Whole-word units are used before orthographic knowledge in perceptual development

Preliteracy Domains and Stages

This article begins by providing a model of the domains of preliteracy development that is derived from a model of the later reading process adapted by Adams (1990) from Seidenberg and McClelland (1989). Adams' model, as the one for preliteracy development offered here, contains four components: an orthographic, phonological, meaning, and context processor. Two of the preliteracy processors — the orthographic and the phonological—- contain various subskills that are foundational for later development of the form aspect of print. Two other processors — the meaning and the context — contain subskills foundational to the meaning component of print. The relationship of the various subskills in the preliteracy model to prereading activities and later reading is discussed. The model is then related to two stages of preliteracy development revised from those presented by van Kleeck (1995). The first stage emphasizes the meaning and functions of print. The second stage adds, in separate activities, an emphasis on print form (letters; sounds in words) and early form-meaning correspondences (letter knowledge and phonological awareness are related to meaning at the word level). Developmental progressions for various preliteracy skills are provided in this section. Finally, formal and informal methods of assessing all of the domains of preliteracy development are discussed. Approaches to teaching or intervention are interspersed throughout the article as the development and nature of numerous preliteracy subskills are discussed.

The N400 and the fourth grade shift

While behavioral and educational data characterize a fourth grade shift in reading development, neuroscience evidence is relatively lacking. We used the N400 component of the event-related potential waveform to investigate the development of single word processing across the upper elementary years, in comparison to adult readers. We presented third graders, fourth graders, fifth graders, and college students with a well-controlled list of real words, pseudowords, letter strings, false font strings, and animal name targets. Words and pseudowords elicited similar N400s across groups. False font strings elicited N400s similar to words and letter strings in the three groups of children, but not in college students. The pattern of findings suggests relatively adult-like semantic and phonological processing by third grade, but a long developmental time course, beyond fifth grade, for orthographic processing in this context. Thus, the amplitude of the N400 elicited by various word-like stimuli does not reflect some sort of shift or discontinuity in word processing around the fourth grade. However, the results do suggest different developmental time courses for the processes that contribute to automatic single word reading and the integrative N400.

Behavioral and ERP evidence of word and pseudoword superiority effects in 7- and 11-year-olds

In groups of 7-year-olds and 11-year-olds, event-related potentials (ERPs) were recorded to briefly presented, masked letter strings that included real word (DARK/PARK), pronounceable pseudoword (DARL/PARL), unpronounceable nonword (RDKA/RPKA), and letter-in-xs (DXXX, PXXX) stimuli in a variant of the Reicher-Wheeler paradigm. Behaviorally, participants decided which of two letters occurred at a given position in each string (here, forced-choice alternatives D and P). Both groups showed evidence of behavioral word (more accurate choices for letters in words than in baseline nonwords or letter-in-xs) and pseudoword (more accurate choices for letters in pseudowords than in baseline nonwords or letter-in-xs) superiority effects. Electrophysiologically, 11-year-olds evidenced superiority effects on P150 and N400 peak amplitude, while 7-year-olds showed effects only on N400 amplitude. These findings suggest that the mechanisms underlying the observed behavioral superiority effects may be lexical in younger children but both sublexical and lexical in older children. These results are consistent with a lengthy developmental time course for automatic sublexical orthographic specialization, extending beyond the age of 11.

Behavioral and ERP evidence of word and pseudoword superiority effects in 7- and 11-year-olds

In groups of 7-year-olds and 11-year-olds, event-related potentials (ERPs) were recorded to briefly presented, masked letter strings that included real word (DARK/PARK), pronounceable pseudoword (DARL/PARL), unpronounceable nonword (RDKA/RPKA), and letter-in-xs (DXXX, PXXX) stimuli in a variant of the Reicher-Wheeler paradigm. Behaviorally, participants decided which of two letters occurred at a given position in each string (here, forced-choice alternatives D and P). Both groups showed evidence of behavioral word (more accurate choices for letters in words than in baseline nonwords or letter-in-xs) and pseudoword (more accurate choices for letters in pseudowords than in baseline nonwords or letter-in-xs) superiority effects. Electrophysiologically, 11-year-olds evidenced superiority effects on P150 and N400 peak amplitude, while 7-year-olds showed effects only on N400 amplitude. These findings suggest that the mechanisms underlying the observed behavioral superiority effects may be lexical in younger children but both sublexical and lexical in older children. These results are consistent with a lengthy developmental time course for automatic sublexical orthographic specialization, extending beyond the age of 11.

