This paper will discuss the true definition of intelligence and the various forms it can take, the methods used to measure it, and include an evaluation of the issues surrounding the limits of tests and societal pressures that come about as a result of this concept.


There are many different definitions and interpretations of what intelligence is; a simple search on Google will provide you with ‘the ability to acquire and apply knowledge and skills’; but, if one delves deeper, we find sources such as the Mainstream Science on Intelligence (Wall Street Journal, 1994) stating that intelligence is:

A very general mental capability that, among other things, involves the ability to reason, plan, solve problems, think abstractly, comprehend complex ideas, learn quickly and learn from experience.

This seems much more reasonable if we consider the fact that intelligence isn’t purely about recognising patterns in shapes on a piece of paper, which is all an IQ test (the most prevalent method of measuring intelligence) seems to consider. Intelligence is not merely about academic skill, but rather a deeper capability of understanding and adapting to our situations and surroundings.  However, despite this, only fifty-two out of a possible one hundred and thirty one researchers signed this definition, showing the continuing disparity of what this concept we’ve come up with is really about. The whole idea of having a number defining one’s level of thinking also places a lot of pressure on people to perform well, and on the other end of the spectrum, constantly prove themselves, which ultimately raises the question of whether we should attempt to measure intelligence (whatever that may be) at all.

Before making a decision about the fairness of measuring intelligence and the ways of doing so, we need to be able to define intelligence and classify the various forms it appears in. The concept was put forward first by Charles Spearman, an English psychologist, in 1904. He coined the term ‘general intelligence’, or ‘g’, based on people’s performance across a variety of mental tests. Recent research[1] has shown that this single intelligence corresponds with the lateral prefrontal cortex of the brain, as this is the only area with increased blood flow when patients attempted puzzles. However, many have questioned Spearman’s theory, especially the simplistic nature of the concept of ‘g’ and whether we can treat intelligence as a single entity. The dependence of intelligence on biological make-up is also debated, as socio-economic factors such as education could also have an effect. Scientists have therefore recently come up with alternate theories of multiple types of intelligence, postulating that intelligence is made up of several independent abilities, all of which contribute to the performance of an individual.

But there is still disagreement between the scientists putting forward these new theories. A psychologist named Robert Sternberg (listed as one of the ‘Top 100 Psychologists of the 20th Century’ in the APA Monitor, 2002) proposed that there are 3 fundamental aspects to intelligence: analytical, practical, and creative. He believes that traditional intelligence tests (such as IQ) only focus on the


analytical aspect. Another type of intelligence which Sternberg seems to have missed is ‘emotional intelligence’, developed by Daniel Goleman and several other researchers. Goleman reported on the brain and behavioral sciences for The New York Times, and wrote a book called ‘Emotional Intelligence[2] in 1995, which was on The New York Times bestseller list for more than a year, and had more than 5 million printed copies worldwide. This type of intelligence is often mentioned in media, and refers to the ability to understand and be aware of one’s own emotions, as well as of other people, enabling an individual to handle social interactions and relationships. In addition, American psychologists Raymond Cattell (whose professional writings ranked as the seventh most frequently cited in psychology journals in the last 100 years) and John Horn (who won the Annual Prize for Distinguished Publications in Multivariate Psychology – SMEP – in 1972) identified two types of intelligence: fluid intelligence and crystallized intelligence. The former is described as ‘the general ability to think abstractly, reason, identify patterns, solve problems, and discern relationships’. This depends on one’s natural ability and cannot be acquired through education or training. Fluid intelligence is used when solving puzzles, answering riddles, and coming up with strategies to solve an issue. The common term ‘street smarts’ is a fair representation of high fluid intelligence. Crystallized intelligence, however, is the opposite; it is about having knowledge or skills which are obtained through learning and experience. Unlike fluid intelligence, this can, and most likely will, increase throughout a person’s life. An example which is often cited is vocabulary, as this increases with every school year.

