Donald Shankweiler

Explicit Syllable and Phoneme Segmentation in the Young Child.

Abstract To write a language, one must first abstract the unit to be used from the acoustic stream of speech. Writing systems based on the meaningless units, syllables and phonemes, were late developments in the history of written language. The alphabetic system, which requires abstraction of the phonemic unit of speech, was the last to appear, evolved from a syllabary and, unlike the other systems, was apparently invented only once. It might therefore be supposed that phoneme segmentation is particularly difficult and more difficult, indeed, than syllable segmentation. Speech research suggests reasons why this may be so. The present study provides direct evidence of a similar developmental ordering of syllable and phoneme segmentation abilities in the young child. By means of a task which required preschool, kindergarten, and first-grade children to tap out the number of segments in spoken utterances, it was found that, though ability in both syllable and phoneme segmentation increased with grade level, analysis into phonemes was significantly harder and perfected later than analysis into syllables. The relative difficulties of the different units of segmentation are discussed in relation to reading acquisition.

Hemispheric Specialization for Speech Perception

Earlier experiments with dichotically presented nonsense syllables had suggested that perception of the sounds of speech depends upon unilateral processors located in the cerebral hemisphere dominant for language. Our aim in this study was to pull the speech signal apart to test its components in order to determine, if possible, which aspects of the perceptual process depend upon the specific language processing machinery of the dominant hemisphere. The stimuli were spoken consonant‐vowel‐consonant syllables presented in dichotic pairs which contrasted in only one phone (initial stop consonant, final stop consonant, or vowel). Significant right‐ear advantages were found for initial and final stop consonants, nonsignificant right‐ear advantages for six medial vowels, and significant right‐ear advantages for the articulatory features of voicing and place of production in stop consonants. Analysis of correct responses and errors showed that consonant features are processed independently, in agreement with ea...

Cognitive profiles of reading disability: Comparisons of discrepancy and low achievement definitions.

To examine the validity of distinguishing children with reading disabilities according to discrepancy and low-achievement definitions, we obtained four assessments of expected reading achievement and two assessments of actual reading achievement for 199 children, 7.5-9.5 years old. These assessments were used to subdivide the sample into discrepancy and low-achievement definitional groups who were compared on 9 cognitive variables related to reading proficiency. Results did not support the validity of discrepancy versus low achievement definitions. Although differences between children with impaired reading and children without impaired reading were large, differences between those children with impaired reading who met IQ-based discrepancy definitions and those who met low reading achievement definitions were small or not significant

Identification of consonants and vowels presented to left and right ears

The results of earlier studies by several authors suggest that speech and nonspeech auditory patterns are processed primarily in different places in the brain and perhaps by different modes. The question arises in studies of speech perception whether all phonetic elements or all features of phonetic elements are processed in the same way. The technique of dichotic presentation was used to examine this question. The present study compared identifications of dichotically presented pairs of synthetic CV syllables and pairs of steady-state vowels. The results show a significant right-ear advantage for CV syllables but not for steady-state vowels. Evidence for analysis by feature in the perception of consonants is discussed.

Phonology and the Problems of Learning to Read and Write

Learning to read and write depends on abilities that are language related but that go beyond the ordinary abilities required for speaking and listening. Research has shown that the success of learners, whether they are children or adults, is related to the degree to which they are aware of the underlying phonological structure of words. Poor readers are often unable to segment words into their phonological constituents and may have other phonological deficiencies as well. Their difficulties in naming objects and in comprehending sentences, for example, may also stem from a basic problem in the phonological domain.

Subtypes of Reading Disability: Variability around a Phonological Core.

