What is Moderation?
Moderation in behavioral science occurs when the strength or direction of a relationship between two variables depends on a third variable (the moderator). It answers the question: for whom or under what conditions does the effect occur?
How it works
A moderator changes the size or direction of an effect without being caused by the independent variable (unlike a mediator, which is caused by it). Gender might moderate the effect of a health message: the message works for women but not men. Age might moderate the effect of a nudge: it works for younger adults but not older adults. Identifying moderators is critical for targeting: rather than applying one intervention to everyone, you can match interventions to the subgroups for whom they work best.
Applied example
A study finds that financial incentives increase gym attendance, but only for people who are not already intrinsically motivated to exercise. For intrinsically motivated people, incentives have no effect or even reduce attendance. Intrinsic motivation is the moderator that determines whether incentives help or harm.
Why it matters
Moderation explains why interventions work for some people and not others, enabling personalized approaches rather than one-size-fits-all solutions.
