This task was adapted for children by Casey (Casey et al., 1995). It involves monitoring a series of letters for a repeat “two-back.” Letters are presented for 500 msec each, separated by a 1 sec interval. Participants must continually update their working memory in order to compare the current letter to the letter shape presented two trials back. Imaging studies, including that of Casey, find lateral prefrontal activation with this task. The Letter Two Back total correct score was the dependent variable used in analyses.
