The basic mechanism of hedonic adaptation
Hedonic adaptation refers to the phenomenon whereby people react strongly to positive or negative changes in their circumstances for a time, only for that reaction to fade as the weeks pass until they return to an emotional baseline known as the set point. Brickman and Campbell gave the phenomenon its conceptual form in 1971 under the name of the hedonic treadmill. Early work pointed to cases such as lottery winners returning within months to roughly the level of happiness they reported before winning, and people who sustain severe disabilities recovering much of their happiness. Later research, however, reports that the effects of major life events do not always disappear entirely, and that the baseline itself can shift and stay shifted. In neuroscientific terms, the mechanism of reward prediction error in the dopamine system is involved. A novel reward triggers a large release of dopamine, but when the same reward is repeated the prediction is updated and the dopamine response diminishes. This is the neural basis of what we ordinarily call getting used to something.
Hedonic adaptation in romantic relationships
In romantic relationships, hedonic adaptation shows itself plainly as the decline of passion. The intense excitement, craving, and euphoria of early love arise from an overactivation of the dopamine system, but as neural adaptation to the partner as a source of reward proceeds, the pleasure obtained from that same person decreases. The passionate feelings of early love usually settle down gradually over a period of months to years, and when that happens varies widely from couple to couple. This is not a deterioration in the quality of the relationship; it is a normal process of neural adaptation. Many couples nonetheless interpret the decline as love having gone cold and mistake it for evidence that something is wrong between them. Understanding hedonic adaptation matters precisely because it prevents that misreading and allows the value of what comes after the decline of passion, namely companionate love, to be recognized for what it is. Sonja Lyubomirsky's research has shown that the rate of hedonic adaptation varies between individuals, and that deliberate activity such as practicing gratitude and sharing novel experiences can slow the process down.
Countermeasures, and hedonic adaptation in compatibility assessment
Several scientifically supported methods exist for working against hedonic adaptation. The first is introducing novel shared experiences, following Aron's self-expansion theory. New activities reactivate the dopamine system, and the pleasure they produce is attributed to the relationship with the partner. The second is the conscious practice of gratitude: putting appreciation into words as a daily habit, in order to block the adaptation that turns a partner's presence into something taken for granted. The third is arranging a measure of distance and then reunion, since a temporary separation heightens the reward response when the two come back together. Where personality comes in, high openness may be associated with some resistance to hedonic adaptation. Couples high in openness pursue novel experiences together readily and tend to revitalize the relationship almost as a matter of course. Where both partners are low in openness, the need to introduce novelty deliberately is correspondingly greater. When passion begins to feel thinner, taking that as a sign of having grown used to the same stimulus rather than as a loss of feeling for the other person saves you from hastily doubting the relationship itself. Growing used to things cannot be avoided, but once you can see what the two of you have grown used to, it also becomes clearer what to make new next.