring General Intelligence in Psychology, the factor g, that is to say, a biological characteristic that is behind the treatment of all cognitive tasks. It is not a direct measure (as one’s height can be measured directly with a meter), but an indirect measure (as if someone’s height was measured by reference to the size of its shadow on uneven ground): the measurement is not perfect.

IQ is the term invented by Wechsler in 1939, inventing the Wechsler Adult Intelligence Scale (WAIS) in an attempt to follow up Spearman’s factors. It is, therefore, an artificial means of measuring talents or intelligence.

The IQ score only evaluates some form of intelligence using our logic. It does not evaluate other types of intelligence (e.g., creativity). Throughout our lives, we face challenges; we face certain issues for which we must make decisions. It is these executive functions that are in the foreground and therefore evaluated by a test like IQ. We can, therefore, think that the IQ score is not a stable value but fluctuates over time.

A “gifted” or “genius” would be a person whose IQ is 130 or more.

People with these characteristics usually have a great deal of difficulty in solving logic problems. A person over 115 IQ is above the average, and those below average are those who have an IQ between 70 and 80 points and they often have difficulty thinking abstractly. People with a 70 coefficient usually have cognitive, memory, and language difficulties.

Why is an individual gifted? IQ is directly related to parents’ IQ, i.e., it is genetic or hereditary. However, a part of our intellectual capacity depends on our life story and the use we make of our brains.

Long ago, it was thought that the differences between the intellectual level of people depended exclusively on this genetic factor. It was believed that IQ “was already manufactured.” However, studies show that the combination of early and adequate stimulation to the environment is essential for brain development. Good brain training, specific to each cognitive function, refines and improves our abilities.

The University of Rochester has published a study to measure IQ by sight. The test is very simple: it implies that the eyes follow the movement of a bar on the computer screen to the right and left. The bars have three different sizes. Those who follow more precisely the movements of the smaller bar, which is limited to the central circle of the visual field, are those who have a higher IQ.

III – What Is Intelligence in Psychology?

*** Cognitive Intelligence

It is the set of cognitive or intellectual skills required to acquire knowledge and use that knowledge effectively to solve problems whose purpose and structure are well-defined.

What is called intelligence, conceived as a whole, is, in reality, the result of many superimposed mental faculties.

The best way to qualify intelligence is to say that it is a mental skill associated with not only cognitive operations, and that allows understanding the information, learning from it, and using it in an effective way.

According to the American Association of Psychology, it is the capacity by which individuals are able to understand complex things and cope and solve certain complications through reasoning; according to the capacity of each person, he is said to be more or less intelligent than the others.

Mainstream Science on Intelligence has proposed a second definition, supported by more than 50 researchers. Intelligence is understood to include the ability to reason, solve problems, abstract, to plan.

Intelligence is not only the ability to learn books but also the skills to resolve conflicts and know what to do at any given moment.

*** Types of intelligence in


According to Harvard University psychologist Howard Gardner, every human being has many kinds of intelligence at birth that will develop to a greater or lesser degree depending on the individual.

– linguistic or verbal intelligence (use words easily, both orally and in writing)

– Logico-mathematical intelligence (solve mathematical problems and know how to reason in the abstract)

– Naturalistic intelligence (using their own environment to understand the world)

– Spatial intelligence (ability to think in three dimensions and visualize space)

– Musical intelligence (aptitude for music)

– Kinesthetic intelligence (ability to express an idea or emotion by gesturing or doing a physical activity)

– Intrapersonal intelligence (ability to know oneself well)

– Interpersonal intelligence (the ability to perceive emotions and moods in others).

*** Emotional intelligence

Emotional intelligence is measured by the emotional quotient (EQ) and can be defined by:

– The understanding of his emotions

– Control of emotions and impulses

– Understanding the emotions of others and how to react to them

– Inspiration and influence on others

– The development of emotions and the management of conflicts.

The concept of QE corresponds to a mix of General Intelligence (G-factor) and personality.

IV – Intelligence Test

The first test of modern intelligence in the history of IQ was developed in 1904 by Alfred Binet (1857-1911) and Theodore Simon (1873-1961).

In order to establish the intellectual faculties of a person, one must perform various types of tests. In these tests, we include problems with words or numbers, shapes, and drawings, in order to define the individual’s IQ capacity of the individual.

This test consists of several components, such as logical reasoning, identification of rhymes, and the designation of objects.

When we talk about intelligence, we mean our ability to learn quickly and adapt to new situations. These tests are supposed to measure our vocabulary, our ability to solve problems, to reason logically, and so on.

Recent studies have shown that intelligence quotients are changing throughout our lives.

