Implications of the links with education, culture, and reciprocity
Our analyses indicate that childhood education/experiences and reciprocity are significantly associated with current self-regulating hand hygiene attitudes in Japan. While no causal relationships can be derived from these findings, they may suggest that well-designed school education could allow students to exhibit more positive attitudes toward personal and communal hygiene during childhood and beyond. Thus, it is likely that such positive childhood handwashing education would be conductive to wearing a mask, preventing spreading of infection through touch, refraining from making clusters, and adopting various self-care measures during a pandemic. Furthermore, our results suggest that hygiene education could be more beneficial when it is used in conjunction with other intervention components, such as strengthening teachers’ engagement in hygiene-related initiatives both within and outside classroom, and developing interactive teaching methods that promote personal hygiene (e.g., handmade soap-making class, exercises involving dining table etiquette). We posit that these and similar school programs [38,39,40]Footnote 8 would increase the likelihood that students would develop beneficial attitudes toward hand hygiene, and would gain greater appreciation of its role in personal and community health .
It is also worth noting that, although invisible and often difficult to identify, the prevailing cultural norms are significantly associated with personal attitudes toward daily hygiene. Therefore, analyzing cultural factors can be important for identifying how people in different regions formulate the attitudes toward hygiene at the individual level. Interestingly, our analyses suggest that even a limited exposure to handwashing experience at shrines is associated with greater adherence to handwashing practices (as established when comparing respondents that washed hands as a part of purification ritual only a few times relative to those who never did). Furthermore, as shown in Tables 2 and 3, participants that selected “often” and “always” when responding to the survey question probing into their childhood handwashing practices at shrines are more likely to wash their hands with soap as well as water. This significant link between the childhood cultural experiences at shrines and people’s everyday hand hygiene practices implies that exposure to the handwashing customs at shrines during childhood is not limited to the ritual experiences but may extend to more positive attitudes toward overall hygiene in daily life even among people who could potentially assign greater value to hand hygiene. These potential associations between the purification ritual customs and daily hygiene routines are also observed in other regions with different religious beliefs and norms (e.g., [20, 41, 42]).Footnote 9
In contrast to the handwashing education at school and handwashing experiences at shrines that could be directly related to the likelihood that an individual would wash hands in all relevant situations, the role of childhood living environment in current hand hygiene practices may not be so obvious. Nonetheless, in our analyses, we posit that living in close proximity to shrines in childhood is likely to play a role in people’s attitudes toward reciprocal inclinations. As shown in Panel B of Table 2 (as well as in Appendix 4), reciprocity reduced the size of pertinent coefficients of living environment near shrines, implying that these factors are interrelated, as suggested by Ito et al. . This association is also supported by our additional evidence suggesting a direct link between living near shrines as a child and reciprocal inclinations, which was statistically significant even after controlling for other demographic and labor-related variables (undocumented). Furthermore, our findings indicate that those who lived close to shrines in childhood visited shrines more frequently, as were thus more likely to partake in purification customs than their counterparts that did not live near shrines.Footnote 10
Lastly, our analyses suggest that positive reciprocal inclinations could be associated with individuals’ disposition toward more stringent self-regulating behaviors at times of health crises, as this link remains significant even after adjusting for other related confounders (such as childhood education and experiences). In other words, individuals that tend to care for others would likely comply with public health policies even if adherence is not mandatory. Furthermore, as discussed above, as reciprocal inclinations can be developed through childhood education and experiences, these other-regarding preferences are also indirectly associated with hand hygiene attitudes through the confounders (i.e., education/residence), suggesting that, as hypothesized in the empirical framework, reciprocity as the concomitant variable lies on the direct path between confounding and outcome variables.
Retrospective responses and recall bias
As questions related to childhood education and experiences required retrospective responses, our estimation results could suffer from the recall bias. For example, it is likely that those who pay more attention to personal hygiene would have a stronger impression of the hygiene education received in childhood, which would be reflected in their survey responses. However, several important attempts were made to mitigate such issues.
First, the survey questions probing into the childhood education/experiences were carefully worded to avoid obvious connection between the topics discussed and current handwashing practices. Specifically, the questions used to gather the data pertaining to the confounding variables (education/residence) probed into teachers’ involvement in students’ discipline, class content, and childhood living environment, rather than respondents’ actual handwashing behavior in childhood.Footnote 11 In particular, we postulated that the childhood sociodemographic information (i.e., whether shrines/temples were in close proximity to the respondents’ home/route to school and were constantly in line of sight) can be recalled with a more sufficient degree of accuracy, and would less be linked to the current hygiene behavior than other retrospective variables.Footnote 12 It is also worth noting that we provided “do not remember” as one of the multiple choices and confirmed that gender and age are not potentially associated with these retrospective responses (Appendix 6).Footnote 13 Furthermore, we also assessed the robustness of our results by applying the models to subsamples comprising of young and old cohorts, confirming that the results are in general consistent with the main findings.Footnote 14
Still, we acknowledge that the adoption of an indirect retrospective measure cannot completely eliminate the risk of recall bias. For example, some people might recall their childhood experiences better than others, which would be particularly problematic if those with a more vivid memory responded to the survey items pertaining to their childhood experiences more positively even though their childhood experiences did not differ from those of the respondents that had less accurate recollection of this period. This would mean instead that it would not cause a significant problem if those with a better memory responded more positively because they indeed had more experiences than their counterparts.
