Three levels from the Kaufman Assessment Battery for Children (K-ABC) standardization sample were randomly selected and their subtest score intercorrelations were subjected to factor analysis. The analyses yielded minor inconsistencies which suggest the instrument does not primarily measure simultaneous and sequential processing and achievement as…

Some evidence supports the hypothesis that formal operational reasoning ability (at least that measured by Piagetian tasks) is a unified process. The purpose of this research was to determine: (1) if conservation tasks, such as conservation of number, liquid amount, weight and volume, are unifactor; and (2) if conservation tasks form a scale of…