Intelligence :
Human intelligence


The issues concerning human intelligence are: what it is, what does it enable the owner to do and how can you measure it.

It is still difficult to provide a meaningful definition that clearly describes intelligence and separates it as a concept. This difficulty makes discussion of other aspects of intelligence also difficult. It may be argued that intelligence enables people to get the best jobs or reach the highest levels of academic success. It could be argued that intelligence is a requirement for innovators, inventors.

These claims for the value of intelligence naturally lead to a desire to want to measure intelligence. Colleges want to select the students most likely to succeed, business managers want to select the most able staff, the RAF wants to end up with the best pilots etc. Although there is much disagreement on the value of measures of intelligence or Psychometrics, many claim that such measurement techniques are valuable tools.


A question that seems to be associated with great personal feelings is the question as to whether phsychometrics fulfil their claims to provide good measures of intelligence and future performance. The feelings seem to arise from personal commitment to a particular approach.

Users of psychometric tests argue that they do select the best staff, students etc. Opponents argue that such tests only test a limited range of skills and can be greatly biased. They also claim that the widespread use of such tests represents a self fulfilling prophecy. Tests are used to select for the best jobs or best student places and then studies show that the best jobs or students also score highest in the tests.

It is claimed that tests, with proper analysis of the results, can provide an indicator called 'g' that represents a general intelligence figure for an individual. It is also claimed that this measure correlates well with success in an individual.


Is there a specific site in the brain that is given over to intelligence, Probably not. However, the greater proportion of the brain is devoted to sensing, interpretation and control, These are very complex tasks. Long Term Memory also accounts for considerable brain volume. Intelligence is not associated with a single task, it is a cooperating blend of functions and abilities. Tasks that are associated with intelligence are more likely to be working memory, problem solving and consciousness. Many of the individual components of these functions have been located in the general area of the frontal lobes. This is the most recent area of the brain to evolve.



It is argued that the particular measure 'g' for general intelligence is a good predictor of academic performance, employment, divorce etc. This is not just speculation it is reinforced from the correlation of those who score high in measures of 'g' and those who achieve success.

This view is challenged by psychologists such as Sternberg who point out that since the tests are used to selectively control access to schools, colleges and the workplace, then it is not surprising that the top places are occupied by high scorers.

Gifted Individuals

The study of particularly gifted people points to the conclusion that intelligence consists of a multiplicity of skills. There are well documented cases of individuals who may otherwise be regarded as generally retarded, who possess phenomenal skills in one particular field. Such specific skills include music, mathematics, spatial representation etc. Examples of such people can be seen in Book 11. It can be argued that such examples of extreme unevenness in the giftedness of individuals is strong evidence for a multiplicity view of intelligence.


It is suggested that it may be possible to artificially enhance performance (Intelligence) through the use of drugs. Scientists have searched for such drugs in the pursuit of relief from and cure of Alzheimer's and similar diseases. In some cases it has been shown that the drugs that provide such relief can also enhance performance in healthy individuals. There is now an interest in researching for so called 'smart drugs'. Some studies have shown that widely available substances can affect cognitive abilities. Caffeine is thought to enhance mental alertness, nicotine has been shown to improve short term memory and most of all, glucose (in sugar) is said to be the smartest of these, with studies showing improvements in Alzheimer's and Downs Syndrome sufferers who use it. The studies that highlight these benefits have so far been small and are not conclusive. Each of the three substances mentioned have problems associated with them and they are not recommended as cognitive enhancers.



Normal human decision making is far from rational. Observations have shown that humans do not consider all options but select the first option which satisfies minimum requirements (Herbert Simon). When faced with too many alternatives, humans may select one feature and choose a minimum requirement for that feature, eliminating all alternatives which do not comply (Amos Tversky). Tversky and Kahneman showed that humans are more likely to base decisions on bias and heuristics than on rational probability.

Although human error in decision making has been well established, it is possible for people to improve the situation.


People have beliefs about orders of events which use a heuristic know as representativeness.

For instance, in families which have six children they may believe that the birth order of GBGBBG is more likely than BGBBBB because the sexes in the former is more representative of the population in general.

Equally, people may believe that the lottery numbers 1,2,3,4,5,6 are more unlikely to occur than 9,16,24,28,34,42 because the latter seems to be closer to what actually occurs even though it may never have actually occurred.


An adjustment from an anchor heuristic is where people asked to conduct an estimate, use a part analysis to extrapolate from. For instance, where subjects were asked to form an very quick estimate from the following two computations:

  1. 8 x 7 x 6 x 5 x 4 x 3 x 2 x 1
  2. 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8

the median estimates from the groups was 2250 for (1) and 512 for (2). In fact the correct answer is 40320 for both.


Humans take information which is more readily available to guide their decision, rather than considering the logical possibilities. For instance, two groups of people were asked to estimate the number of words in a 2000 word passage which contained the forms (one group of people for each form):

  1. _ _ _ _ i n g
  2. _ _ _ _ _ n _

The conclusion that there were almost twice as many of the first form than the second is clearly incorrect.

Another example of the inappropriate use of this heuristic is shown by a survey of college students who were asked two questions about a health survey.

  1. What percentage of men surveyed had one or more heart attacks.
  2. What percentage of men surveyed are both over 55 and have had one or more heart attacks.

Results showed that 65% of those asked gave higher estimates for the second question than the first.


Other heuristics lead people to assess risk by preferring small but certain gains over large but uncertain gains.

People are also predisposed to remember events which are supportive of personal prejudice than events which are not.

People often exhibit overconfidence in their incorrect judgements, a factor which has been shown in several experiments. Overconfidence is a source of many errors in business judgement.

Hindsight bias can be shown to occur in decision making. When people are asked to predict the outcome of an event, they may do so with even chances of success. However, when they are told the results in advance they frequently explain that the results were obvious and that they would have predicted them without the prior knowledge.


A good all round reference to human intelligence and brain networks is the paper from the American National institute for health.