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ABSTRACT: : To use Sternberg's Additive Factor Method to determine whether patients with mild Alzheimer disease (AD) are slow in information processing and/or response execution.
: We gave an odd-even categorization task to 16 patients with probable mild AD and 17 age-matched healthy controls. We recorded reaction and movement times to stimuli varying for noise, target set size, stimulus-response compatibility, and fore-period interval, to probe the cognitive and motor stages of information processing.
: Both groups performed the task accurately, indicating good preservation of odd-even categorization in mild AD. The AD group's reaction times were similar to the controls' across conditions, and not selectively affected in any of the cognitive stages of the Additive Factor Method. However, the AD group's movement times were slower than the controls' across conditions.
: AD patients' performance on a task requiring categorization ability was slowed more by motor than cognitive components of information processing. When evaluating the performance of patients with AD in reaction-time paradigms, we should not attribute group differences solely to differences in cognitive processing. Execution components should also be considered.
Cognitive and behavioral neurology: official journal of the Society for Behavioral and Cognitive Neurology 12/2012; 25(4):175-85. · 1.09 Impact Factor
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ABSTRACT: Frost presents an explanatory theory of reading that generalizes across several languages, based on a revised role of orthographic coding. Perceptual and psychophysical evidence indicates a decay of letter position encoding as a function of the eccentricity of letters (crowding); this factor may account for some of the differences in the languages considered by Frost.
Behavioral and Brain Sciences 08/2012; 35(5):294-5. · 25.06 Impact Factor
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ABSTRACT: In this study, we examined the effect of multiple versus single stimulus presentation in typically developing readers and children with developmental dyslexia. The tasks involved either reading single words or arrays of words or naming single or multiple colors and digits (rapid automatized naming or RAN). To be able to compare these sets of conditions, we recorded total response times (i.e., the time between stimulus onset and the end of the participant's vocal response) in all cases. The study included 43 typically developing readers and 25 children with dyslexia. Results indicate that typically developing readers have a clear advantage with multiple over single items on both RAN and reading tasks. The children with dyslexia showed a moderate advantage for multiple stimuli in naming colors and digits but presented the opposite pattern in reading. With regard to reading, the disproportionate impairment of the children with dyslexia in dealing with multiple arrays suggests difficulty in integrating the multiple subcomponents of the reading task over and above the basic nuclear deficit in decoding words. Regarding the RAN tasks, results confirm that the requirement of integrating multiple subcomponents may be critical in mediating the predictive value of these measures on reading.
Child Neuropsychology 08/2012; · 1.80 Impact Factor
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ABSTRACT: Stress assignment to Italian polysyllabic words is unpredictable, because stress is neither marked nor predicted by rule.
Stress assignment, especially to low frequency words, has been reported to be a function of stress dominance and stress neighbourhood.
Two experiments investigate stress assignment in sixth-grade, skilled and dyslexic, readers. In Experiment 1, skilled readers
were not affected by stress dominance. Dyslexic children, although affected by word frequency, made more stress regularisation
errors on low frequency words. In Experiment 2, stress neighbourhood affected low frequency word reading irrespective of stress
dominance for both skilled and dyslexic readers. Words with many stress friends were read more accurately than words with
many stress enemies. It is concluded that, in assigning stress, typically developing and developmental dyslexic Italian readers
are sensitive to the distributional properties of the language.
KeywordsDevelopmental dyslexia–Stress assignment–Stress dominance–Stress neighbourhood–Word frequency
Reading and Writing 04/2012; 24(4):443-461. · 1.44 Impact Factor
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ABSTRACT: The acquisition of reading skill was studied in 503 Italian children in first to eighth grade using a task that required reading
of lists of words and non-words. Analysis of the metric characteristics of the measures indicated that reading speed but not
accuracy was normally distributed across all ages considered. The role of specific effects (length, word frequency, and lexicality)
versus global factors in reading speed was examined using the Rate–Amount Model (RAM). A global processing factor accounted
for a large portion of the variance. Specific influences of length, frequency, and lexicality were detected in different periods
of development over and above the global processing factor. Length modulated performance at early stages of learning and progressively
less later on; in the case of non-words, the effect of length was large but did not change as a function of grade. The lexicality effect, present at all ages for high frequency words and by third grade for low frequency words increased with reading practice
indicating a progressive differentiation in the ability to read words and non-words. Finally, the effect of word frequency
was highest in third grade and then decreased. These findings are discussed in terms of their relevance for reading acquisition
in a language with transparent orthography and their implications for evaluating developmental reading deficits. Overall,
it is proposed that RAM is a useful tool for disentangling the role of specific versus global factors in reading development.
