Effects of d-amphetamine and diazepam on paired and grouped primate food competition

Two male and two female rhesus monkeys (Macaca mulatta) were the subjects of an experiment designed to assess the effect of d-amphetamine (DA; 0.125, 0.5 and 2.0 mg/kg, IM) and diazepam (DZP; 0.5 and 2.5 mg/kg, IM) on food-getting behavior in paired and group competition. Paired competition results show that in some cases submissive animals, that had previously failed to obtain apple pieces, were successful in obtaining some apple pieces when either the dominant animal of the pair or both subjects were given 0.5 mg/kg DA or 2.5 mg/kg DZP. Results revealed the same effect when all animals (group competition) were given 0.125 and 2.0 mg/kg DA and 2.5 mg/kg DZP. These results appear to indicate that the effect of drugs on food-getting behavior in competitive situations is in some manner influenced by the social status of the animal.