Gloria Di Filippo

Length Effect in Word Naming in Reading: Role of Reading Experience and Reading Deficit in Italian Readers

Vocal reaction times (RTs) in naming 3- to 8-letter words were measured in proficient and dyslexic readers (Study 1). In proficient readers, RTs were independent of word length up to 5-letter words, indicating parallel processing. In the 5- to 8-letter range, RTs increased linearly, indicating sequential processing. Reading experience was associated with both faster discrimination of individual elements and parallel processing of increasingly large word parts. In dyslexics, RTs increased linearly with increasing length indicating reliance on sequential decoding. Individual analysis indicated 2 profiles of RTs (Types A and B). In Study 2, the distinction between A and B dyslexics was not associated with the use of different reading procedures. However, a more marked speed deficit characterized Type B dyslexics.

Italian developmental dyslexic and proficient readers: Where are the differences?

Italian dyslexic children are characterized by a pervasive reading speed deficit, with relatively preserved accuracy. This pattern has been associated with predominant use of the nonlexical reading procedure. However, there is no evidence of a deficit in the lexical route of Italian dyslexics. We investigated both lexical and nonlexical reading procedures in dyslexic children through two marker effects, namely, the word frequency effect and the effect of contextual grapheme-to-phoneme conversion rules. Although dyslexics were slower and less accurate than controls, they were affected by word frequency, grapheme contextuality, and their interaction in a similar manner as average readers. These results show the use of lexical reading in Italian dyslexics, and refute the claim of a deficit in whole-word processing with consequent over-reliance on the nonlexical route.

Rapid naming, not cancellation speed or articulation rate, predicts reading in an orthographically regular language (Italian)

This study examined the influence of rapid automatization naming (RAN) measures on various parameters of reading performance in children who were native speakers of a language with a shallow orthography (Italian). Participants included 281 children enrolled in first-to-sixth grade. They were given a Naming test, in which they had to name rapidly matrices of colors, objects, or digits, a Cancellation test, using the same stimulus materials, and an oral Articulation test. Performance on all tests improved steadily across ages tested. Performance on the Naming test, but not on the Cancellation and Articulation tests, predicted speed and accuracy in reading; none of these measures reliably predicted the reading comprehension measure. Data on a Blending test were also available for a subsample of first- and third-graders. Both RAN and phonological ability contributed independently to the prediction of reading ability (accuracy and speed) in these participants. The results extend observations on RAN to an orthographically shallow language (Italian) and suggest an element of continuity between languages with opaque and transparent orthographies.

Do phonologic and rapid automatized naming deficits differentially affect dyslexic children with and without a history of language delay? A study of Italian dyslexic children.

ObjectiveThe study aims to verify whether phonologic and rapid automatized naming (RAN) deficits are present and associated in Italian dyslexic children and whether they differentially affect dyslexics with and without a history of previous language delay (LD). BackgroundAccording to the phonologic core deficit hypothesis, dyslexia may stem from impairment of the representation and manipulation of phonemes and may be closely associated with oral language deficits. However, deficits in tasks not requiring fine-grained phonologic representations, such as RAN, have also been described in dyslexic children. MethodsThirty-seven children were selected on the basis of a reading deficit and were assigned to 2 groups according to whether or not they had a history of early LD as determined retrospectively by parental report. A battery of reading and writing, verbal working memory, metaphonologic, RAN, and visual search tests were administered. ResultsRAN deficits were shared by most dyslexics (with and without a history of LD), whereas phonologic deficits were mainly associated with a previous LD. This last condition did not result in a more profound impairment of reading and writing decoding skills. ConclusionIn a shallow orthography such as Italian, RAN, not phonologic deficits, may represent the main cognitive marker of developmental dyslexia.

Lexicality and Stimulus Length Effects in Italian Dyslexics: Role of the Overadditivity Effect

The effect of lexicality and stimulus length was studied in 32 third- and fourth-grade Italian dyslexics and in 86 age-matched controls. A visual lexical decision task was used. As proposed by Faust et al. (1999), the results were analyzed in terms of raw reaction time (RT) data and using the z-score transformation to control for the presence of overadditivity effects. In terms of RTs, dyslexics showed a larger difference between words and nonwords (lexicality effect) and between short and long stimuli (length effect) than proficient readers. When data were transformed into z scores, only the group by length interaction remained significant while that with lexicality vanished. This pattern indicates that stimulus length has a specific role in Italian dyslexics’ reading deficit; in contrast, slowness in responding to nonwords was not specific but was interpreted as one aspect of dyslexics’ general inability to deal with alphabetical material (overadditivity effect).

Naming speed and visual search deficits in readers with disabilities: evidence from an orthographically regular language (Italian).

