Does SDGs Advertising Promote Ethical Consumer Behavior?: An Integrative Model of Ethical Consumption with Elements of Communication Strategy and Rational Purchase

Abstract

Sustainable Development Goals (SDGs) advertising is still not widespread due to uncertainty about its profitability for business, though awareness of the SDGs has been remarkably raised among corporations and consumers recently. Therefore, the main purpose of this study is to analyze the influence of general SDGs advertising on consumers’ ethical consumption intentions. This study proposes an integrative ethical consumption model in which new determinants related to rational consumption and SDGs advertising are included. The proposed ethical consumption model was validated by analyzing responses from 350 consumers in Japan using structural equation modeling (SEM), and the results demonstrate that ethical consumption intentions are constructed by attitudes toward ethical consumption, together with subjective norms and feasibility assessments. Moreover, this study found that, as a consumer views SDGs advertisements more frequently, they show greater ethical interest, which further increases their ethical consumption intentions. However, no significant evidence reveals that it can also improve the level of knowledge of the SDGs. The findings of this study contribute to the theoretical understanding of ethical consumption from the corporation aspect, providing quantitative evidence for corporations to better allocate resources toward profitable SDGs advertising that aligns with customer behavior.

1. Introduction

1.1. The Current State of Ethical Consumption and the Growing Awareness of the SDGs

In the last few decades, with uncountable ecological and social crises taking place all over the world, public concern for environmental protection and social justice has emerged as a common global tendency. Consumers’ concerns with ethical responsibility and moral values have increased to a level at which their consumption attitudes and behaviors are affected [1]. A large-scale survey conducted in 60 countries in 2015 is strong evidence supporting the previous statement; 66% of 30 thousand questioners were willing to pay more money for brands who are committed to positive social and environmental impacts, which has been increasing by more than 10% year-to-year [2]. According to a Japanese survey, approximately 30% of individuals who are considering purchasing ethical products and services are willing to pay up to 5% more for them, and around 10% are willing to pay more than 10% [3]. In response to these significant changes in ethical consumption, many researchers have suggested that organizations should consider examining their strategies with respect to sustainable development to keep up profitability and eliminate possible risks [4].

Furthermore, as the Sustainable Development Goals (SDGs) were adopted by the United Nations in 2015, the SDGs have rapidly drawn attention not only from Europe but also from some regions of Asia, Japan included. What is notable is that issues regarding production and consumption are highlighted in the development agenda for the first time. In addition, ‘Responsible Production and Consumption’ is set up as the twelfth goal in the hope of promoting economic activities that improve the quality of life of society as a whole by reducing resource degradation, pollution and waste. In contrast to the past, when manufacturers and companies held a dominant position in the market and were primarily responsible for business activities, the twelfth SDG recognizes the roles of producers, consumers and all sectors of society in achieving sustainable develop in the market. The government’s role in regulating markets to ensure fair competition and prevent market failures has remained relatively consistent, and there is a growing expectation for consumers to make responsible choices about resource consumption that may have an impact on future generations. In addition, SDGs communication between corporations and consumers, which cultivates a better understanding of sustainable concepts and practices in society, is thus gaining increasing importance today. A possible outcome of this trend is that the heightened awareness of the SDGs may further encourage ethical consumption practices, making a remarkable impact on the overall business landscape.

1.2. The Perception Gap between Consumers and Corporations in Japan

Intending to uphold competitiveness in this fast-changing and diverse business world, many corporations in Japan have started engaging themselves in some forms of social contributions, Corporate Social Responsibility (CSR) activities and Creating Shared Value (CSV). In 2020, 36.5% of Japanese corporations were implementing CSR activities without any specific goals, and 25.2% established precise goals to achieve. This means that over 60% of Japanese corporations in total are already undertaking activities in line with CSR [5]. Similarly, as the SDGs provide a powerful framework for businesses to make social contributions, they also become an indispensable option regarding differentiation strategies, and there are upward trends in applying the SDGs to businesses. From 2020 to 2021, the percentage of Japanese corporations proactively integrating or planning to integrate the SDGs into their businesses climbed by more than 15% to 39.7% [6].

