People overlook subtractive solutions to mental health problems.

To solve problems, people tend to add new components to them rather than subtract from them. Across eight experimental and naturalistic studies, we examined if more additive (to start something new or do more) than subtractive advice (to stop or do less) is given when humans and artificial intelligence give mental health advice. Compared to subtractive advice, additive advice was recommended more frequently and was rated as more effective and feasible. Several moderators of this effect are explored: Older people are more additive than younger people, who we are advising (e.g., strangers/friends) matters, as does the type of pre-existing mental health-affecting activities (e.g., gambling versus avoiding exercise). People overlook subtractive advice when advising others and instead tell them to do more. Future research must explore the contribution of this additive advice bias to people's sense of being overwhelmed.