The effects of single acute doses of diazepam were examined in eight male subjects using three performance tasks. The tasks included visual search, visual search and tracking in a divided-attention situation, and information processing rate. All subjects received four treatments averaging roughly 9.0, 4.5, 2.3 and 0 mg. At each treatment session, performance was examined at 12 time points in 23 hours after treatment. Significant impairment was found for 8 hours after treatment.