Economic simulations have even been used in experiments, such as those done by Donald Broadbent on learning and cognition that revealed how people often have an aptitude for mastering systems without necessarily comprehending the underlying principles. Other games are used to study the behavior of consumers. An early economic sim by Danielle Bunten Berry, "M.U.L.E.", released in 1983, foreshadowed events that would transpire later in video gaming history, especially in the MMOG market, with regard to player cooperation and simulated economies. The game was Electronic Arts' most highly awarded game, despite selling only 30,000 copies. That same year, Epyx released the business sim "Oil Barons".