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Biomedical subjects

L S Siegel

Publications and source records attributed to L S Siegel.

At least 19 recordsLinked to original sources
PubMed2001

Phonological processing in reading Chinese among normally achieving and poor readers.

Ninety-four children in grades one to six (7 to 12 years old) in Hong Kong were individually administered a Chinese reading test consisting of 80 characters that varied in frequency (high or low) and orthographic structure (simple or complex). Phonological processing tasks, including short-term memory, pseudo-character recognition, and tone discrimination, were also administered. During reading, younger normal and poor readers made more semantic and visual errors, whereas older and normally achieving children made more phonologically related errors. Normally achieving readers also performed at a higher level than poor readers on short-term memory, pseudo-character recognition, and tone discrimination tasks. Phonological processing apparently plays a significant part in the development of reading skills in Chinese.

Child↗
PubMed2001

Speech perception, lexicality, and reading skill.

This study examined the interaction between speech perception and lexical information among a group of 7-year-old children, of which 26 were poor readers and 36 were good readers. The children's performance was examined on tasks assessing reading skill, phonological awareness, pseudoword repetition, and phoneme identification. Although good readers showed clearly defined categorical perception in the phoneme identification task for both the /bif/-/pif/ and the /bis/-/pis/ continua, the category boundary for /bif/-/pif/ was at longer VOTs than the boundary for /bis/-/pis/, which characterizes the classic lexicality effect. Poor readers showed less sharply defined categorical perception on both continua. Although poor readers did not show the classic lexicality effect, lexicality did affect the overall rate with which phonemes were identified as /b/ or /p/ at each VOT. These findings suggest that the lexicon may operate as a compensatory mechanism for resolving ambiguities in speech perception. Furthermore, statistical correction for group differences in phoneme identification made group differences in phoneme deletion disappear, suggesting that deficits in speech perception may play a causal role in the phonological core deficit associated with reading failure.

Awareness↗
PubMed2001

Short-term memory, working memory, and inhibitory control in children with difficulties in arithmetic problem solving.

The relations between short-term memory, working memory, inhibitory control, and arithmetic word problem solution were studied in children who were poor in arithmetic problem solving (n = 23). The children were compared with a group of good problem solvers (n = 26), matched for vocabulary, age, and gender. The results corroborate the hypothesis of poor problem solvers' general deficit in inhibitory processes. They had lower scores and made more intrusion errors in a series of working memory tasks requiring inhibition of irrelevant information. The results showed that problem solving performance is related to the ability of reducing the accessibility of nontarget and irrelevant information in memory. Span tasks that imply passive storage of information showed that poor problem solvers were impaired when they have to retain numerical information, but they did not differ from children who did not have difficulty with mathematics when the material included words.

Child↗
PubMed2000

Working memory, inhibitory control, and reading disability.

The relationships among working memory, inhibitory control, and reading skills were studied in 966 individuals, 6-49 years old. In addition to a standardized measure of word recognition, they received a working memory (listening span) task in the standard, blocked format (three sets containing two-, three-, or four-item trials) or in a mixed format (three sets each containing two-, three-, and four-item trials) to determine whether scores derived from the standard format are influenced by proactive interference. Intrusion errors were investigated in order to determine whether deficits in working memory were associated with the access, deletion, or restraint functions of inhibitory control. The results indicated that deficits in working memory were characteristic of individuals with reading disabilities at all ages. These deficits may be associated with the access and restraint functions of inhibition. Working memory skills increased until the age of 19. The blocked format showed a gradual decline in adulthood whereas the mixed format did not. The different patterns suggest that the decline in working memory skills associated with aging may result from growing inefficiencies in inhibitory control, and not diminished capacity.

Adolescent↗
PubMed1998

Reading and spelling acquisition in French: the role of phonological mediation and orthographic factors.

The objective of this research was to study the development of reading and spelling in French. The two main hypotheses were that (1) phonological mediation is the primary process in the acquisition of these skills and that (2) the use of phonological mediation may allow the construction of the orthographic lexicon. In January and June, first graders (n = 57) were required to read and spell items designed to assess the variables of regularity, graphemic complexity, frequency, lexicality and analogy. The findings of the January session partially corroborated the first hypothesis as a regularity effect, but no frequency effect and no word superiority, were found both in reading and spelling. The main contradictory finding was the presence, in early reading only, of a facilitative effect of analogy. The changes in the frequency and the lexicality effects between the two sessions in reading and in spelling indicated that the children were able to rapidly construct an orthographic lexicon. However, this procedure did not entirely replace phonological mediation since a regularity effect and regularization errors were observed and increased between sessions. The second hypothesis was supported as relationships were found to exist between early phonological skills and subsequent orthographic skills. Finally, we observed that French children were using graphemes (not only letters), in the early stage of reading, and, to a lesser extent, in the early stage of spelling. The findings are discussed in the context of developmental models of reading and spelling.

