Physiological synchrony between mothers and their children was associated with a mixed set of emotional and behavioral outcomes during a laboratory stress task. Higher synchrony in a measure called RSA was linked to higher positive affect after the task, but also to more mother-reported internalizing symptoms, a broad term for inward emotional difficulties. The same RSA measure was linked to fewer mother-reported externalizing symptoms, or outward behavioral difficulties.
These were associations, not proof that synchrony caused a child's mood or behavior. In this analysis, synchrony meant that the mother and child's physiological trajectories changed together over the task; it did not establish that either person regulated the other's physiology.
A laboratory stress test
The analysis included 173 mothers and their children. Mothers had a mean age of 41.60 years, while the youth had a mean age of 9.54 years; the children were 8 to 12 years old, and 53 percent were female. Eligibility required English proficiency, co-residence, and no diagnosed developmental disorder in the child.
Before the stressor, mothers were randomly assigned to one of three memory-task conditions: relational savoring, an academic condition, or a control condition. The researchers included that assignment as a covariate, so the analysis accounted for it when estimating the links between synchrony and well-being.
The youth then completed six unsolvable computer puzzles, each lasting 60 seconds, while their mothers observed. ECG was recorded continuously from both members of each pair.
The researchers examined respiration rate, RMSSD and RSA. Respiration rate was treated as a broad autonomic index, while RMSSD and RSA were treated as indices of parasympathetic-mediated functioning, a technical label for one part of automatic physiological regulation.
To estimate synchrony, the team used multilevel latent growth models. In practical terms, the models estimated how each person's physiology changed across the six puzzle periods and then tested whether the two trajectories moved together. The researchers used linear trajectories because a quadratic model did not improve the representation of change.
One signal, several outcomes
The task was accompanied by lower positive affect after the puzzles and higher negative affect. Both changes were statistically significant.
Greater RSA synchrony was associated with higher post-stressor positive affect even after pre-stressor positive affect was taken into account. The reported p value was 0.003, and the standardized association coefficient was 0.50.
Greater RSA synchrony was also associated with higher mother-reported internalizing symptoms. The reported p value was 0.003 and the standardized coefficient was 0.48. At the same time, greater RSA synchrony was associated with lower mother-reported externalizing symptoms, with a p value of 0.04 and a standardized coefficient of -0.31.
The other results were less conclusive. RMSSD synchrony showed a nonsignificant trend toward greater anxiety symptoms, with a p value of 0.08. Respiration-rate synchrony showed a marginal trend toward fewer mother-reported externalizing symptoms, with a p value of 0.06, which was not conventionally statistically significant.
No physiological synchrony index was significantly associated with youth-reported anxiety, depressive symptoms or aggression. No synchrony index was significantly associated with post-stressor negative affect after the corresponding pre-stressor affect measure was taken into account.
The mixed pattern argues against treating physiological synchrony as a universal sign of healthy or unhealthy functioning. Coordinated trajectories may have different meanings across outcomes, and the analysis could not show whether mothers influenced their children's physiology, children influenced their mothers' physiology, or both were responding in parallel.
What the pattern does not tell us
The study's timing leaves an important question open. Synchrony and most well-being measures were assessed concurrently, so the analysis cannot establish which came first or determine the direction of the relationship. The pre-stressor and post-stressor affect measures provide a sequence for affect, but the symptom outcomes were not measured that way.
The design also did not include behavioral observations that could distinguish adaptive co-regulation from shared arousal or mutual dysregulation. The synchrony measure captured broad trends across six one-minute task periods, not moment-to-moment or lagged coordination.
Because the sample included only mothers and their preadolescent children, the findings cannot be assumed to apply directly to fathers, other caregivers or more socioeconomically diverse families.
Further work would need to combine physiological recording with behavioral observation, follow families over time or use lagged analyses, and test whether the pattern holds across different caregivers, stressors, physiological measures and timescales.
The funding statement identifies research funds from the principal investigator's institution, the University of California, Irvine.
Paper data and sources
Original title: The role of mother-youth biobehavioral synchrony during stress in predicting youth well-being
Authors: Rowley C, Ford J, Li F et al.
Journal/Repository: Frontiers in child and adolescent psychiatry
Status: Peer-reviewed
First online: 2026-10-19
DOI: Not available
Original paper · Full text