The children's size-ordering task: a new measure of nonverbal working memory.

We present a new measure of nonverbal working memory for children, entitled the Children's Size-Ordering Task (CSOT). Two separate studies were conducted to test the utility of and partially validate this measure. Three specific hypotheses were investigated, namely that: (1) CSOT performance would correlate with age; (2) the CSOT would correlate with established measures of working memory; and (3) children with ADHD would exhibit weaker performance on the CSOT relative to typically developing community control children. Participants across both studies included 50 children with ADHD and 50 control children matched by age and gender. Collectively, the results of both studies supported all three hypotheses. These findings lend support to the CSOT as a valid and effective measure of nonverbal working memory.