The subject of human intelligence and how to measure it has a dark
history and remains one of the most controversial areas in psychology.
Despite this, intelligence tests are still used in many countries to
inform sensitive decisions – from whether a child is provided with
extra help at school to whether a job candidate should be hired or not.
What is intelligence?
In everyday life, intelligence is a familiar but incredibly vague concept.
We might all agree that a professor of astrophysics is in some sense
highly intelligent. But imagine if the same professor made a habit of
getting lost, offending colleagues or losing money on risky investments.
In these cases we might just as readily say that they were rather stupid,
socially inept or unwise. Conversely, a gangster with no qualifications to
their name might not be considered intelligent in an academic sense,
but we might refer to their street smarts – their understanding of who to
trust and how to avoid trouble. Common sense, creativity, tactical nous,
mathematical genius, people skills, literary talent – in common parlance,
all these abilities are at times seen as forms of intelligence.
The mainstream scientific view of intelligence is that it reflects the
“fitness” or efficiency of the brain and nervous system. The idea that
intelligence is more than just an abstract or subjective concept has been
supported by findings showing that someone who displays evidence
of cleverness in one domain, say maths, also tends to excel in other
domains too, such as language and spatial processing – an observation
that has come to be known as g or general intelligence. Moreover, people’s
performance on written or computerized tests of their mental skills and
knowledge also correlate with extremely basic tests of their reaction time
(their speed of mental processing), providing further support for the idea
that intelligence is the manifestation of an efficient nervous system.