DP006
Wearing School Uniforms in Childhood Linked with Wearing Anti-COVID-19 Masks
in Adulthood through Other-Regarding Preferences: An Instrumental Variable Approach

Sun Youn Lee, Meiji Gakuin University
Shusaku Sasaki, Osaka University
Fumio Ohtake, Osaka University

Wearing School Uniforms in Childhood Linked with Wearing Anti-COVID-19 Masks in
Adulthood through Other-Regarding Preferences: An Instrumental Variable Approach †Sun Youn Lee 1, Shusaku Sasaki 2, Fumio Ohtake 3
First Draft: October 24, 2023
Abstract
Amidst the ongoing COVID-19 pandemic's gradual subsidence, governments worldwide,
including Japan, had commenced the relaxation of mandatory mask-wearing regulations as ofJuly 2022 at the time of this research. Despite the relaxation, a considerable number of individuals
in Japan continued to wear masks in public settings, even when no longer obligatory. While recent
research has explored risk-averse and psychological factors underpinning this behavior, we positthat in the Japanese context, an individual’s mask usage is intricately tied to their school
experiences during childhood and their preferences in relation to others (namely, other-regarding
preferences) that could be influenced by these childhood experiences, given the close connection
between the education system and societal values. Our study centers on the impact of wearing
school uniforms during elementary school, a pivotal childhood experience in Japan. This
experience could potentially shape an individual's sense of similarity with others during theirformative years. By utilizing exogenous variations stemming from the expansion of the apparelindustry across regions—a strategy employed by the Japanese government to boost theeconomy—we aim to investigate the causal effect of school uniforms. Our findings unveil adistinctive association, albeit confined to the younger cohort, wherein individuals who wore
school uniforms during childhood tend to persistently wear masks when in the presence of local
people, even when no mandate for mask-wearing exists due to significant physical distancing.
These formative childhood experiences, which our research has found to be significantly
correlated with other-regarding preferences such as reciprocal inclinations and prosocial
tendencies, can influence younger individuals to adhere to behavioral norms within their socialgroups.
Keywords: COVID-19, school uniform, social preference, mask wearing, instrumental variable
JEL Classification Number: D90, D91, I12

We obtained ex-ante approval from the ethics committee of the Graduate School of Economics, Osaka
University [No. R40627]. This study is supported by the Grant‐in‐Aid for Scientific Research [Grant
No.20H05632] provided by the Japan Society for the Promotion of Science to Fumio Ohtake, and the JST
PRESTO [Grant No. JPMJPR21R4] provided by the Japan Science and Technology Agency to Sasaki
Shusaku. The authors are responsible for any errors in this article.
1
Corresponding Author, Faculty of International Studies, Meiji Gakuin University, E-mail:sylee@k.meijigakuin.ac.jp
2
Center for Infectious Disease Educzation and Research (CiDER), Osaka University, E-mail:ssasaki.econ@cider.osaka-u.ac.jp
3
Center for Infectious Disease Education and Research, Osaka University (CiDER), Graduate School of
Economics, E-mail: ohtake@cider.osaka-u.ac.jp†

11. Introduction
Mask usage has been widely recognized as one of the most effective measures to curtailthe transmission of respiratory diseases to others within the community, receiving significant
emphasis from various governments, and being embraced by the general public (Latkin et al., 2021;
World Health Organization (WHO), 2022). As the pandemic waned and the post-pandemic era
dawned, many governments relaxed mandatory mask-wearing mandates, leading to mask-wearing
becoming a personal choice in the majority of countries as of July 2022 at the time of this research.
Despite the relaxation of these regulations, some individuals continued to opt for wearing masks
when in the presence of others, driven by concerns about disease transmission to themselves andothers. This behavior persisted even in situations where significant physical distancing wasmaintained, and people were not engaged in close interactions. Recent research delves into thesocial and psychological factors influencing this mask-wearing behavior, highlighting thesignificant impact of social norms and conformity within society (Nakayachi et al., 2020).
Additionally, individual preferences related to others (referred to as other-regarding preferences orsocial preferences), altruistic tendencies, empathy, the influences of social connections, and selfregarding (or others-regarding) risk-averse tendencies have been identified as contributing factors(Asri et al., 2021; Cheng et al., 2020; Pfattheicher et al., 2020; Tunçgenç et al., 2021).
This article examines mask usage among individuals living in Japan, which is renownedfor having the highest life expectancy at birth and citizens’ heightened awareness of hygiene invarious facets of daily life (Ikeda et al., 2011). A significant number of people in Japan continued
to wear masks even when the Japanese government had released guidelines indicating that wearing
masks outdoors was deemed unnecessary, except in situations where individuals engaged inconversations within a 2-meter distance (Ministry of Health, Labour, and Welfare, 2022). Given
the potential link between health-related behavior and social influences, as indicated by previous
research (Asri, et al., 2021; Nakayachi et al., 2020; Tunçgenç, et al., 2021), this study observes
people's behavior in a quasi-experimental survey setting influenced by their social ties and concern
for others. By investigating potential differences in behavior when social ties are influential, ourprimary goal is to identify an unconscious but significant factor that motivates individuals to be
mindful of others in their community, leading to persistent mask-wearing despite sufficientdistancing. We focus on a prominent childhood experience in Japan—the wearing of school
uniforms—suggesting that individual preferences for social interactions (hereafter, other-regarding
preferences) develop early in life through experiences of wearing school uniform and accumulate
over time. Considering the close relationship between the education system and social norms, andrecognizing the significance of elucidating this connection to inform future public health policies
and school education initiatives, this study aims to unravel the origins and evolution of hygienerelated behavioral tendencies within society, as shaped by individuals' childhood experiences.
Numerous studies have explored the impact of uniforms on various aspects such asconformity to institutional objectives, classroom discipline (Murry, 1997; Stover, 1990), a sense of2

