A lexigram represents a word but is not necessarily indicative of the object referenced by the word. Lexigrams were notably used by the Georgia State University Language Research Center to communicate with bonobos and chimpanzees. Researchers and primates were able to communicate using lexigram boards made in up to three panels with a total of 384 keys.
The language was developed by Ernst von Glasersfeld and used by Duane Rumbaugh and Sue Savage-Rumbaugh (lexigram: ) of Georgia State University while working with primates at the Yerkes National Primate Research Center of Emory University in Atlanta, Georgia. Primates were taught to communicate by means of a lexigram board, a computerized array of keys labeled with lexigrams. Von Glasersfeld coined the term "lexigram" in 1971, created the first 120 of them, and designed the grammar that regulated their combination. This artificial language was called Yerkish in honor of Robert M. Yerkes, the founder of the laboratory within which the lexigrams were first used.
The first ape trained to communicate in Yerkish was the chimpanzee Lana, beginning in 1973 within the context of the LANA project.