Effects of mother’s imitation on speech sounds in infants with Down syndrome

•This is the first study to show effects of contingent vocal imitation in infants with Down syndrome.•Imitating infant’s vocalizations may help increase infant’s rate of speech sounds.•This study shows how using the relative strengths in socialization in Down syndrome may help improve relative weaknesses in expressive language. The Down syndrome behavioral phenotype includes delays in making speech sounds, production of more non-speech sounds than speech sounds, and contrasting strengths in social development. Within a behavior analytic framework, we conceptualize characteristics of the Down syndrome behavioral phenotype as creating a context for impairments in speech sound development that suggest interventions caregivers can use to improve speech sounds. We examined one intervention, the effects of mother’s contingent vocal imitation, on rate of speech and non-speech sound production in infants with Down syndrome using an ABAB design. Mothers responded favorably to learning to imitate their infants’ vocalizations and their contingent vocal imitation was associated with increases in infant speech sounds. The increases in infant speech sound suggest the promise of this approach and future research examining variations in contingent vocal imitation and additional outcomes.