Reading and Writing 04/2012; 22(9):1053-1079. · 1.44 Impact Factor
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ABSTRACT: The general goal of the study was to identify global and specific components in developmental dyslexia using various manipulations based on the rapid automatization paradigm (RAN). In two experiments, we used both factor analysis and the Rate-and-Amount Model to verify if one (or more) global factor(s) and a variety of specific effects contribute to the naming (and visual search) deficits in children with dyslexia. Results of Experiment 1 indicated the presence of three global components: pictorial naming, detailed orthographic analysis, and visual search. Pictorial naming is predicated by typical RAN tasks (such as naming colors or objects), independent of set size, but also from a variety of other tasks including Stroop interference conditions. The detailed orthographic analysis factor accounts for naming of orthographic stimuli at high set size. Visual search marked tasks requiring the scanning of visual targets. Results of Experiment 2 confirmed the separation between the pictorial naming and detailed orthographic analysis factors both in the original sample and in a new group of children. Furthermore, specific effects of frequency, lexicality, and length were shown to contribute to the reading deficit. Overall, it is proposed that focusing on the profile of both global and specific effects provides a more effective and, at the same time, simpler account of the dyslexics' impairment.
Child Neuropsychology 10/2011; 18(4):356-91. · 1.80 Impact Factor
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ABSTRACT: Evidence is mixed concerning the relationship between stability of ocular dominance and reading deficits. Contrasting results may be due to the use of different tests of dominance, different samples of readers, and different scoring methods. The aim of this study was to investigate the relationship among ocular dominance, general visual abilities, and reading performance, and to evaluate the consistency and reliability of different tests of ocular dominance and the effects of different types of eye dominance scoring.
In a group of young adults, we measured: (a) main optometric parameters; (b) reading time and accuracy; and (c) ocular dominance in two sighting and four motor tests. Dominance was determined using different scoring methods (relative, absolute, and binary scores).
All dominance tests showed good levels of internal reliability. Sighting tests were consistent regardless of the scoring method, and all participants had stable dominance. Three of four motor tests were moderately consistent when dominance was measured with relative scores but not when it was measured with absolute or binary scores. No relationship was found between stability of dominance and reading performance, regardless of the type of test or scoring method. No systematic pattern of correlation was found between binocular vision variables and dominance measures.
Choosing the type of motor test to measure ocular dominance is crucial, because the level of consistency among tests is low to moderate. Furthermore, motor tests were not correlated with reading performances. Present results suggest caution when trying to link reading difficulties with specific profiles of ocular dominance.
Optometry and vision science: official publication of the American Academy of Optometry 08/2011; 88(11):1353-62. · 1.53 Impact Factor
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ABSTRACT: A previous study reported that, similar to young and adult skilled readers, Italian developmental dyslexics read pseudowords made up of a root and a derivational suffix faster and more accurately than simple pseudowords. Unlike skilled readers, only dyslexic and reading-matched younger children benefited from morphological structure in reading words aloud. In this study, we show that word frequency affects the probability of morpheme-based reading, interacting with reading ability. Young skilled readers named low- but not high-frequency morphologically complex words faster than simple words. By contrast, the advantage for morphologically complex words was present in poor readers irrespective of word frequency. Adult readers showed no facilitating effect of morphological structure. These results indicate that young readers use reading units (morphemes) that are larger than the single-grapheme grain size. It is argued that morpheme-based reading is important for obtaining reading fluency (rather than accuracy) in transparent orthographies and is useful particularly in children with limited reading ability who do not fully master whole-word processing.