unity (Brunsma and Rockquemore, 1998), and self-concepts (Jarchow, 1992). These investigations
have highlighted the influence of school uniforms on how individuals perceive others as well asthemselves, potentially shaping their preferences for interpersonal interactions. The influence of
these other-regarding preferences is supported by a significant body of empirical evidence acrosssociology, psychology, and economics, demonstrating their impact on individuals' social andeconomic choices (Fehr and Schmidt, 2006). Such preferences extend to activities like voting(Fong, 2001), property rights allocation (Anderhub, Gachter, and Konigstein, 2002), and variations
in wage earnings (Bewley, 1999). Motivated by the aforementioned relevant literature, Lee et al.
(2021) explored the impact of childhood school uniform experiences on the development of otherregarding preferences in individuals' later lives. Utilizing economic and political exogenous factors
as instruments, the study identified a causal relationship between school uniform wearing and theformation of reciprocal and distributive preferences.
In line with the previous literature, our investigation centers on the impact of wearing
school uniforms during elementary school, an essential childhood experience in Japan, on the
hygiene-related behaviors in later life. We postulate that, in the Japanese context that places greatemphasis on the awareness of others in the community, mutual commitments in building social
relationships (Yamagishi and Yamagishi, 1994), the mask usage can be directly linked with theseother-regarding preferences, which can significantly be influenced by an individual's school
experiences during childhood. However, isolating the causal effect of this childhood experience
poses challenges. School uniform policies in elementary schools serve multiple purposes, such asenhancing educational motivation, reducing the burden on working parents, and promoting school
administration objectives that prioritize school discipline (Bamba, 2009; Namba, 2018), which canaffect students’ behavioral traits in later life. These multiple unobserved factors need to bedisentangled to examine the direct and causal effect of the experiences of wearing school uniforms
on the later-life behaviors including the mask wearing. For this, we utilized external variations
resulting from the expansion of the apparel industry across different regions, a strategy
implemented by the Japanese government to stimulate economic growth, to examine the "causal"
impact of school uniforms.
The primary findings of this study reveal that younger individuals with experiences of wearing
school uniforms tend to choose to wear masks in situations where it is not mandatory but whenlocal people are in visible proximity. Considering the significant physical distance between
individuals, their decision to wear masks seems to be influenced less by disease mitigation andmore by their concern for how they are perceived by others. The connection between these otherregarding preferences, which encompass the concept of mutual expectations, perceptions, andcommitments, and childhood experiences, is only evident among the young cohort. This suggeststhat the young cohort may subconsciously draw upon these ingrained other-regarding preferencesdeveloped during their childhood school environment when deciding whether to wear masks.
Our objective is to make a contribution to the existing body of literature concerning the3educational, economic, behavioral, and psychological factors associated with public hygiene
practices during and post-pandemic. We aim to achieve this by presenting our empirical findings,
which illuminate the underlying factors influencing individual behavior, particularly thoseestablished during the early developmental stages within a school environment. This added insighthas the potential to enhance our comprehension of societal dynamics and individual behaviors in
the country under study, thereby offering valuable implications for the formulation of future school
policies and public health strategies.
2. Research Context and Survey Design
This research was conducted during a period when the Japanese government had issued
guidelines stating that mask-wearing was not considered necessary outdoors, except in scenarios
where individuals engaged in conversations within a distance of 2 meters (Ministry of Health,Labour, and Welfare, 2022). We deliberately designed the study setting to involve individuals
positioned more than 2 meters apart from each other, aiming to identify those who exhibit aconsistent tendency to wear masks even in this situation. Furthermore, we differentiate this setting
based on the presence of others, operating under the assumption that the inclination for constantmask-wearing can be reinforced when individuals from the same community are present, especially
if they possess stronger preferences and tendencies to be conscious of others. In this context,
wearing a mask does not serve the purpose of disease prevention but rather reflects a (un)conscious
concern about how one is perceived by others.
We posit that individuals inclined towards considering others' perspectives are more likely
to adhere to mask-wearing, even when in the presence of others situated at a distance exceeding 2
meters. Our primary research objective is to identify the underlying driver motivating individuals
to wear masks in the aforementioned scenario. We theorize that individuals' perceptions of others
are shaped and developed during childhood, significantly influencing their subsequent behaviors
related to social interactions. Of childhood education and experiences that affect the formulationof individuals' perceptions, our focus centers on whether respondents wore school uniforms during
their elementary school years.
To address this hypothesis, we conducted an online survey utilizing quasi-experimental
scenarios through MyVoice.com Ltd., a platform specializing in online surveys and experiments.
The platform has a registered user base of approximately one million adults residing throughout
Japan who serve as response monitors. From this extensive pool, we carefully selected 6,000
participants, aiming to mirror the proportions of a nationally representative sample in terms of age(20-69 years), gender (male and female), and region (across 10 geographical areas). Out of theseparticipants, 5,652 were ultimately utilized for our primary estimation. We conducted separate
estimations based on the mean age, aligning with our hypothesis that childhood experiences may
influence later-life hygiene behavior in distinct ways for younger individuals (ages 22 to 48)
4compared to older cohorts (ages 49 to 67). This differentiation takes into consideration variables
that could differ depending on the age group, such as the duration since elementary school
graduation and pertinent medical considerations. Furthermore, for the purpose of robustness checks,
we conducted additional estimations using a subset of the sample that attended public elementary
schools and those who reported never changing elementary schools. This approach was taken toaccount for potential biases in cases where respondents changed schools, which might affect thedirect relevance of prefectural information about their home address at the age of six to theirexperience of wearing school uniforms.
2.1. Primary Outcomes: Mask-Wearing Behavior
We constructed three outcome variables that indicate an individual’s decision to wear amask where the scenario is different, using two sets of questions for non-anonymous andanonymous situations. The foundational questions designed for a quasi-experimental scenario tomeasure respondents' mask-wearing choices in each of the anonymous and non-anonymous
situations are as follows. For a non-anonymous situation, currently, you are outdoors, walking
alone on a sidewalk along a "one-way, two-lane major road." There is no one else walking on
your side of the sidewalk, and no cars are passing by. On the other hand, on the opposite side of
the sidewalk, "you can see many people from your local area walking together." In this situation,
would you choose to wear a mask, or would you completely remove your mask? In contrast, asfor the anonymous situation, the scenario of the presence of local people within sight distance ischanged to "there is no one else walking" on the opposite side of the sidewalk (Q1 and Q2 inAppendix 1).
It is worth emphasizing once more that at the time of the research, the Japanese
government had issued guidelines stating that wearing masks outdoors was considered
unnecessary, except when individuals engaged in conversations within a 2-meter distance(Ministry of Health, Labour, and Welfare, 2022). We intentionally designed the study scenario
with individuals positioned over 2 meters apart from each other, specifically to identify those who
consistently demonstrate the tendency to wear masks even in such circumstances. Approximately
70% of respondents indicated that they would remove their masks when there is no one around.
However, the percentage of those who would do the same in a situation where people are present
decreased to 50% (Panel A in Table 1). It is reasonable to anticipate that individuals are more
likely to wear masks when not alone. However, it's important to recognize that our quasiexperimental setup situates the presence of others at a distance greater than 2 meters, where
wearing masks are not required. Our focus is directed towards individuals who adjust their maskwearing behavior in response to the presence or absence of others in these scenarios.
To explore these behavioral changes in mask-wearing, we derived a variable bysubtracting responses in anonymous situations from those in non-anonymous situations, which is5our first outcome variable. Given that responses to each question are binary (1 indicating mask
removal, 0 otherwise), a value of 1 (approximately 22% of respondents) reflects individuals who
only remove masks in anonymous scenarios. Conversely, a value of 0 (approximately 77%)
indicates a consistent choice of mask removal or retention in both anonymous and non-anonymous
scenarios (Panel A in Table 1). Moreover, a value of -1 (approximately 2%) signifies those whosolely remove masks when others are present on the opposite sidewalk. As this particular behavior,indicated by a value of -1, may be influenced by measurement errors or unpredictable actions, we
treated them as either 0 or omitted from analyses. In subsequent sections, since the results are notsignificantly different 4 and we plan to utilize a larger sample for other outcome variables, we
provide results that incorporate these cases as 0 within the sample. We also discuss outcomesachieved without their inclusion in Section 4.
[Table 1 is here]
Subsequent to the foundational questions (Question 1 and Question 2 in Appendix 1), we
conducted a series of four additional questions to evaluate individuals' Willingness to Pay (WTP)or Willingness to Accept (WTA) concerning the choice to wear or remove masks (from Questions
1-1P to 1-2A in Appendix 1) in both non-anonymous and anonymous situations. More specifically,
we assessed an individual's WTP for their decision to wear or remove a mask and their WTA toswitch from one choice of mask-wearing behavior to the other. These WTP and WTA questions
encompassed a range of amounts, from JPY 1 to 500, and we calculated the mean values of thepreceding and current choices, with the initial choice allowing for 0 and the final choice allowing
for 700. To transform the WTA amounts into WTP, we used negative payments, resulting in a
WTP range of -600 to 600 for both wearing and removing masks.
After this conversion, we generated four distinct variables representing WTP for wearing
masks and WTP for removing masks in both anonymous and non-anonymous situations (variables
C to F, as displayed in Panel B and C of Table 1). Subsequently, we constructed our second andthird outcome variables. The second outcome variable, WTP for wearing masks, was generated bysubtracting WTP responses in anonymous situations (D) from those in non-anonymous situations(C). A higher value in this variable indicates a greater willingness to pay for wearing masks whenin the presence of others, reflecting a stronger preference for wearing masks in crowded situations.
Conversely, the third outcome variable, WTP for removing masks, was obtained by subtracting
WTP responses in non-anonymous situations (F) from those in anonymous situations (E). A higher
value in this variable signifies a higher willingness to pay for removing masks when alone. This
captures the inclination to pay more for the freedom to remove masks when no one is present. Thus,

4

The results are detailed in Section 4 and provided in Appendix 7.

