IQ-Brain Blog

The different types of intelligence

Raymond Cattell observed different types of intelligenceThere is no hard and fast consensus in the academic literature about how many different types of intelligence exist. In the early twentieth Century, the English psychologist Charles Spearman observed that a general factor (G or g factor),  served to explain much of the consistency in baseline performance of an individual across a multitude of intelligence tests. In simple terms, the g-factor could therefore be likened to a global or general intelligence. The higher someone’s G, the better they were likely to perform across a variety of IQ tests, even though each of these might measure a different aspect of human intellect. Spearman also believed that people possess specific or special abilities, but that G was more closely related to the concept of general intelligence. Spearman could therefore be viewed as a proponent of the single, global IQ score.

Cattell proposed two different types of intelligence

Spearman’s doctoral student Raymond Cattell in the 1940s decomposed his mentor’s theory of G into two principal components: (1) Fluid Intelligence (Gf); and (2) Crystallized intelligence (Gc). Fluid intelligence represents an individual’s ability to solve ‘novel’ or new problems. Crystallized intelligence on the other hand, is the aspect of human intelligence that can be learned in school. So Gf can be likened to raw processing power of the brain, while Gc is closer to a body of knowledge. This is often known as Gc-Gf theory.

Cattell’s theoretical foundation of human intelligence did not gain prominence until the 1960s, when his doctoral student John Horn decided to re-popularize his mentor’s forgotten Gc-Gf theory.  This theory was eventually merged with that of John Carroll, which resulted in what is widely known as CHC theory of cognitive abilities.

CHC theory further dissects G, and Gf-Gf to include seven broad abilities including:

Gc-related sub-indexes:

  • Quantitative reasoning (Gq)
  • Reading and writing ability (Grw)

Gf-related sub indexes:

  • Short-term memory (Gsm)
  • Long-term storage and retrieval (Glr)
  • Visual processing (Gv)
  • Auditory processing (Ga)
  • Processing speed (Gs)

CHC is today the most widely accepted theory of intelligence with several of the major professional IQ tests having been reviewed to incorporate test items to measure several of these broad abilities. Well-known tests such as the Stanford-Binet V and Weschler Adult Intelligence Scales IV typically incorporate four of the seven broad abilities:

Factor indexes (different types of intelligence) of WAIS-IV:

  • Verbal comprehension index (Gc)
  • Perceptual reasoning index (Gv / Gf)
  • Working memory index (GSm)
  • Processing speed index (Gs)

Glr and Ga may be difficult to measure in a short IQ test. Nonetheless, it becomes clear that there are different types of intelligence.

Although G is perhaps an overly simplistic concept, it still resonates in society with the global IQ score being given significant consideration. However, it is important to realize that Global intelligence can be decomposed into different types of intelligence as shown above.

Click here to get an assessment of your Fluid Intelligence (Gf).

Does IQ change as you get older?

IQ and ageAs different people and you will get a different answer. Some say that IQ and age are not related variables. But you look at the data more closely and you can see that the answer is clearly “yes they can change – to some degree”.

Children go through periods of very rapid mental development, so unsurprisingly, mental development and IQ can change year on year for young children.

For Groups, IQs have been shown to be fairly constant from early adulthood through to adulthood (Salter 2008).

  • The coefficient of correlation between IQ at age 5 and IQ at age 40 is 0.50-0.60 (i.e.55%)
  • The coefficient of correlation between IQ at age 9 and IQ at age 40 is 0.70 (i.e. 70%)
  • IQs at ages 10 &12 predict IQs at ages 17 & 18 at a correlation coefficient of 0.98 (i.e. 98%)

Although it is not yet fully established scientifically whether puberty is a defining moment from a brain development standpoint, intuition and statistics suggest that it might be. From Salter’s study, it is clear that IQs at ages 10-12 (very close to puberty) are much better predictors of IQs in adulthood.

There is clearly a relationship between IQ and age.

So it’s not just about ‘feeling good’ on test day which may impact the result of your IQ test, but rather the admission that people’s IQs tend to change slightly over time.

Several studies on ageing have also been performed which suggests that fluid intelligence (i.e. the ability to solve novel problems) may peak in the mid-to-late 20s, whilst crystallized intelligence (i.e. the ability to retain and apply formal educational instruction) may peak in the mid-50s.

So people who argue that IQs are fixed and immutable are simply wrong. There should be no doubt about the fact that IQ and age are related variables. On an absolute basis, IQs vary quite substantially during our lifetime and lifestyle choices can impact the growth of IQ (e.g. learning new skills or remaining longer in formal education can increase IQ) or precipitate its decline (e.g. unhealthy lifestyles or taking drugs). But ipsative IQ tests should be comparing your test scores against those of people in your age bracket to give you a true representation of how bright you are relative to the relevant population subset. When using ipsative tests only, your IQ is likely to be much more stable than would otherwise be the case. In summary, IQ and age are related and is it wrong to think that your IQ will never change as you get older.

Click here to get an accurate assessment of your fluid intelligence on our culture-fair IQ test.

IQ testing is nothing new

Mozart was subjected to IQ testing at age 8Some critics have either attempted to dismiss IQ testing as being baseless or lacking scientific measurement. What these people often forget is that IQ testing is not a new concept and has been around for millennia.

Although the blood relatives of the modern-day IQ test came to life in the late 1890s, cognitive ability tests can be traced back to 4000 B.C. In Asia, it is believed that the Chinese Emperor gave proficiency tests to his officials every third year.

This Chinese tradition continued as 1,000 years later, the Chan Dynasty was reported to have administered proficiency tests to would-be officials, which on the face of it appears like a sensible practice.

Over 700 years later in in Europe, Mozart had been ordered to be tested by King George the 3rd, with the test having been administered by philosopher Daines Barrington around 1763. Mozart had composed his first symphony by age 8.

IQ testing has always been around in one form or another

So human beings have always been interested in the measurement of intelligence, but it was not until Frenchman Alfred Binet came along that cognitive ability tests would receive a major scientific upgrade. Grand children of Binet’s tests are still in existence today, over a century later. But Binet’s greatest contribution to the science of IQ testing are not his questions per se, but rather the introduction of the concept of error in testing. That is, unlike height or body weight, or even strength, the measurement of human intelligence cannot be done with pinpoint accuracy, which is why an individual’s global IQ score must not be viewed as immutable or absolute, but rather a snapshot of someone’s intellectual ability at a particular point in time.

To get a snapshot of your IQ, click here.