Animals are sometimes used in studies on memory, especially visual memory. One typical setup for these types of experiments involves having a rat try to find its way out of a maze or trap. The purpose of these kinds of experiments is to see whether the test animals are capable of memorizing paths and retracing their steps to the exit. Less common animal memory tests use chimpanzees and gorillas, and usually involve testing to see whether the animals can recall words used by humans to issue commands.
Animals have long been used in studies in learning and cognition. One of the most famous experiments in the psychology of learning was the "Pavlov's Dog" experiment, wherein it was demonstrated that a dog who had learned to associate the sound of a bell with feeding time would begin to salivate at the sound of a bell. Studies like these are only useful in evaluating behavioral learning, as animals are not believed to be capable of abstract understanding.
Animals are used in studies on communication in non-human species. Some researchers test whether great apes such as chimpanzees and gorillas are capable of learning words in human languages, while other researchers investigate intraspecies communication within groups of more remote species. The results of these studies have profound implications for philosophical debates regarding animal sentience, as they shed light on questions relating to the capacity of animals to engage in abstract thought.
Lab rats are sometimes used in addiction studies. Because it is illegal for a doctor to intentionally expedite the death of a patient, lab rats are used in addiction studies that test the more extreme consequences of long-term drug addiction. In some of these studies, doctors will give the rats a choice between morphine and food to see whether the rats will self-administer morphine at the expense of basic life necessities. These studies can provide insight into the nature of seemingly irrational behavior observed in addicts.