Traditional economic theory suggests that people make
decisions based on the expected change in their level of
‘well-being’, where the technical term for well being is
‘utility’. An increase in an individual’s utility may relate to
any number of events, such as a pay rise, the purchase of
a new stereo, an improvement in health or an improvement
in local biodiversity. However, the effect of the same event
on increases (or decreases) in utility varies between people
and between times in a single person’s life – so not all
events bring the same level of increase in utility every time
they occur.