However, on the consumer side, the situation is obviously different. Despite increasing efforts of Japanese corporations to participate in social contribution activities, consumers in Japan pay scant attention to ethical consumption or ethical products. Only 12.2% of consumers know the term ‘ethical consumption’, and less than 5% in total are somehow purchasing ethical products [7]. The primary reasons why individuals are not putting their ethical intentions into practice are that they lack an effective method to determine whether products or services are ethical and that the price of such items is typically higher than that of other similar products that are available in the market [3]. From the data, it is apparent that corporations’ efforts and resources devoted to contributing to society have a limited or even no effect on consumer purchase behavior. Hence, there is a high chance that the demand for ethical products becomes much lower than the supply, leading to difficulties maintaining or expanding the ethical market in Japan. Without sufficient statistical research to prove the profitability of those SDGs activities, it is not sustainable to continue them over a period of time, thus bringing more positive impacts to corporations and society as well.

1.3. The Importance of SDGs Advertising in the Era of Digitalization

Advertising can be considered an effective means for corporations to bridge the gap with their consumers [8], and even simply providing generic information via official recommendations and labels on products can also drive changes in consumer choices [9]. Unfortunately, not all corporations can effectively make good use of it, especially regarding the SDGs. When asked whether a corporation has managed to spread information about their SDGs activities, 93% of respondents answered in the negative, and the most common reasons were that they ‘have not yet established a mature enough way to communicate externally’ and they ‘are not able to allocate resources or costs for it’ [10]. In addition, based on interviews with the sustainability departments of two Japanese companies, the main problems were that they ‘cannot justify the meaning of spending resources on it because the effect on the business is not proven’, and ‘the effective way to do so is still uncertain’. As a result, it is important and necessary to prove the profitability of SDGs advertising to businesses. If there is sufficient statistical research supporting this, corporations would become more willing to mobilize resources to that end, and the vicious circle can be thus stemmed.

In the era of digitalization, the proliferation of advertising channels, accessible information and digital platforms have facilitated new forms of cooperation and relationships between companies and consumers. Advertising, as a communication tool, has become increasingly complex to study due to the multitude of channels and options that are available to individuals to proactively choose their own preferred mode of communication and information sources. Consequently, personalization has gained significant prominence in advertising. Research has demonstrated that the personalization of advertising content may generate additional value through digitalization by extending the reach of the company’s content and improving customer experience, ultimately generating additional revenue [11,12]. Moreover, numerous studies have presented that corporate ethical activities such as CSR and SDGs play a crucial role in stakeholder communication and engagement, preserving brand identity and augmenting customer satisfaction [13,14]. As such, it is imperative to investigate SDGs advertising in the current era of rapid digitalization.

Based on this, the main purpose of this study is to examine the influence of SDGs advertising on consumers’ ethical consumption intentions by investigating the key factors and the decision-making process involved in ethical consumption from a corporate perspective. This study first proposes an integrative ethical consumption model based on a restructured Theory of Reasoned Action (TRA) model for ethical behavior, which takes into consideration both rational purchasing and SDGs advertisements. The development of this proposed model is explained in Section 2.3. Then, a quantitative methodology is employed to develop measures and validate the model. In the end, theoretical contributions, practical implications, limitations and future research are examined to conclude this study.

To highlight the key points of this study, Figure 1 shows the process of ethical consumption, including two unneglectable elements: SDGs advertisements, and price and quality. Corporations distribute products to the market, and customers exhibit purchasing behavior, followed by the ethical consumption decision-making process. In this decision-making process, ethical elements such as positive anticipated affection and altruism are typically given priority; however, other personally rational factors, such as perceived quality and price, which potentially have an impact on their decisions, are often disregarded or analyzed independently in most cases. Further details are expounded in Section 2.1. As this study aims to assist companies in improving their SDGs advertising policies, which could ultimately increase their profits, the model’s factors are recommended to be controllable by the companies.

To elaborate on this study’s expected contribution to the development of an ethical market, an extended cycle is presented in Figure 2. The cycle is based on the continuous, upward-moving cycle proposed by Schlegelmilch and Pollach [15], which illustrates the ideal relationship among company behavior, ethics communication and public perceptions. The cycle explains the need for companies to adjust their messages to stakeholders whenever there are changes in their behavior, to ensure consistency between performance and perceptions. Regarding SDGs communication, company behavior can be considered their SDGs activities. It is important to note, however, that not all companies finetune their SDGs activities only based on public perceptions, but rather they prioritize profits associated with those activities. To encourage companies to adjust their policies to be more aligned with customers’ expectations, it is crucial to increase consumer participation, which can be considered a form of ethical consumption, and this step should be added between company behavior and public perceptions. By doing so, consumers can send a signal through their purchase behavior to companies to prioritize SDGs practices in order to meet their demands and preferences.