*** Standardized score

The standard intelligence tests used by clinical psychologists for diagnostic purposes, such as the Wechsler scale, are designed so that they are not easy to prepare because the content is surprisingly kept secret and is changed regularly so that the score given by a person is always relative.

Even as we get a better education and are more qualified in IQ tests – a phenomenon known as the “Flynn effect” – our score does not change at all, and this is because the IQ score system takes into account the degree of improvement expected over time, then it is discarded. The tests done when you are older are adapted to this age and therefore do not include learning. This type of account is called a “standardized score” because it hides its true score and simply represents its position relative to its peers, who are also expected to become smarter or at least at the same pace.

*** Standardization of a test

To standardize a test is to transform it into a systematic and relatively immutable procedure; this operation is aimed at controlling the situation in which an individual will pass the test. Standardization makes it possible to recreate a test environment that is always identical to that used for calibration to ensure that the starting conditions of the test are the same for everyone at all times.

*** Flynn effect

The “Flynn effect” – named after the researcher (James Flynn) who brought it to light – that is, the steady increase in IQ among populations due to improved lifestyles.

The Flynn effect corresponds to the quasi-regular increase in IQ throughout the 20th Century. This increase varied according to the country – stronger in the northern countries than in those in the south – but it reached important figures (+ 1 standard deviation/generation). It required regular re-calibration of IQ tests. It can be seen that it closely resembles that of increasing size and life span over the same period.

This effect slowed down at the end of the 20th century and finally reversed in Western countries at the beginning of the 21st century.

Several hypotheses have been put forward to explain it, including:

Influence of the food => what measures the IQ has indeed increased

– Influence of stimuli at a very young age (television)

– Either the tests measure less well than before (are skewed) => or there has been no increase in what the IQ measures.

– Either these stimuli have an effect on the growth =>, or there is indeed an increase in what the IQ measures.

“Profit,” which has been calculated at three IQ points per decade, has been observed in infants, preschool children, school-aged children, and adults. The generational increase in intelligence occurs between the more and the less intelligent.

In reality, this means that we have all become smarter in our lives, and the IQ tests and the scoring system of the same are constantly adjusted to ensure that the average IQ is kept at 100, despite an increase well marked on the gray matter around the world. Psychologists know that intelligence scores are subject to cultural influence and social opportunities.

V – Studies on the Intellectual Quotient

When we learn, read a book, listen to a piece of music, or observe a painting, physical changes occur in the brain, and new structures and connections are created, which allows us to improve our intelligence.

1 – The Intellectual Coefficient Fluctuates During Adolescence

Researchers at the University College of London, in a study published in the scientific journal Nature in 2011, prove that IQ is not stable over the course of life (in the absence of brain damage and neurodegenerative diseases) and that the score of a child’s IQ test should no longer be used to predict future academic and career performance.

In practice, the researchers examined 33 healthy adolescents, first in 2004 when they were 12 to 16 years old (14 years old on average), then a second time in 2007-2008 when they were between 15 and 20 years old (18 years old on average). Different tests measured their verbal and non-verbal IQ, and these young people underwent a structural and functional brain scan by MRI at each examination. Individual IQs ranged from 77 to 135 points on the first test and 87 to 143 points on the second, which confirmed the wide range of intellectual abilities among these individuals.

The researchers found that verbal and non-verbal IQ varied considerably among participants between 2004 and 2008. Some individuals had improved their performance compared to their peers, with an increase of up to 20 points in their IQ. global. For others, however, their performance had dropped, with a drop in IQ also reaching 20 points. The researchers say that these changes are not due to a change in performance related to mood or concentration that day; they are real because they are correlated to changes in the structure of certain brain regions.

Reading, naming, and problem-solving areas were more active in those whose IQ had increased. This means that a stimulated brain develops new connections between neurons.

2 – Short-Term Training Memory Increases Pure Intelligence

A group of scientists from the University of Michigan, in one of the results of research on intelligence in 2008, showed that short-term memory could be the most important foundation for pure intelligence.

In their study, adult volunteers were trained in a difficult task of short-term memory: listening to a sequence of letters while simultaneously watching a series of computer screens that showed a blue square in different places. They asked the participants to determine whether the letter was pronounced or the location of the square corresponding to that of the screens presented before.

The more they practiced and stimulated their short-term memory, the much better the improvement of the purest form of brainpower, the “liquid” intelligence, which is the ability of volunteers to reason and solve problems independently—prior knowledge.

The reasoning test segment used something called a progressive matrix: visualizing three geometric configurations and choosing from many options the one that best fits the model.

*** The Training of the Memory Increases Pure Intelligence, and It Is, Therefore, the Best Way to Increase IQ.

It has also been found that language-related changes in IQ are associated with variations in a particular region of the brain, specifically in the left motor cortex. Moreover, concerning non-verbal tests, the reason may be an increase in the gray matter in the anterior cerebellum – which controls the sensory and motor part of the body -.

