Early numeracy skills in children with intellectual disabilities between age groups 4–7 years: developmental patterns and interrelationships

The aim of the present study was to investigate the Early Numerical Skills between mental age groups by conducting Bonferroni-adjusted multiple comparisons. Moreover, the differences related to the etiological basis of Intellectual Disabilities (IDs) were examined. A quantitative approach was employed through the administration of the Utrecht Early Numeracy Test (2008), in a sample of N = 310 children with IDs and mental age ranging from 4;06 to 7;01 (years; months) (M = 6.02, SD = .714). The measurement equivalence in terms of gender and etiology of IDs (organic and non-organic etiology) was examined and confirmed through CFA. In addition, the initial sample was divided into three mental age groups [ < 5 (≤69 months), 6 (70-81 months) and ≥7 (≥82 months)]so as to investigate the effect of mental age on early numerical skills. Applying the Bonferroni-adjusted multiple comparisons between the groups, statistically significant differences were revealed in early numerical skills. Application of structural equation modelling confirmed significant differences across mental age groups and etiology of ID. Findings are discussed with reference to educational implications associated with the instructional practices of numeracy skills in preschool and first grade children with IDs.