Child↗
PubMed1996

The development of phonological rules and visual strategies in average and poor spellers.

To investigate the development of phonological and visual skills used in spelling, 420 children between the ages of 6 and 16 completed the spelling dictation test of the Wide Range Achievement Test-Revised. The misspellings were scored for phonological as well as visual accuracy using a constrained (inclusion of position cues) and an unconstrained system. Poor spellers made fewer phonologically accurate and fewer visual matches than age-matched average spellers. Poor spellers produced significantly more misspellings that were close visual matches to the target word and fewer phonologically unconstrained misspellings than spelling grade-matched average spellers. The groups did not differ in their production of phonologically constrained misspellings. Average spellers used a phonological approach more frequently than a visual approach, while the reverse pattern was true for poor spellers. When phonological rules are less well developed, then individuals are more likely to use orthographic skills.

Achievement↗
PubMed1994

Subtypes of learning disabilities in adolescents and adults.

This study tested the hypothesis that a classification scheme developed for the subtyping of learning disabilities in children, when applied to a population of adolescents and adults, would result in subtyping into discrete and relatively homogeneous groups in terms of cognitive functioning and achievement. We compared three groups, arithmetic disability (AD), reading disability (RD), and reading and arithmetic disabilities (RAD), among themselves and with a comparison group with normal achievement (NA) on a variety of cognitive and achievement measures. The main findings were as follows: (a) Each of the groups differed significantly from the others on tests of reading, spelling, memory, and other cognitive measures; (b) both the RD and RAD groups showed a deficit in phonological processing, vocabulary, spelling, and STM; (c) the AD group performed similarly to the NA group on pseudoword reading and phonological processing, but did more poorly than the NA group on word reading and vocabulary; (d) on many tasks the RAD group performed more poorly than the other groups; and (e) the AD and RAD groups performed more poorly than the NA and RD groups on a visual-spatial task. This study demonstrated the validity of this classification scheme for the subtyping of learning disabilities in adolescents and adults.

Adolescent↗
PubMed1994

Preference for visual scanning strategies versus phonological rehearsal in university students with reading disabilities.

This study investigated strategic preferences for visual scanning versus phonological rehearsal for recognizing words, pronounceable letter strings, and symbol strings by university students with reading disabilities (RD). Forty-seven subjects participated in this study: 20 students with reading disabilities who reported current difficulties in reading, as well as problems in learning to read at an early age; 15 students with learning disabilities (LD) who reported current difficulties in learning in areas other than reading but did not recall difficulties in learning to read; and 12 nondisabled readers (NR). The main dependent measures were response latency on a matching task for words, nonwords, and symbol strings, and posttest verbal reports of strategies used. Results showed that (a) most subjects in the NR group consistently used a strategy of phonological rehearsal for both words and nonwords, whereas most subjects with RD consistently used a strategy of visual scanning for these tasks, and (b) the NR group responded significantly faster than did the RD and LD groups to all three types of stimuli. The results indicate differences between university students who have a reading disability and nondisabled readers in strategic preferences for processing phonological information, with a clear preference by the former for using visual scanning rather than phonological rehearsal in matching tasks of words and nonwords.

Adult↗
PubMed1993

Is the Continuous Performance Task a valuable research tool for use with children with Attention-Deficit-Hyperactivity Disorder?

The Continuous Performance Task (CPT) has become a popular research tool used to distinguish children with Attention-Deficit-Hyperactivity Disorder (ADHD) from their normal peers. Whether hyperactive children have a vigilance decrement remains an ongoing controversy. The theoretical basis of the CPT and variables known to influence performance are examined in order to interpret the inconsistencies evident in the research. Studies which employed the CPT in order to examine the possibility of sustained attention deficits in children with ADHD will be reviewed. The results are examined in light of group selection criteria, task variables and situational and external variables. It is concluded that there is no compelling evidence for a sustained deficit in ADHD children. An alternative theoretical model for understanding the results of CPT performance in ADHD children is provided.

