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
Japanese macaque Japanese macaque is very familiar in Japan, so when Japanese people simply say "saru", they usually have in mind the Japanese macaque. The Japanese macaque is sexually dimorphic. Males weigh on average , while females average . Macaques from colder areas tend to weigh more than ones from warmer areas. Male average height is and female average height is . Their brain size is about . Japanese macaques have short stumps for tails that average in males and in females. The macaque has a pinkish face and posterior. The rest of its body is covered in brown or greyish hair.