A field-descriptive and experimental study of verbal behaviour in one year old children

This investigation consisted of field-descriptive and experimental analysis of young children's verbal behaviour, aiming at the identification and description of parental verbal stimulation and assessment of reinforcement variables. Five 21-month-old children and their respective mothers participated in the field-descriptive study. Observational sessions were carried out at the subjects' home and in a playroom; the situation was one of free-play. Verbal behaviour was taped; non-verbal behaviour was recorded according to selected categories. The audio-tapes were submitted to a technique designed to record the kind and frequency of utterances and the temporal interval between them. The interactive sequences of mother-child utterances were analysed with regard to these three aspects. Indices were computed to describe the characteristics of the patterns of interaction with regard to maternal verbal behaviour and to the child's verbal performance. The results indicated relationships among the categories aid descriptive indices of maternal behaviour and the child's speech: 1) the frequency of the child's verbalisations did not relate to the total amount of maternal verbal output in itself but to the mother's utterances which consisted of a direct response, within 4 sec, to the child's previous utterance; 2) the child's usage of speech correlated with the degree in which the mother responded selectively to the child's utterances; 3) the mother presented different verbal responses as consequences to the child's utterances, which had significant differential effects on the child's verbal performance as related to initiation, maintenance and ending of verbal chains of interaction. Two out of these five children participated in the experimental study which tested the effectiveness of 'repetition' (plus praise and/or the subject's name) as compared with the effectiveness of a material reinforcer (a small toy) on the emission of "correct utterances" as opposed to "incorrect utterances". The verbal reinforcer was delivered by a 'talking clown' and the material reinforcer by feeder. The results indicated that the verbal reinforcer was relatively more effective in controlling the subjects' rate of 'correct' verbal responses. When reinforcement was delayed the main effect observed was the decrease of rate of responses during the verbal periods to a level similar to that observed during the periods of contingent material reinforcement. The results were discussed within a reinforcement theory framework, and suggestions concerning certain methodological requirements to analyse parental stimulation in relation to children's language development were presented.