The relationship between prelinguistic vocalization and later expressive vocabulary in young children with developmental delay

This study tested the relationship between prelinguistic vocalization and e xpressive vocabulary 1 year later in young children with mild to moderate d evelopmental delays. Three vocalization variables were tested: rate of all vocalization, rate of vocalizations with consonants, and rate of vocalizati ons used interactively The 58 toddlers in the study were 17-34 months old, not sensory impaired, and had Bayley Mental Development Indices (Bayley, 19 69; Bayley, 1993) from 35-85. In addition, the children had fewer than 3 wo rds in their expressive vocabularies and during classroom observation each showed at least one instance of intentional prelinguistic communication bef ore testing. Selected sections of the Communication and Symbolic: Behavior Scales procedures (CSBS; Wetherby & Prizant, 1993) were administered at the beginning and at the end of the study. The vocal measures were obtained in the initial CSBS session. One measure of expressive vocabulary was obtaine d in the CSBS session at the end of the study In addition, expressive vocab ulary was measured in a nonstructured play session at the end of the study We predicted that rate of vocalization, rate of vocalizations with consonan ts, and rate of vocalizations used interactively would all be positively re lated to later expressive vocabulary The results confirmed the predictions.