It is also known that there are differences in IQ between men and women; it does not mean that one is smarter than the other, but that they have different cognitive skills; similarly, for people belonging to one or other cultures, beyond social learning, there is a certain predisposition to develop IQ of a specific form.

3 – A Different Intelligence at Each Age of Life

According to a study by the Massachusetts Institute of Technology (MIT), published in the journal Psychological Science in March 2015, the facets of intelligence would not age the same way, some even improving over the years.

To reach this conclusion, the researchers collected data from two websites ( and offering IQ, memory, and language tests. The responses of 48537 individuals aged 10 to 89 years were analyzed according to the age and mental capacity needed to solve the requested exercise, from arithmetic to the perception of emotions.

Up to now, specialists have agreed to distinguish two types of intelligence, defined in 1971 by the British psychologist Raymond Cattell: one called “fluid,” including logic and problem-solving, and the other called “crystallized,” “Which increases throughout life by the accumulation of knowledge or experiences.

*** Fluid Intelligence

According to his work, fluid intelligence, which includes short-term memory, speed, and coding capabilities – replacing numbers with symbols in a limited time, reproducing a geometric design after 10 seconds of observation – would be optimal between 19 and 20 years and then decrease rapidly.

*** Crystallized Intelligence

The so-called crystallized intelligence, illustrated by tests of vocabulary, general knowledge, comprehension, arithmetic, and similarity – knowing how two objects are similar – would, on the contrary, improve throughout life and fall only with senility.

Other faculties that cannot be associated with the two known types of intelligence have emerged from this data processing. The best results in tests requiring an analysis of the situation – finding the missing part of an object or assembling images to trace a story – and those involving so-called working memory were obtained by participants aged 25 to 35 years.

Working memory requires the use of several cognitive functions, including short and long-term memories, to react quickly to a given problem.

Researchers believe that this could be the result of a more robust university education, having a job that requires a lot of reading and copying of knowledge, and the existence of good opportunities for intellectual stimulation when one comes to old age.

VI – Factors That Reduce Intelligence

As many times as intelligence can be improved or intelligence quotient increased, there are also factors that reduce intelligence… By example :

1 – The Diet

High-fat foods affect brain activity, veiling the function of dopamine, the neurotransmitter responsible for motivational production.

In addition, studies show that high-fat diets also affect responsiveness, as well as memory, and cause depression.

2 – Multitasking

Although there is the idea that the brain is able to do many things at once, the fact is that this organ can only do one thing at a time, but it makes the task change so quickly that it gives people the impression of doing many things at once.

By making these changes so quickly, we spend more glucose, the energy source of the brain, and we decrease the IQ since by performing various tasks, we prevent the generation of deep thoughts. Also, the thoughts become less recent and more superficial; this is how we are not focused on any of the tasks performed.

3 – Technology

It is true that new technologies save us a lot of time and effort. Still, they also affect memory by gradually delegating the storage of information to electronic devices such as smartphones or computers.

This is because we have less information and less time because now when we need to look for information, we just go to a search engine and put a link that leads us to the desired topic instead of remembering names, dates, and other data to search directly.

4 – Television

Television can affect intelligence, which was verified by psychologist Markus Appel, who conducted a study that showed 81 participants in a supposed reality TV show about an athlete. After showing this program, he applied a knowledge test.

Those who watched television before answering the exam had more errors than those who did not see the program; it is because when we receive recent information, we remain consciously present from so that the brain is predisposed to this information.

5 – Changes in Sleep Schedules

Change sleep schedules or try to adjust sleep time to another country’s schedule, and regular sleep disruption affects the circadian rhythm, which indicates when it’s time to sleep because it’s night or day, which affects memory and the birth of new neurons.

In Summary on Intelligence in Psychology

Although motor and cognitive abilities may be thought to be as diverse as water and oil, many studies have shown that the development of sensorimotor skills can improve cognitive skills. Nobody knows how that goes, of course, but it is postulated that the two brain systems are more interconnected than we think. Thus, it is possible to increase IQ by learning to knit, listen to classical music, or juggle.

Exercising short-term memory – in essence, the brain’s notebook – can be the lever to increase our intelligence.

A person may have high logical or mathematical ability but be unable to create artistic work and vice versa. Currently, IQ measurement and subject abilities are intended to be a tool to help people know their strengths and weaknesses in order to work and improve them.

It is difficult to agree on a universal definition of intelligence. It encompasses the ability to know and understand, to solve problems, to adapt to new situations, and to learn. These different conceptions of intelligence make it possible to affirm that there is not only one type of intelligence but several.

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