Salivary a-amylase and heart rate as markers of an infant's emotional contagion response using maternal factors as predictors

Abstract

Scope and Method of Study:

Empathy generates interest due to its implications for prosocial development. Work in this area examining infant populations is limited, specifically between 3 and 9 months of age, however, in part due to difficulties in measurement. While mature empathy is not developed until a later age, a rudimentary version of empathy referred to as emotional contagion (EC) does appear to be present. One purpose of the present study was to examine whether a recent form of measurement of the sympathetic nervous system (SNS) called salivary a-amylase (sAA) could be used in addition to heart rate (HR) as a method of assessing EC in 3 and 6 month old infants. Furthermore, evidence reviewed suggests that maternal responsiveness appears to mold empathy development. Infants and their mothers (N = 36) visited the laboratory when the infants were 3 and 6 months of age. Mothers were assessed through self-report measures on parenting risk, parenting stress, and parenting styles at the 3-month visit only. At both visits infants were played a 5 min recording of another infant crying. During this time, HR data was collected and sAA (6 month visit only) from infant saliva was collected before and after the cries played.

Findings and Conclusions:

Results showed that both HR (non sig.) and sAA levels (sig.) increased in response to the cries. Such results lend support to the use of sAA as a measurement of EC in infants at the age of 6 months and suggest that the developmental emotional contagion response appears to be an increase in SNS arousal. Relations between HR and sAA, while present, were not uniform. HR difference at 6 months was positively correlated to post cry sAA levels and greater differences in sAA. Few relations were found between HR at 3 months and maternal factors and no significant correlations were seen with maternal factors and sAA or HR at 6 months. Greater changes in HR were associated with lower levels of maternal stress and level of permissiveness was negatively related to baseline HR. Data presented might suggest a developmental difference between infant ages concerning their SNS or an inconsistency in the developmental trajectory of emotional contagion. Limitations and suggestions for future research were also discussed.