The modified cycle in this study consists of four distinct steps that should be executed separately by both consumers and corporations. Corporations carry out their ‘corporate ethical activities’ and adjust ‘ethics communication’ with their stakeholders, and they respond to these ‘public perceptions’ through ‘ethical consumption’. In this cycle, corporations receive monetary and reputational incentives, which are primarily determined by consumers’ purchase behavior in the ethical market. As a result, corporations provide information about their SDGs activities as input to facilitate circulation. On the other hand, consumers acquire knowledge and interest regarding SDGs from company messages and give back their resources, such as money, time and attention, to the market. This exchange creates a feedback loop between consumers and corporations that promotes the ethical practices of both sides in the market. The results of this study could imply whether SDGs advertising can help activate this circulation.

2. Literature Review

2.1. Ethical Consumption

Ethical consumption can trace its history back to the 1980s or even earlier, and it has been exhaustively discussed as one of the highly concerned consumer behaviors. The concept is said to have first appeared in a British non-profit magazine called Ethical Consumer, which shares information on the social, ethical and environmental issues of companies, having called for boycotts in the 1980s [3]. As the ethical awareness of British consumers increased in the 1990s, ethical consumption has expanded to more types of consumer behaviors, such as the ‘buycott’, which means preferentially purchasing products. Apart from the behavior itself, the object of ethics varies from person to person. For instance, in addition to environmental approaches in the past, there are strong concerns about the ‘people’ aspect, and ethical consumerism is defined as ‘buyer behavior that reflects a concern with the problems of the Third World and incorporates all the principles of environmental consumerism and more’ [15]. It is undeniable that, though ethical consumption has been developed for many years, its definition is yet divergent. Most of the time, other concepts, such as green consumerism and business ethics, are partially holding similar meanings [3]. As it is difficult to assemble an entire list of all activities that are possibly associated with ethical consumption, Crane and Matten suggested a relatively inclusive definition of ethical consumption: ‘the conscious and deliberate decision to make certain consumption choices due to personal moral beliefs and values’ [16].

To enhance the contextualization of Japan’s actual business landscape, certain definitions within Japan are also taken into account. In Japan, the Consumer Affairs Agency defines ethical consumption as ‘consumption activities by each individual consumer considering the resolution of social issues and supporting businesses that address such issues’ in their official report [3]. In addition, several Japanese scholars have also admitted the difficulty of summarizing this concept in one single definition. Common explanations in Japan are ‘Consumption behavior that takes into account people, society and the environment, including local revitalization and employment’ [17] and ‘consumer purchase behavior that contributes to proactively tackling environmental and social problems through the selection of products and services based on bioethics, environmental ethics and social ethics’ [18].

In this study, the definition of consumption is narrowed down to consumers’ purchase behavior only in response to the main purpose of this study, instead of that in a broad sense that also includes boycotts and protests against unethical companies. Furthermore, because the SDGs are determined by 193 countries to perform more actions to achieve a better and more sustainable future for all [19], it could be considered a comprehensive elaboration of ethics today. Therefore, in this study, ethical consumption is defined as ‘purchase behavior that contributes to the SDGs’.

2.1.1. Determinants of Ethical Consumption

Various determinants influencing consumers’ ethical consumption have been identified in prior studies. Although ethical behavior has been studied mainly with statistical methods, researchers in this aspect have gradually been attaching more importance to consumers’ lifestyles and psychological factors since the 1990s. Kaiser and Shimoda proposed responsibility as a predictor of ecological behavior, analyzing the differences between moral and conventional responsibilities in terms of influence during the decision-making process [20]. Grob proved that attitudes, emotions and personal–philosophical values have a strong effect on environmental behavior [21]. Li put more focus on consumers’ psychological process and suggested several novel determinants, such as attitude toward eco-buying behavior, effectiveness assessment, perceived social norms, sense of social responsibility and man–nature orientation [22]. Some other researches have also examined how attitude, personality and perceived social norms specifically influence pro-environmental behaviors and intention [23,24].

