The second objective is to test the adequacy of average DAT occupancy in a range of later times for each dose. The times chosen (8, 10 and 12 hours) correspond to times Focalin XR has been shown to be clinically effective in an analogue classroom study. A range of times have been chosen since, while effective at 12 hours, the degree of clinical effectiveness decreased with later time periods. The adequacy of DAT occupancy across this range of time periods will provide important details on the in vivo molecular action of the medicine at periods of critical clinical activity.