Abstract
Dyslexia is a neurodevelopmental condition characterized by reading difficulties, yet there is growing evidence for coinciding social and emotional strengths. In our previous work, we found children with dyslexia displayed greater emotional facial behavior to affective stimuli than their well-reading peers, an enhancement that related to better social skills. Traditional measures provide static "snapshots" of emotional facial behavior but overlook important dynamic information about the face's movements that may confer interpersonal advantages. Here, we examined whether variability in emotional facial behavior was heightened in children with dyslexia and associated with social communication benefits. We coded the second-by-second intensities of ten emotional facial behaviors in 54 children (ages 7-14) with (n = 33) and without (n = 21) dyslexia while they watched five emotion-inducing film clips. For each trial, we calculated two facial behavior variability scores: a within-emotion variability score (the second-by-second intensity changes within each category of emotional behavior) and a between-emotions variability score (the total number of changes between categories of emotional behavior). Parents also reported on children's real-world communication skills. Linear mixed-effects models (controlling for age, sex, and total facial behavior) revealed that children with dyslexia had higher within-emotion facial behavior variability but not higher between-emotions facial behavior variability than those without dyslexia. Across the sample, greater total within-emotion facial behavior variability correlated with higher parent-reported functional communication-the ability to express ideas in ways that others can easily understand. These findings suggest nuanced emotional facial behavior dynamics contribute to social strengths in dyslexia. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10919-025-00490-3.