Attention↗
PubMed1992

An evaluation of the discrepancy definition of dyslexia.

The purpose of this study was to determine whether children with dyslexia, that is, children whose reading levels were significantly lower than would be predicted by their IQ scores, constituted a distinctive group when compared with poor readers, that is, children whose reading scores were consistent with their IQ scores. The performance of children with dyslexia, poor readers, and normally achieving readers was compared on a variety of reading, spelling, phonological processing, language, and memory tasks. Although the children with dyslexia had significantly higher IQ scores than the poor readers, these two groups did not differ in their performance on reading, spelling, phonological processing, or most of the language and memory tasks. In all cases, the performance of both reading disabled groups was significantly below that of nondisabled readers. The findings were similar whether absolute difference or regression scores were used. Reading disabled children, whether or not their reading is significantly below the level predicted by their IQ scores, experience significant problems in phonological processing, short-term and working memory, and syntactic awareness. On the basis of these data, there does not seem to be a need to differentiate between individuals with dyslexia and poor readers. Both of these groups are reading disabled and have deficits in phonological processing, verbal memory, and syntactic awareness.

Achievement↗
PubMed1992

Language intervention with children who have developmental delays: effects of an interactive approach.

The interactive model of language intervention instructs parents to use techniques that promote reciprocal social interactions and facilitate the development of communication and language abilities. In this evaluation study, 32 mothers and their preschool-age children with developmental delays were randomly assigned to treatment and control (delayed treatment) groups. Consistent with the interactive model, mothers in the treatment group became more responsive, less directive, and provided clearer linguistic models. Furthermore, these changes were maintained for at least 4 months after intervention, and involvement in the parent-centered intervention program did not increase maternal stress. More important, these changes were accompanied by concomitant increases in children's use of vocal turns. Contrary to predictions, developmental improvements in children's communicative and linguistic abilities were comparable in both groups. Findings suggest that an interactive model may afford a useful adjunct to other intervention approaches by instructing parents on how to promote children's use of existing abilities, but an interactive model may have no effect on language acquisition of at least some children with developmental delays.

Adult↗
PubMed1991

Left ear dichotic listening performance on consonant-vowel combinations and digits in subtypes of reading-disabled children.

Twenty reading comprehension-disabled (CD) and 20 reading comprehension and word recognition-disabled (CWRD), right-handed male children were matched with 20 normal-achieving age-matched controls and 20 normal-achieving reading level-matched controls and tested for left ear report on dichotic listening tasks using digits and consonant-vowel combinations (CVs). Left ear report for CVs and digits did not correlate for any of the groups. Both reading-disabled groups showed lower left ear report on digits. On CVs the CD group showed a high left ear report but only when there were no priming precursors, such as directions to attend right first and to process digits first. Priming effects interfered with the processing of both digits and CVs. Theoretically, the CWRD group seems to be characterized by a depressed right hemisphere, whereas the CD group may have a more labile right hemisphere, perhaps tending to overengagement for CV tasks but vulnerable to situational precursors in the form of priming effects. Implications extend to (1) subtyping practices in research with the learning-disabled, (2) inferences drawn from studies using different dichotic stimuli, and (3) the neuropsychology of reading disorders.

Attention↗
PubMed1991

A dose-response analysis of the effects of methylphenidate on the peer interactions and simulated classroom performance of ADD children with and without conduct problems.

To examine the social effects of methylphenidate, groups of 15 attention-deficit disordered boys with (ADD) and 15 ADD boys without conduct problems (ADD/CP) were paired with normal peers. ADD and ADD/CP children showed a different pattern of responses to methylphenidate. While on task behavior in ADD/CP dyads increased at 0.15 mg/kg doses, increases in ADD dyads were not observed until doses reached 0.50 mg/kg. Although controlling interaction in ADD children decreased at 0.15 mg/kg, the controlling behavior of ADD/CP children did not decline at either dose. Peers of both ADD and ADD/CP children showed reciprocal declines in controlling behavior. In both free play and cooperative task situations, 0.15 mg/kg increased social interaction in ADD boys and decreased social interaction in ADD/CP boys.

Achievement↗
PubMed1990

The clinical significance of neurocognitive impairments among children with psychiatric disorders: diagnosis and situational specificity.

