Primary Hypotheses: 1. Baseline primary outcome measures will be impaired in SPD subjects compared to controls. 2. SPD subjects on DAR-0100A will show improvement on primary measures greater than healthy controls and SPD patients randomized to placebo between baseline and Day 4. 3. SPD patients will show significant improvements on primary outcome variables on drug compared to placebo but not on comparis¬on perceptual (JLOT) and processing speed/attentional tasks (Trails A).