• Infants and toddlers first interactions with their parents

Newborn babies are often placed naked on their mother’s bare chest immediately after birth. This “skin to skin” experience has been shown to promote greater infant respiratory, temperature, and glucose stability, and to reduce crying (an indicator of decreased stress).

The influence of contact with the mother on infant physiology and behavior may reflect the fact that affective states can be transferred between two people via synchronized physiologic responses.

Waters and colleagues explored how touch mediates contagion of positive and negative affective states between mothers and their infants (aged 12–14 months). Mothers either watched videos of nature scenes and a slideshow of family members or gave a 5-min speech to a panel who responded with negative non-verbal feedback to induce either a positive/relaxed or negative/stressed mood, respectively. When mothers were subsequently reunited with their infants, half were placed in their mother’s lap (touch condition), and half were placed in a highchair next to the mother (no-touch condition).

Physiological measures confirmed that the negative/stress task induced sympathetic nervous system reactivity, and the positive/relaxation task induced parasympathetic nervous system reactivity in mothers. Importantly, these physiological states transferred to the infants: there were increases in parasympathetic nervous system activity in infants whose mothers completed the positive/relaxation task, and increases in sympathetic nervous system activity in infants whose mothers completed the negative/stress task.

Moreover, synchronization of mother-infant parasympathetic activity was stronger following the positive-relaxation task regardless of touch condition. In contrast, synchronization of mother-infant sympathetic activity was stronger following the negative/stress task, and this effect increased over time in the touch condition but decreased over time in the no-touch condition.

These results suggest that both high- and low-arousal affective states transfer between mothers and infants, and touch plays a critical role in the transmission of stress.

Waters et al. induced differences in maternal mood to test influences on infant affective state. Mascaro and colleagues examined whether there are naturally occurring differences in overt paternal behavior toward boy and girl children (1–2 years old).

Fathers wore an electronically-activated recorder that intermittently recorded ambient sound on one weekend day and one weekday. Fathers of daughters were more attentive, sang more, and used more analytical language when interacting with their daughters, whereas fathers of sons engaged in more rough-and-tumble play and used more achievement language with their sons.

Linguistic differences between fathers of daughters and fathers of sons were specific to direct interactions with their child, and were not observed in other interactions (e.g., with colleagues) recorded by the device. Subsequent fMRI data acquired while fathers looked at photographs of their children did not reveal neural responses that mediated the link between child gender and paternal behavior, but fathers of daughters had stronger neural responses in the medial orbitofrontal cortex to their daughter’s happy facial expressions, whereas fathers of sons had stronger responses in the same region to their son’s neutral facial expressions.

These exploratory results suggest that real-world paternal behavior and neural responses differ as a function of child gender, which may have implications for child social, emotional, and cognitive outcomes.


Waters, S. F., West, T. V., Karnilowicz, H. R., & Mendes, W. B. (2017). Affect contagion between mothers and infants: Examining valence and touch. Journal of Experimental Psychology: General, 146(7), 1043–1051.

Mascaro, J. S., Rentscher, K. E., Hackett, P. D., Mehl, M. R., & Rilling, J. K. (2017).

Child gender influences paternal behavior, language, and brain function. Behavioral Neuroscience, 131(3), 262–273.