Delay discounting: Pigeon, rat, human—does it matter?

Abstract

Delay discounting refers to the decrease in subjective value of an outcome as the time to its receipt increases. Across species and situations, animals discount delayed rewards, and their discounting is well-described by a hyperboloid function. The current review begins with a comparison of discounting models and the procedures used to assess delay discounting in nonhuman animals. We next discuss the generality of discounting, reviewing the effects of different variables on the degree of discounting delayed reinforcers by nonhuman animals. Despite the many similarities in discounting observed between human and nonhuman animals, several differences have been proposed (e.g., the magnitude effect; nonhuman animals discount over a matter of seconds whereas humans report willing to wait months, if not years before receiving a reward), raising the possibility of fundamental species differences in intertemporal choice. After evaluating these differences, we discuss delay discounting from an adaptationist perspective. The pervasiveness of discounting across species and situations suggests it is a fundamental process underlying decision making.

Effects of delay and probability combinations on discounting in humans

“…The s parameter is often added to discounting models describing human choice as the current value of commodities at long delays or high odds against tend to level off. The s parameter reflects nonlinear scaling of amount and delay based on power laws from psychophysical research (see Vanderveldt et al, 2016 for overview). Values of s less than 1.0 account for such flattening.…”

Age and impulsive behavior in drug addiction: A review of past research and future directions

“…Delay discounting procedures have also been studied using other non-human animals such as pigeons, rhesus monkeys, chimpanzees and bonobos (for review see Vanderveldt, Oliveira, & Green, 2016), and dogs (e.g. Wright, Mills, & Pollux, 2012) with response types such as pecking response keys, pressing response levers, and depressing wooden panels, respectively.…”

White matter correlates of temporal discounting in older adults

“…Temporal discounting is a concept from the field of behavioral economics that refers to the tendency to prefer a more immediate and smaller reward over a larger reward offered at a later time [see Frost and McNaughton (2017), and Vanderveldt et al (2016), for reviews]. This tendency reflects a form of decision-making impulsivity, or more specifically, a difficulty in appreciating the greater value of future events in comparison to the value of current events (Reynolds and Schiffbauer 2005).…”