A decade later, the theory of there being more than one type of intelligence was affirmed with Howard Gardner’s Theory of Multiple Intelligences in 1983[3]. The nine types he proposed are[4]:

  • Logical-Mathematical (describing inductive/deductive reasoning and calculating ability)
  • Linguistic (the ability to use words effectively)
  • Visual-Spatial (having a high awareness of shapes and surroundings)
  • Naturalistic (having sensitivity for all living and non-living elements in nature)
  • Musical (being sensitive to rhythm and sound)
  • Existential (having a high capacity to tackle existentialism issues and questions)
  • Bodily-Kinesthetic (using physicality to manipulate objects and other elements around you)
  • Interpersonal (the ability to sense the feelings and motives of others)
  • Intrapersonal (self-awareness)


There is a possibility of possessing all of these types of intelligence, but it is mainly a matter of some types being higher or more apparent than others. Although there are certain criticisms, such as whether there is sufficient empirical evidence to support this conceptualization, the theory has been met with a strongly positive response from many educators, and has even been applied to the structure of schooling and education initiatives.

There are several ways of measuring intelligence, but by far the most common method is the Standard IQ Test, developed by French scientists Alfred Binet and Theodore Simon. The original purpose was to assess children at school, so the mentally-handicapped and children with behavioral issues would be able to receive adequate and appropriate education[5]. This formed the basis of the standard modern intelligence test, having been modified into the Stanford-Binet test and the Wechsler Adult Intelligence Scale along the way, producing the famous ‘intelligence quotient’, or IQ. The score is based on a group of people representative of a wider population, with most people falling into the 90-110 region. The test measures a range of abilities such as mathematical, verbal, spatial, memory and reasoning. However, there have been several criticisms of standard intelligence tests such as this; scientists, psychologists, educators and members of the public do not believe that the IQ test is an accurate measure of intelligence. With these views, they challenge the concept of general intelligence (which was explained earlier), claiming that standard tests do not take genetic, cultural and social influences into account, nor the personality of the person taking the test. Some critics also feel that there may be serious cultural biases, reducing the validity of the test as a measure of the cognitive ability of different races. And as expected, there is debate surrounding whether intelligence is a fixed quantity capable of being measured.

James Flynn, a New Zealand intelligence researcher and member of the editorial board of Intelligence[6] (a peer-reviewed academic journal of psychology covering intelligence and psychometrics, and the official journal of the International Society for Intelligence Research), noticed a trend in IQ scores, and therefore intelligence, increasing over time[7],[8],[9]. As IQ scores are not absolute numbers, but rather comparisons with the general population, a score of 100 is always average; however, each generation of tests has become more challenging and is graded more harshly due to the apparently increasing intelligence and knowledge of the population as a whole, based on the fact that each generation tends to score much higher than the previous generation. There are several proposed


explanations for the Flynn Effect[10], including the increased access to education, exposure to spatial reasoning tasks, test bias and even improved health, nutrition, and services for people with disabilities and low IQ, thus decreasing the occurrence of intellectual disabilities.

There may not be a way of measuring the multiple intelligences mentioned earlier, but a number of alternative intelligence tests have been proposed[11]. These include:

  • Peabody Picture Vocabulary Test – a person is asked to select a picture from a group of four which best defines a given word
  • Raven’s Progressive Matrices – a person is shown a matrix of patterns with one missing
  • Visual Illusions (Psychophysics), which measures one’s ability to perform a visual task, and looks at how illusions question our perception
  • Elementary Cognitive Tasks, which assess a person’s response to stimuli and determine how fast the brain works
  • Psychometric/Aptitude Tests, commonly used in recruitment and academic selection, focusing on specific abilities required for certain roles and predicting a candidate’s future performance in a given field

Taking into account the various criticisms of the standard IQ test, and the areas of intelligence which the alternatives assess, it is clear that there is no particular test which can effectively measure intelligence as a whole, and perhaps a combination of several tests would have to be used in order to gain an understanding of one’s strengths and weaknesses in each field.

Even after taking into consideration the multiple forms in which intelligence can manifest, one more element which can be argued to affect intelligence significantly is attention. The Handbook of understanding and measuring intelligence[12] highlights that many of the psychologists and researchers mentioned previously (i.e. Spearman, Binet and Sternberg) recognised the importance of attention. It also points out that the relationship between attention and intelligence is complicated and partly a matter of semantics – ‘the branch of linguistics and logic concerned with meaning’. The contributors to this handbook are all experts in intelligence, with a background in methodology or theory, and designed this publication for scholars and psychology professionals. As William James wrote, ‘the number of


things we may attend to is altogether indefinite, depending on the power of the individual intellect’. The aspects of a situation we decide to pay attention to would certainly have an impact on how we utilise and apply certain logic and reasoning, falling under the domain of fluid intelligence.

