Residual differences in language processing in compensated dyslexics revealed in simple word reading tasks

Using regional cerebral blood flow as an index of cerebral activity we studied dyslexic and control subjects during simple word reading tasks. The groups were pre-tested for reading skill and the dyslexic group had a lower reading performance but could read and comprehend standard texts. The aim was to elucidate differences in the cerebral activation pattern during reading. The tasks were simple enough that performance differences between the groups could be excluded. We found specific differences between the two groups that were dependent on the language task. When the visual route for language information was used, minor qualitative differences were found between the groups pertaining to the dominant hemisphere. Increasing the complexity of the task by using pseudowords activated the left frontal region more in the dyslexic group than in the control group. A similar effect was seen in a minor region in extrastriate lateral occipital cortex (BA 19). This finding indicates that the dyslexics used areas in these regions that the controls did not. On the other hand, the dyslexics activated less in the right angular gyrus, right dorsolateral prefrontal cortex, and in the right pallidum. Reading skill correlated with the level of activity in the right frontal cortex. We conclude, that cerebral activation pattern elicited by reading is different in dyslexics compared to controls in spite of an almost complete functional compensation.     

Impaired oral reading in two atypical dyslexics: a comparison with a computational lexical-analogy model

A computational model of reading was developed based upon the notion that the structural relationship between orthography and phonology is of greater importance than the dimension of semantics for the reading aloud of single words. Degradation of this model successfully simulated the reading performance of two patients with atypical acquired dyslexia. The first patient CAV, studied and described in the literature by Warrington in 1981, presented with unusual concrete word dyslexia, i.e., he had a category-specific reading deficit for concrete words compared with abstract words. The second patient BG is a phonological dyslexic who, although displaying a strong concreteness effect (concrete words read better than abstract words), was able to read functors individually perfectly well, a pattern that is rarely if ever seen. The computational model was used to generate a set of words for which it was predicted that BG would show no concreteness effect. The results of BG's reading of these words were consistent with this prediction, thereby providing greater support for the validity of the model. It is concluded that a computational approach that attempts not only to reproduce the core symptoms of the major varieties of acquired dyslexia but also to simulate clinical data from specific patients has much to contribute to the understanding of cognitive deficits and to the design of effective rehabilitation strategies.     

Speech-mediated retention in dyslexics

Dyslexics (6 to 9 yr. old) and a control group of 12 normal readers (second-graders) were tested on a memory task with rhyming and non-rhyming items. The most important finding is that both groups were penalized by rhyme, indicating speech coding. It was observed that the dyslexics were not less penalized by rhyme than were controls. The present results are compared with those of other recent studies.     

Neuropsychological profile of adult dyslexics

One hundred and fifteen adults with well-documented childhood reading status underwent a series of neuropsychological tests including tests of memory, attention, phonological processing, and visual perceptual skills in an attempt to define the neuropsychological profile of dyslexia in adulthood. Compared to a normal nonreading disabled sample, subjects with a history of reading disability performed consistently poorer on most neuropsychological tests. However, after covarying for intelligence and socioeconomic status, only tests of rapid naming, phonological awareness, and nonword reading were significant discriminating measures. The hypothesis that deficits in phonological processing comprise the core cognitive deficits in adults with a history of reading disability was supported. Independent of current adult reading ability, measures of nonword reading, phonological awareness, and rapid naming serve as indicators of a childhood history of reading disability.     

Auditory frequency discrimination in adult developmental dyslexics

Developmental dyslexics reportedly discriminate auditory frequency poorly. A recent study found no such deficit. Unlike its predecessors, however, it employed multiple exposures per trial to the standard stimulus. To investigate whether this affects frequency discrimination in dyslexics, a traditional two-interval same-different paradigm (2I_1A_X) and a variant with six A-stimuli per trial (2I_6A_X) were used here. Frequency varied around 500 Hz; interstimulus interval (ISI) ranged between 0 and 1,000 msec. Under 2I_1A_X, dyslexics always had larger just noticeable differences (JNDs) than did controls. Dyslexic and control JNDs were equal at shorter ISIs under 2I_6A_X, but dyslexics became worse than controls at longer ISIs. Signal detection analysis suggests that both sensory variance and trace variance are larger in dyslexics than in controls.     

Cross-modality temporal processing deficits in developmental phonological dyslexics

Neuroanatomical evidence suggests that poor readers may have abnormal lateral (LGN) and medial (MGN) geniculate nuclei responsible for temporal processing in visual and auditory domains respectively (Livingstone & Galaburda, 1993). Although behavioral evidence does support this neuroanatomical evidence in that poor readers have performed poorly on visual and auditory tasks thought to require the utilization of the LGN and MGN, respectively, appropriate examination of the coexistence of these behavioral abnormalities in the same population of poor readers has yet to take place. The present study examined correlations between visual and auditory temporal processing scores of all readers (collapsed groups), good readers, and poor readers who were isolated into phonological and surface dyslexic subtypes. The same subjects and data from Cestnick and Coltheart (1999) and Cestnick and Jerger (2000) were used to run the analyses. Results demonstrated a multitude of correlations between these tasks for the phonological dyslexic group only. It is contended that cross-modality temporal processing deficits may exist in poor nonlexical (phonological dyslexics) as opposed to poor lexical (surface dyslexics) readers. It is conceivable that phonological dyslexics may also have deficiencies within the LGN and MGN, or perhaps within systems related to these nuclei. The precise cause of these processing patterns and correlations is still unknown.     

Electronic media use, reading, and academic distractibility in college youth.

