Context-appropriate infant physiological functioning may support emotion regulation and mother–infant emotion coregulation. Among a sample of 210 low-income Mexican-origin mothers and their 24-week-old infants, dynamic structural equation modeling (DSEM) was used to examine whether within-infant vagal functioning accounted for between-dyad differences in within-dyad second-by-second emotion regulation and coregulation during free play. Vagal functioning was captured by within-infant mean and variability (standard deviation) of respiratory sinus arrhythmia (RSA) during free play. Infant emotion regulation was quantified as emotional equilibria (within-person mean), volatility (within-person deviation from equilibrium), carryover (how quickly equilibrium is restored following a disturbance), and feedback loops (the extent to which prior affect dampens or amplifies subsequent affect) in positive and negative affect during free play; coregulation was quantified as the influence of one partner's affect on the other's subsequent affect. Among infants with lower RSA variability, positive affect fluctuated around a higher equilibrium, and negative affect fluctuated around a lower equilibrium; these infants exhibited feedback loops where their positive affect dampened their subsequent negative affect. As expected, infants with higher mean RSA exhibited more volatility in positive affect, feedback loops between their positive and negative affect, and stronger mother-driven emotion coregulation. The results highlight differences in simultaneously occurring biological and emotion regulation.

与情境相适应的婴儿生理机能可能支持情绪调节和母婴情绪协同调节。在 210 名墨西哥裔低收入母亲及其 24 周大婴儿的样本中，使用动态结构方程模型 (DSEM) 来检查婴儿内迷走神经功能是否解释了二元体内第二个二元体之间的二元体差异。自由游戏期间的秒级情绪调节和协同调节。迷走神经功能是通过自由游戏期间呼吸性窦性心律失常 (RSA) 的婴儿内均值和变异性（标准差）捕获的。婴儿情绪调节被量化为情绪平衡（人内平均值）、波动性（人内偏离平衡）、遗留（干扰后恢复平衡的速度）、自由游戏期间正面和负面影响的反馈回路（先前影响抑制或放大后续影响的程度）；共同调节被量化为一个伙伴的影响对另一个伙伴后续影响的影响。在 RSA 变异性较低的婴儿中，积极影响在较高平衡附近波动，而消极影响在较低平衡附近波动；这些婴儿表现出反馈循环，他们的积极影响会抑制他们随后的消极影响。正如预期的那样，平均 RSA 较高的婴儿在积极情感、积极和消极情感之间的反馈循环以及更强的母亲驱动的情绪协同调节方面表现出更大的波动性。结果突出了同时发生的生物和情绪调节的差异。