Applied Psycholinguistics 06/2011; 32(03):513 - 532. · 0.95 Impact Factor
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ABSTRACT: The study explored the different influences of roots and suffixes in reading aloud morphemic pseudowords (e.g., vetr-ezza, “glass-ness”). Previous work on adults showed a facilitating effect of both roots and suffixes on naming times. In the present study, pseudoword stimuli including roots and suffixes in different combinations were administered to sixth-grade children with dyslexia (N=22) and skilled readers (N=44), matched for chronological age. Indeed, the sequential reading strategy of less proficient readers (particularly for pseudowords) should favour the emergence of differences between left and right constituents (root and suffix, respectively) in reading performance. Results showed that for both children with dyslexia and skilled young readers the onset of pronunciation depended exclusively on roots, while there was no significant effect of suffixes. However, both roots and suffixes led to higher levels of accuracy than matched orthographic strings of letters. Posthoc regression analyses confirmed the morphological nature of the root and suffix effects, over and above the effects of the frequency of their orthographic patterns. Results indicate that the position of the reading units within the letter string, as well as their differential effects on latencies and accuracy, should be taken into account by models of morphological processing in word recognition and reading and by applied intervention research.
Language and Cognitive Processes 05/2011; 26(4-6):777-793. · 1.54 Impact Factor
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ABSTRACT: Although developmental dyslexia is often referred to as a cross-modal disturbance, tests of different modalities using the same stimuli are lacking. We compared the performance of 23 children with dyslexia and 42 chronologically matched control readers on reading versus repetition tasks and visual versus auditory lexical decision using the same stimuli. With respect to control readers, children with dyslexia were impaired only on stimuli in the visual modality; they had no deficit on the repetition and auditory lexical decision tasks. By applying the rate-amount model (Faust et al., 1999), we showed that performance of children with dyslexia on visual (but not auditory) tasks was associated with that of control readers by a linear relationship (with a 1.78 slope), suggesting that a global factor accounts for visual (but not auditory) task performance. We conclude that the processing of linguistic stimuli in the visual and auditory modalities is carried out by independent processes and that dyslexic children have a selective deficit in the visual modality.
Neuropsychologia 03/2011; 49(7):1718-29. · 3.64 Impact Factor
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ABSTRACT: We tested the influence of list context on word frequency and length effects on the reading aloud of Italian developmental dyslexics and skilled peers. The stimuli were presented either in mixed blocks (alternating words and nonwords) or in pure blocks. The analyses based on the rate-and-amount model ( Faust et al., 1999 ) indicated that group differences in reaction times between dyslexic and skilled readers (a) were well accounted for in terms of global components and (b) were modulated by context in the case of words but not in the case of nonwords. ANOVAs on z-transformed reaction time data further indicated the influence of stimulus length. Importantly, the frequency effect interacted with context: Controls showed a list context effect for high- and low-frequency words, while dyslexics showed a list context effect only for high-frequency words. The effect of length on reading times remained unaffected by context manipulation. It is proposed that this pattern of results may be accounted for by hypothesizing two separate deficits: An early graphemic impairment affecting performance independently of context and a later inefficiency in activating entries in the orthographic lexicon as a function of context demands.
Child Neuropsychology 03/2011; 17(5):459-82. · 1.80 Impact Factor
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ABSTRACT: Italian children with surface dyslexia and dysgraphia show defective orthographic lexical processing in both reading and spelling. It is unclear whether this parallelism is due to impairment of separate orthographic input and output lexicons or to a unique defective lexicon. The main aim of the present study was to compare the single- versus dual-lexicon accounts in dyslexic/dysgraphic children (and in normal but younger children). In the first experiment, 9 Italian children with surface dyslexia and dysgraphia judged the orthographic correctness (input lexicon) of their phonologically plausible misspellings (output lexicon) and of phonologically plausible spellings experimentally introduced for words they consistently spelt correctly. The children were generally impaired in recognizing phonologically plausible misspellings. Parallel deficits in reading and spelling also emerged: Children were more impaired in judging items they consistently misspelt and more accurate in judging items they always spelt correctly. In a second experiment, younger normal children with reading/spelling ability similar to that of the dyslexic/dysgraphic children in the first experiment (but younger) were examined. The results confirmed a close parallelism between the orthographic lexical representations used for reading and spelling. Overall, findings support the hypothesis that a single orthographic lexicon is responsible for reading and spelling performance in both dyslexic/dysgraphic and normal (but younger) children.
