Changes in cardiac rate of human infants as a measure of their ability to discriminate between speech and non-speech stimuli

Abstract

Past experimental research has tried to evaluate the behaviour of infants to changes in speech stimuli without including non-speech control conditions. In a generalization of Moffitt (1971 ), this study included two square waves with roughly the same degree of difference in fundamental frequency as the consonant-vowel syllables "bah" and "gah". Infant cardiac rate changes were used as a measure of listening to changes in these speech and non-speech stimuli. Habituation and disinhibition were analysed separately There was nothing in either analysis which supported Moffitt's contention that infants react to changes in consonant-vowel syllables in a linguistically relevant manner. However, the infants responded differently to speech and non-speech stimuli when repeatedly presented, but did not behave differently to changes in these stimuli. This could be related to differences in the degree of autonomic changes which occur in response to the presentation of different types of aural stimuli.