6

the second and third outcomes similarly imply a stronger preference for wearing masks only in thepresence of others.
2.2. Secondary Outcomes: Other-regarding Preferences
In order to gain insight into the potential underlying mechanism explaining the impact ofchildhood experiences wearing school uniforms on adult mask-wearing tendencies, we aim to
explore the connection between school uniforms and other-regarding preferences, including
reciprocal inclinations and inequity aversion, during adulthood. To establish this connection, we
initially constructed variables to assess positive and negative reciprocal preferences by asking
respondents to rate their level of agreement with the following statements: (i) "If others do me afavor, I am prepared to return it;" (ii) "If others treat me in a very hostile manner, I will makesacrifices until I can exact revenge on them, even if it may come at a high cost." Ratings for eachstatement were provided on a 5-point Likert scale, ranging from 1 (strongly disagree) to 5 (strongly
agree). We also computed the average value of positive and negative reciprocity.
Furthermore, we assessed distributive preferences by gauging the degree of inequity
aversion. Building on the approach employed by Bartling, et al. (2009) 5 and guided by the work of
Sheremeta and Shields (2013), respondents were categorized into three groups: those who areahead-averse, those who are behind-averse, and those who are prosocial. The first two categories
prefer equal treatment with others, regardless of whether they receive more or less, respectively.
On the other hand, those classified as prosocial are inclined to enhance the wealth of others if doing
so does not impact their own wealth, implying that they can contribute to others' well-being without
personal cost.
According to our data, with the mean value of positive reciprocity surpassing that ofnegative reciprocity (Appendix 2), respondents appear to exhibit a stronger inclination toward
positive reciprocity. While this contrasts with findings from Offerman (1999) and Charness andRabin (2002), where participants displayed a stronger inclination to punish harmful actions overrewarding friendly behavior, a similar tendency was observed in the study using Japanese data (Leeet al., 2021). Roughly 80% of our respondents demonstrate behind-averse and prosocial tendencies,
regardless of their age cohort. In comparison, around 60% of the young cohort and 70% of the oldcohort exhibit ahead-averse tendencies. The overall trend aligns with previous literature that has
used Japanese data, although based on different samples (Lee et al., 2021).

5“Imagine either you or someone that you do not know personally receives some money. You can decide howmuch you and the anonymous other receive and the other person will not know your decision.” The respondents
were provided with four choices, and in each case they were expected to select either Option A (equal
distribution, with 10,000 yen given to them and the “anonymous other”) or Option B, under which the monetaryamounts given to them/other varied as follows: Choice 1 (10,000 yen / 6,000 yen); Choice 2 (16,000 yen / 4,000yen); Choice 3 (10,000 yen / 18,000 yen); and Choice 4 (11,000 yen / 19,000 yen).

7

2.3. School Uniforms in Japan
In Japan, elementary school (grades 1-6) and junior high school (grades 7-9) aremandatory, followed by senior high school and tertiary education. Public elementary schools are
assigned based on family residential addresses, constituting about 98% of schools, while theremaining schools are private and national schools. 6 During the Meiji period (1868-1912), school
uniforms were first introduced in elite schools, with only a limited number of institutions enforcing
them (Bamba, 2009). In those early years, schools recommended dress codes referred to as"standard clothes," which were not compulsory uniforms (Namba, 2018). During the Taisho period(1912-1926), attitudes began to change when there was a growing preference for Western-style
attire due to hygiene concerns and convenience. However, parents lacked the know-how to dress
their children appropriately, leading schools to introduce various standard clothes options such as
sailor suits and jumper skirts, which were practically seen as mandatory school uniforms since most
students wore them every day (Namba, 2018).
Following World War II, there was a restructuring of pre-war junior high schools toaccommodate compulsory education. In the 1960s, public junior high schools introduced uniform
mandates, but they faced opposition from student protests and concerns regarding freedom of
expression. Additionally, parental preferences varied, with some emphasizing academic focus andothers valuing students' expression. Consequently, some schools abandoned uniform requirements,
while others reinstated them in the late 1970s. These conflicting viewpoints, both in favor andagainst school uniform policies, especially during the 1960s and 1970s, resulted in differences in
the adoption of uniforms both between and within schools and prefectures. These variations
underscore the importance of considering endogenous effects when assessing the impact of
uniforms. This study posits that as uniform implementation reflects parental and school preferences,these preferences can influence school uniform policies and potentially shape students' preferences,subsequently impacting their hygiene-related behavioral tendencies, including mask-wearing
behaviors, later in life.
According to our data, the proportion of respondents who wore school uniforms during
their elementary school years is approximately 23% 7, and this percentage remains similar acrossdifferent age cohorts (see Appendix 2). The distribution of school uniform experiences varies
significantly among prefectures, as demonstrated by the distinct differences observed (seeAppendix 3). In specific prefectures such as Fukui, Kagawa, Okayama, and Shimane, theprevalence of childhood school uniform wear exceeded 85%, while, in other prefectures like
Hokkaido, Nagano, and Akita, the percentage was less than 5%. In sum, while school uniform

6

7

Relevant
statisticalinformationcanbeobtainedfromhttps://www.mext.go.jp/b_menu/toukei/chousa01/kihon/1267995.htm

the

MEXT

websiteat

According to the findings of an online survey conducted in 2013 by a private school uniform company, Kanko(https://kanko-gakuseifuku.co.jp/media/homeroom/131231), approximately 20% of Japanese elementary
schools were reported to have implemented a school uniform policy.

8

adoption has generally increased in Japan since the 1960s, there are noticeable variations in theprevalence of adoption or abolishment across different prefectures over the past few decades. It
is noteworthy that the overall trend is similar to related literature that used different samples (Leeet al., 2021).
2.4. Utilizing an Economic Exogenous Element as an Instrument
For our instrumental variable (IV), we first calculated the ratio of value added by the apparelindustry to that generated by the manufacturing industry, denoted as "Apparel," based on dataobtained from Industry Statistics. To cater to the age range of our respondents, spanning from 22
to 67 years, our focus was on the years 1960 to 2005, which encompassed the one-year periods
preceding the respondents' enrollment in elementary school. To relate the Apparel information toeach respondent, we utilized two pieces of information: the year in which they were five years old(i.e., the year before starting elementary school), and the prefecture of residence at age six,
assuming that their family's residence remained constant in the preceding year. This entailed
creating a matrix dataset spanning 45 years (from 1960 to 2005) multiplied by the 47 prefecturesin Japan.
Our IV was then constructed based on the value of the Apparel in "neighboring" prefectures.
To facilitate this, Japan's 47 prefectures were grouped into 10 administrative regions 8, and theaverage Apparel value for neighboring prefectures (excluding the one where the respondent lived
at age six) was calculated. This approach was chosen due to the potential influence of neighboring
prefectures' apparel industry status and school uniform production levels on the implementation ofschool uniform policies (Yamamura, 2009). It's essential to note that we deliberately focused on
the Apparel in "neighboring" prefectures, as Apparel within one's own prefecture might beinfluenced by endogenous factors. That is, the adoption of school uniform policies could directly
affect the demand for the local apparel industry, potentially creating a correlation between school
uniforms and the Apparel within one's own prefecture. Moreover, considering that school decisions
to implement uniform policies might be influenced by the prevailing trends in the regional apparelindustry around the time of elementary school admission, for enhanced accuracy in capturing
regional trends, we calculated the average Apparel value over the five-year period leading up to
the respondents' enrollment in elementary school.
Significant variations in the IV are evident across prefectures during two distinct time periods,
divided by age group: the young cohort (<49) and the old cohort (see Appendix 3). We organized
the IV by prefecture, using the percentage of respondents who wore school uniforms during
elementary school as a basis. Subsequently, we categorized the 47 prefectures into two groups,
separating those with more than 10% of former residents who wore school uniforms from the rest.
8

The 10 administrative regions are as follows: Hokkaido, Tohoku, Kanto (North/ South), Tokai, Hokuriku, Kinki,
Chugoku, Shikoku, Kyushu (including Okinawa).

9

Notably, we observed that the apparel industry thrived in the former group of prefectures for boththe young and old cohorts, implying the link between the prevalence of the apparel industry andthe implementation of school uniform policies across prefectures.
3. Empirical Specifications
In our economic model, we use the following equations to examine factors influencing maskwearing behavior.
𝑦𝑦1𝑖𝑖 = 𝛽𝛽𝑥𝑥1𝑖𝑖 (𝑘𝑘𝑖𝑖 |𝐷𝐷𝑖𝑖 = 𝑗𝑗) + 𝜀𝜀1𝑖𝑖 , 𝑗𝑗𝑗𝑗{0,1} (1)𝑦𝑦2𝑖𝑖 = 𝛽𝛽𝑥𝑥1𝑖𝑖 (𝑘𝑘𝑖𝑖 |𝐷𝐷𝑖𝑖 = 𝑗𝑗) + 𝛾𝛾𝑥𝑥2𝑖𝑖 (𝑘𝑘𝑖𝑖 |𝐷𝐷𝑖𝑖 = 𝑗𝑗) + 𝜀𝜀2𝑖𝑖 , 𝑗𝑗𝑗𝑗{0,1} (2)𝑥𝑥�1𝑖𝑖 = 𝑥𝑥1𝑖𝑖 + 𝑢𝑢𝑖𝑖 (3),where 𝑦𝑦1𝑖𝑖 and 𝑦𝑦2𝑖𝑖 are a binary indicator representing whether an individual decide to wear a mask ornot. These indicators are used to explore the impact of hypothesized scenarios on mask-wearing

behavior. These scenarios involve a survey respondent walking alone on a sidewalk along a one-way,

two-lane major road, with either no one else present or local people walking on the opposite sidewalk.
The variable 𝑥𝑥1𝑖𝑖 represents the intended width and distance that respondents are expected to perceive

when answering the questions. However, individual biases may arise due to differences in perception
among respondents. For example, the perceived width and distance of a two-lane major road may varyfrom person to person, or respondents may not fully grasp subtle differences between seemingly similar
questions pertaining to anonymous and non-anonymous scenarios. In Eq. (3), 𝑥𝑥�1𝑖𝑖 accounts for thewidth and distance between sidewalks as actually perceived by respondents, taking into consideration
the aforementioned potential biases. 9

