There are many theories surrounding infant imitation; however, there is no research to our knowledge evaluating the reliability of listener perception of vocal imitation in prelinguistic infants. This paper evaluates intra- and inter-rater judgments on the degree of “imitativeness” in utterances of infants below 12 months of age. 18 listeners were presented audio segments selected from naturalistic recordings to represent in each case a parent vocal model followed by an infant utterance ranging from low to high degrees of imitativeness. The (...) naturalistic data suggested vocal imitation occurred rarely across the first year, but strong intra- and inter-rater correlations were found for judgments of imitativeness. Our results suggest salience of the infant’s vocal imitation despite its rare occurrence as well as active perception by listeners of the imitative signal. We discuss infant vocal imitation as a potential signal of well-being and as an indicator of language learning and vocal communication skills as perceived by caregivers. (shrink)

SummaryThe relationship between inter-generational social mobility of sons and daughters between 1958 and 1991 and biosocial variables, i.e. birth order, number of children in family, father's social class, region, educational attainment of child and father, educational and cognitive test scores, was studied in a large British cohort study. The data used were collected as part of the British National Child Development Study. The extent of social class mobility was determined inter-generationally and was categorized as none, upwardly mobile or downwardly mobile. (...) All of the biosocial variables were associated with social mobility when analysed separately. Multivariate analyses revealed that the most significant predictor of mobility categories in both sexes was education of the cohort member, followed by social class of the father. In both sexes mathematics score was a significant predicator, while in sons reading and non-verbal IQ scores were also important predictors. In the light of these results, it appears that social mobility in Britain takes place largely on meritocratic principles. (shrink)

Birth order has been examined over a wide variety of dimensions in the context of modern populations. A consistent message has been that it is better to be born first. The analysis of birth order in this paper is different in several ways from other investigations into birth order effects. First, we examine the effect of birth order in an egalitarian, small-scale, kin-based society, which has not been done before. Second, we use a different outcome measure, fertility, rather than outcome (...) measures of social, psychological, or economic success. We find, third, that being born late in an egalitarian, technologically simple society rather than being born early has a positive outcome on fertility, and fourth, that number of older siblings and sibling set size are even stronger predictors of fertility, especially for males. (shrink)