Animal testing on non-human primates between the monkeys natural behaviors versus the behaviors expressed by the diazepam induced monkeys in thirteen different locations inside the maze. Scientist Barros and his colleagues created this model to allow the monkeys to roam a less confined environment and slightly eliminate outside factors that may induce stress. Many of the best-known allegations of abuse made by animal protection or animal rights groups against animal-testing facilities involve NHPs. The so-called "pit of despair" was used in experiments conducted on rhesus macaque monkeys during the 1970s by American comparative psychologist Harry Harlow at the University of Wisconsin–Madison.<ref name="Blum1994/95">Blum, Deborah. "The Monkey
White-cheeked macaque "Macaca". In terms of outward appearance, it closely resembles the Assam macaque, which is one of the reasons the two were believed to be the same species until recently. The main differences between the two include the presence of white, elongated whiskers on the face of the white-cheeked macaque, which are absent from other species. The whiskers begin to grow as the creatures approach sexual maturity, and eventually cover the whole face, giving the animals a rounded facial appearance. The white-cheeked macaque also grows dense hair along its neck, while not growing any hair along its short tail. Additionally, there