Why Time Discounting Should Be Exponential: A Reply to Callender

According to Craig Callender (2020), the “received view” across the social sciences is that, when it comes to time and preference, only exponential time discounting is rational. Callender argues that this view is false, even pernicious. Here I endorse what I take to be Callender’s main argument, but only insofar as the received view is understood in a particular way. I go on to propose a different way of understanding the received view that makes it true. In short: When time discounting is suitably conceived, the exponential form of the discounting function is indeed uniquely rational.

Study of Intertemporal Discounting According to Age Groups

The paper focuses on the topic of intertemporal discounting of individuals according to age groups. Using the sample of examined individuals, it aims to verify the hypothesis that the patience of individuals decreases with their increasing age. The study included a total of 599 individuals with an average age of 38.3 years (min. 16 and max. 82 years) who answered classical questions focused on time discounting and impulsive behaviour. In total, four possible scenarios were analysed: a small reward (CZK 100) with a delay of 1 day, a small reward with a delay of 1 month, a large reward (CZK 100,000) with a delay of 1 day and a large reward with a delay of 1 month. The delayed reward was always increased by 10% (i.e., CZK 110 or CZK 110,000). The basic hypothesis was that with increasing age, the subjective discount rate increases i.e., patience decreases. The above-mentioned 4 scenarios were evaluated for the hypotheses, while only three of the four scenarios were confirmed for all hypotheses. The results in the examined individuals suggest that with increasing age, there is a decrease in patience and at the same time a decrease in impulsive behaviour. These findings may have an overlap in consumption or savings in relation to the aging population.

Social background and school track choice: An analysis informed by the rational choice framework

We investigate social inequalities based on social background in the choice of the academic track among equally performing students, and how indicators derived from the rational choice framework contribute to account for such inequalities. We discuss the main theoretical concepts underpinning rational choice theory as applied to educational decisions: perceived costs, benefits, and risks of failure; relative risk aversion; and time-discounting preferences. In the empirical section, we use a unique dataset concerning the transition to different tracks in upper secondary school in a large Southern Italian region. By using various regression methods and the Karlson/Holm/Breen decomposition technique, we show that social inequalities in access to the academic track are considerable, even in recent cohorts, and that they are largely not explained by previous academic performance. Indicators linked to key concepts proposed by the rational choice theory—as measured in this study—account, as a whole, for 31% of the gap based on parental education, and for 40% of the gap based on parental occupation. The most important sources of inequalities among those this study examines are the expected benefits associated with the educational alternatives and the time-discounting preferences, while relative risk aversion and the perceived chances of success play negligible roles.

In search of determinants of time-discounting in monetary choices: Personal characteristics matter only a little

Time-discounting in monetary choices is determined by the aspects related to the reward, contextual factors, and characteristics of a person. In the present study (Ntotal = 1134), we examined how well do personal characteristics (sociodemographic, financial situation, self-control, cognitive abilities, negative experiencing, and trustfulness) predict time-discounting in both hypothetical and real reward scenarios. The results of the regression analyses indicate that the characteristics of a person explain only a small proportion of the variance in time-discounting (R2 ranged from .10 to .19). The only substantive predictors of time-discounting in monetary choices were financial literacy and a general tendency to delay gratification. We conclude that there still is much work to be done in explaining what determines time-discounting, however, we suggest shifting the focus from the personal characteristics to the characteristics of the reward and contextual factors.

In search of determinants of time-discounting in monetary choices: Personal characteristics matter only a little

Time-discounting in monetary choices is determined by the aspects related to the reward, contextual factors, and characteristics of a person. In the present study (Ntotal = 1134), we examined how well do personal characteristics (sociodemographic, financial situation, self-control, cognitive abilities, negative experiencing, and trustfulness) predict time-discounting in both hypothetical and real reward scenarios. The results of the regression analyses indicate that the characteristics of a person explain only a small proportion of the variance in time-discounting (R2 ranged from .10 to .19). The only substantive predictors of time-discounting in monetary choices were financial literacy and a general tendency to delay gratification. We conclude that there still is much work to be done in explaining what determines time-discounting, however, we suggest shifting the focus from the personal characteristics to the characteristics of the reward and contextual factors.

Relationship between rice farming and polygenic scores potentially linked to agriculture in China

Following domestication in the lower Yangtze River valley 9400 years ago, rice farming spread throughout China and changed lifestyle patterns among Neolithic populations. Here, we report evidence that the advent of rice domestication and cultivation may have shaped humans not only culturally but also genetically. Leveraging recent findings from molecular genetics, we construct a number of polygenic scores (PGSs) of behavioural traits and examine their associations with rice cultivation based on a sample of 4101 individuals recently collected from mainland China. A total of nine polygenic traits and genotypes are investigated in this study, including PGSs of height, body mass index, depression, time discounting, reproduction, educational attainment, risk preference, ADH1B rs1229984 and ALDH2 rs671. Two-stage least-squares estimates of the county-level percentage of cultivated land devoted to paddy rice on the PGS of age at first birth ( b = −0.029, p = 0.021) and ALDH2 rs671 ( b = 0.182, p < 0.001) are both statistically significant and robust to a wide range of potential confounds and alternative explanations. These findings imply that rice farming may influence human evolution in relatively recent human history.

The Effect of Social Distance on Intertemporal Choice of Reward Processing: An Event-Related Potentials Study

Social factors can affect the processing of intertemporal choice, but the influence of social distance on the rewarding process of intertemporal choice is unclear. Therefore, by designing a novel cognitive resource competition paradigm for undifferentiated intertemporal choice, this article aims to explore the influence of social distance on intertemporal choice reward processing at the electrophysiological level. It was found that compared with the stranger condition, P3a is greater in the friend condition, which means social distance is evaluated in the early stage. In addition, different brain regions in the early stages are taking charge of processing the soon-but-small (SS) and later-but-lager (LL) reward in intertemporal choice. There is an interaction effect between social distance (friend vs. stranger) and intertemporal choice (SS reward vs. LL reward) on P3b. Under friend conditions, the P3b induced by LL reward is more positive than SS reward. Under the condition of choosing the LL reward, the P3b induced by friend is more positive than stranger. This result shows that in the latter stage of reward processing, the evaluation process of time discounting is less sensitive in LL reward for friend caused by lack of cognitive resources which is occupied when dealing with social distance in advance, and thus the degree of time discount was reduced. These findings demonstrate that P3b is the key index of time discounting and immediate and delayed rewards are valued in different brain regions.

Temporal Discounting for Multidimensional Economic Agents

Individuals frequently place a higher value on money and goods today than they would in the future. This is known as temporal or time discounting, and most economic models include discount functions to represent such utility over time. In this paper we evaluated traditional models with experimental data from the scientific literature and constructed our own samples for comparison. In addition, we evaluated the prediction accuracy of the models and proposed new hybrid solutions. Our investigation aims to contribute to a better understanding of human nature in complex processes.