Inequity aversion is a fundamental social preference. Concern for others’ welfare is yet another fundamental social preference. What do people prefer when maximizing others’ welfare creates an inequality that disadvantages them? Prior research has shown that people’s preferences depend on their level of agency, that is, their control over the allocation. Behaviorally, agentic decision makers have been shown to be more likely to prefer allocations that give another person more than them, compared to non-agentic ones. However, the cognitive processes underlying this shift of preference remain unclear. Here, we used mouse-tracking and reaction times to investigate how agency shapes social preferences in such cases. We examined decision conflict, the level of conflict experienced in arriving at a given choice, as a way to uncover whether different underlying social preferences are at play when one has versus does not have agency. We predicted an interaction effect of agency and choice on conflict, where choosing the prosocial option would be associated with less conflict in the Agency condition compared to the No-Agency condition, and that the opposite would be true for the equitable option. In our task, on each of trial, participants were presented with two allocation options: an equitable option (eg, 50 cents for self, 50 cents for other) and an inequitable and prosocial option, favoring the other participant over oneself (eg, 50 cents for self, 70 cents for other). Agentic participants chose one option to be implemented, whereas non-agentic participants indicated their preference, knowing that the lab manager had already made the decision. In two studies (N= 586), including a preregistered one, an interaction effect emerged in both mouse trajectory and reaction time analyses. These results suggest that agency alters social preferences during the decision-making process, and challenge traditional inequity aversion models claiming that people inherently dislike inequitable outcomes. Granting agency may be a powerful tool for maximizing social welfare in situations where equity and prosocial behavior are at odds.

The “EIP-1599 algorithm” is used by the Ethereum blockchain to assemble transactions into blocks. While prior work has studied it under the assumption that bidders are “impatient”, we analyze it under the assumption that bidders are “patient”, which better corresponds to the fact that unscheduled transactions remain in the mempool and can be scheduled at a later time. We show that with “patient” bidders, this algorithm produces schedules of near-optimal welfare, provided it is given a mild resource augmentation (that does not increase with the time horizon). We prove some generalizations of the basic theorem, establish lower bounds that rule out several candidate improvements and extensions, and propose several questions for future work.

We provide bounds on the tail probabilities for simple procedures that generate random samples without replacement, when the probabilities of being selected need not be equal.

Increasing inequality in free-market economies worldwide undermines stability, fueling extremism and crime. We consider an abstract model of an expanding economy with connected agents, which captures the circularity and dynamism of real economies. The agents, acting as producers, continuously produce and trade goods, while adjusting their strategies for investing in these goods based on past performance. This adjustment process is based on tit-fortat responses to mirror the market behaviors of others. We show this model captures central phenomena observed in real-life markets such as growth, inequality, and free-riding. Specifically, we find that the economy grows whenever growth is feasible within the parameters of the model. However, growth is accompanied by rising inequality, with rich and poor agents emerging and the gaps between their fortunes expanding over time.

We consider a utilitarian planner with the power to design a discrete choice set for a heterogeneous population with bounded rationality. We find that optimal paternalism is subtle. The policy that most effectively constrains or influences choices depends on the preference distribution of the population and on the choice probabilities conditional on preferences that measure the suboptimality of behavior. We first consider the planning problem in abstraction. We next examine policy choice when individuals measure utility with additive random error and maximize mismeasured rather than actual utility. We then analyze a class of problems of binary treatment choice under uncertainty. Here we suppose that a planner can mandate a treatment conditional on publicly observed personal covariates or can decentralize decision making, enabling persons to choose their own treatments. Bounded rationality may take the form of deviations between subjective personal beliefs and objective probabilities of uncertain outcomes. We apply our analysis to clinical decision making in medicine. Having documented that optimization of paternalism requires the planner to possess extensive knowledge that is rarely available, we address the difficult problem of paternalistic policy choice when the planner is boundedly rational.

