Early life experiences influence the regulatory and relational capacities of a developing human. Under healthy conditions, mothers and newborns achieve synchrony in their social interactions wherein the infant signals the caregiver, who, in return, responds sensitively and contingently. These healthy interactions provide an optimal environment, nourishing the development of self-regulation. The Still Face Paradigm is used frequently as a lab-controlled situation for studying self-regulation in infants. The lab task interrupts contingent interaction between mother and infant, typically eliciting affective responses indicative of the infant's self-regulatory skills. The current study proposed implementation of longitudinal statistical techniques which allow for the examination of response patterns during the socially stressful task with the mother and infant, specifically examining and comparing the intercepts and slopes of affect within each segment of the task. It was concluded that 15-second intervals are ideally reliable and able to detect differences in change among the three segments of the Still Face Paradigm.