Our main focus is on 𝑘𝑘𝑖𝑖 , a binary indicator denoting whether an individual wore a school

uniform during their elementary school years. To examine the uniform effects in the presence andabsence of local people, we differentiate between non-anonymous and anonymous situations using thevariable 𝑥𝑥2𝑖𝑖 . This variable takes the value 1 if respondents can observe multiple people from their local

area walking along on the opposite side of the sidewalk, and 0 otherwise. We reasonably assume thatparticipants in this quasi-experimental setting should not have cognitive biases when understanding
whether people are present on the opposite side of the sidewalk while reading and responding to therelated questions.
We aim to eliminate errors stemming from individual perception differences and any potential
presence bias when answering the two similar questions, as indicated by Eq. (3). For this, we subtracted
Eq. (1) from Eq. (2), which benefits from responses provided by the same individuals, helping address

9

By incorporating Eq. (3) into Eq. (1), we can arrange the equation as follows.
𝑦𝑦1𝑖𝑖 = 𝛽𝛽(𝑥𝑥�1𝑖𝑖 − 𝑢𝑢𝑖𝑖 )𝑘𝑘𝑖𝑖 + 𝜀𝜀1𝑖𝑖= 𝛽𝛽𝑥𝑥�1𝑖𝑖 𝑘𝑘𝑖𝑖 + (𝜀𝜀1𝑖𝑖 − 𝛽𝛽𝛽𝛽𝑖𝑖 𝑘𝑘𝑖𝑖 )𝐶𝐶𝐶𝐶𝐶𝐶(𝑥𝑥�𝑘𝑘,𝑦𝑦)
𝐶𝐶𝑜𝑜𝑣𝑣((𝑥𝑥+𝑢𝑢)𝑘𝑘,𝛽𝛽𝛽𝛽𝛽𝛽+𝜀𝜀)
𝛽𝛽𝜎𝜎 2
̂𝛽𝛽 ==, 𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝛽𝛽̂ = 2 𝑥𝑥 2
𝑉𝑉𝑉𝑉𝑉𝑉(𝑥𝑥�𝑘𝑘)

𝑉𝑉𝑉𝑉𝑉𝑉((𝑥𝑥+𝑢𝑢)𝑘𝑘)

𝜎𝜎𝑥𝑥 +𝜎𝜎𝑢𝑢

Considering Eq. (1), biases may arise due to measurement errors, leading to a downward bias towards zero.

10

(un)observed individual factors, and the potential variations in how respondents interpreted the quasiexperimental scenarios. The focus of our analysis is represented by Eq. (4), derived from the subtractionof Eq. (1) and (2), which removes individual fixed factors (e.g., gender, age, education, etc.).
𝑌𝑌𝑖𝑖 (𝑦𝑦2𝑖𝑖 −𝑦𝑦1𝑖𝑖 ) = 𝛾𝛾𝑥𝑥2𝑖𝑖 𝑘𝑘𝑖𝑖 + 𝜀𝜀2𝑖𝑖 − 𝜀𝜀1𝑖𝑖 (4)𝑌𝑌𝑖𝑖 (𝑦𝑦2𝑖𝑖 −𝑦𝑦1𝑖𝑖 ) = 𝛾𝛾𝑥𝑥2𝑖𝑖 𝑘𝑘𝑖𝑖 + 𝑿𝑿𝑖𝑖 𝛽𝛽𝑋𝑋 + 𝜀𝜀2𝑖𝑖 − 𝜀𝜀1𝑖𝑖 (5)In Eq. (5), we incorporate 𝑿𝑿𝒊𝒊 , a vector encompassing individual and household characteristics,

that could be possibly correlated with a respondent’s biases including perception differences in thisquasi-experimental setting. This vector includes various individual characteristics, family variables, andbackground information related to household and parental attributes. 10 Even after subtracting Eq. (1)from Eq. (2) and adjusting for individual and household controls, notably, biases could still be correlatedwith the indicator of wearing school uniforms, denoted as 𝜀𝜀2𝑖𝑖 − 𝜀𝜀1𝑖𝑖 . Addressing these biases

necessitates addressing two concerns: the non-random nature of introducing school uniform policies
and potential self-sorting into schools with such policies.

𝑘𝑘𝑖𝑖 = 𝒁𝒁𝑖𝑖 𝛼𝛼1 + 𝛿𝛿𝑋𝑋𝑖𝑖 𝛼𝛼𝑋𝑋 + 𝜈𝜈𝑖𝑖 (6)To mitigate these concerns, we employ instrumental variable (IV) regression, expressed in Eq.
(6), where 𝒁𝒁𝑖𝑖 serves as the IV. We conduct estimations both with and without controls (𝑋𝑋𝑖𝑖 ) for both Eq.
(4) and (5). Our IV, the ratio of value added by the apparel industry to that generated by the

manufacturing industry (Apparel) in “neighboring” prefectures, is considered orthogonal to school andindividual characteristics. The Eq. (6) is a first-stage equation, which is followed by the second stage
Eq. (4) and (5) of the IV estimation.
All reported standard errors are clustered at the regional level, corresponding to the prefecturein which respondents lived at the age of six. For subsequent analyses, Eq. (4) and (5) are estimatedseparately by age, guided by our hypothesis that the effect of childhood experiences on later-life hygiene
behavior may differ between younger and older cohorts. This distinction considers factors that could
vary depending on the age cohort, such as the time span after elementary school graduation and relevant
medical considerations.

10

In particular, the individual characteristics encompass various factors, such as age dummies, gender, marital
status, the type of elementary school attended (private, public, national, etc.), and educational attainment.
Additionally, we consider family variables that are likely to influence individuals' decisions regarding maskwearing. These family variables include the number of household members, the presence of a baby, elementary
to high school students within the household, members aged over 65, and individuals with medical conditions,
We also incorporate control variables related to the educational attainment of both the father and mother, andthe employment status of both parents at the time when respondents were six years old that could impact the
selection of an elementary school based on school uniform policies.

114. Main Results
In Table 2, we present the impact of our IV in the first-stage estimation. The upper panel
displays results without controls, while the lower panel includes results with controls. Irrespectiveof the inclusion of controls, we observe a significant positive correlation between the average
prevalence values of the Apparel in the "neighboring" prefectures, where students lived just before
entering elementary school, and the implementation of school uniform policies. This finding
strongly indicates that a higher prevalence of the apparel industry in neighboring prefecturesenhances the probability of schools implementing school uniform policies during the examined
years, possibly facilitated by the relatively lower cost of manufacturing school uniforms.
Furthermore, it should be emphasized that the F values for all sample restrictions surpass thethreshold of 10, a widely recognized criterion among researchers to indicate robust instrument
strength and mitigate concerns about weak identification (Staiger and Stock, 2005).
[Table 2 is here]
The main estimation results are reported in Table 3. We present results without controls in theupper panel, as shown in Eq. (4), and results with controls in the lower panel as indicated in Eq. (5).
Our primary objective is to identify individuals who consistently prefer wearing masks in nonanonymous situations, characterized by the presence of many local people walking along on the
opposite side of the sidewalk, while opting to remove their masks when alone. For this, we hypothesizedthat individuals who choose to wear masks in situations where it is not obligatory, but local people arewithin sight distance, may exhibit this behavior due to other-regarding preferences influenced by theirchildhood experiences of wearing school uniforms. Regardless of control adjustments, we found thetendency of wearing masks only in the presence of people form the local community exclusively within
the young cohort, aged below 49, corresponding to the mean age of our sample. The choice of maskwearing among the young cohort in the presence of local community members suggests that, despite
the absence of mandatory mask requirements due to a substantial distance from others, their awarenessof fellow community members motivates them to consistently wear masks.
[Table 3 is here]

