Intelligence Quotient

Of the different methods that purport to measure intelligence, the most famous is
the IQ (Intelligence Quotient) test, which is a standardized test designed to measure
human intelligence as distinct from attainments.
Intelligence quotient is an age-related measure of intelligence level. The word
quotient means the result of dividing one quantity by another, and one definition of
intelligence is mental ability or quickness of mind.
Usually, IQ tests consist of a graded series of tasks, each of which has been standardized
with a large representative population of individuals in order to establish
an average IQ of 100 for each test.
It is generally accepted that a person’s mental ability develops at a constant rate
until about the age of 13, after which development has been shown to slow down,
and beyond the age of 18 little or no improvement is found.
When the IQ of a child is measured, the subject attempts an IQ test that has been
standardized, with an average score recorded for each age group. Thus a 10-yearold
child who scored the result that would be expected of a 12-year-old would have
an IQ of 120, or 12/10 × 100:

Because after the age of 18 little or no improvement is found, adults have to be
judged on an IQ test whose average score is 100, and the results graded above and
below this norm according to known test scores.
Like so many distributions found in nature, the distribution of IQ takes the form
of a fairly regular bell curve (see Figure 0.1 below) in which the average score is 100
and similar proportions occur both above and below this norm.
There are a number of different types of intelligence tests, for example Cattell,
Stanford-Binet and Wechsler, and each has its own different scales of intelligence.
The Stanford-Binet is heavily weighted with questions involving verbal abilities
and is widely used in the United States. The Weschler scales consist of two separate

verbal and performance sub-scales each with its own IQ rating. On the Stanford-
Binet scale half the population fall between 90 and 110 IQ, half of them above 100
and half of them below; 25 per cent score above 110; 11 per cent above 120; 3 per cent
above 130 and 0.6 per cent above 140. At the other end of the scale the same kind of
proportion occurs.
Although it is IQ tests that we are specifically concerned with in this book it
should be pointed out that IQ tests are just one part of what is generally referred to
as psychometric testing. Such test content may be addressed to almost any aspect of
our intellectual or emotional make-up, including personality, attitude, intelligence
or emotion. Psychometric tests are basically tools used for measuring the mind; the
word metric means measure and the word psycho means mind. There are two types
of psychometric tests that are usually used in tandem by employers. These are
aptitude tests, which assess your abilities, and personality questionnaires, which
assess your character and personality.

Aptitude tests are also known as cognitive, ability or intelligence (IQ) tests. Such tests
are designed to test your ability to comprehend quickly under strictly timed conditions.
Cognition may be broadly defined as knowing, perceiving and thinking and it is studied
by psychologists because it reveals the extent of a person’s ability to think.
There are many different types of tests. However, a typical test might consist of
three sections each testing a different ability, usually comprising verbal reasoning,
numerical ability and diagrammatic, or spatial, reasoning. In order to give you the
opportunity to practise all types of questions that you are likely to encounter in
actual IQ tests, the tests that have been compiled for this book are multi-discipline
and include a mix of verbal, numerical and diagrammatic questions, as well as additional
questions involving logical thought processes as well as a degree of lateral
thinking.
In the past 25 years psychometric testing has been brought into widespread use
in industry because of the need for employers to ensure they place the right people in
the right job at the outset. One of the main reasons for this is the high cost of errors in
today’s world of tight budgets and reduced profit margins. To recruit a new member
of staff an employer has to advertise, consider each application, reduce the applicants
to a shortlist, interview and then train the successful applicant. If the wrong hiring
choice has been made, then the whole expensive process has to be repeated.

It is important that such tests are evaluated in tandem with each other. If a person
scores well on an aptitude test it does not necessarily mean that they will be suited to the
job: whilst you may be good at doing something, you may dislike it intensely, and
success in most tasks is heavily dependent on your personal qualities and your attitude.
Although it is generally accepted that a person’s IQ remains constant throughout
life and therefore it is not possible to increase your actual IQ, it is possible to
improve your performance on IQ tests by practising the many different types of
question and learning to recognize the recurring themes.
Besides their uses in improving one’s performance on IQ tests, practice on the
type of questions contained in this book has the added advantage of exercising the
brain. Our brains need exercise and care in the same way as other parts of the body.
We eat the right foods to keep our heart healthy, we moisturise our skin to keep it
from drying out and, just as gymnasts strive to increase their performance at
whatever level they are competing by means of punishing training schedules and
refinement of technique, there are exercises, or mental gymnastics, we can do to
increase the performance of our brains and enhance quickness of thought.
Many people still have the outdated belief that there is little they can do to
improve the brain they are born with and that brain cells continually degenerate
with age: but, in fact, our brain cells continually develop new and stronger connections
and adult brains can grow new cells irrespective of age.
The main thing is to use your brain continually. For example, the more we practise
at tests of verbal aptitude the more we increase our ability to understand the
meaning of words and use them effectively; the more we practise at maths the more
confident we become when working with numbers, the better our ability to perform
arithmetic operations accurately, and the quicker we become at performing these
operations; and the more we practise our ability to move our fingers and manipulate
small objects the more dextrous we become at operations involving this type of
aptitude, and the quicker we become at performing them accurately.
The tests that follow have been compiled for this book and are not, therefore, standardized,
so an actual IQ assessment cannot be given. However, a guide to assessing
your performance for each test is provided below as well as a cumulative guide for
your overall performance on all 25 tests.
Atime limit of 90 minutes is allowed for each test. The correct answers are given at the
end of the book, and you should award yourself one point for each completely correct
answer. Calculators may be used to assist with solving numerical questions if preferred.
Use the following table to assess your performance in each of the 25 tests:

One test:
Score Rating
36–40 Exceptional
31–35 Excellent
25–30 Very good
19–24 Good
14–18 Average