Can conditioned reinforcers and Variable-Ratio Schedules make food- and fluid control redundant? A comment on the NC3Rs Working Group's report

This commentary challenges the conclusions of the NC3Rs Working Group's recent special report that food- or fluid control is sometimes necessary to conduct modern neuroscientific investigations in macaque monkeys (Prescott et al., 2010). Given the potential suffering of animals subjected to food- or fluid control, the decision to subject an animal to such practices should be taken hesitantly. That decision hinges on to which extent the animal is willing to be involved in the task. The authors have done a scientific literature search and express expert opinion, but fail to mention two techniques that may greatly influence the animals’ motivation to participate in the task and thus reduce the need for food- or fluid control, namely (1) the use of conditioned reinforcers in addition to primary reinforcers; and (2) the use of Variable-Ratio Schedules rather than continuous reinforcement. An ethical and humane approach to animal experimentation suggests that all options should be explored and thoroughly investigated before resorting to methods potentially challenging the animals’ welfare.

► Cross-discipline fertilization may improve animals’ welfare.
► Dietary control may be redundant – alternatives suggested.
► Conditioned reinforcers improve animals’ motivation to perform a task.
► Variable-Ratio Schedules involve surprises and enhance motivation.
► Aversive stimuli inhibit responses and should be avoided.