Behavioral Expressions of Jealousy Across the First Two Years of Life: Associations with EEG Asymmetry, Cortisol Reactivity and Attachment Security

Jealousy is understood as a system of physiological, behavioral, and emotional
responses, yet few studies have examined these aspects of jealousy simultaneously in
infants. Further, jealousy paradigms have not been examined as a potential stressor in
infancy and thus typical cortisol reactivity and regulation patterns in response to jealousy
paradigms have not been observed. In addition, the contribution of attachment security to
infant expressions of jealousy has been vastly understudied. The present study seeks to
fill the current gaps in the infant jealousy literature by investigating quantitative and
qualitative changes in infant jealousy across the first two years of life. Data was collected
longitudinally and mother- infant dyads were asked to participate when infants were 12-
months and 24-months of age. Associations between behavioral jealousy responses,
baseline EEG activity, stress reactivity and attachment security were examined.
Differences in approach behaviors and behavioral arousal were found across conditions and were consistent with previous studies (Hart & Carrington, 2002; Mize & Jones,
2012). Findings relating to EEG activity pointed to a relationship between left EEG
asymmetry and global approach behaviors across time. Cortisol reactivity was found to
be associated with attachment security but reactive cortisol concentrations compared to
baseline cortisol concentrations do not indicate that the paradigm was an effective
stressor. Attachment security was found to be associated with proximity behaviors in 12-
month olds but not 24-month olds. Finally, a linear regression revealed that attachment
security, EEG asymmetry, and cortisol reactivity at 12-months are significant predictors
of behavioral jealousy responses at 24-months. Changes in behavioral and physiological
measures across time indicate that jealousy continues to develop during the second year
of life but may have different underlying processes than the processes that contribute to
jealousy expression in 12-month-olds.