In particular, findings from the first column of the young cohort reveal a significant factor
influencing the inclination to consistently wear masks in non-anonymous situations—theexperience of wearing school uniforms during elementary school years. This discovery indicatesthat young individuals who wore uniforms are more likely to wear masks when surrounded by local
people. This inclination becomes further evident when examining various variables related to12willingness to pay (WTP) for wearing masks, as shown in the second and third columns. The
positive correlation observed in the second column suggests that younger individuals withchildhood experiences of wearing school uniforms are more likely to pay for wearing masks whenamong community members, who are in a substantial but recognizable distance. This coefficient isnotably associated with WTP for non-anonymous situations compared to anonymous situations.
Additionally, the third column reflects the opposite scenario in terms of mask usage, where young
respondents are willing to pay to remove masks in anonymous situations against non-anonymous
situations. The implications align with the second column, indicating that younger individuals withchildhood experiences of wearing school uniforms tend to remove masks only when the local
people are not present.
On the other hand, when Ordinary Least Squares (OLS) regressions are conducted using
the identical sample size as that employed for the IV analysis in each outcome variable, the OLS
coefficients tend to be smaller and often insignificant in all columns, with the exception of one case(i.e., WTP for removing masks in the third column among the entire sample) (Appendix 4). The
differences in coefficients obtained from OLS and IV estimations suggest a downward bias
attributed to endogenous factors related to childhood school uniform policies. Furthermore, we findthe consistency of results remaining evident even when restricting the sample to those who attended
public elementary schools (Appendix 5), and those who attended the same public elementary
school for six years without transferring (Appendix 6). As discussed in Section 2.1, around 2% of
respondents indicated a preference for wearing masks only in anonymous situations, which could
result from measurement error or reflect unpredictable behavior. We conducted robustness checks
by re-estimating the entire regressions without including this subset of samples (Appendix 7). The
results for the robustness tests (Appendix 5 to 7) remained substantially consistent with those of
the main estimation (Table 2). As their responses did not significantly affect the overall pattern ofmask-wearing behaviors in quasi-experimental scenarios, we included these respondents whenanalyzing other outcome variables to maintain an adequate sample size.
5. Discussions
We observe a distinct age-based difference in mask-wearing tendencies linked to childhood
experiences of school uniforms. This discrepancy could be attributed to the fact that the older cohort,facing a higher risk of infection during the pandemic, might adhere to mask-wearing in all scenarios asa precaution against disease (Asri et al., 2021; Omori et al., 2020). Consequently, given the limited
variation in mask-wearing among the older cohort, individual disparities in childhood experiences andpotential accumulated social preferences may not be influential in their health-related decision-making.
Another plausible explanation for mask-wearing tendencies at the presence of people from thesame community only observed among the young cohort could be their significant concern for others
within their community and their desire to be viewed as individuals who prioritize the well-being ofothers. This predisposition could have been cultivated through their experiences of wearing school13uniforms during childhood. To further explore the underlying mechanism of mask-wearing behavior
when local people are present at a distance surpassing 2 meters, we employ Eq. (5) alongside outcome
variables that encompass a range of other-regarding preferences. The results presented in Table 4
suggest that the younger cohort, who had experiences of wearing school uniforms during theirelementary school years, exhibited the propensity for reciprocal behaviors and prosocial preferences
over another individual's material payoffs, provided that one's own outcomes remain unaffected. These
preferences embody the notion of valuing mutual interactions. Given the substantial distance between
individuals, their decision to wear masks seems to be driven less by disease mitigation and more by
their consideration for how they are perceived by others. In other words, these younger individuals, whodemonstrate care for others and engage in reciprocal actions, may unconsciously draw upon these
unconsciously learned other-regarding preferences from their childhood school environment when
making decisions about mask-wearing.
[Table 4 is here]
We further conducted regression analyses to explore whether the behavior of the young
cohort is linked to the degree of conformity 11 as discussed in recent research (Nakayachi et al.,2020). The results revealed that individuals with school uniform experiences are more inclined toconform to others' behavior, especially among the older cohort. 12 This indicates that conformity toothers' behavior might have an impact on their mask-wearing behavior, but it doesn't appear to be
the primary factor driving the young cohort's decision to wear masks when others are in their sightdistance. Rather, their choice to wear masks seems to be driven by their consideration for mutual
relationships, commitments, and interactions, rather than mere compliance with the behavior of
their acquaintances. Our finding concerning the other-regarding preferences of the younger cohortaligns with the research conducted by Asri et al. (2021), which established a link between selfregarding risk and other-regarding preferences and mask-wearing behavior among 840 employees
from Swiss hospitals. Their study suggested that younger individuals emphasize concern for others,
while older ones prioritize personal risk.
In contrast, individual inclinations and preferences towards others are not evident among
the older cohort, and if present, they are inversely related to the childhood experiences of school
uniforms. This suggests that childhood school experiences do not significantly influence theirtendencies towards reciprocity. Notably, the older cohort with these school experiences does notexhibit a tendency for inequity aversion. These differences by the age cohort may be attributed toAdditionally, we measured the degree of conformity by evaluating responses to the statement: "I feel reassured
when I engage in behaviors similar to those of people around me."12
The results have not been reported but can be provided upon inquiry. The statistical significance of therelationship between prior school uniform experiences and the tendency to conform to others' behavior isobserved at the 1% level only among the older cohort.
11

14

the passage of time since their elementary school graduation or the possibility that the school
environment has varying associations with the development of social preferences depending on thetime period.
The combined findings can be interpreted in line with previous research, suggesting thatthe behavior of the young cohort mirrors that of their peers. This strong sense of reciprocity is often
driven by reciprocal fairness (Falk and Fischbacher, 2006; Rabin, 1993) and inequity aversion(Fehr and Schmidt, 1999), as well as the concept of similarity noted by Ordabayeva and Fernandes(2017) who observed a preference for egalitarian resource distribution among those who emphasize
similarities over differences. We propose that these other-regarding preferences may be reinforced
by environmental factors, such as school experiences, where a sense of belonging fostered byschool uniforms (La Pointe, Hollomon, and Alleyne, 1993) can amplify such tendencies. Theseother-regarding preferences shaped by the childhood school experiences could then influence theirhealth-related decision-making, such as mask-wearing behavior.
6. Concluding Remarks
The childhood experiences of wearing the same clothes could develop the ease ofidentifying ingroup members fosters mutual assurance, potentially leading to the development ofreciprocal preferences and egalitarian attitudes in adulthood, as indicated in our study, which
affects their later-life behavior. The implications of our findings hold significance for Japanesesociety, where networks and mutual commitments underpin the strength of relationships andcooperative behaviors. While Yamagishi and Yamagishi (1994) noted lower general trust levels
among Japanese compared to Americans, they highlighted the distinct role of "mutual assurance"
within Japanese society, driven by stable interpersonal and inter-organizational relationships anda distinct ingroup/outgroup divide (Yum, 1988). These preferences for reciprocity and inequity
aversion, rooted in a culture of mutual assurance and group identity, elucidate the consistent maskwearing behavior of the Japanese in the presence of others. This behavior can be traced back tochildhood experiences with school uniforms. Mask-wearing goes beyond disease prevention; it
reflects social preferences and interactions with others within the given society.

