Belief that happiness/contentment reaches a stable and entropic level over time in spite of positive or negative emotional “ups” and “downs.” This steady-state level of happiness forms the basis by which the impact of upward or downward shifts are perceived.
Source: Behavioral Science Lab, 2017
People get used to changes in life experiences, a process which is referred to as ‘hedonic adaptation’ or the ‘hedonic treadmill’. Just as the happiness that comes with the ownership of a new gadget or salary raise will wane over time, even the negative effect of life events such as bereavement or disability on subjective well-being tends to level off, to some extent (Frederick & Loewenstein, 1999). When this happens, people return to a relatively stable baseline of happiness. It has been suggested that the repetition of smaller positive experiences (‘hedonic boosts’), such as exercise or religious practices, has a more lasting effect on our well-being than major life events (Mochon et al., 2008).
Source: Behavioral Economics