Later, as approaches of behavioral economics and social psychology have become popular, studies about ethical consumption have also paid more attention to cognitive factors, such as risk and responsibility attribution, countermeasure effectiveness, feasibility and perceived benefit and cost, as well as psychological factors, such as empathy toward the socially vulnerable [25,26]. Nevertheless, it has been stated that the demographic factors of consumers have been overlooked because too much focus has been placed on the internal cognitive process theory when studying ethical consumption. Therefore, despite the conventional approach, Hoshi took the viewpoint that consumer behavior is a form of the combination of personal value orientation and the state of society, and he concentrated on demographic factors and factors related to social stratification, namely years of education, generational income and group status [27]. Recently, more innovative factors have been introduced into studies on ethical consumption. For example, Oh and Yoon proposed an ethical consumption intention model by including altruism, emotional factors and self-identity based on the theory of planned behavior [28]. Lee, Jin and Shin put weight on a new factor called cosmopolitanism, a value that transcends ethnicity and nation, seeing the world as one community [29]. It is close to the concept of ‘leave no one behind’ in the SDGs.

2.1.2. Ethical Consumption Decision-Making Process

In the social psychology field, the inconsistency between attitudes and behavior is often spotted, and ethical behavior is no exception. There are two theoretical models that are most frequently used to explain this, namely the Theory of Reasoned Action (TRA) [30] and the Theory of Planned Behavior (TPB) [31]. These two theories assume that an individual’s decision to engage in a specific behavior is always logical, goal-oriented or reasoned by evaluating the available information, and can be predicted from their intentions. According to TRA, the behavioral intention of an individual is determined by two factors; the first one is the attitude toward a specific behavior, which is multiplied by their beliefs on the consequences of this behavior and their evaluation of these consequences. The second factor is the subjective norm, which is determined by the normative beliefs of an individual and by their motivation to comply with the norms. As an extension from TRA, TPB states one more factor influencing the behavioral intention in the model, and that factor is perceived behavioral control, which means whether an individual believes they can control their behavior. This depends on the perception of both internal and external factors, such as personality, accessible resources and support.

Apart from this, to better generalize the determinants of ethical behaviors, Hirose proposed a tentative model of environment-conscious behavior, which consists of two phases, namely the goal intention formation phase and the behavioral intention formation phase [25]. In the first phase, based on their perception of environmental seriousness, responsibility and effectiveness, an individual decides on a general goal intention, which is a facilitating factor implying whether they are willing or keen to solve the related issues. After that, in the second phase, an individual evaluates those inhibiting factors, such as feasibility, benefit–cost and social norms, and considers the goal intention decided in the first phase to form a specific behavioral intention that has a dominant impact on the behavior. Although this model is homogeneous to TPB in terms of the key determinants, the sequence of intention formations and its importance are highlighted.

To further organize those variants of ethical behavior decision-making models and eliminate the deficiencies of each model, Toyoda proposed an integrative model referring to the TRB model [31], the two-stage model [25] and the dual-process of reactive and intentional decision making [32]. The special feature of the model is that it makes TRB the basis, while adopting the concepts of facilitating and inhibiting factors to further specify the model for ethical behavior. He also conducted a questionnaire regarding fair-trade products to collect data and analyzed them via covariance structure analysis, proving that the model is appropriate to apply to ethical consumption as well [33].

From the previously introduced theories, there is a tendency that research on ethical purchase behavior puts much emphasis on consumers’ perception and psychological factors, and external stimuli such as price and quality of products are not taken seriously to the same degree. Indeed, the external stimulus can be associated with attitudes and feasibility in the models, but their importance and relationships with other factors in the model are not sufficiently elaborated. Therefore, taking into account these elements could contribute to making the ethical consumption model more comprehensive and applicable for real businesses.

2.2. Rational Consumption

Sproles and Kendall define consumers’ purchase decision-making as ‘a mental orientation characterizing a consumer’s approach to making choices’ and divide it into eight types of mental orientations [34]. Those proposed mental orientations can be further classified into the following five factors influencing purchase decision making, namely (1) quality and price, (2) the behavior of people around us, (3) brand, (4) the accessibility of relevant information and (5) emotional association.

Apart from the definition of possible determinants, some studies have modelled rational purchase decision making, focusing on the more business-related factors such as quality and price. Zeithaml took an unconventional approach by including the concept of sacrifice, emphasizing consumers’ perceived value as the most significant factor and proposing the means–end model to explain the process from the formation of perceived value to purchase behavior [35]. Perceived value is composed of perceived quality and perceived cost, and the perceived quality is combined with perceived cost to include intrinsic attributes such as color and taste expressed by the product, and extrinsic attributes such as brand power and advertising effects. On the other hand, the perceived cost is further classified into monetary cost and nonmonetary cost, such as time and effort. Factors in the model that was proposed by Zeithaml are similar to the eight mental orientations suggested by Sproles and are verified through this exploratory research.

