Development of inattention, impulsivity, and processing speed as measured by the d2 Test: results of a large cross-sectional study in children aged 7-13.

The development of three aspects of selective attention was studied in 451 Dutch schoolchildren attending second to sixth grade. Selective attention was measured with the d2 Test of attention. The largest age differences were found for processing speed that continued to improve until the sixth grade. Impulsivity, as measured by the percentage of errors of commission, decreased until the fourth grade. Inattention, measured by the percentage of errors of omission, was stable in all grades. Processing speed and impulsivity were correlated with the score on the Attention Problems subscale of the Child Behavior Checklist. These results imply that selective attention continues to develop, at least, until the end of elementary school. The findings are support for a step-wise model of cognitive development (P. Anderson, 2002).