Background The role of social ties, other-regarding preferences, and cultural traits in boosting community resilience and minimizing citizens’ vulnerability to crises such as COVID-19 is increasingly being recognized. However, little is presently known about the possible routes through which such personal preferences and cultural norms pertinent to social behaviors are formulated. Thus, in this paper, factors that can be potentially associated with individuals to self-regulate strict hand hygiene practices before the pandemic, during the state of emergency, and after the state of emergency was lifted in Japan are investigated. Focus is given to the handwashing education in primary school, a cultural practice originating from the old Shinto tradition, and individuals’ reciprocal inclinations. As people in Japan are known to be highly conscious of hygiene in all aspects of their daily life and are less likely to contract an infection, evidence obtained in this specific context could contribute to the better understanding of individuals’ health-related behaviors in general, and during crises in particular. Methods Using the data derived from a four-wave nationwide longitudinal online survey, we examined the extent to which elementary school education, childhood cultural experiences at shrines, and individual other-regarding preferences are associated with self-regulating hand hygiene practices prior to the pandemic and people’s efforts to comply with the government-imposed measures aimed at preventing the spread of COVID-19 infection during the state of emergency. We also investigated the long-term trends in the relationships among these factors (i.e., after the abolishment of the state of emergency) using panel data. Results Our findings reveal that childhood education and cultural experiences related to handwashing practices, as well as reciprocal inclinations, are significantly associated with Japanese attitudes toward personal hygiene (beyond handwashing practices) prior to, during, and after the state of emergency. In recognition of the possible effects of recall bias and measurement errors, several important attempts to mitigate these issues were made to strengthen the value of our findings. Conclusions The importance of school education received during childhood, as well as culture and other-regarding preferences, in the individual attitudes toward hand hygiene in adulthood highlighted in this study contributes to the better understanding of the role that these factors play in the variations in voluntary compliance with strict hand hygiene practices before and during an uncertain and prolonged crisis.

Nudge-based messages have been employed in various countries to encourage voluntary contact-avoidance and infection-prevention behaviors to control the spread of COVID-19. People have been repeatedly exposed to such messages; however, whether the messages keep exerting a significant impact over time remains unclear. From April to August 2020, we conducted a four-wave online survey experiment to examine how five types of nudge-based messages influence Japanese people’s self-reported preventive behaviors. In particular, we investigate how their behaviors are affected by repeated displays over time. The analysis with 4241 participants finds that only a gain-framed altruistic message, emphasizing their behavioral adherence would protect the lives of people close to them, reduces their frequency of going out and contacting others. We do not find similar behavioral changes in messages that contain an altruistic element but emphasize it in a loss-frame or describe their behavioral adherence as protecting both one’s own and others’ lives. Furthermore, the behavioral change effect of the gain-framed altruistic message disappears in the third and fourth waves, although its impact of reinforcing intentions remains. This message has even an adverse effect of worsening the compliance level of infection-prevention behaviors for the subgroup who went out less frequently before the experiment. The study’s results imply that when using nudge-based messages as a countermeasure for COVID-19, policymakers and practitioners need to carefully scrutinize the message elements and wording and examine to whom and how the messages should be delivered while considering their potential adverse and side effects.

We examined whether the knowledge that your private donation has a large number of potential recipients causes you to give more or less. We found that the people with blood type O are more likely to have donated blood than those with other blood types, by using a Japan's nationally representative survey. This association was found to be stronger in a subsample of individuals who knew and believed that blood type O can be medically transfused into individuals of all blood groups. However, we found that blood type O does not have any significant relationship with the other altruistic behaviors (registration for bone-marrow donation, intention to donate organs, and the making of monetary donations) and altruistic characteristics (altruism, trust, reciprocity, and cooperativeness). After further analyses, we confirmed that the wider number of potential recipients of blood type O donations promoted the blood-donation behaviors of the people with this blood type.

We test the equivalence of income and consumption taxes through a choice experiment. Under a given set of income and consumption parameters, subjects were asked to choose among an income tax of 20%, a consumption tax of 25% (which is an equivalent tax burden), a consumption tax of 22%, and a consumption tax of 20%. Our results showed that subjects prefer income tax to consumption tax when the nominal consumption tax rate is higher than the nominal income tax rate. However, subjects tend to prefer consumption tax to income tax when the nominal tax rates are identical. Our result, that subjects prefer income tax to consumption tax despite a higher tax burden, implies the consumption tax miscalculation bias. The consumption tax miscalculation bias is one where subjects miscalculate the amount of consumption tax as if it is declared by tax inclusive, as in the case of income tax, despite consumption tax being tax exclusive. If the income tax burden is equivalent to the consumption tax burden, subjects prefer income tax. This result implies that income and consumption taxes are not equivalent due to the consumption tax miscalculation bias.

There have been numerous studies in which the biological role of oxytocin in trusting behavior has been investigated. However, a link between oxytocin and trust in humans was discovered only in one early study. We hypothesized that there is a large interindividual variation in oxytocin sensitivity, and that such variation is one reason for the doubt surrounding the role of oxytocin in trusting behavior. Here, in a double-blind, prospective, case-control study, we administered intranasal oxytocin to participants of trust and risk games. We measured salivary oxytocin concentration, relating it to the amount of money transferred among participants (a proxy for trust) and the autism-spectrum quotient (AQ). A one-sided Fisher’s exact test was performed to detect differences between the oxytocin and placebo groups in the proportions of investors who transferred the maximum amount of money. We discovered a tendency for participants who received oxytocin to transfer higher amounts of money to co-participants than those who received a placebo (P = 0.04). We also revealed a high degree of interindividual variation in salivary oxytocin concentrations after oxytocin administration. After stratifying the samples with respect to oxytocin sensitivity, oxytocin-sensitive participants in the oxytocin group also transferred higher amounts of money than those in the placebo group (P = 0.03), while such a tendency was not observed for oxytocin-insensitive participants (P = 0.34). Participants with lower AQ scores (less severe autistic traits) exhibited a greater tendency toward trusting behavior after oxytocin administration than did those with higher AQ scores (P = 0.02). A two-sample t-test that was performed to detect significant differences in the mean transfers between the oxytocin and placebo groups indicated no significant between-group difference in the mean transfers (P = 0.08). There are two possible interpretations of these results: First, there is no effect of oxytocin on trust in humans; second, the effects of oxytocin on trust in humans is person-dependent. However, the results should be interpreted with caution as the effect size was not larger than the minimal detectable effect size and the results were not statistically significant (P > 0.05) after Bonferroni corrections.