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18

Table 1. Outcome Variables: Mask-Wearing Behavior

Panel A
Whole Sample (N=5,652)
Young Cohort - Age<49 (n=3,156)
Old Cohort - Age>=49 (n=2,496)

Panel B
Whole Sample (N=5,489)
Young Cohort - Age<49 (n=3,051)
Old Cohort - Age>=49 (n=2,438)

Panel C
Whole Sample (N=5,494)
Young Cohort - Age<49 (n=3,054)
Old Cohort - Age>=49 (n=2,440)

binary (A)binary (B)binary (A-B)

Wearing a Mask in the
Non-anonymous Situation

Removing a Mask in the
Anonymous Situation

Outcome 1: Wearing a Mask in the
Non-anonymous Situation, but
Removing a Mask in the
Anonymous Situation

Mean
0.20
0.19
0.22

Std. dev.
0.44
0.44
0.44

Mean
0.69
0.68
0.72

Std. dev.
0.46
0.47
0.45

Mean
0.49
0.48
0.50

Std. dev.
0.50
0.50
0.50

continuous (C)continuous (D)continuous (C-D)

WTP for Wearing a Mask
in the Non-anonymous Situation

WTP for Wearing a Mask
in the Anonymous Situation

Outcome 2: The Difference in
WTP for Wearing a Mask (fromNon-anonymous to Anonymous)Mean-13.85-10.21-18.43

Std. dev.
265.93253.80280.40Mean-71.87-55.54-92.33

Std. dev.
284.80268.61302.68

Mean
56.73
44.38
72.18

Std. dev.
215.74193.53239.81

continuous (E)continuous (F)continuous (E-F)

WTP for Removing a Mask
in the Anonymous Situation

WTP for Removing a Mask
in the Non-anonymous Situation

Outcome 3: The Difference in WTP
for Removing a Mask (fromAnonymous to Non-anonymous)

Mean-50.73-50.26-51.31

Std. dev.
246.22244.90247.91

Mean-126.85-118.40-137.46

Std. dev.
262.66260.78264.67

Mean
74.20
65.73
84.79

Std. dev.
206.61
197.16217.43

Note: This table presents a summary of the descriptive statistics for outcome variables, labeled "outcome #no" in the far-right column, each derived from thesubtraction of two sets of responses related to wearing/removing a mask in both anonymous and non-anonymous situations. These three outcome variables
will be utilized as the primary outcomes in the subsequent analyses.

Table 2. IV Estimations - First Stage Results
Estimations w/o controls
Whole Sample
School Uniform Experiences (=1)
Young Cohort - Age<49
School Uniform Experiences (=1)
Old Cohort - Age>=49
School Uniform Experiences (=1)
Estimations w/t controls
Whole Sample
School Uniform Experiences (=1)
Young Cohort - Age<49
School Uniform Experiences (=1)
Old Cohort - Age>=49
School Uniform Experiences (=1)

Coefficient (Std. Err)
9.079 ***

F-Value
17.27 ***

(2.184)7.204 ***

10.86 ***

(2.186)
13.669 ***38.12 ***

(2.214)
Coefficient (Std. Err)
9.289 ***

F-Value
18.34 ***

(2.169)7.532 ***

11.38 ***

(2.233)13.519 ***36.67 ***

(2.232)

Notes: We use, as an endogenous variable, a binary indicator denoting whether an individual wore aschool uniform during their elementary school years and use, as an instrumental variable, the average
Apparel in neighboring prefectures. The upper panel presents results of first stage estimation without
controls, whereas the lower panel incorporates results with controls, which encompass individual
characteristics and household backgrounds (refer to Appendix 2 for further details). Standard errors areindicated in parentheses. ***, **, and * denote significance levels of p < .01, p < .05, and p < .1,
respectively.

Table 3. School Uniform and Mask Removal Behavior (IV Estimations - Second Stage Results)(1) binary(2) continuous(3) continuous

Estimations w/o controls

Outcome 1: Wearing a Mask in
the Non-anonymous Situation,
but Removing a Mask in the
Anonymous Situation

Outcome 2: The Difference in
WTP for Wearing a Mask
(from Non-anonymous
to Anonymous)

Outcome 3: The Difference in
WTP for Removing a Mask
(from Anonymous
to Non-anonymous)

Whole Sample

0.0901**31.790147.6305*(0.045)(24.227)(27.568)0.2175***76.3400**

82.8013**(0.083)(32.644)(40.615)-0.0575-6.6886

16.8174(0.058)(36.062)(33.689)(4) binary(5) continuous(6) continuous

Estimations w/t controls

Outcome 1: Wearing a Mask in
the Non-anonymous Situation,
but Removing a Mask in the
Anonymous Situation

Outcome 2: The Difference in
WTP for Wearing a Mask
(from Non-anonymous
to Anonymous)

Outcome 3: The Difference in
WTP for Removing a Mask
(from Anonymous
to Non-anonymous)

Whole Sample

0.1032**31.204850.0601*(0.048)(21.712)(25.899)0.2321***72.4475**

82.6763**(0.080)(32.901)(36.043)-0.0638-15.4774

14.8409(0.061)(36.606)(34.717)

School Uniform Experiences (=1)
Young Cohort - Age<49
School Uniform Experiences (=1)
Old Cohort - Age>=49
School Uniform Experiences (=1)

School Uniform Experiences (=1)
Young Cohort - Age<49
School Uniform Experiences (=1)
Old Cohort - Age>=49
School Uniform Experiences (=1)

Note: The upper panel presents results without controls, whereas the lower panel incorporates results with controls, which encompass individual
characteristics and household backgrounds (refer to Appendix 2 for further details). Standard errors are indicated in parentheses. ***, **, and *denote significance levels of p < .01, p < .05, and p < .1, respectively.

Table 4. School Uniform and Other-regarding Preferences (Other IV Estimations - Second Stage Results)(1) binary(2) binary(3) binary

Estimations w/t controls

Prosociality

Ahead Aversion

Behind Aversion

Whole Sample

0.0359-0.0726-0.1138**(0.041)(0.054)(0.048)0.1233**0.0383-0.1141(0.062)(0.077)(0.083)-0.0819*-0.2108***-0.0927(0.048)(0.082)(0.060)(4) continuous(5) continuous(6) continuous

Estimations w/t controls

Total Reciprocity

Positive Reciprocity

Negative Reciprocity

Whole Sample

0.13990.1843**0.0955(0.106)(0.092)(0.157)0.27910.3065*0.2516(0.178)(0.176)(0.229)-0.0658

0.0120-0.1436(0.100)(0.119)(0.147)

School Uniform Experiences (=1)
Young Cohort - Age<49
School Uniform Experiences (=1)
Old Cohort - Age>=49
School Uniform Experiences (=1)

School Uniform Experiences (=1)
Young Cohort - Age<49
School Uniform Experiences (=1)
Old Cohort - Age>=49
School Uniform Experiences (=1)

Note: The upper panel presents results without controls, whereas the lower panel incorporates results with controls, which
encompass individual characteristics and household backgrounds (refer to Appendix 2 for further details). Standard errors
are indicated in parentheses. ***, **, and * denote significance levels of p < .01, p < .05, and p < .1, respectively.

Appendix 1. Two Sets of Questions for Non-Anonymous and Anonymous Situations
I. First Set of Questions (“Non-anonymous” Situation):
Question 1. You are currently outdoors, walking alone on a sidewalk along a 'one-way, twolane major road.' On your side of the sidewalk, there are no other pedestrians, and no cars are
passing by. On the opposite side of the sidewalk, you can see many people from your local area
walking together. In this scenario, would you choose to wear a mask or completely remove yourmask?
Option 1. I would wear a mask.
Option 2. I would completely remove the mask.
Below are a series of four subsequent questions (i to iv).
If you have chosen option 1 in Question 1, please respond to the following questions,
Questions 1-1P and 1-1A.
i.

Question 1-1P (Willingness-to-Pay): Suppose that you would have to pay varying amountsof money as taxes to continue wearing a mask. In this scenario, would you be willing to
pay any amount and keep the mask on? Or would you choose to remove the mask
completely? Please provide your response for each specified amount of money.

ii.

I would pay 1 JPY and wear a mask.

I would remove the mask completely.

I would pay 5 JPY and wear a mask.

I would remove the mask completely.

I would pay 10 JPY and wear a mask.

I would remove the mask completely.

I would pay 50 JPY and wear a mask.

I would remove the mask completely.

I would pay 100 JPY and wear a mask.

I would remove the mask completely.

I would pay 200 JPY and wear a mask.

I would remove the mask completely.

I would pay 300 JPY and wear a mask.

I would remove the mask completely.

I would pay 500 JPY and wear a mask.

I would remove the mask completely.

Question 1-1A (Willingness-to-Accept): Suppose you would receive varying amounts ofmoney as subsidies for stopping wearing the mask. In this scenario, would you wear themask? Or would you like to receive any amount and remove the mask completely? Pleaseprovide your response for each specified amount of money.
I would wear a mask.

I would receive 1 JPY and remove the mask completely.

I would wear a mask.

I would receive 5 JPY and remove the mask completely.

I would wear a mask.