Being referred to as ‘intelligent’ is regarded as one of the best compliments someone can hope for. People who have ‘high levels’ of intelligence receive respect and admiration, although we can now see that this may concern only a few of the multiple types of intelligence. In spite of this, there is a negative aspect to being described as intelligent, as it can be quite restricting and place a lot of pressure on individuals. If one is expected to excel at everything, even the smallest mistake will be criticised. This is mainly due to the fact that most people have a single perception of what intelligence is, and either do not consider, or are simply unaware of the various types, choosing to focus on whether an individual has a wide knowledge and skill-set, and how they can effectively apply said characteristics. On a simple level, this appears to cover both fluid and crystallized intelligence, but as we expand into Gardner’s theory, most types are completely omitted. The definition of intelligence has been narrowed to only mean things academic, and this attitude seeps through into the ways we measure this concept, such as the IQ test. Another problem with all of test taking is that they arguably never test ‘intelligence’ on its own, but also one’s mood and state of mind, which would definitely affect one’s performance on the day and consequently the results. The fact that Binet himself thought that the IQ test that he developed himself was an inadequate measure for intelligence, pointing out the inability of the test to consider creativity and emotional intelligence, once again proves the existence and significance of these issues.

There are ongoing efforts to demonstrate how the IQ test can be used for good[13]; in 2002, the execution of criminally convicted individuals with intellectual disabilities was ruled unconstitutional, meaning that IQ tests have technically prevented them from facing a cruel punishment in the US court of law. As well as this, tests may be a more objective method of identifying children who could benefit from special education services, but once again, an issue arises in ethnic minorities and those whose parents have a low income being underrepresented (test bias).

Although intelligence tests have been used to influence positive change and give a basic understanding and overview of the mental capabilities of an individual compared to the general population, the widespread debate over their validity and morality introduces doubt as to whether we



should measure it at all. In my opinion, I believe that it is unfair to measure and define intelligence in the ways that we do currently; ultimately, the use of these tests in such a wide range of settings and the changing attitudes towards individuals based on their performance only confirms the immense value which society places on intelligence, and our strong (but arguably unnecessary) desire to define it.



  • Cole, M., Yarkoni, T., Repoys, G., Anitcevic, A. and S. Braver, T. (2012). Global connectivity of prefrontal cortex predicts cognitive control and intelligence.
  • Goleman, D. (1995). Emotional intelligence.
  • Anon, (n.d.). Intelligence.
  • Flynn, J. (2007). Solving the IQ Puzzle. Scientific American Mind, 18(5), pp.24-31.
  • Flynn, J. (2009). What is intelligence?. Cambridge: Cambridge University Press.
  • Flynn, J. (2012). Are we getting smarter?.


  • Wilhelm, O. and Engle, R. (2005). Handbook of understanding and measuring intelligence. Thousand Oaks, Calif.: Sage Publications.


[1] W. Cole, M., Yarkoni, T., Repoys, G., Anitcevic, A. and S. Braver, T. (2012). Global connectivity of prefrontal cortex predicts cognitive control and intelligence.

[2] Goleman, D. (1995). Emotional intelligence.

[3] Howard Gardner, multiple intelligences and education. [online] Available at:

[4] Cleverism. (2017). Types of Intelligence and How to Find The One You Are Best In. [online] Available at:


[5] (2003). [online] Available at:

[6] Anon, (n.d.). Intelligence.

[7] Flynn, J. (2007). Solving the IQ Puzzle. Scientific American Mind, 18(5), pp.24-31.

[8] Flynn, J. (2009). What is intelligence?. Cambridge: Cambridge University Press.

[9] Flynn, J. (2012). Are we getting smarter?.


[10] A-G, P. (2018). The Flynn Effect. [online] Therapy Blog. Available at: [Accessed 3 Apr. 2019].

[11] (2017). Alternatives to the Standard IQ Test. [online] Available at:

[12] Wilhelm, O. and Engle, R. (2005). Handbook of understanding and measuring intelligence. Thousand Oaks, Calif.: Sage Publications.


[13] The Conversation. (2018). The IQ test wars: why screening for intelligence is still so controversial. [online] Available at:

Photo Credits due to:

Malhar Mukne