Activities that require focused attention, such as reading, are declining among American youth, while activities that depend on multitasking, such as instant messaging (IMing), are increasing. We hypothesized that more time spent IMing would relate to greater difficulty in concentrating on less externally stimulating tasks (e.g., academic reading). As hypothesized, the amount of time that young people spent IMing was significantly related to higher ratings of distractibility for academic tasks, while amount of time spent reading books was negatively related to distractibility. The distracting nature and the context of IMing in this population are described.     

New and updated tests of print exposure and reading abilities in college students

The relationship between print exposure and measures of reading skill was examined in college students (N = 99, 58 female; mean age = 20.3 years). Print exposure was measured with several new self-reports of reading and writing habits, as well as updated versions of the Author Recognition Test and the Magazine Recognition Test (Stanovich & West, 1989). Participants completed a sentence comprehension task with syntactically complex sentences, and reading times and comprehension accuracy were measured. An additional measure of reading skill was provided by participants' scores on the verbal portions of the ACT, a standardized achievement test. Higher levels of print exposure were associated with higher sentence processing abilities and superior verbal ACT performance. The relative merits of different print exposure assessments are discussed.     

Self-construal predicts reading motivation: A comparison between Hispanic American and Japanese college students

Social Psychology of Education - Self-construal refers to how individuals view themselves independently from others (Independent self-construal) or interdependently with others (Interdependent...     

EEG alpha asymmetry in dyslexics during speaking and block design tasks

Lateral specialization for speech and spatial construction was investigated in a highly screened group of dyslexic and normal-reading boys, age 9-13, by examining the extent to which their EEG alpha asymmetry changed from one task to the other. EEG was recorded from central, midtemporal, and parietal leads during several minutes of spontaneous narrative speech, and while the child constructed block designs. The dyslexics showed the same strongly task-dependent asymmetry as the normal readers, comparable to that observed in our adult populations. The observations were confirmed with a second independently chosen cohort of subjects. This result is discussed in terms of the constraints it places on models of dyslexia which invoke disorders of lateral specialization and hemisphere integration.     

The reading ability of good and poor temporal processors among a group of college students

In this study, we examined whether good auditory and good visual temporal processors were better than their poor counterparts on certain reading measures. Various visual and auditory temporal tasks were administered to 105 undergraduates. They read some phonologically regular pseudowords and irregular words that were presented sequentially in the same ("word" condition) and in different ("line" condition) locations. Results indicated that auditory temporal acuity was more relevant to reading, whereas visual temporal acuity was more relevant to spelling. Good auditory temporal processors did not have the advantage in processing pseudowords, even though pseudoword reading correlated significantly with auditory temporal processing. These results suggested that some higher cognitive or phonological processes mediated the relationship between auditory temporal processing and pseudoword reading. Good visual temporal processors did not have the advantage in processing irregular words. They also did not process the line condition more accurately than the word condition. The discrepancy might be attributed to the use of normal adults and the unnatural reading situation that did not fully capture the function of the visual temporal processes. The distributions of auditory and visual temporal processing abilities were co-occurring to some degree, but they maintained considerable independence. There was also a lack of a relationship between the type and severity of reading deficits and the type and number of temporal deficits.     

Developmental dyslexics do not fit in boxes: Evidence from the case studies

Abstract

An examination is undertaken of conclusions drawn from some case studies of developmental dyslexia which have categorised subjects as phonological or surface dyslexics. Various criticisms are advanced of the conclusions drawn from these studies, such as the absence of data from a proper sample of poor readers to illustrate the distribution of performance on specific aspects of reading, the lack of agreed criteria for the classifications made, and inadequate analysis of the error data.

It is concluded that no good grounds exist for the claim that developmental dyslexics fall into clearly distinguishable categories, determined by different specific processing deficits. Seymour (1986) reached a similar conclusion and suggested that a large number of different patterns of deficit exist. However, it is suggested here that all the cases discussed showed a deficit in phonological processes and that differences in performance on such aspects of reading as the ability to read irregularly spelled words, the frequency of “don't know” responses, and ability to read nonwords result from differences in the strategy adopted to cope with the difficulty. Snowling (1987) has made a similar suggestion. The importance of considering strategic differences when investigating reading behaviour is stressed, together with the need to consider factors affecting strategy choice.     

Variation among developmental dyslexics: evidence from a printed-word-learning task

A word-learning task was used to investigate variation among developmental dyslexics classified as phonological and surface dyslexics. Dyslexic children and chronological age (CA)- and reading level (RL)-matched normal readers were taught to pronounce novel nonsense words such as veep. Words were assigned either a regular (e.g., "veep") or an irregular (e.g., "vip") pronunciation. Phonological dyslexics learned both regular and exception words more slowly than the normal readers and, unlike the other groups, did not show a regular-word advantage. Surface dyslexics also learned regular and exception words more slowly than the CA group, consistent with a specific problem in mastering arbitrary item-specific pronunciations, but their performance resembled that of the RL group. The results parallel earlier findings from Manis, Seidenberg, Doi, McBride-Chang, & Petersen [Cognition 58 (1996) 157-195] indicating that surface dyslexics and phonological dyslexics have a different profile of reading deficits, with surface dyslexics resembling younger normal readers and phonological dyslexics showing a specific phonological deficit. Models of reading and reading disability need to account for the heterogeneity in reading processes among dyslexic children.     

Missing -ing in reading: Developmental changes in reading units

College students and school children between the ages of 6 and 10 were asked to search four 50-word passages for instances of the target letter n. The subjects made most letter detection errors on the function words in and and, and on the suffix morpheme -ing. This “missing letter” effect showed a developmental trend, with the proportion of errors on function words and suffix morphemes increasing as a function of school grade. The data are consistent with the hypothesis that frequent linguistic entities such as word-boundary morphemes tend to be unitized in fluent reading, and that the ability to form such units is acquired gradually in the course of learning to read.