Impact of parity and salivary hormonal levels on motivation towards infant emotions

We studied 54 Finnish first-time mothers and 42 non-mothers in a pay-per-view key-press task where the participants were shown 20 infant faces with smiling and crying expressions. Participants were able to adjust the time each face was visible. In addition, salivary testosterone, estradiol, and cortisol levels were measured and their impact on motivation towards infants analyzed. When controlling for the hormonal levels, happy infant faces were viewed longer than crying faces and there was no difference in mean viewing times between mothers and non-mothers. An interaction between parity and emotion emerged: mothers were more motivated to view happy faces and less motivated to view crying infant faces than non-mothers. Testosterone had a significant effect on viewing times: the higher the testosterone levels were, the shorter amount of time infant faces were viewed. This indicates that testosterone is inversely associated with approach motivation to emotional infant stimuli. This study is the first to compare mothers and non-mothers in a task measuring motivational responses to infant stimuli and indicates that the difference between the approach motivation caused by happy and distressed infant emotions might be more heightened in new mothers.