The Corsi Blocks task (adapted from Milner, 1971) was included as a measure of nonverbal WM. The apparatus consisted of 10 blocks spread in a random array on a wooden base that was placed between the participant and the experimenter. The blocks were labeled from 1 to 10 on the back so that the numbers could be seen only by the experimenter. The forward condition was always administered first; the experimenter followed a standardized list of number sequences that she tapped out at the rate of one block per second, and then the child was asked to tap the same blocks in the same order. The backward condition followed the same procedure except that block positions needed to be recalled in reverse order, providing a more challenging measure of nonverbal WM. There were two practice trials before each condition. For each direction, the minimum span was two and the maximumspan was nine. Each span was made up of two trials for each sequence length. Children needed to correctly re-tap at least one of the two trials to successfully complete that span length. A score out of 88wascalculated for each condition as the number of blocks correctly recalled by the end of the last successfully completed span plus 1. Testing continued until the end of the sequences with nine blocks, although the score used for the analyses was based only on performance up to the n + 1 list.