Discounting environmental outcomes: Temporal and probabilistic air-quality gains and losses.

Much human choice and decision-making research has employed a discounting framework to help aid our understanding of how time, uncertainty, and other factors influence an outcome’s value. Most of this research, however, is limited to the study of monetary outcomes. The purpose of the present study was to assess the discounting of an environmental outcome—changes in air quality. Participants made repeated choices between a smaller, immediate (or certain) and larger, later (or uncertain) change in air quality. Using the Air Quality Index, an interval scale developed by the Environmental Protection Agency that quantifies the density of air particulate matter (e.g., pollution), these changes were framed as either an “improvement” (gain) or “worsening” (loss) of air quality. The rate of discounting delayed environmental gains did not differ significantly from delayed environmental losses, although a small-to-medium effect size was observed between these conditions. In contrast, probabilistic environmental gains were discounted substantially more than probabilistic environmental losses. Finally, the discounting of all environmental outcomes was well described by a hyperboloid in which the independent variable (delay until or odds against the outcome) is exponentiated. These findings not only show the potential for studying environmental decision making within a discounting framework, they are the first to demonstrate a sign effect (i.e., gain–loss difference) with probabilistic environmental outcomes. (PsycINFO Database Record (c) 2019 APA, all rights reserved)