The overall objective of this paper is to assess the clinical significance of neurocognitive impairments (NCI) among children with psychiatric disorders. One hundred and fifty-three children referred to a mental health clinic underwent neuropsychological testing. Their parents were interviewed to obtain background information and data on their children's behavior. Parents and teachers also filled out behavior checklists. The results suggest that neurocognitive impairments are: (1) more strongly associated with externalizing rather than internalizing psychiatric diagnoses; and (2) are correlated with psychiatric symptoms at school, but not at home. The implications for understanding the impact of neurocognitive impairments on the situational specificity of psychiatric symptoms are discussed.

Affective Symptoms↗
PubMed1990

Learning disability, inferential skills, and postfailure reflectivity.

Children with learning disabilities (LD) were compared with normally achieving children (NA) on two aspects of problem solving: inferential skills and response to errors in an academic content-free task. We tested 33 normally achieving children and 69 children with LD, aged 7 years 10 months to 16 years 4 months, on the PAR (PAttern Recognition) task, a computer-based, self-paced learning sequence. The children with LD were subtyped in two different ways: first, as children with only an arithmetic disability (AD), or with both arithmetic and word-recognition disabilities (AD/WRD); and second, as children with LD and attention deficit disorder (ADD), or LD without ADD. Results showed that on inferential skills, children with LD (without subtyping), children with AD/WRD, and children with LD with and without ADD scored significantly lower on the PAR task than children in the NA group. Also, an interaction was found between the NA and LD (without subtyping) groups and age, whereby children with LD improved their scores on PAR with age significantly more than normally achieving children. On attention to errors, children with both arithmetic and word-recognition disabilities scored significantly lower than children with only arithmetic disability or NA. It appears that the meta-cognitive skill of monitoring errors may be a major source of difficulty in problem solving for children with both arithmetic and word-recognition disabilities.

Achievement↗
PubMed1989

The development of working memory in normally achieving and subtypes of learning disabled children.

Working memory has been proposed as an important component of reading and arithmetic skills. The development of working memory was studied in normally achieving and subtypes of learning disabled children. The performance of reading disabled (RD), arithmetic disabled (ARITHD), and attentional deficit disordered (ADD) children, age 7-13, was compared to normal achievers (NA) on 2 working memory tasks, 1 involving sentences and the other involving counting. There was a significant growth of working memory as a function of age. In addition, the RD children had significantly lower scores on both tasks. The ARITHD children had significantly lower scores only on the Working Memory--Counting task, and the ADD group had scores similar to the normally achieving children except at the youngest age level in the Working Memory--Sentences task. Thus, a reading disability appears to involve a generalized deficit in working memory. Children with an arithmetic disability do not have a generalized language deficit but have a specific working memory deficit in relation to processing numerical information. As children with ADD did not have deficits in these tasks, working memory may not have significant attentional components. An important component of the development of reading and computational arithmetic skills appears to be the growth of working memory for language and numerical information.

Achievement↗
PubMed1989

A study of synchronization of quantal transmitter release from mammalian motor endings by the use of botulinal toxins type A and D.

1. The effects of botulinum toxin (BoTx) types A and D on spontaneous and evoked phasic transmitter release were studied in the isolated extensor digitorum longus muscle of the rat or the levator auris longus muscle of mice. 2. The toxins were injected subcutaneously into the hindleg of adult rats or the dorsal aspect of the neck of mice. At various times after the injection the muscles were removed from the anaesthetized animal and neuromuscular transmission examined in vitro by conventional intracellular techniques. 3. Both toxins reduced spontaneous transmitter release recorded as the frequency of miniature end-plate potentials but BoTx type D was less effective in that respect than the type A toxin. 4. With both toxins the block of evoked phasic transmitter release, recorded as end-plate potentials, was almost complete. As previously reviewed by Simpson (1986) the block produced by BoTx type A was partially reversed by procedures which elevate the intraterminal level of calcium ions. However, in BoTx type D-paralysed muscles such procedures failed to restore phasic transmitter release but caused a period of high-frequency asynchronous transmitter release following each nerve impulse. 5. To investigate if the lack of synchronization of evoked transmitter release observed in BoTx type D-paralysed muscles was due to alterations in presynaptic currents we examined, by perineural recordings, the Na+, fast K+, slow K+, K+-Ca2+-dependent and the Ca2+ currents in BoTx type D-paralysed muscles. These presynaptic currents were not altered as compared to unpoisoned controls. 6. We suggest that there exists a presynaptic process, which in addition to Ca2+ influx participates in transmitter synchronization and which is a main target for BoTx type D action.

4-Aminopyridine↗