Eight measures of cognitive and language functions in 232 children were subjected to multiple methods of cluster analysis in an effort to identify subtypes of reading disability. Clustering yielded 9 reliable subtypes representing 90% of the sample, including 2 nondisabled subtypes, and 7 reading-disabled subtypes. Of the reading-disabled subtypes, 2 were globally deficient in language skills, whereas 4 of the 5 specific reading-disabled subtypes displayed a relative weakness in phonological awareness and variations in rapid serial naming and verbal short-term memory. The remaining disabled subtype was impaired on verbal and nonverbal measures associated with rate of processing, including rate and accuracy of oral reading. Studies showed evidence for discriminative validity among the 7 reading-disabled subtypes. Results support the view that children with reading disability usually display impairments on phonological awareness measures, with discriminative variability on other measures involving phonological processing, language, and cognitive skills.

An Event-related Neuroimaging Study Distinguishing Form and Content in Sentence Processing

Two coordinated experiments using functional Magnetic Resonance Imaging (fMRI) investigated whether the brain represents language form (grammatical structure) separately from its meaning content (semantics). While in the scanner, 14 young, unimpaired adults listened to simple sentences that were either nonanomalous or contained a grammatical error (for example, Trees can grew.), or a semantic anomaly (for example, Trees can eat.). A same/different tone pitch judgment task provided a baseline that isolated brain activity associated with linguistic processing from background activity generated by attention to the task and analysis of the auditory input. Sites selectively activated by sentence processing were found in both hemispheres in inferior frontal, middle, and superior frontal, superior temporal, and temporo-parietal regions. Effects of syntactic and semantic anomalies were differentiated by some nonoverlapping areas of activation: Syntactic anomaly triggered significantly increased activity in and around Brocas area, whereas semantic anomaly activated several other sites anteriorly and posteriorly, among them Wernickes area. These dissociations occurred when listeners were not required to attend to the anomaly. The results confirm that linguistic operations in sentence processing can be isolated from nonlinguistic operations and support the hypothesis of a specialization for syntactic processing.

The Angular Gyrus in Developmental Dyslexia: Task-Specific Differences in Functional Connectivity Within Posterior Cortex

Converging evidence from neuroimaging studies of developmental dyslexia reveals dysfunction at posterior brain regions centered in and around the angular gyrus in the left hemisphere. We examined functional connectivity (covariance) between the angular gyrus and related occipital and temporal lobe sites, across a series of print tasks that systematically varied demands on phonological assembly. Results indicate that for dyslexic readers a disruption in functional connectivity in the language-dominant left hemisphere is confined to those tasks that make explicit demands on assembly. In contrast, on print tasks that do not require phonological assembly, functional connectivity is strong for both dyslexic and nonimpaired readers. The findings support the view that neurobiological anomalies in developmental dyslexia are largely confined to the phonological-processing domain. In addition, the findings suggest that right-hemisphere posterior regions serve a compensatory role in mediating phonological performance in dyslexic readers.

Language mechanisms and reading disorder: A modular approach

Abstract In this paper we consider a complex of language-related problems that research has identified in children with reading disorder and we attempt to understand this complex in relation to proposals about the language processing mechanism. The perspective gained by considering reading problems from the standpoint of language structure and language acquisition allows us to pose specific hypotheses about the causes of reading disorder. The hypotheses are then examined from the standpoint of an analysis of the demands of the reading task and a consideration of the state of the unsuccessful reader in meeting these demands. The remainder of the paper pursues one proposal about the source of reading problems, in which the working memory system plays a central part. This proposal is evaluated in the light of empirical research which has attempted to tease apart structural knowledge and memory capacity both in normal children and in children with notable reading deficiencies.

Auditory Selective Attention: An fMRI Investigation

In the present experiment, 25 adult subjects discriminated speech tokens ([ba]/[da]) or made pitch judgments on tone stimuli (rising/falling) under both binaural and dichotic listening conditions. We observed that when listeners performed tasks under the dichotic conditions, during which greater demands are made on auditory selective attention, activation within the posterior (parietal) attention system and at primary processing sites in the superior temporal and inferior frontal regions was increased. The cingulate gyrus within the anterior attention system was not influenced by this manipulation. Hemispheric differences between speech and nonspeech tasks were also observed, both at Brocas Area within the inferior frontal gyrus and in the middle temporal gyrus.