I would receive 10 JPY and remove the mask completely.

I would wear a mask.

I would receive 50 JPY and remove the mask completely.

I would wear a mask.

I would receive 100 JPY and remove the mask completely.

I would wear a mask.

I would receive 200 JPY and remove the mask completely.

I would wear a mask.

I would receive 300 JPY and remove the mask completely.

I would wear a mask.

I would receive 500 JPY and remove the mask completely.

If you have chosen option 2 in Question 1, please respond to the following questions,
Questions 1-2P and 1-2A.
iii.

Question 1-2P (Willingness-to-Pay): Suppose that you would have to pay varying amountsof money as taxes to remove the mask completely. In this scenario, would you wear themask? Or would you be willing to pay any amount and remove the mask completely? Pleaseprovide your response for each specified amount of money.

iv.

I would wear a mask.

I would pay 1 JPY and remove the mask completely.

I would wear a mask.

I would pay 5 JPY and remove the mask completely.

I would wear a mask.

I would pay 10 JPY and remove the mask completely.

I would wear a mask.

I would pay 50 JPY and remove the mask completely.

I would wear a mask.

I would pay 100 JPY and remove the mask completely.

I would wear a mask.

I would pay 200 JPY and remove the mask completely.

I would wear a mask.

I would pay 300 JPY and remove the mask completely.

I would wear a mask.

I would pay 500 JPY and remove the mask completely.

Question 1-2A (Willingness-to-Accept): Suppose that you would receive the following
amounts of money as subsidies for starting to wear a mask. In this scenario, would you
like to receive any amount and start to wear a mask? Or would you remove the mask
completely? Please provide your response for each specified amount of money.

v.
I would receive 1 JPY and wear a mask.

I would remove the mask completely.

I would receive 5 JPY and wear a mask.

I would remove the mask completely.

I would receive 10 JPY and wear a mask.

I would remove the mask completely.

I would receive 50 JPY and wear a mask.

I would remove the mask completely.

I would receive 100 JPY and wear a mask.

I would remove the mask completely.

I would receive 200 JPY and wear a mask.

I would remove the mask completely.

I would receive 300 JPY and wear a mask.

I would remove the mask completely.

I would receive 500 JPY and wear a mask.

I would remove the mask completely.

II. Second Set of Questions (“Anonymous” Situation):
Question 2. You are currently outdoors, walking alone on a sidewalk along a 'one-way, twolane major road.' On your side of the sidewalk, there are no other pedestrians, and no cars are
passing by. Furthermore, there is no one else walking' on the opposite side of the sidewalk. In
this scenario, would you choose to wear a mask or completely remove your mask?
Option 1. I would wear a mask.
Option 2. I would completely remove the mask.
The same series of four subsequent questions (i to iv), as presented in the first set ofquestions, were provided in the same manner to assess WTP and WTA
for each choice option in Question 2.

Appendix 2. Descriptive Statistics
Whole Sample(N=5,652)

Young Cohort(N=3,156)

Old Cohort(N=2,496)

0.232
0.015

0.232
0.015

0.232
0.014

0.636
0.802
0.857
3.519
4.035
3.003

0.585
0.759
0.848
3.501
3.962
3.040

0.700
0.857
0.868
3.541
4.127
2.956

0.501
14.531
0.546
2.860
0.085
0.101
0.057
0.098
0.276

0.505
14.625
0.434
3.027
0.146
0.155
0.074
0.070
0.252

0.496
14.411
0.688
2.648
0.008
0.033
0.037
0.133
0.307

0.047

0.048

0.045

632.165615.060

653.793

0.174

0.179

0.167

0.032

0.039

0.024

Public0.938
Private (Buddhist)
0.003
Private (Catholic)0.004
Private (Protestant)
0.002
Private (Other religious)
0.001
Private (Other)
0.021
Mother's Employment Status
Employed full-time (Company/Government)
0.186
Employed full-time (Self-employed)
0.111
Employed part-time (Company/Government)
0.221
Employed part-time (Self-employed)
0.050
Neither employed nor working
0.349
At that time, father or mother was absent (due to deat
0.008
Don't know / Don't remember
0.076
Father's Employment Status
Employed full-time (Company/Government)
0.744
Employed full-time (Self-employed)
0.174
Employed part-time (Company/Government)
0.004
Employed part-time (Self-employed)
0.004
Neither employed nor working
0.005
0.026
At that time, father or mother was absent (due to deat
Don't know / Don't remember
0.043
Mother's and Father's Education Attainment (12 dummies for Each)
Due to space constraints, parent's education attainment will be omitted.

0.924
0.004
0.004
0.003
0.001
0.026

0.956
0.002
0.003
0.000
0.001
0.014

0.209
0.064
0.252
0.040
0.332
0.007
0.096

0.156
0.170
0.182
0.063
0.370
0.008
0.050

0.769
0.125
0.003
0.003
0.005
0.030
0.064

0.711
0.236
0.006
0.004
0.005
0.021
0.017

Main Independent Variable and IV
School Uniform Experiences (=1)
Apparel in neighboring prefectures (IV)
Other-regarding preferences
Ahead aversion
Behind aversion
Prosocial tendencies
Reciprocity (average)
Positive reciprocity
Negativer reciprocity
Individual and household characteristics
Female (=1)
Years of education
Married (=1)
Number of cohabiting family members
Cohabiting infant/toddler (=1)
Cohabiting elementary school student (=1)
Cohabiting junior high school student (=1)
Cohabiting high school student (=1)
Cohabiting 65 years and older elderly (=1)
Cohabiting family employed in the medical
industry (=1)
Household annual income
Household annual income information is notprovided (=1)
Types of elementary school
National

Note: This table summarizes all variables used for the main estimation of Eq. (4) with the entire sample, and it is followed by separate
sections for the young and old cohorts.

Appendix 3. School Uniforms Experiences and IV by Prefecture

Prefecture where a
respondent lived at
age 6+RNNDLGǀ
Aomori
Iwate
Miyagi
Akita
Yamagata
Fukushima
IbarakiTochigi
Gunma
Saitama
Chiba
Tokyo
Kanagawa
NiigataToyamaIshikawa
Fukui
Yamanashi
NaganoGifu
Shizuoka
Aichi
Mie
Shiga
Kyoto
Osaka
+\ǀJR
Nara
Wakayama
Tottori
Shimane
Okayama
Hiroshima
Yamaguchi
Tokushima
KagawaEhime.ǀFKLFukuoka
Saga
Nagasaki
KumamotoƿLWDMiyazakiKagoshima
Okinawa

ApparelProportion of
in "neighboring" prefectures
respondents(Apparel=Ratio of thewearing school
added value in the apparel
uniforms in eachindustry to that in theprefecture
manufacturing industry)
3.5%
10.4%
6.2%
6.4%
4.4%
12.0%
30.0%
10.2%
7.9%
6.4%
7.1%
6.9%
11.7%
7.2%
10.4%
41.5%
58.7%
90.0%
9.7%
3.9%
24.1%
24.1%
18.4%
17.8%
28.6%
8.3%
42.1%
19.0%
60.7%
31.6%
15.4%
85.2%
86.2%
66.2%
80.5%
82.4%
88.5%
66.3%
17.4%
20.8%
28.3%
11.5%
42.0%
1.8%
6.1%
72.3%
5.1%

0.007
0.027
0.026
0.025
0.027
0.032
0.027
0.012
0.011
0.012
0.004
0.007
0.007
0.008
0.021
0.020
0.020
0.023
0.011
0.012
0.003
0.009
0.009
0.008
0.011
0.011
0.012
0.012
0.009
0.011
0.033
0.036
0.030
0.037
0.040
0.034
0.036
0.032
0.035
0.019
0.019
0.017
0.018
0.020
0.017
0.018
0.026

ApparelApparelin neighboring in neighboring
prefectures
prefectures(young cohort) (old cohort)
0.009
0.038
0.035
0.036
0.042
0.043
0.036
0.008
0.008
0.009
0.004
0.005
0.005
0.006
0.028
0.029
0.027
0.029
0.010
0.009
0.003
0.008
0.008
0.007
0.009
0.009
0.009
0.010
0.008
0.010
0.032
0.036
0.033
0.035
0.039
0.037
0.041
0.036
0.035
0.026
0.025
0.024
0.024
0.025
0.024
0.023
0.027

