Endowment Effect Experiment (IMAGE) University of Pennsylvania Caption University of Pennsylvania psychologist Coren Apicella works with the Hadza people of Northern Tanzania. As one of the last hunter-gatherer societies on Earth, and with little to no contact with outsiders, the Hadza present a rare opportunity to investigate whether economic biases are innate or learned. Here, Apicella gives a participant a choice to trade one package of cookies for another. In similar experiments done in Western industrialized societies, a common bias known as the "endowment effect" causes participants to stick with whatever item they are given first, rather than to trade for another, far more often than would be expected if they were making a rational decision. The most isolated Hadza tribes traded close to the expected rate, while Hadza tribes who has more contact with tourists traded less often. Credit Eduardo Azevdeo Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.