Date of this Version
Stevens, J.R. (2017). Intertemporal choice and delayed gratification. In J. Call (Ed.), APA handbook of comparative psychology (pp. 535-552). Washington, D.C.: APA Press.
A parasitoid wasp has deposited half of her eggs in a host. She now faces the choice between depositing her remaining eggs in the same host or searching for another. Continuing to deposit in the current host provides the immediate payoff of completing her reproductive duties, allowing her to move on to other activities such as foraging or searching for another mate. Searching for another host, in contrast, delays the payoffs of reproducing until a suitable host is found. This wasp faces an intertemporal choice—that is, a choice between options that involve payoffs available at different times (Read, 2004; Stevens, 2010). These choices typically involve a smaller option available sooner and a larger option available later. In the wasp example, depositing all eggs in one host provides the smaller, sooner option because, though curtailing search sooner, increased offspring competition and risk of total failure reduces the overall benefit of this option. The larger, later option of continuing to search involves a time delay but yields a higher payoff with reduced competition and probability of total brood failure. In addition to reproductive decisions, animals make these choices on a daily basis when foraging, searching for a mate, seeking shelter, avoiding predators, and interacting with social partners (Stevens, 2010). Many aspects of life history theory provide examples of intertemporal choices. For instance, allocating energy toward reproduction or growth is a classic life history tradeoff that pits the smaller, sooner payoffs of reproducing now vs. the larger, later payoffs for growing and delaying reproduction. At this level of analysis, organisms without a central nervous system, such as plants and bacteria, make intertemporal choices (Kacelnik, 2003). Though not well researched outside of the animal kingdom, researchers have explored intertemporal choices in a wide range of animal species, including insects, fish, birds, rodents, dogs, and primates (Table 1). Comparative psychologists have investigated both why individuals should choose either the smaller, sooner or larger, later option via modeling approaches and how different psychological mechanisms regulate intertemporal choice.