A Systematic Review of Definitions of Nonverbal and Minimally Verbal in the Autism Research Literature
This systematic review evaluated definitions of “nonverbal” or “minimally verbal” in intervention studies that focused on improving expressive verbal communication in children with autism spectrum disorder (ASD). We reviewed sample size, number of participants, participant age, participant sex, and assessment measures used to determine communication ability. Our review yielded relatively few studies focusing on verbal expressive communication with nonverbal or minimally verbal children with ASD. Further, we found large inconsistencies in definitions of “nonverbal” and “minimally verbal” and measures used to assess verbal communication ability. Guidelines are suggested in order to standardize terminology and allow for aggregation of research data that can inform best practice for interventions tailored to this population. Suggestions include creating a more uniform assessment protocol with systematic descriptions of early communication learners, as this is a foundational step for understanding the heterogeneity in nonverbal and minimally verbal children with ASD and replicating research findings for this subgroup.