Are there independent lexical and nonlexical routes in word processing? An evaluation of the dual-route theory of reading

One of the most popular and influential theories of word processing, dual-route theory, proposes that there are two functionally independent means of processing words, one involving access to lexical knowledge and the other involving nonlexical grapheme-to-phoneme conversion. Three topics germane to this theory are the processing of nonwords, spelling regularity effects, and the manner in which reading may be impaired following selective damage to either route. This paper evaluates evidence on these topics, and in each case the claims of the theory for an independent nonlexical processing route are called into question. This conclusion is further supported by a discussion of the linguistic constraints that limit any nonlexical grapheme—phoneme conversion process. Some alternative approaches to visual word processing, which share the assumption that lexical knowledge can guide the assembly of phonological information, are discussed. It is argued that these approaches should direct future research.

The N400 in beginning readers

In an event-related potentials study of brain-behavior relations during learning-to-read, girls in first grade viewed known words, unknown words, difficult words, and nonwords presented in list form. Participants were divided into low-ability and high-ability reading groups based on standardized test scores. During the 300- to 600-ms epoch, low-ability readers lacked a substantial N400 while high-ability readers evidenced a large, widely distributed negativity to all word types. During the 600- to 1,000-ms epoch, high-ability readers showed effects of repetition while low-ability readers did not. The findings indicate a less selective neurocognitive word-processing system in children as compared to adults and suggest that the N400 may serve as an oblique index of the automaticity of lower level processing.

Reading Development and Attention to Letters in Words

Four groups of Dutch readers, (a) beginners, second grade elementary school students with 2 years of reading experience, (b) advanced readers, sixth grade elementary school students with 6 years of reading experience, (c) expert readers, university students with 14 years of reading experience, and (d) poor readers, aged 13 years with 2 years of delay in reading skill, were presented with short stories followed by multiple-choice text comprehension questions. Participants were asked to read the stories for meaning and to circle the letter t whenever it occurred in the text. Five types of detection locations were defined: (1) verb suffix, (2) noun final, (3) intra word, second letter, (4) intra word, prefinal letter, and (5) definite article, final t. Differential detection patterns as a function of reading development were obtained. Beginning readers did not differ in detecting the final t in verbs and nouns, whereas expert readers showed a strong attentional bias to verb suffixes as compared with noun endings. Expert readers missed more intra word letters. In all groups prefinal letters were detected better than second letters in words, thus suggesting a general attentional bias for orthographic information in the second part of Dutch words. The t in the definite article was missed most often in all groups, which suggests sensitivity to word frequency at early stages in reading development. Poor readers did not show differential performance patterns as compared to the other reading groups. The overall developmental pattern can be characterized as a shift from attention for single letter information to attention for more complex morphological information in text. Copyright 2000 Academic Press.

Is phonology bypassed in normal or dyslexic development?

A pervasive assumption in most accounts of normal reading and spelling development is that phonological coding is important early in development but is subsequently superseded by faster, orthographic coding which bypasses phonology. We call this assumption, which derives from dual process theory, the developmental bypass hypothesis. The present study tests four specific predictions of the developmental bypass hypothesis by comparing dyslexics and nondyslexics from the same families in a cross-sectional design. The four predictions are: 1) That phonological coding skill develops early in normal readers and soon reaches asymptote, whereas orthographic coding skill has a protracted course of development; 2) that the correlation of adult reading or spelling performance with phonological coding skill is considerably less than the correlation with orthographic coding skill; 3) that dyslexics who are mainly deficient in phonological coding skill should be able to bypass this deficit and eventually close the gap in reading and spelling performance; and 4) that the greatest differences between dyslexics and developmental controls on measures of phonological coding skill should be observed early rather than late in development.None of the four predictions of the developmental bypass hypothesis were upheld. Phonological coding skill continued to develop in nondyslexics until adulthood. It accounted for a substantial (32-53 percent) portion of the variance in reading and spelling performance in adult nondyslexics, whereas orthographic coding skill did not account for a statistically reliable portion of this variance. The dyslexics differed little across age in phonological coding skill, but made linear progress in orthographic coding skill, surpassing spelling-age (SA) controls by adulthood. Nonetheless, they didnot close the gap in reading and spelling performance. Finally, dyslexics were significantly worse than SA (and Reading Age [RA]) controls in phonological coding skill only in adulthood.