Physiological measurement of emotion from infancy to preschool: A systematic review and meta‐analysis

INTRODUCTION: Emotion regulation, the ability to regulate emotional responses to environmental stimuli, develops in the first years of life and plays an important role in the development of personality, social competence, and behavior. Substantial literature suggests a relationship between emotion regulation and cardiac physiology; specifically, heart rate changes in response to positive or negative emotion‐eliciting stimuli. METHOD: This systematic review and meta‐analysis provide an in‐depth examination of research that has measured physiological responding during emotional‐evoking tasks in children from birth to 4 years of age. RESULTS: The review had three main findings. First, meta‐regressions resulted in an age‐related decrease in baseline and task‐related heart rate (HR) and increases in baseline and task‐related respiratory sinus arrhythmia (RSA). Second, meta‐analyses suggest task‐related increases in HR and decreases in RSA and heart rate variability (HRV), regardless of emotional valence of the task. Third, associations between physiological responding and observed behavioral regulation are not consistently present in children aged 4 and younger. The review also provides a summary of the various methodology used to measure physiological reactions to emotional‐evoking tasks, including number of sensors used and placement, various baseline and emotional‐evoking tasks used, methods for extracting RSA, as well as percentage of loss and reasons for loss for each study. CONCLUSION: Characterizing the physiological reactivity of typically developing children is important to understanding the role emotional regulation plays in typical and atypical development.