The primary goal of this study is to examine rhythm sensitivity as a predictor of response to naturalistic developmental behavioral intervention (NDBIs) in autistic toddlers. Toddlers receive either Reciprocal Imitation Training (RIT), an evidence-based NDBI that supports children's imitation and social communication skills, or a music-enhanced version of RIT. Throughout their participation in the intervention, toddlers will complete study procedures of viewing naturalistic videos of infant-directed singing and other social scenes while eye gaze data is collected.