What would make you happy?  A new car?  A new house?  Better health?  A better relationship?  A financial windfall?  Or none of the above?


According some psychologists, the correct answer is “none of the above.”  They describe a “hedonic treadmill,” which inevitably returns people to their baseline level of happiness.  The concept was first suggested by psychologists Philip Brickman and Donald Campbell in 1971 and has been supported by several studies.  According to this theory, just as we experience sensory adaptation when our eyes adjust to a suddenly bright room, we experience emotional adaptation to life events.  Thus, that new car may thrill you the first week or so, but in fairly short order you return to your old-car level of happiness.


What evidence is there that we’re stuck in happiness homeostasis?  In an early study, lottery winners were found to be no happier than non-winners.   Individuals who sustained spinal cord injuries had strong negative emotions a week after their accidents, but were happy two months later.  Also, nationwide surveys in some countries found that increases in income weren’t associated with gains in life satisfaction.


The research support for the hedonic treadmill, never especially strong, has eroded some over the years.  For one thing, economists Betsey Stevenson and Justin Wolfers found that, on a sample of nations from which there is extensive survey data, life satisfaction increased as per capita GDP increased.  There would have been no such increase if everyone adapted to changes in life circumstances, as the hedonic treadmill would have it.  See Wolfers’ description of the findings here.   Also, an article in the American Psychologist by Ed Diener, Richard Lucas, and Christie Napa Scollon presented evidence that happiness levels can change over time.  For example, in a longitudinal study in Germany following individuals over a 17 year period, 24% of study participants had significantly changed levels of happiness over the course of the study.  A study spanning five years before and five years after major life events found that three such events—being widowed, divorcing, and being laid off from work—resulted in long-lasting changes in life satisfaction.  A fourth event—getting married—resulted only in short-term changes in life satisfaction followed by return to baseline. 


Diener et. al. point out that the research findings that they summarize do hide individual differences in adaptation.  For example, though on average people return to baseline after marrying, some research participants evidenced lasting improvements in their satisfaction level, while others showed long term declines.


The hedonic treadmill hasn’t been entirely discarded, but it certainly is not the universal phenomenon that Brickman and Campbell envisioned.  Significant life events can sometimes result in a permanent change in one’s life satisfaction.  Of equal interest, it now seems that at least some deliberate efforts to change life satisfaction can be successful.  In fact, some psychologists have designed intervention programs of this sort.  A book-length description of such a program is Sonja Lyubomirsky’s The How of Happiness.  Happiness seekers, get off your treadmills!