The aim of this study was to evaluate if children with Developmental Dyscalculia (DD) exhibit a general deficit in magnitude representations or a specific deficit in the connection of symbolic representations with the corresponding analogous magnitudes. DD was diagnosed using a timed arithmetic task. The experimental magnitude comparison tasks were presented in non-symbolic and symbolic formats. DD and typically developing (TD) children showed similar numerical distance and size congruity effects. However, DD children performed significantly slower in the symbolic task. These results are consistent with the access deficit hypothesis, according to which DD children's deficits are caused by difficulties accessing magnitude information from numerical symbols rather than in processing numerosities per se.

Although basic numerical skills have been widely studied in the last years, very few studies have undertaken a developmental approach. The present study evaluated the development of the magnitude comparison basic numerical ability, in children from first, third and sixth grades by means of the subject's response time in numerical tasks presented in symbolic and non-symbolic formats. The results showed a significant decrease on quantities processing speed as age increases, which suggests numerical skills tend to become automatic with instruction. The differences found, concerning the general achievement pattern in each school year, might express the maturational specificities of the numerical representation system through development.

Introduction: The Center for Epidemiologic Studies Depression Scale – Revised (CESD-R) was developed to provide an efficient screening scale for depression syndrome, mimicking the original CESD, one of the most widely used screening tools to measure depressive symptoms globally. This investigation examined the factor structure of the CESD-R with a non-clinical Brazilian population. Method: We performed exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) of two adult samples, and also conducted invariance analysis by sex and place of residence of the participants. The full sample consisted of 1,427 adults, divided into two groups. The first sample (n = 400) was used for the EFA and the second sample (n = 1027) for the CFA. Results: The EFA indicated an internal structure composed of a single factor, which explained 53.2% of the variance. The CFA attested to the unidimensionality of the measure. Fit indices and reliability indicators showed values higher than expected, without modifications in the initial structure. The model was invariant in relation to the variables investigated at four different levels (configural, metric, scalar, and strict). Conclusions: Our findings support the utility of the CESD-R and suggest its validity for application to the Brazilian population in general.

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