Effects of hyoscine and meciozine on vigilance and short-term memory.

An investigation was made of the effects of 1 mg. hyoscine hydrobromide and of 50 mg. meclozine hydrochloride on the performance of tasks of vigilance and short-term memory. In further trials the effects of these drugs were measured after ingestion of 32 g. ethyl alcohol. Efficiency was impaired by hyoscine taken alone, but meclozine alone had no significant effect. The effect of hyoscine was substantially increased by the presence of alcohol and under these conditions the effect of meclozine was equally great. The vigilance task appeared to be more sensitive to the effects of the drugs than the memory task, and possible reasons for this are considered in the discussion.