In a fast-changing world, understanding how organisms adapt to their environment is a pressing necessity. Research has focused on genetic adaptation, while our understanding of non-genetic modes is still in its infancy. The host-associated microbiome can be considered a non-genetic mode of adaptation, which can strongly influence an organism’s ability to cope with its environment. However, the role of the microbiome in host ecological dynamics is largely unexplored, particularly in animal communities. Here, we discuss the following hypothesis: invasive species may rapidly adapt to local conditions by adopting beneficial microbes from similar co-occurring native species. This occurs when the invader’s fitness is influenced by adaptation to local conditions that is facilitated by microbes acquired from native microbiomes. We present a minimal mathematical model to explore this hypothesis and show that a delayed acquisition of native microbes may explain the occurrence of an invasion lag. Overall, our results contribute to broadening the conceptualization of rapid adaptation via microbiome transfer and offer insights towards designing early intervention strategies for invasive species management.

Objective

This study investigated the role of nontypical development in the relative dominance in twins' relationships throughout childhood.

Background

Dominance dynamics, affecting siblings' well-being, are different in twins than in singletons for whom age and development often dictate sibling hierarchy. These dynamics in twins, who share similar ages and developmental contexts, remain underexplored and demand further understanding.

Method

A longitudinal study surveyed 1,547 mothers and 536 fathers of 322 monozygotic (sharing nearly 100% genes) and 1,199 dizygotic (sharing 50% genetic variance) twin pairs, aged 3 to 8–9. Both parents reported on the twins' relationships. Mothers reported whether either twin had a developmental condition.

Results

No dominance difference was found in similar developmental conditions dyads, whether both twins had typical or nontypical development. However, in dyads where twins differed in the developmental condition, nontypically developing twins were less dominant than their typically developing cotwins. This dominance imbalance persisted throughout childhood, even if initial developmental issues were resolved.

Conclusion

From parents' perspectives, nontypical development does not, in itself, prevent children from demonstrating dominance behaviors in twinship, but it is more likely that the asymmetry in developmental conditions is associated with the relationship between the twins.

Implications and Recommendations

According to parents' perceptions, twins with nontypical development might experience imbalances in their relationship throughout childhood when their co-twin is a typically developing child. However, demonstrating dominance might be possible for them in other contexts. Understanding these dominance dynamics is vital for caregivers, informing tailored parenting strategies and interventions to support the well-being of children.

Mating success depends on many factors, but first of all, a male and a female need to meet at the same place and time. The circadian clock is an endogenous system regulating activity and sex-related behaviors in animals. We studied bumble bees (Bombus terrestris) in which the influence of circadian rhythms on sexual behavior has been little explored. We characterized circadian rhythms in adult emergence and locomotor activity under different illumination regimes for males and gynes (unmated queens). We developed a method to monitor adult emergence from the pupal cocoon and found no circadian rhythms in this behavior for either males or gynes. These results are not consistent with the hypothesis that the circadian clock regulates emergence from the pupa in this species. Consistent with this premise, we found that both gynes and males do not show circadian rhythms in locomotor activity during the first 3 days after pupal emergence, but shortly after developed robust circadian rhythms that are readily shifted by a phase delay in illumination regime. We conclude that the bumble bees do not need strong rhythms in adult emergence and during early adult life in their protected and regulated nest environment, but do need strong activity rhythms for timing flights and mating-related behaviors. Next, we tested the hypothesis that the locomotor activity of males and gynes have a similar phase, which may improve mating success. We found that both males and gynes have strong endogenous circadian rhythms that are entrained by the illumination regime, but males show rhythms at an earlier age, their rhythms are stronger, and their phase is slightly advanced relative to that of gynes. An earlier phase may be advantageous to males competing to mate a receptive gyne. Our results are consistent with the hypothesis that sex-related variations in circadian rhythms is shaped by sexual selection.

Although online reviews are used by many people to make decisions, these reviews may be biased. On the basis of 1.2 billion observations across five leading online review platforms and two lab studies (n = 1,172 and n = 1,165; US respondents fluent in English), we provide evidence for a consistent and systematic gender rating gap: women’s mean online review ratings are significantly more favourable than men’s. We suggest that although men and women, on average, generally do not differ in their ‘real’ attitudes, their ratings do differ when it comes to online reviews. Our lab studies revealed that such differences are due to gender differences in the propensity to share negative attitudes online, possibly due to women’s greater concern about social consequences. Our findings highlight the need for societal change to create conditions in which people, particularly women, feel comfortable publicly expressing genuine attitudes, especially in cases of dissatisfaction, without being concerned about the consequences.