THE ROUGH GUIDE TO PSYCHOLOGYModern intelligence tests give the test-taker a standardized score,
known as their intelligence quotient (IQ), that shows how well they
have done relative to a large comparison-sample of healthy adults
or, in the case of a child, in comparison with other children of their
age. When someone achieves a raw score that equates to the average
performance of the comparison sample, this is converted to 100.
Approximately half the general population has an IQ lower than 100,
while has have a higher intelligence. A difference of one standard
deviation from the average intelligence – standard deviation is the
square root of the average amount of deviation from the average
score – equates to about 15 IQ points. This means that a person with
an IQ of 115 is considered to have scored higher than 84 percent of
the population. Traditionally, an IQ score of 70 or less is considered
12 3456 78Developed by John C. Raven as a way of gauging abstract, non-verbal intelligence,
Raven’s Progressive Matrices are still considered to be one of the most effective
ways of assessing general intelligence. (The correct answer is No.1.)