A test of anxiety that distinguishes between the actions of benzodiazepines and those of other minor tranquilisers and of stimulants.

The effects of minor tranquilisers and of stimulant drugs were studied in the Social Interaction test of anxiety in which the illuminance and unfamiliarity of the test arena are manipulated. Acute administration of sodium phenobarbitone (25 mg/kg) was without effect. Acute administration of sodium phenobarbitone (35 mg/kg) and of meprobamate (60 mg/kg) produced sedation: both locomotor activity and social interaction were reduced. On the other hand, amphetamine sulphate (2 mg/kg) and caffeine citrate (20 mg/kg) reduced social interaction, but increased locomotor activity. Chronic administration dissociated the pattern of results produced by sodium phenobarbitone (35 mg/kg) from that produced by flurazepam (0.5 mg/kg). With chronic treatment (5 days) neither drug reduced motor activity, but whereas phenobarbitone increased social interaction regardless of the test illuminance and unfamiliarity, the increase produced by flurazepam was limited to the more stressful test conditions, i.e., when the arena was unfamiliar or brightly lit.