Cogmed Training: Participants will perform the Cogmed WM training program via web-based software on a personal computer. If they do not have a personal computer, we will provide them with a laptop to borrow for the six weeks of training. Participants will train for 45 minutes per day, five days per week, for six weeks. Memory stimuli are presented in a computerized system in a total of eight visuospatial and verbal WM training exercises. Each training exercise consists of 15 trials. The exercises are in a video game format—with colorful graphics and crisp sound. In one spatial WM exercise the child remembers the sequence in which rows of lights turn on; in a verbal WM exercise the child recalls numbers in the reverse order in which they are given. The child uses a computer mouse to click the answers and earns points for performing well. The exercises train the child to attend to the screen and to visualize the location and remember the stimuli. For each of the eight WM training exercises difficulty is adjusted by changing the number of stimuli to be remembered. Training is performed close to the capacity of the individual by using an adaptive staircase method that adjusts difficulty on a trial-by-trial basis. At the end of each training day an Improvement index is calculated that measures improvement during the training period. The Improvement index is based on the person's results on three exercises.