ABSTRACT
In psychopharmacological research concerned with the possible role played by various neurotransmitter systems in learning, the use of aversive stimuli is extensive. Some researchers may be interested in this class of stimuli per se, they may for example be interested in neurotransmitter systems mediating nociception, but many researchers employ aversive stimuli in learning experiments for convenience. Aversive stimuli such as electrical footshock are easy to deliver in discrete episodes and can easily be quantified. Furthermore, they have unconditioned effects that are less influenced by the animals’ state by comparison to many appetitive stimuli such as food, for example, that is most effective in appropriately deprived animals. The effects of aversive stimuli on learning are also relatively free of satiation effects unlike those of food which weaken as the animal eats more.
