Phonological processing and emergent literacy in younger and older preschool children

Abstract

Phonological awareness, phonological memory, and phonological access to lexical storage play important roles in acquiring literacy. We examined the convergent, discriminant, and predictive validity of these phonological processing abilities (PPA) in 389 3-, 4-, and 5-year-old children. Confirmatory factor analysis supported the validity of each PPA as separate from general cognitive ability and separate from each other. Multigroup structural equation modeling (SEM) with mean structure demonstrated that older preschoolers have better developed latent PPA than younger preschoolers but that the structure of PPA is equivalent. RAN was found uniquely associated with letter knowledge and text discrimination in younger preschoolers, and PA was found uniquely associated with word reading skills in older preschoolers. Finally, general cognitive ability was only indirectly associated with emergent literacy via PPA. These results highlight the importance of PPA in the early literacy development of English-speaking preschool children.

Keywords Phonological awareness * Phonological memory * Rapid naming * Emergent literacy * Phonological processing * Children * Reading * Phonological sensitivity * Short-term memory * Preschool

Consensus has emerged from three decades of literacy research that difficulty with the mental processing of phonological information is a core deficit that accounts for many children's difficulties in learning to read (Adams, 1990; Stanovich, 1988). Phonological processing refers to the use of the sound structure of oral language in processing written and oral information. More specifically, research with school-age children has identified three interrelated phonological processing abilities (PPA) that are important for reading and writing: phonological awareness (PA), phonological memory (PM), and efficiency of phonological access to lexical storage (a.k.a. RAN; for review see Wagner & Torgesen, 1987). How the various PPA are related to each other and what roles they play in literacy development are issues of considerable theoretical and practical importance. The answers to these questions are likely to have significant implications for the development of assessment batteries, for the improvement of our ability to identify children at risk for reading difficulties, and for pinpointing potential loci of intervention.

PA refers to one's ability to detect or manipulate the sounds in his or her oral language (for review, see Anthony & Francis, 2005). PA encompasses phoneme awareness, the ability to manipulate individual sounds (phonemes) in words, and rudimentary phonological awareness skills, such as judging whether two words rhyme. PM refers to the coding of information in a sound-based representation system for temporary storage. PM is utilized during all cognitive tasks that involve processing sound information. Individuals' PM capacity is often operationalized by auditory span tasks, like digit span. RAN refers to the efficiency of retrieving phonological codes from memory. Individual differences in efficiency of retrieving phonologically stored information from memory are typically operationalized by performance on rapid autonomic naming tasks in which individuals verbally identify common objects, letters, or numbers as quickly as possible.

Numerous correlational and longitudinal studies demonstrate that PA, PM, and RAN are reliable individual predictors of reading achievement. Moreover, increasingly more comprehensive and sophisticated multivariate research has been conducted in an effort to determine which PPA are the best predictors of reading achievement and which PPA are uniquely important for literacy development. Depending on what demographic, phonological, and reading-related constructs are assessed and included in the statistical models, some studies have shown that PA is uniquely predictive of reading (Bryant et al., 1989, 1990; Wagner et al., 1994), some studies have shown that PM is uniquely predictive of reading (Rapala & Brady, 1990; Rohl & Pratt, 1995; Snowling et al., 1986; Stone & Brady, 1995), and some studies have shown that RAN is uniquely predictive of reading (Felton & Brown, 1990; Griffiths, 1991; Wagner et al., 1997; Wolf & Obregon, 1992). Of course a superior approach is to examine the relative predictive contributions of PA, PM, and RAN in the context of all other PPA and all known predictors of literacy (e.g., language ability and orthographic knowledge). Employing a latent variable approach further strengthens such investigations by providing more reliable estimates of the true associations among the psychological constructs than those obtained by observed scores. To our knowledge, only three longitudinal investigations of the relations among all three latent PPA and latent reading abilities have been conducted (see below).

First, Wagner and colleagues have conducted the most comprehensive line of research in the area of PPA to date (Wagner & Torgesen, 1987; Wagner et al., 1993, 1994, 1997). Their research boasts impressive sample sizes, both cross-sectional and longitudinal designs, inclusion of general ability covariates and autoregressors, and use of structural equation modeling (SEM) to examine relations among latent PPA and latent literacy skills. In a number of studies, Wagner and colleagues compared alternative models of the factor structure of PPA in over 200 typically developing, English-speaking, school-age children. Initial findings and subsequent replications supported a measurement model of PPA in which PA, PM, and RAN were distinguishable but moderately correlated phonological abilities. Additionally, PA and RAN demonstrated unique predictive relations with word reading.