PURPOSE: To characterize the development of classification and seriation notions in children with Down syndrome. METHODS: The sample was composed of 15 children with chronological ages between five and 13 years old. Subjects were placed in the pre-operational period of cognitive development and arranged in three egalitarian groups, according to their mental age. Mean mental ages were 3.4 years for G1, 4.3 years for G2, and 5.4 years for G3, as measured by the Primary Test of Nonverbal Intelligence (PTONI), administered in a different session than the others tasks. Children were submitted to classification tasks using non-figurative and figurative materials, and seriation tasks using bowls and sticks of different sizes. Subjects were individually assessed in different sessions for classification and seriation tasks, with no previously established order. All sessions were registered in video and transcribed in specific protocols. RESULTS: Statistically significant differences between G1 and G3 were observed for figural classification, with a higher use by G1 and no use by G3, and for non-figural classification with semantic characteristics with a lower use by G1 and a higher use by G3. For seriation, statistically significant results were obtained for comparisons between G1 and G3 regarding the empirical kind, and for comparisons between G3 and the other groups regarding the intermediate kind. Operational seriation was observed only for G3. CONCLUSION: Within- and between-group analysis showed the progressive and cumulative character of classification and seriation notions. Moreover, the studied children followed the same acquisition order observed in typical development. Clinical Trials registration # NCT00952354.
Down syndrome; Language development; Cognition; Child development; Discrimination learning
