Mood (Psychology)--Physiological aspects.

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.

Previous research has shown that the intrapersonal characteristics (e.g.,
temperament) of children are associated closely with alterations in the functioning of the
hypothalamic-pituitary–adrenal (HPA) stress axis. However, consistently capturing direct
associations between these characteristics and stress reactivity of the HPA axis has, at
times, yielded disparate findings. Thus, using the Rothbart model of temperament
(Rothbart & Derryberry, 1981) as a guide, the main goal of this project was to investigate
and identify intrapersonal characteristics that moderate associations between other
intrapersonal characteristics of the child and stress reactivity during development (e.g.,
trait by trait interactions). Additionally, study variables were assessed for meaningful
associations and, on average differences between those who responded to the stressor
paradigm and those who did not. A sample of 45 male and 37 female students (n=82, M=
9.66 yrs.) from six, fourth and fifth grade classes partook in a mathematically based stressor paradigm administered in the classroom. Salivary cortisol and behavior measures
were collected in two waves over a 7-week period. Several significant results emerged.
Overall, children who responded to the stressor paradigm had significantly higher levels
of traits associated with a more inhibited behavioral style. Further, several meaningful
interactions surfaced in which intrapersonal characteristics of various categories,
including reactive, regulatory, and ambiguous, interacted with one another to predict
stress reactivity. Of note, the majority of the interactions involved self-regulation and
surgency. These two intrapersonal characteristics interacted with several others, helping
to elucidate the unique influences of these intrapersonal characteristics on each other and,
subsequently, stress reactivity of the HPA axis. These results illustrate that interactions
between multiple intrapersonal characteristics should be taken into consideration in the
future when studying the relationships between intrapersonal characteristics and stress
reactivity of the HPA axis.