Neuroticism is the flip side of
extraversion and describes a person’s
sensitivity to negative emotion. High
scorers are hesitant, vigilant and
nervous. Place them in a scanner,
show them negative images and their
brain will flare up far more than the
brain of a low scorer. Unsurprisingly
perhaps, high scorers on neuroticism
tend to suffer from higher rates of
depression and anxiety. It’s the deep
brain structures of the limbic system
that underlie neuroticism, including
the reactivity of the amygdala (see
p.39). The reason evolution hasn’t
eradicated neuroticism from the
genome is because in dangerous
circumstances, caution pays.
Conscientiousness is akin to will-
power. It describes our ability to
resist immediate temptation for the benefit of later gain. A high scorer
on this dimension will be disciplined and well-organized. Research
shows that highly conscientious personalities live longer and excel at
work. The relevant brain system here is the inhibitory mechanisms
of the frontal lobes. The price of too much control is a loss of flex-
ibility and spontaneity, which can manifest as obsessive compulsive
personality disorder. People who match this description tend to live
by exceedingly strict routines and find it difficult to cope with any
unpredictability.
Agreeableness describes a person’s friendliness and ability to engage
with others. The extrovert may seek out human company, but isn’t neces-
sarily a pleasant person to be around. A high scorer in agreeableness,
by contrast, is defined by their ability to understand and relate to other
people’s emotions. They are likely to work in a caring profession, be
family-oriented and a good listener. The brain systems underlying this
trait have to do with the ability to empathize and think of things from
other people’s perspectives. We haven’t all evolved to be high scorers on
this dimension, because caring too much for other people’s needs is
never going to be a winning strategy, especially when there are others in
the world ready to exploit your selflessness.
Shakespeare’s Hamlet, who
embodies the Renaissance
melancholic type, would nowadays
be considered highly neurotic.