Optimizing Early Intervention for Preschoolers\u27 Vocabulary Development

Preschool is a critical time in children’s oral language and pre-literacy skill development, but this development varies greatly among children. Those with smaller vocabularies are at greater risk for developing future language and reading difficulties that persist throughout their education. Because vocabulary knowledge is essential for later reading success, early instruction in preschool is key. To better understand how to enhance preschoolers’ word learning, the current dissertation contains three studies that examined the benefits of explicit vocabulary instruction and identified the factors that best facilitated vocabulary learning among a diverse group of young children. To aid in the early identification and intervention process, we must understand what these factors are, and how they contribute to preschool children’s vocabulary acquisition. Study 1 evaluated the effects of an automated, small-group intervention designed to teach preschoolers challenging vocabulary words. We sought to extend previous efficacy studies by determining the effects of doubling the number of words taught from two to four words per book. Seventeen preschool children listened to one prerecorded book per week for nine weeks. Each storybook had embedded, interactive lessons for four target vocabulary words. Each lesson provided repeated exposures to words and their definitions, child-friendly contexts, and multiple opportunities for children to respond verbally to instructional prompts. Participants were asked to define the weekly targeted vocabulary before and after intervention. A repeated acquisition design was used to examine the effects of embedded lessons in books on the learning of target vocabulary words. Treatment effects were observed for all children across many of the books. Learning of at least two points (i.e., one word) was replicated for 74.5% of 149 books tested across the 17 participants. On average, children learned to define 47% of the target vocabulary words (17 out of 36). Results support teaching four challenging words per book, as children learned substantially more words when four words were taught, in comparison to previous studies. Study 2 investigated the child, family, and classroom-level factors that relate to the vocabulary learning of 112 preschool children. A secondary data analysis was conducted using the results of an investigation examining the effects of a supplemental preschool vocabulary program. Structural equation modeling (SEM) revealed significant relations between child, family, and classroom-level factors and word learning including the child’s language skills and classroom environment. The family’s socioeconomic status related significantly to both children’s language skills and the classroom environment, but not directly to word learning. However, the Classroom Environment and Language Skills construct were moderate predictors of vocabulary learning. Understanding the individual factors that are most related to preschoolers’ word learning will aid in the development of effective strategies to enhance young children’s vocabulary acquisition. Study 3 investigated how lexical characteristics of words relate to vocabulary learning in 112 preschool children. A secondary data analysis using multilevel modeling was used to examine the effects of a supplemental preschool vocabulary program to determine if relations between lexical characteristics and word learning exist, and to what extent these characteristics predict word learning in young children. The contributions of the following lexical characteristics to the learning of 72 words were investigated: word frequency, age of acquisition, level of concreteness, neighborhood density, and phonotactic probability. Findings indicate that significant relations exist between word learning and all five of the lexical characteristics. When differences between children are controlled, word frequency, age of acquisition, level of concreteness, neighborhood density, and phonotactic probability accounted for approximately 2% of the variance in vocabulary learning, whereas the differences among children accounted for 26% of the variance. Further investigation is warranted to determine the impact lexical characteristics have on vocabulary learning. This has potential to inform the development of a word selection framework that will organize vocabulary targets into a developmentally appropriate sequence based on relevant predictors of word learning. Understanding the individual differences that are most predictive of vocabulary learning will aid in the development of a flexible instructional program designed to meet the diverse needs of preschoolers. Intervening at such a critical time in children’s oral language and pre-literacy skill development has the potential to reduce the prevalence of reading difficulties among our most vulnerable populations