Symbols Build Communication and Thought: The Role of Gestures and Words in the Development of Engagement Skills and Social‐emotional Concepts during Toddlerhood

Social skills and symbol skills are positively associated in middle childhood, but the relation between these domains is less clear in newly verbal toddlers. Vygotsky proposed that symbols are both tools for interaction and mental tools for thought. Do symbols help even very young children build skills for interacting with and conceptualizing the social world? Longitudinal data from 108 children and mothers were collected when children were 14, 24, and 36 months. Children's gestures and words during mother–child interactions were used as symbol skill indicators to predict children's abilities to engage others and the number of social‐emotional concepts children portray during play. In a series of growth models, words had a stronger effect on engagement skills whereas early gesture use predicted later development of social‐emotional concepts. Therefore, even in early development, symbols serve as both communication tools and mental tools to construct understanding of the social‐emotional world.     

RANDOM THRESHOLD MODELS APPLIED TO INFLATED ZERO CLASS DATA

For a random component threshold model, the threshold parameters are functions of a linear combination of fixed and random components. This paper describes estimation procedures in terms of composite link functions. The models give a good fit to the frequency of use of medical procedures in the different counties of Washington State, USA. Suitable models for studying change in county effects in successive years are developed.     

Parenting Supports for Early Vocabulary Development: Specific Effects of Sensitivity and Stimulation through Infancy

Growing recognition of disparities in early childhood language environments prompts examination of parent–child interactions, which support vocabulary. Research links parental sensitivity and cognitive stimulation to child language, but has not explicitly contrasted their effects, nor examined how effects may change over time. We examined maternal sensitivity and stimulation throughout infancy using two observational methods—ratings of parents’ interaction qualities and coding of discrete parenting behaviors—to assess the relative importance of these qualities to child vocabulary over time and determine whether mothers make related changes in response to children's development. Participants were 146 infants and mothers, assessed when infants were 14, 24, and 36 months. At 14 months, sensitivity had a stronger effect on vocabulary than did stimulation, but the effect of stimulation grew throughout toddlerhood. Mothers’ cognitive stimulation grew over time, whereas sensitivity remained stable. While discrete parenting behaviors changed with child age, there was no evidence of trade‐offs between sensitive and stimulating behaviors, and no evidence that sensitivity moderated the effect of stimulation on child vocabulary. Findings demonstrate specificity of timing in the link between parenting qualities and child vocabulary, which could inform early parent interventions, and support a reconceptualization of the nature and measurement of parental sensitivity.     

MODELLING TRUNCATED AND CLUSTERED COUNT DATA

Count response data often exhibit departures from the assumptions of standard Poisson generalized linear models. In particular, cluster level correlation of the data and truncation at zero are two common characteristics of such data. This paper describes a random components truncated Poisson model that can be applied to clustered and zero‐truncated count data. Residual maximum likelihood method estimators for the parameters of this model are developed and their use is illustrated using a dataset of non‐zero counts of sheets with edge‐strain defects in iron sheets produced by the Mobarekeh Steel Complex, Iran. The paper also reports on a small‐scale simulation study that supports the estimation procedure.     

Small area estimates of labour force participation under a multinomial logit mixed model

Summary.  A new methodology is developed for estimating unemployment or employment characteristics in small areas, based on the assumption that the sample totals of unemployed and employed individuals follow a multinomial logit model with random area effects. The method is illustrated with UK labour force data aggregated by sex–age groups. For these data, the accuracy of direct estimates is poor in comparison with estimates that are derived from the multinomial logit model. Furthermore, two different estimators of the mean-squared errors are given: an analytical approximation obtained by Taylor linearization and an estimator based on bootstrapping. A simulation study for comparison of the two estimators shows the good performance of the bootstrap estimator.     

Developmental Trends in Self-regulation among Low-income Toddlers

The attainment of self‐regulatory skills during the toddler years is an understudied issue, especially among low‐income children. The present study used growth modeling to examine the change over time and the final status in children's abilities to self‐regulate, in a sample of 2,441 low‐income children aged 14 to 36 months. Positive growth in their self‐regulation occurred between 14 and 36 months, but individual variation was observed in both the growth rates and final status. Children who showed high degrees of negativity at 14, 24 and 36 months grew at slower rates than other children. Boys and children high in negativity had lower scores in self‐regulation at 36 months than girls and children with low negativity, whereas higher quality mother–child interactions at 14 and 24 months were associated with better self‐regulation at 36 months. The results suggest that some children may be at risk for developing problems in regulation because of mother–child interaction patterns and child characteristics such as high negativity.