Helping others can entail risks for the helper. For example, when treating infectious patients,
medical volunteers risk their own health. In such situations, helping-decisions should depend on
the individual’s valuation of others’ well-being (social preferences) and the degree of personal risk
the individual finds acceptable (risk preferences). We investigate how these distinct preferences
are psychologically and neurobiologically integrated when helping is risky. We used incentivized
decision-making tasks (Study 1, N=292, mean age=22.3±3.7, 142 female) and manipulated
dopamine and norepinephrine levels in the brain by administering methylphenidate, atomoxetine,
or placebo (Study 2, N=154, mean age=23.7±3.9, 77 female). We find that social and risk
preferences are independent drivers of risky helping. Methylphenidate increased risky helping by
selectively altering risk- rather than social preferences. Atomoxetine influenced neither risk nor
social preferences and did not affect risky helping. This suggests that methylphenidate-altered
dopamine concentrations affect helping decisions that entail a risk to the helper
