Scatterplots with regression lines relating interpersonal smile coordination (unfamiliar condition) to scores on parent rating scales of social–emotional functioning. SRS-2 SCI, Social Responsiveness Scale, Second Edition Social Communication and Interaction T-Score (higher scores = more social atypicality); Vineland-II Socialization, Vineland Adaptive Behavior Scales, Second Edition Socialization standard score (higher scores = better adaptive social skills); IRI Total, Interpersonal Reactivity Index (higher scores = more empathy).