Vocalization and looking behaviour of Down's syndrome infants.

Abstract

The effect of contingent and non-contingent vocal stimulation on vocalization and looking behaviour was investigated for 10 Down's syndrome infants. There were two experimental sessions consisting of four stages, namely 1 min base-line, 1 min experimental condition, a further 1 min base-line and a final 2 min experimental condition. Maternal vocal stimulation was contingent upon infant vocalization for the experimental conditions of one session and was presented every 10 s independent of infant vocalization for the experimental conditions of the other session. Neither condition increased infant vocalization but there was a significant decrease in looking at mother during the base-line stages which followed maternal vocalization (F = 5.07, d.f. = 4, 28, P less than 0.01). It is suggested that looking behaviour may be an important indication of competence in pre-linguistic social communication for developmentally delayed infants.