I.Q. Test Information

The tests

The IQ tests produced by ThinkWare are designed to measure the five most important domains of intelligence — the ability to recognise and decode visual patterns — visual cognitive ability; the ability to recognise numerical patterns and solve problems — numerical ability; the ability to use our native language — verbal-linguistic ability; the ability to come to true conclusions about stated facts — logical deduction; and the ability to put all these other skills to practical and creative use — creative ability.

Sometimes it can be important to test a specific IQ domain. For example, an employer considering applicants for the post of trainee architect, would be wise to choose the one with the highest combined visual cognitive and numerical ability. Performance in school or college does not always reflect innate ability, because subjects who find themselves lacking an any area are likely to study harder for exams. These subjects may perform well academically, but have a tendency to make more mistakes in situations which they have never encountered before.

IQ tests, on the other hand, are specifically designed to test innate ability. Separate tests are available from ThinkWare to measure each domain. Combined tests are available to determine the overall IQ.


It is often beneficial to give test applicants a short informal test, which is not time limited, to familiarise them with the type of tests they will encounter during the official test. This helps to balance out inequities caused by test sophistication — applicants who have completed a number of IQ tests become familiar with typical problems and their methods of solution.

IQ distribution

Around fifty per cent of the population fall within the normal range of between 90 and 110. Very few people within this range achieve academic distinction, although much depends on the character of the individual, and the subjects being studied. Determination and hard study can be a good substitute for intelligence. It can even foster that quality. Occasionally, exceptional people towards the top of the normal range manage to become officers in the armed forces or achieve managerial positions in employment.

Most people who stay on at school taking academic subjects beyond the minimum leaving age are at the bright end of normal. Teachers come into the top six per cent with average IQs of around 130. Only around four per cent of the population have IQs of 140, and around seventy per cent of those at this level and above, according to a Californian study, are in professional or managerial positions — college lecturers, doctors, top business people, writers, and professors.

The IQ/job performance relationship

Studies have shown that IQ tests are a better predictor of future performance in both education and work, than any other form of selection, providing a more accurate indication of who is likely to succeed than even the most experienced personnel director or teacher.

In fact, interview based selection has negative predictive power, which is to say that those persons we instinctively feel will be good based on interview selection, are those people who do the least well, with lower production, more on-the-job mistakes, more time off sick, and poorer results in job evaluation tests. Interview based selection tests only the skill of the applicant at being interviewed, which is not the skill required in most jobs.

IQ tests, on the other hand, measure the ability to perform a large number of mental tasks effectively, and these are the same abilities that effective employees have — in jobs that require intelligence as the prime asset.

In jobs that require skill as the prime asset, the most effective method of selection is a skill-test combined with an aptitude tests to measure the more abstract or mental areas of skill. A major company once selected carpenters by interview — they got good talkers, but they did not get good carpenters.


The table of occupations below provides only tendencies, and is far from comprehensive. If you do not find your occupation or area of interest here, use the nearest equivalents. The physical position of each occupation within the table is meant to show where that occupation lies according to IQ — the higher the position, the higher the IQ. But of course, nothing is written in stone. Studies of applicants for membership of Mensa have shown that there is a spread of occupations throughout IQ levels. That said, it is rare to find an academic with an IQ of less than 130, or a road-sweeper with an IQ of over 120.

Please do not be offended if your occupation appears to be in a lower category here than you would expect. This table is intended as a rough guide only, and is based on average IQ levels. As you will be aware, to obtain an average we must take into account scores which are very much above the average, as well as those which are below the average.


What an IQ test can do for you personally

Taking an IQ test can transform your life. Victor Serebriakoff, founder and honorary international president of Mensa, tells of how the discovery that he had a high IQ, after taking an army IQ test, changed all his expectations and led to a life of achievement that he would never have thought possible.

Some people of high intelligence are trapped by circumstances into jobs that are far beneath them. Others may be simply lazy, and can’t be bothered obtaining the qualifications that would enable them to move up. That is a pity, because it has been shown that every extra year in education is worth around sixteen per cent extra income. We tend to get into our occupations before we gain an appreciation of our own potential. Then, once we qualify in that area we are unlikely to change careers unless external events force us to do so.

There are many secretaries, carpenters, labourers, and salespersons with IQ levels above most doctors, but their potential remains dormant.

— John Bremner (IQ and aptitude test designer. Mensa puzzle designer.) —


The opinions expressed in this document are John Bremner’s, and not those of Mensa Ltd.