The training techniques adopted in order to force circus animals to perform unnatural tricks are often barbaric. Many trainers use some degree of "negative reinforcement", training the animals by punishing them through physical intervention or withholding of food when they do not comply with commands or perform the tricks required. The brutality of the training of elephants and big cats for circuses, in countries all over the world, has been exposed by the international media. .
The training of animals at Chinese zoos, safari parks, and marine parks is difficult to observe as it is carried out in private areas away from the public. Observations that have been made include the use of both negative and positive reinforcement techniques.