Abstract
Delay-discount rates (or rates of time preference) are associated with rates of consumption and a variety of impulsive behaviors. Despite the importance of discounting, little is known about its covariates. We estimated discount rates for money and candy rewards in each of four quarters for 154 Tsimane' Amerindians (10-80 years of age). The Tsimane' are a horticultural and foraging society in the tropical rain forest of Bolivia. Discount rates increased with age, decreased with educational levels and literacy, and tended to decrease as recent income rose. Rates were not associated with wealth, nutritional status, or moderate drug use. There were low but reliable correlations between discount rates across quarters, suggesting that a person's discount rate is a somewhat stable characteristic that is also strongly influenced by situational factors. © 2002 Elsevier Science B.V. All rights reserved.