Scientist with monkey in special primate restraining chair. A visual stimulation box is located above the monkey's head. The scientist holds a plug which connects the booth to electric relay racks. Although advances have been made in humane animal testing, primates are still widely used for scientific and medical research. Animal testing, also known as animal experimentation, animal research, and in vivo testing, is the use of non-human animals in experiments that seek to control the variables that affect the behavior or biological system under study. Animal rights organizations question the need for and legitimacy of animal testing, arguing that it is cruel and poorly regulated or that animals have the intrinsic right not to be used or harmed in experimentation.