Cortisol reactivity, maternal sensitivity, and infant preference for mother's familiar face and rhyme in 6‐month‐old infants

Abstract

This study investigated how cortisol (stress) reactivity and mothers' behavioural sensitivity affect familiarity preferences in 6‐month‐old infants. Relations between sensitivity and stress were explored using saliva samples taken from mothers and infants before, and 20 min after, two preferential looking experiments. Photographs and voice recordings from infants' mothers were incorporated into standard visual preference tasks. Sensitivity was assessed by determining the degree of behavioural synchrony between mother and infant from a 10‐min interaction period preceding the preferential looking experiments. Results showed that decreasing infant cortisol reactivity and greater maternal sensitivity were associated with familiarity preferences for mother's face stimuli. For the experiment with voice stimuli, a sex difference was obtained in the relationship between the directionality of cortisol reactivity and familiarity preferences. Results are related to a parallel study with 3‐month‐old infants, and issues are discussed in terms of infants' developing emotional independence from mother.

Keywords:

• cognitive
• infant
• social interaction
• mothers
• quantitative

Acknowledgements

The research was funded by a NIH NIGMS grant (#3S06 GM008136) and the NIH MBRS RISE grant program (#6M61222). We thank Elizabeth Arias, Leila Diaz, Carla Escabi‐Ruiz, Lori Fields, Erin Johns, Denisse Licon, Xavier Peña, Katie Silva, and Roseanna Villarreal, for help with data collection and coding, Dr. Megan Gunnar for her helpful comments, and the mothers and infants who participated in this study.

Notes

1. To establish whether or not there was a difference in cortisol reactivity between those infants with usable looking time data and those without, two‐tailed paired samples t‐tests were conducted between log₁₀ T1 and T2 values for infants whose looking time data could not be analyzed, separately for the faces and rhymes experiments. As was the case in the larger sample, log₁₀ T1 and T2 values for the infants whose looking time data could not be included were not significantly different from each other, for both the faces and the rhymes experiment (p>.05).