Relationship between Temperamental Dimensions and Infant Limb Movement Complexity and Dynamic Stability

Dimensions of infant temperament describe behavioral responses to stimulation; however, motor systems undergo considerable changes throughout infancy, and they are also affected by caregivers’ mental well-being. In this paper, we investigate temperamental associations with high-level measures of motor system organization at 6 and 12 months of age across three different social interaction tasks. To capture the effects of caregiver mental well-being, we also include maternal trait anxiety in the analysis. In a longitudinally studied sample of 83 (at 6 months) and 59 (at 12 months) infants, we measured their limb movements with wearable accelerometers during three tasks with their caregiver (book sharing, manipulative toys, and rattle-shaking). We used Multidimensional Recurrence Quantification Analysis (MdRQA) and extracted the variables of Entropy and Mean Line, which provide information about motor systems’ complexity and stability, respectively. Using mixed-effects models, we evaluated the predictive effect of task and temperamental variables: Negative Affectivity (NEG), Positive Affectivity or Surgency (PAS), and Orienting and Regulatory Capacity (ORC). Our results suggest that Negative Affectivity predicted increased motor system Entropy and Mean Line at 6 months as well as longitudinally at 12 months. Temperamental variables measured at 12 months of age did not predict infants’ motor systems’ complexity and stability at the same time point. However, only at 12 months of age, Entropy and Mean Line were modulated by task. Finally, higher maternal anxiety (measured at 4 months of an infant’s age) predicted decreased motor systems’ Entropy and Mean Line at 12 months of age. Our results have implications for understanding the early developmental pathways of motor system organization and its relationship with temperament, as well as the influence of caregiver mental well-being on infant’s motor development.