Cognitive Neuropsychology 01/2011; · 2.13 Impact Factor
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Cortex 10/2010; 46(10):1211-5. · 6.08 Impact Factor
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ABSTRACT: The aim of this study was to examine longitudinally the acquisition of reading fluency in a shallow orthography from the very beginning using eye movement recordings. The development of reading fluency is easier to examine in shallow (such as German, Finnish, or Italian) rather than in opaque (such as English or French) orthographies because the former limit the presence of speed-accuracy trade-offs at early stages of acquisition. To date, only cross-sectional eye movement studies of reading development are available.
One normally developing child was assessed at the very beginning of first grade and at the end of the first, second, and fifth grades. Eye movement parameters during reading, reading speed and accuracy in a standard reading test, and vocal reaction time at onset to single words varying in length were measured.
Reading fluency improved dramatically during the first grade and progressively less thereafter: the word-length effect decreased abruptly by the end of the first grade and then less onwards. The rate of improvement closely followed a power function. This pattern held for standard reading tests, various eye movement parameters during reading, and vocal reaction times to single word onset.
These longitudinal observations indicate the rapid acquisition of reading fluency in a transparent orthography showing that the largest changes occurred within the first year of education.
Medical science monitor: international medical journal of experimental and clinical research 02/2010; 16(3):SC1-7. · 1.70 Impact Factor
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ABSTRACT: Lachmann and Van Leeuwen (2008) proposed two diagnostic subtypes of developmental dyslexia in a language with transparent orthography (German). The classification was based on reading time, rather than reading errors, for lists of words and nonwords. The two subtypes were "frequent-word reading impaired" (FWRI) and "nonword reading impaired" (NWRI). Notably, FWRI were very slow in reading high-frequency words but as fast as controls in reading nonwords; ca. one-third of these children showed this "reversed lexicality effect" in a particularly marked fashion (i.e., read nonwords two to three times faster than high-frequency words). Since Italian is a highly transparent language, we applied this classification to 87 third- and sixth-grade dyslexics from various previously published studies. Some children showed a marked lexicality effect, while others showed small or no difference between word and nonword reading speed. However, regardless of stimulus length, grade and presence/absence of a previous language delay, no child showed a marked reversed lexicality effect; more generally, no child could be classified as FWRI. These findings indicate that the search for subtypes of developmental dyslexia in transparent orthographies still constitutes an open question.
Cognitive Neuropsychology 12/2009; 26(8):752-8. · 2.13 Impact Factor
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ABSTRACT: This study evaluated letter recognition processing in Italian developmental dyslexics and its potential contribution to word reading. Letter/bigram recognition (naming and matching) and reading of words and non-words were examined. A group of developmental dyslexics and a chronologically age-matched group of skilled readers were examined. Dyslexics were significantly slower than skilled readers in all tasks. The rate and amount model (RAM, Faust et al., 1999) was used to detect global and specific factors in the performance differences controlling for the presence of over-additivity effects. Two global factors emerged. One ("letter-string" factor) accounted for the performance in all (and only) word and non-word reading conditions, indicating a large impairment in dyslexics (more than 100% reaction time - RT increase as compared to skilled readers). All the letter/bigram tasks clustered on a separate factor ("letter" factor) indicating a mild impairment (ca. 20% RT increase as compared to skilled readers). After controlling for global factor influences by the use of the z-score transformation, specific effects were detected for the "letter-string" (but not the "letter") factor. Stimulus length exerted a specific effect on dyslexics' performance, with dyslexics being more affected by longer stimuli; furthermore, dyslexics showed a stronger impairment for reading words than non-words. Individual differences in the "letter" and "letter-string" factors were uncorrelated, pointing to the independence of the impairments. The putative mechanisms underlying the two global factors and their possible relationship to developmental dyslexia are discussed.
Cortex 08/2009; 46(10):1272-83. · 6.08 Impact Factor
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ABSTRACT: Language delay is a frequent antecedent of literacy problems, and both may be linked to phonological impairment. Studies on developmental dyslexia have led to contradictory results due to the heterogeneity of the pathological samples. The present study investigated whether Italian children with dyslexia showed selective phonological processing deficits or more widespread linguistic impairment and whether these deficits were associated with previous language delay. We chose 46 children with specific reading deficits and divided them into two groups based on whether they had language delay (LD) or not (NoLD). LD and NoLD children showed similar, severe deficits in reading and spelling decoding, but only LD children showed a moderate impairment in reading comprehension. LD children were more impaired in phonological working memory and phonological fluency, as well as in semantic fluency, grammatical comprehension, and verbal IQ. These findings indicate the presence of a moderate but widespread linguistic deficit (not limited to phonological processing) in a subset of dyslexic children with previous language delay that does not generalize to all children with reading difficulties.
