In order to further our understanding of the nature of hormonal interactions in nurturing behavior, the present study used functional magnetic resonance imaging (fMRI) and a double-blind placebo-controlled OT administration between-subjects protocol to examine the influence of exogenous OT and endogenous T on selective attention to the BS in nulliparous women. To assess selective attention to the BS we used an implicit association task. Implicit association tasks have the advantage that the degree of attentional capture by an infant as opposed to an adult face can be determined implicitly by the mean reaction time (RT) of the participant, with a shorter RT indicating faster attentional processing of the baby schema and increased action. Previous neuroimaging studies combined passive viewing and explicit evaluation tasks (e.g., cuteness perception on a Likert-Scale), which are more vulnerable to experimenter demand effect. Further, these studies do not allow the assessment of the mechanism that promotes faster reactions to infants. Building on previous findings6 we hypothesized that OT administration would compensate the negative effects of high endogenous T on attentional processing of the BS, probably through the modulation of activation in key nodes of the mesolimbic reward system.