Time preference, also known as time discounting or temporal discounting, is a fundamental concept in behavioral economics. It describes the relative value an individual places on receiving a good or benefit sooner rather than later. Essentially, it's about how much we discount future rewards or costs compared to immediate ones. This concept is not just an abstract economic theory; it has significant applications in diverse fields such as finance,
health, and even climate change policy, influencing both individual choices and broader societal decisions.
Mathematical Models of Discounting
Time preferences are mathematically represented through discount functions. Historically, traditional economic models often assumed an exponential discount function, which implies a steady, monotonic decrease in preference as the time delay increases. This model suggests that the rate at which we discount the future remains constant, regardless of how far into the future the event is. However, more recent neuroeconomic models have introduced the hyperbolic discount function. This alternative model is particularly important because it can explain the phenomenon of "preference reversal," where an individual's preference for a reward might change as the timing of the reward gets closer.
One common hyperbolic delay discounting equation is expressed as v/V = 1/(1+kD), where 'v' is the discounted value, 'V' is the non-discounted value, 'k' is the discount rate, and 'D' is the delay. This model is useful for comparing different discounting scenarios because the 'k' parameter offers an easily interpretable measure of the discount rate. Another significant model is quasi-hyperbolic discounting, which accounts for a "first-day effect." This effect highlights that people tend to place a much greater value on immediate rewards compared to those even slightly in the future. For instance, someone might strongly prefer $10 today over $11 tomorrow, but their preference for $10 in 100 days versus $11 in 101 days might be different, even though the time difference is the same. This present bias is captured by a beta parameter in the quasi-hyperbolic model.
Factors Influencing Individual Time Preference
An individual's time preference is not static; it can be influenced by a variety of factors. Age and income, for example, play a complex role. While a meta-analysis suggested no overall effect of age alone on discounting, further research indicates that within specific income groups, age does matter. Younger, low-income individuals tend to exhibit higher discounting than older, low-income individuals. This is attributed to a "scarcity mindset," where the distress caused by scarcity leads to a stronger desire for immediate rewards. When controlling for this scarcity, age-related differences in discounting among low-income groups tend to disappear.
Gender and race also correlate with time preference. Studies have shown that men generally exhibit a higher rate of discounting than women, often choosing sooner rewards. This has been theorized to relate to women's ability to delay gratification, which is also observed in behaviors like saving and investment, and potentially in their role in parenting. Racial differences have also been noted, with some studies indicating that Black children and respondents, across various contexts, may display higher discounting or make more impatient decisions compared to other racial groups. Furthermore, an individual's connection to their future self—their ability to envision or empathize with their future—can influence their time preference, with a stronger connection leading to greater ability to delay gratification. Early life stress has also been linked to a more present-focused orientation, as individuals may prioritize managing current situations over future planning.
Real-World Applications and Societal Impact
The concept of time preference extends beyond individual decision-making to broad societal problems, particularly concerning the allocation of resources between current and future generations. Governments frequently use discount rates to model future economic and environmental outcomes, aiming to balance the welfare of present and future populations. For instance, in climate change discussions, the discount rate is crucial for determining the urgency and scale of actions needed to mitigate long-term threats. A lower discount rate implies that future generations' well-being is valued almost as much as the present, suggesting a greater need for immediate action to reduce consumption and invest in climate abatement. Conversely, a higher discount rate would prioritize present benefits.
Economists like Thomas Schelling have framed climate change as an intergenerational discounting problem, emphasizing the ethical considerations of distributing utility across generations. The Stern Review on the Economics of Climate Change, for example, advocated for a very low pure time preference rate, leading to recommendations for urgent and significant climate action. However, this approach has faced pushback, with some economists arguing for higher discount rates that align more closely with market interest rates. The debate over the appropriate climate discount rate highlights the complex interplay of morality, economic principles, and intergenerational equity in policy decisions.
