Dose effects of secobarbital in a Sternberg memory scanning task.

Mean reaction times obtained in a Sternberg memory-scanning task were examined for the effects of secobarbital at two doses (1.47 mg/kg and 2.94 mg/kg) spanning the dose range commonly used in clinical practice. Both doses slowed reaction time significantly, with a more pronounced effect at the higher dose. The discriminability of the probe stimulus interacted with the barbiturate, producing a hyperadditive effect on reaction time, but only at the high dose. There were no other significant interaction effects involving the drug. These data are interpreted as additional support for an hypothesis localizing the effects of secobarbital to stimulus-encoding stages in the reaction process.