Effects of zolpidem (⋄), L-838,417 (□), and diazepam (•) on observable measures related to sedation, including locomotor activity (a) and procumbent posture (sedation, b), in squirrel monkeys (n = 4). Data are expressed as the mean frequency score (±SEM). *, P < 0.05 vs. vehicle, Dunnett's tests.