Child Neuropsychology 07/2009; 15(6):582-604. · 1.80 Impact Factor
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ABSTRACT: We tested the hypothesis that crowding effects are responsible for the reading slowness characteristic of developmental dyslexia. A total of twenty-nine Italian dyslexics and thirty-three age-matched controls participated in various parts of the study. In Experiment 1, we measured contrast thresholds for identifying letters and words as a function of stimulus duration. Thresholds were higher in dyslexics than controls for words (at a limited time exposure) but not for single letters. Adding noise to the stimuli produced comparable effects in dyslexics and controls. At the long time exposure thresholds were comparable in the two groups. In Experiment 2, we measured the spacing between a target letter and two flankers at a fixed level of performance as a function of eccentricity and size. With eccentricity, the critical spacing (CS) scaled in the control group with 0.62 proportionality (a value of b close to Bouma's law, 0.50) and with a greater proportionality (0.95) in the dyslexic group. CS was independent of size in both groups. In Experiment 3, we examined the critical print size (CPS), that is, the increase in reading rate up to a critical character size (S. T. Chung, J. S. Mansfield, & G. E. Legge, 1998). CPS of dyslexic children was greater than that of controls. Individual maximal reading speed was predicted by individual bs (from Experiment 2). The maximal reading rate achieved by dyslexics at CPS (and also for larger print sizes) was below the values observed in controls. We conclude that word analysis in dyslexics is slowed because of greater crowding effects, which limit letter identification in multi-letter arrays across the visual field. We propose that the peripheral reading of normal readers might constitute a model for dyslexic reading. The periphery model accounts for 60% of dyslexics' slowness. After compensating for crowding, the dyslexics' reading rate remains slower than that of proficient readers. This failure is discussed in terms of a developmental learning effect.
Journal of Vision 01/2009; 9(4):14.1-18. · 3.38 Impact Factor
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ABSTRACT: To examine the effect of word length and several sublexical, and lexico-semantic variables on the reading of Italian children with a developmental reading deficit.
Previous studies indicated the role of word length in transparent orthographies. However, several factors that may interact with word length were not controlled for.
Seventeen impaired and 34 skilled sixth-grade readers were presented words of different lengths, matched for initial phoneme, bigram frequency, word frequency, age of acquisition, and imageability. Participants were asked to read aloud, as quickly and as accurately as possible. Reaction times at the onset of pronunciation and mispronunciations were recorded.
Impaired readers' reaction times indicated a marked effect of word length; in skilled readers, there was no length effect for short words but, rather, a monotonic increase from 6-letter words on. Regression analyses confirmed the role of word length and indicated the influence of word frequency (similar in impaired and skilled readers). No other variables predicted reading latencies.
Word length differentially influenced word recognition in impaired versus skilled readers, irrespective of the action of (potentially interfering) sublexical, lexical, and semantic variables. It is proposed that the locus of the length effect is at a perceptual level of analysis. The independent influence of word frequency on the reading performance of both groups of participants indicates the sparing of lexical activation in impaired readers.
Cognitive and behavioral neurology: official journal of the Society for Behavioral and Cognitive Neurology 01/2009; 21(4):227-35. · 1.09 Impact Factor
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ABSTRACT: According to a recent theory of dyslexia, the perceptual anchor theory, children with dyslexia show deficits in classic auditory and phonological tasks not because they have auditory or phonological impairments but because they are unable to form a 'perceptual anchor' in tasks that rely on a small set of repeated stimuli. The theory makes the strong prediction that rapid naming deficits should only be present in small sets of repeated items, not in large sets of unrepeated items. The present research tested this prediction by comparing rapid naming performance of a small set of repeated items with that of a large set of unrepeated items. The results were unequivocal. Deficits were found both for small and large sets of objects and numbers. The deficit was actually bigger for large sets than for small sets, which is the opposite of the prediction made by the anchor theory. In conclusion, the perceptual anchor theory does not provide a satisfactory account of some of the major hallmark effects of developmental dyslexia.
Developmental Science 12/2008; 11(6):F40-7. · 3.89 Impact Factor
