This study investigated how gifted children with dyslexia might be able to mask literacy problems and the role of possible compensatory mechanisms. The sample consisted of 121 Dutch primary school children that were divided over four groups (typically developing [TD] children, children with dyslexia, gifted children, gifted children with dyslexia). The test battery included measures of literacy (reading/spelling) and cognitive abilities related to literacy and language (phonological awareness [PA], rapid automatized naming [RAN], verbal short-term memory [VSTM], working memory [WM], grammar, and vocabulary). It was hypothesized that gifted children with dyslexia would outperform children with dyslexia on literacy tests. In addition, a core-deficit model including dyslexia-related weaknesses and a compensational model involving giftedness-related strengths were tested using Bayesian statistics to explain their reading/spelling performance. Gifted children with dyslexia performed on all literacy tests in between children with dyslexia and TD children. Their cognitive profile showed signs of weaknesses in PA and RAN and strengths in VSTM, WM, and language skills. Findings indicate that phonology is a risk factor for gifted children with dyslexia, but this is moderated by other skills such as WM, grammar, and vocabulary, providing opportunities for compensation of a cognitive deficit and masking of literacy difficulties.

High comorbidity rates have been reported between mathematical learning disabilities (MD) and reading and spelling disabilities (RSD). Research has identified skills related to math, such as number sense (NS) and visuospatial working memory (visuospatial WM), as well as to literacy, such as phonological awareness (PA), rapid automatized naming (RAN) and verbal short-term memory (Verbal STM). In order to explain the high comorbidity rates between MD and RSD, 7–11-year-old children were assessed on a range of cognitive abilities related to literacy (PA, RAN, Verbal STM) and mathematical ability (visuospatial WM, NS). The group of children consisted of typically developing (TD) children (n = 32), children with MD (n = 26), children with RSD (n = 29), and combined MD and RSD (n = 43). It was hypothesized that, in line with the multiple deficit view on learning disorders, at least one unique predictor for both MD and RSD and a possible shared cognitive risk factor would be found to account for the comorbidity between the symptom dimensions literacy and math. Secondly, our hypotheses were that (a) a probabilistic multi-factorial risk factor model would provide a better fit to the data than a deterministic single risk factor model and (b) that a shared risk factor model would provide a better fit than the specific multi-factorial model. All our hypotheses were confirmed. NS and visuospatial WM were identified as unique cognitive predictors for MD, whereas PA and RAN were both associated with RSD. Also, a shared risk factor model with PA as a cognitive predictor for both RSD and MD fitted the data best, indicating that MD and RSD might co-occur due to a shared underlying deficit in phonological processing. Possible explanations are discussed in the context of sample selection and composition. This study shows that different cognitive factors play a role in mathematics and literacy, and that a phonological processing deficit might play a role in the occurrence of MD and RSD.

Although poor Rapid Automatized Naming (RAN) is a risk factor for reading and/or spelling difficulties (RSD) as well as for mathematical difficulties (MD), many questions surround this relationship. The main objective of the present study was to obtain insight in the relationship between alphanumeric vs. non-alphanumeric RAN and reading/spelling and mathematics in groups of 7-to-10-year-old children with RSD, MD, both RSD + MD, and in typically developing (TD) children. Analyses of variance between the groups showed that the RSD and comorbid (RSD + MD) groups were impaired on both alphanumeric and non-alphanumeric RAN, whereas the MD group was impaired only on non-alphanumeric RAN. Furthermore, non-alphanumeric RAN correlated with all measures except spelling, whereas alphanumeric RAN correlated with the reading and spelling measures only. These findings point towards different/additional cognitive processes needed in non-alphanumeric RAN compared to alphanumeric RAN, which affects the relationship with literacy and math.

The present study compared eye movements and performance of a 9-year-old girl with Developmental Dyscalculia (DD) on a series of number line tasks to those of a group of typically developing (TD) children (n = 10), in order to answer the question whether eye-tracking data from number line estimation tasks can be a useful tool to discriminate between TD children and children with a number processing deficit. Quantitative results indicated that the child with dyscalculia performed worse on all symbolic number line tasks compared to the control group, indicated by a low linear fit (R2) and a low accuracy measured by mean percent absolute error. In contrast to the control group, her magnitude representations seemed to be better represented by a logarithmic than a linear fit. Furthermore, qualitative analyses on the data of the child with dyscalculia revealed more unidentifiable fixation patterns in the processing of multi-digit numbers and more dysfunctional estimation strategy use in one third of the estimation trials as opposed to ~10% in the control group. In line with her dyscalculia diagnosis, these results confirm the difficulties with spatially representing and manipulating numerosities on a number line, resulting in inflexible and inadequate estimation or processing strategies. It can be concluded from this case study that eye-tracking data can be used to discern different number processing and estimation strategies in TD children and children with a number processing deficit. Hence, eye-tracking data in combination with number line estimation tasks might be a valuable and promising addition to current diagnostic measures.

This study investigated risk and protective factors associated with dyslexia and literacy development, both at the group and individual level, to gain more insight in underlying cognitive profiles and possibilities for compensation in high-IQ children. A sample of 73 Dutch primary school children included a dyslexic group, a gifted-dyslexic group, and a borderline-dyslexic group (i.e., gifted children with relative literacy problems). Children were assessed on literacy, phonology, language, and working memory. Competing hypotheses were formulated, comparing the core-deficit view to the twice-exceptionality view on compensation with giftedness-related strengths. The results showed no indication of compensation of dyslexia-related deficits by giftedness-related strengths in gifted children with dyslexia. The higher literacy levels of borderline children compared to gifted children with dyslexia seemed the result of both fewer combinations of risk factors and less severe phonological deficits in this group. There was no evidence for compensation by specific strengths more relevant to literacy development in the borderline group. Accordingly, the findings largely supported the core-deficit view, whereas no evidence for the twice-exceptionality view was found. Besides practical implications, the findings also add to knowledge about the different manifestations of dyslexia and associated underlying cognitive factors at the higher end of the intelligence spectrum.Electronic supplementary materialThe online version of this article (doi:10.1007/s11881-015-0106-y) contains supplementary material, which is available to authorized users.