The study examined rapid automatized naming (RAN) in 42 children with reading disabilities and 101 control children—all native speakers of Italian, a language with shallow orthography. Third-, 5th- and 6th-grade children were given a RAN test that required rapid naming of color, object, or digit matrices. A visual search test using the same stimulus material (but not requiring a verbal response) and an oral articulation test were also given. Readers with disabilities performed worse than controls on the RAN test. This effect was larger in higher grades than in lower ones. Readers with disabilities were also slower than controls in performing the visual search test. The pattern of results for the RAN test held constant when the visual search performance was partialed out by covariance analysis, indicating the independence of the 2 deficits. The 2 groups did not differ for articulation rate. Finally, analysis of the pattern of intercorrelations indicated that reading speed was most clearly related to RAN, particularly in the group with reading disabilities. The results extend observations of RAN effects on reading deficits to Italian, an orthographically shallow language.

Is developmental dyslexia modality specific? A visual-auditory comparison of Italian dyslexics

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.

Developmental dyslexia in a regular orthography: can the reading profile be reduced to strategic control?

In languages with regular orthographies, the identification of different forms of reading impairment (such as surface or phonological dyslexia) has proved elusive. Alternatively, it has been proposed that different patterns of errors depend upon strategic choices on the part of the reader. The present study aimed to test this strategic interpretation by evaluating the effectiveness of instructions to read quickly (or accurately) in modifying the reading rate and types of errors of dyslexic children. Further, drawing on an error classification based on the contrast between sounding-out behaviour and word substitution, we examined the types of reading error that best characterize the deficit in a language with regular orthography (Italian). Thirty children with dyslexia and 30 chronologically age-matched controls read aloud passages and word lists with instructions to emphasize either rate or accuracy. When asked to read quickly, children with dyslexia increased their reading rate (although less than skilled children). However, the type of instructions had little influence on reading errors. Therefore, the results did not support the view that strategic control has an important role in modulating the types of reading errors made by children with dyslexia. For word lists, sounding-out behaviour, errors in stress assignment, and form-related nonwords were useful to correctly identifying children with dyslexia. For text passages, sounding-out behaviour and form-related errors were the best predictors of group membership. Thus, specific types of errors are a fundamental component of the reading deficit in children who speak a language with regular orthography over and above their reading slowness.

Reading and lexical-decision tasks generate different patterns of individual variability as a function of condition difficulty

We reanalyzed previous experiments based on lexical-decision and reading-aloud tasks in children with dyslexia and control children and tested the prediction of the difference engine model (DEM) that mean condition reaction times (RTs) and standard deviations (SDs) would be linearly related (Myerson et al., 2003). Then we evaluated the slope and the intercept with the x-axis of these linear functions in comparison with previously reported values (i.e., slope of about 0.30 and intercept of about 300 ms). In the case of lexical decision, the parameters were close to these values; by contrast, in the case of reading aloud, a much steeper slope (0.66) and a greater intercept (482.6 ms) were found. Therefore, interindividual variability grows at a much faster rate as a function of condition difficulty for reading than for lexical-decision tasks (or for other tasks reported in the literature). According to the DEM, the slope of the regression that relates means and SDs indicates the degree of correlation among the durations of the stages of processing. We propose that the need for a close coupling between orthographic and phonological processing in reading is what drives the particularly strong relationship between performance and interindividual variability that we observed in reading tasks.

Analyzing Global Components in Developmental Dyscalculia and Dyslexia

The study examined whether developmental deficits in reading and numerical skills could be expressed in terms of global factors by reference to the rate and amount (RAM) and difference engine (DEM) models. From a sample of 325 fifth grade children, we identified 5 children with dyslexia, 16 with dyscalculia, 7 with a “mixed pattern,” and 49 control children. Children were asked to read aloud words presented individually that varied for frequency and length and to respond (either vocally or manually) to a series of simple number tasks (addition, subtraction, number reading, and number comparisons). Reaction times were measured. Results indicated that the deficit of children with dyscalculia and children with a mixed pattern on numerical tasks could be explained by a single global factor, similarly to the reading deficit shown by children with dyslexia. As predicted by the DEM, increases in task difficulty were accompanied by a corresponding increase in inter-individual variability for both the reading and numerical tasks. These relationships were constant across the four groups of children but differed in terms of slope and intercept on the x-axis, indicating that two different general rules underlie performance in reading and numerical skills. The study shows for the first time that, as previously shown for reading, also numerical performance can be explained with reference to a global factor. The advantage of this approach is that it takes into account the over-additivity effect, i.e., the presence of larger group differences in the case of more difficult conditions over and above the characteristics of the experimental conditions. It is concluded that reference to models such as the RAM and DEM can be useful in delineating the characteristics of the dyscalculic deficit as well as in the description of co-morbid disturbances, as in the case of dyslexia and dyscalculia.