One possible scenario derived from incorrect recall is that some respondents who lived near shrines could have more vivid memories of their handwashing experiences at shrines, which could also be potentially biased by their current handwashing practices. Nonetheless, we argue that the possible recall bias of childhood handwashing experiences in relation to the childhood residence would not play a significant role in the estimation results, given that those who lived near shrines were more likely to visit shrines as children compared to those who did not live near shrines. This distinction suggests that better recollection of handwashing experiences at shrines should arise as a result of more frequent visits to shrines in childhood (and possibly, more exposure to purification rituals) relative to those who did not live near shrines. Consequently, even if our data is subject to recall bias, the information pertaining to childhood handwashing experiences (in relation to their residence) can be said to adequately capture the total amount of exposure to ritual customs (e.g., frequency of visits and/or handwashing experiences), and that is indeed what we aimed to measure.
Moreover, if responses to the survey questions related to childhood experiences were obtained based on inaccurate recall, similar effects would be observed in responses related to both shrines and temples. However, in most cases, the coefficients regarding shrines are only significantly correlated with Japanese people’s handwashing practices (Tables 2 and Appendix 4). We attribute these disparities to a more obvious role of Shinto shrines in the development of the spiritual and socio-psychological values of the neighborhood , which could create social and personal norms related to hand hygiene and care for others’ wellbeing. In contrast, while temples also feature prominently in the life of Japanese people, they tend to be regarded as spaces for meditative practices or rituals, such funerals, which would therefore promote stronger relationships with the ancestors and family members. Thus, if these differences in the role of shrines and temples are appropriately reflected in our estimation results, we postulate that respondents recalled their childhood residence quite accurately.
Other confounders and social desirability bias
It is possible that our respondents developed the hygiene habits examined in this study at home, but our data unfortunately do not allow us to examine the direct link with parental hygiene attitudes and home discipline. While acknowledging that the family’s religious devotion (that requires purification rituals) is not a reflection of the aforementioned parental hygiene disciplines, we investigated its link with current handwashing practices by adding two dummy variables constructed from the responses to the following statements: (1) “There was a Shinto altar in my house when I was a child”; and (2) “There was a Buddhist altar in my house when I was a child.” A household Shinto altar (kamidana in Japanese) is a shelf where “apportioned spirits” (bunrei) of the Gods are enshrined, while Buddhist altars are tables with offerings to enshrine ancestral tablets (ihai) in household Buddhist altars (butsudan). As these altars are linked to handwashing practices, we posit that having altars in their childhood home might have (albeit partly) played a role in their family’s attitudes toward daily hand hygiene. When these dummy variables were included into Eq. (1) and (2), we found that most coefficients related to the education/residence and customs did not change significantly, even though their size was reduced in a few cases (undocumented). This finding suggests that religious devotion practices at home are not meaningfully related to handwashing education received in school and childhood experiences related to shrines.
Considering that regular handwashing is considered a desirable behavior, particularly at times of health crises, when such practices may be prescribed in government-issued guidelines, our survey respondents might have been reluctant to admit that their adherence to this practice is less than optimal, which would introduce social desirability bias into our results. Extant research has cautioned that the data derived from self-reports to direct survey questions about the compliance with social rules in place during the pandemic can be tainted by social desirability bias (e.g., [44, 45]), while several recent studies provide evidence suggesting that the estimates based on such self-report surveys do not significantly suffer from this problem [46,47,48]. To alleviate concerns over the reliability and validity of our results, in line with the work of Daoust et al. , suggesting the efficacy of using a question to soften the social norms of compliance, we probed into the practice of carrying a handkerchief, which was intentionally included in the survey as an additional (seemingly unrelated) question. As a handkerchief (or hand towel) is used in Japan on a regular basis for diverse purposes for wiping sweats, covering one’s mouth (or a part of face) when communicating with others, protecting one’s clothes (or table) when dining, as well as for drying hands after washing [49, 50], it might not be immediately associated solely with hand hygiene. Accordingly, although we associated propensity for carrying a handkerchief with high hygiene standards, this link would not be apparent to the survey participants. The results reported in Appendix 7 indicate that handwashing education at elementary school is also significantly correlated with this alternative indicator of handwashing practices, i.e., carrying a handkerchief outside home. In particular, those who always washed their hands at shrines tend to carry their handkerchief with them at all times, likely because only ladles for water were provided at the shrine entrance without any means of drying one’s hands and face.
Furthermore, to mitigate the effect of measurement errors that would result from not reading questions carefully, one of the survey items required participants to select the far-left choice (among 5 − 1 options, which should be 5). As those that failed to make a correct choice would likely read other questions with less care, we repeated our main estimations using the data provided by including a dummy variable which equals 1 for those that selected 5 (and 0 otherwise) and found these results comparable to the main estimation findings (undocumented).
Despite several important attempts to mitigate the potential biases derived from the survey design and data, our estimation results need to be interpreted with caution, and no causality should be assumed.