Testosterone has been theorized to direct status-seeking behaviors, such as competitive decision-making. However, individual differences in basal cortisol and cues that signal an opponent’s status (an opponent’s gender or a prior win/loss in a competition) may moderate testosterone’s relationship with status-seeking behavior. This experiment (n = 115) examines the causal effect of testosterone treatment on men’s competitive behavior before and after receiving relative performance feedback (i.e. win/loss feedback) in mixed-gender math competitions, while also accounting for the moderating role of endogenous basal cortisol. Men given testosterone treatment who had high basal cortisol showed an increased tendency to compete against female opponents and avoid competition against male opponents; men given testosterone treatment who had low basal cortisol showed the opposite pattern (OR = 2.54, 95%CI [1.47, 4.37], p<.001). After providing trial-by-trial feedback, men given testosterone who had high basal cortisol re-entered competitions against low status opponents (prior losers) and avoided competition against high status opponents (prior winners); men given testosterone who had low basal cortisol preferred to re-enter competitions against high status opponents (prior winners) and avoid low status opponents (prior losers; OR = 10.21, [1.84, 56.54], p = .008). These results provide experimental support for a context-dependent dual hormone hypothesis: Testosterone flexibly directs men’s competitive behavior contingent on basal cortisol levels and cues that signal an opponent’s status.

Caregivers exhibiting low levels of positive caregiving tend to have reduced dynamic range in high- frequency heart rate variability (HRV), an index of parasympathetic nervous system activity. Yet less is known about the involvement of the sympathetic nervous system, which may impact the plausible range of parasympathetic reactivity. Here, caregiver–child dyads completed resting assessments of HRV and pre-ejection period (PEP), followed by a videotaped puzzle task during which HRV was measured and observers coded the degree of caregivers’ positive emotionality. Multilevel modelling was employed to characterize task fluctuations in HRV as a function of resting PEP and caregivers’ positive emotional expressions. Higher frequency of caregiver positivity was associated with greater HRV reactivity in caregivers but not children. Increased caregiver positivity was correlated with longer resting PEP in children. These results replicate findings of greater caregiver parasympathetic flexibility during positive caregiving and extend those findings to children’s resting sympathetic activity.