0.006
0.015
0.017
0.015
0.013
0.019
0.011
0.016
0.015
0.014
0.005
0.010
0.010
0.011
0.013
0.012
0.012
0.015
0.015
0.016
0.004
0.010
0.009
0.010
0.015
0.013
0.014
0.016
0.012
0.014
0.034
0.037
0.028
0.041
0.042
0.033
0.029
0.029
0.024
0.012
0.010
0.011
0.010
0.013
0.008
0.011
0.020

Appendix 4. OLS Regression Results(1) binary(2) continuous(3) continuous

Estimations w/o controls

Outcome 2: The Difference in
Outcome 1: Wearing a Mask in
the Non-anonymous Situation, but WTP for Wearing a Mask
Removing a Mask in the(from Non-anonymous
Anonymous Situation
to Anonymous)

Outcome 3: The Difference in
WTP for Removing a Mask (fromAnonymousto Non-anonymous)

Whole Sample

0.00037.37838.5501(0.013)(6.104)(5.773)0.00557.92207.9498(0.019)(7.807)(6.758)School Uniform Experiences (=1)
Young Cohort - Age<49
School Uniform Experiences (=1)
Old Cohort - Age>=49
School Uniform Experiences (=1)-0.00636.80819.2071(0.020)(9.614)(7.862)(4) binary(5) continuous(6) continuous

Estimations w/t controls

Outcome 2: The Difference in
Outcome 1: Wearing a Mask in
the Non-anonymous Situation, but WTP for Wearing a Mask
Removing a Mask in the(from Non-anonymous
Anonymous Situation
to Anonymous)

Whole Sample

0.00166.92869.9218*(0.014)(6.209)(5.757)0.00486.70308.4361(0.020)(8.211)(6.704)

School Uniform Experiences (=1)
Young Cohort - Age<49
School Uniform Experiences (=1)
Old Cohort - Age>=49
School Uniform Experiences (=1)

Outcome 3: The Difference in
WTP for Removing a Mask (fromAnonymousto Non-anonymous)-0.00785.435810.7073(0.020)(9.411)(8.537)

Note: The upper panel presents results without controls, whereas the lower panel incorporates results with controls, which encompass individual
characteristics and household backgrounds (refer to Appendix 2 for further details). Standard errors are indicated in parentheses. ***, **, and * denotesignificance levels of p < .01, p < .05, and p < .1, respectively.

Appendix 5. IV Regression Results with Restricted Sample (Public Elementary Schools Only)(1) binary(2) continuous(3) continuous

Estimations w/o controls

Outcome 1: Wearing a Mask in Outcome 2: The Difference in
the Non-anonymous Situation, WTP for Wearing a Mask
but Removing a Mask in the(from Non-anonymous
Anonymous Situation
to Anonymous)

Outcome 3: The Difference in
WTP for Removing a Mask
(from Anonymous
to Non-anonymous)

Whole Sample

0.0744*25.970737.7768(0.043)(23.534)(28.553)

0.1694**62.2551**

64.3382(0.070)(29.705)(40.105)-0.0347-2.790916.8174(0.056)(35.102)(33.689)(4) binary(5) continuous(6) continuous

School Uniform Experiences (=1)
Young Cohort - Age<49
School Uniform Experiences (=1)
Old Cohort - Age>=49
School Uniform Experiences (=1)

Estimations w/t controls

Outcome 1: Wearing a Mask in Outcome 2: The Difference in
the Non-anonymous Situation, WTP for Wearing a Mask
but Removing a Mask in the(from Non-anonymous
Anonymous Situation
to Anonymous)

Outcome 3: The Difference in
WTP for Removing a Mask
(from Anonymous
to Non-anonymous)

Whole Sample

0.0895**26.3370

41.3041(0.045)(21.520)(26.720)

0.1926***59.3631*66.8399*(0.069)(31.372)(37.194)-0.0374-6.191114.8409(0.060)(35.509)(34.717)

School Uniform Experiences (=1)
Young Cohort - Age<49
School Uniform Experiences (=1)
Old Cohort - Age>=49
School Uniform Experiences (=1)

Note: The upper panel presents results without controls, whereas the lower panel incorporates results with controls, which encompass individual
characteristics and household backgrounds (refer to Appendix 2 for further details). Standard errors are indicated in parentheses. ***, **, and *denote significance levels of p < .01, p < .05, and p < .1, respectively.

Appendix 6. IV Regression Results with Restricted Sample (Same Public Elementary School for Six Years)(1) binary(2) continuous(3) continuous

Estimations w/o controls

Outcome 1: Wearing a Mask in Outcome 2: The Difference in
the Non-anonymous Situation, WTP for Wearing a Mask
but Removing a Mask in the(from Non-anonymous
Anonymous Situation
to Anonymous)

Outcome 3: The Difference in
WTP for Removing a Mask
(from Anonymous
to Non-anonymous)

Whole Sample

0.1093**22.387732.4560(0.048)(26.439)(23.934)0.2104***51.4872

65.5113*(0.082)(33.502)(35.543)-0.0218-0.7780-1.7677(0.059)(32.125)(28.705)(4) binary(5) continuous(6) continuous

School Uniform Experiences (=1)
Young Cohort - Age<49
School Uniform Experiences (=1)
Old Cohort - Age>=49
School Uniform Experiences (=1)

Estimations w/t controls

Outcome 1: Wearing a Mask in Outcome 2: The Difference in
the Non-anonymous Situation, WTP for Wearing a Mask
but Removing a Mask in the(from Non-anonymous
Anonymous Situation
to Anonymous)

Outcome 3: The Difference in
WTP for Removing a Mask
(from Anonymous
to Non-anonymous)

Whole Sample

0.1148**19.450932.2270(0.053)(24.390)(23.558)

0.2211***40.4873

68.7918**(0.082)(37.369)(33.873)-0.0237-5.2257-2.6363(0.067)(31.221)(32.271)

School Uniform Experiences (=1)
Young Cohort - Age<49
School Uniform Experiences (=1)
Old Cohort - Age>=49
School Uniform Experiences (=1)

Note: The upper panel presents results without controls, whereas the lower panel incorporates results with controls, which encompass individual
characteristics and household backgrounds (refer to Appendix 2 for further details). Standard errors are indicated in parentheses. ***, **, and *denote significance levels of p < .01, p < .05, and p < .1, respectively.

Appendix 7. IV Regression Results with Restricted Sample(1) binary(2) continuous(3) continuous

Estimations w/o controls

Outcome 1: Wearing a Mask in the Outcome 2: The Difference in
WTP for Wearing a Mask
Non-anonymous Situation, but
Removing a Mask in the(from Non-anonymous
Anonymous Situation
to Anonymous)

Outcome 3: The Difference in
WTP for Removing a Mask (fromAnonymousto Non-anonymous)

Whole Sample

0.0801*

25.1282

49.4270*(0.046)(23.552)(27.230)0.1853**70.6303**87.8690**(0.080)(31.793)(43.979)-0.0433-13.3239

12.9774-0.05-35.323(33.193)(4) binary(5) continuous(6) continuous

School Uniform Experiences (=1)
Young Cohort - Age<49
School Uniform Experiences (=1)
Old Cohort - Age>=49
School Uniform Experiences (=1)

Estimations w/t controls

Outcome 1: Wearing a Mask in the Outcome 2: The Difference in
WTP for Wearing a Mask
Non-anonymous Situation, but
Removing a Mask in the(from Non-anonymous
Anonymous Situation
to Anonymous)

Outcome 3: The Difference in
WTP for Removing a Mask (fromAnonymousto Non-anonymous)

Whole Sample

0.0904*26.0133

50.1678*-0.049-21.223-26.3620.1988**70.8550**

85.6085**(0.079)(31.999)(39.106)-0.049-21.5961

12.9774-0.056-35.682-33.193

School Uniform Experiences (=1)
Young Cohort - Age<49
School Uniform Experiences (=1)
Old Cohort - Age>=49
School Uniform Experiences (=1)

Note: Approximately 2% of respondents preferred wearing masks only in anonymous situations, which could be due to measurement error or unpredictedbehavior. We conducted robustness checks by re-estimating the regressions without these samples.The upper panel presents results without controls, whereas
the lower panel incorporates results with controls, which encompass individual characteristics and household backgrounds (refer to Appendix 2 for further
details). Standard errors are indicated in parentheses. ***, **, and * denote significance levels of p < .01, p < .05, and p < .1, respectively.