2.3. The Hypothesized Model

According to the purpose of this study and the literature review mentioned in the previous sections, the integrative model proposed by Toyoda [33] is first selected as the basis of the hypothesized model in this study, for the reason that it is a relatively comprehensive model of ethical consumption that is validated by data collected in Japan. As briefly introduced in Section 2.1.2, Toyoda’s model is a variant of the TRB model [31], suggesting that there exists a positive relationship among attitudes, subjective norms and feasibility toward behavioral intention. In other words, when an individual has a positive attitude, which means that they feel appropriate, a perceived subjective norm makes them feel obligated, and feasibility makes them feel capable of performing the behavior. Then, the intention to execute the behavior becomes stronger. The behavioral intention here means that the motivation for an individual to perform the behavior is based on both impulsive and planned factors.

Moreover, Toyoda adopted the two-phase intention formation process [25] and stated that objective intention toward ethical contribution can facilitate the attitude toward a specific ethical behavior, ethical consumption included. On the other hand, in the dual-process of reactive and intentional decision making, there is a determinant called behavioral willingness to accept eco-friendly behavior, and it is described as ‘an openness to or acceptance of the circumstances conducive to socially undesirable behavior, regardless of the individual’s goals or intentions’ and negatively influences the behavior [32]. However, Toyoda named it ‘behavior acceptance’ in his research and gave it a simpler definition—the ‘sense of security that an individual feels when it is not possible to be blamed when not performing a specific ethical behavior’. Moreover, as he considered behavior acceptance an inhibiting factor, he made the hypothesis that there is a correlation between behavior acceptance and feasibility assessment, and this is proved in the result. In this study, to make this factor easier to understand, it is renamed to ‘unethical behavior acceptance,’ and one more assumption here is that, if an individual realizes that even unethical consumption is acceptable, ethical consumption conversely turns into a psychological burden to them, lowering their feasibility assessment.

Another notable point is that, although the two-phase intention formation process shows that the objective intention is correlated with the perceptions of environmental seriousness and responsibility, Toyoda thought that, in a broad sense, ethical behavior is not always provoked by the seriousness of the issue, and normally, consumers do not feel responsible for the issue. These two factors were thus deleted in his study to reduce model complexity. Even so, as this study focuses on advertising strategies that can be described as a sort of customer education, these two factors are unneglectable. From an educational perspective, senses of effectiveness, urgency and responsibility can be considered the key components of ‘interest’, which are defined as ‘readiness to proactively select a specific object’ [36]. In addition, the direct influence of interest on environment-conscious behavioral intentions is verified by statistical research [37]. Consequently, a more essential factor for consumers’ reception of information ‘interest’ is added to replace the perceptions of environmental seriousness, responsibility and effectiveness. Based on the consideration above, the following hypotheses are included.

Hypothesis 1 (H-1). 

Attitudes toward ethical consumption positively influence ethical purchase intention.

Hypothesis 2 (H-2). 

Subjective norms positively influence ethical purchase intention.

Hypothesis 3 (H-3). 

Feasibility assessment positively influences ethical purchase intention.

Hypothesis 4 (H-4). 

Objective intentions toward ethical contributions positively influence ethical purchase intention.

Hypothesis 5 (H-5). 

Unethical behavior acceptance negatively influences feasibility assessment.

Hypothesis 6 (H-6). 

Ethical interest positively influences objective intentions toward ethical contribution.

In order to make the hypothesized model in this study more applicable for proving the profitability of SDGs advertising, the AIDMA model, a well-known consumer behavior model in the traditional marketing environment, has great value for reference. It demonstrates that, along the decision-making process, consumers experience five stages, from exposure to information to the ultimate purchase behavior: Attention, Interest, Desire, Memory and Action [38]. This model qualitatively proposes that consumers feel interested in a specific object only after becoming aware of the object. As times and consumer behavior change, more modern consumer behavior models are advocated, such as the AISAS (Attention, Interest, Search, Action, Share) [39] and AISDALSLove (Attention, Interest, Search, Desire, Action, Like/dislike, Share and Love/hate) models [40]. However, regardless of which model it is, the process from attention or awareness to interest is mutually promoted and proved in various research. Apart from traditional consumer behavior, when focusing on the psychological processes toward environmental issues, some questionnaire surveys share the same results, indicating that interest occurs after knowledge acquisition [41].

Some other researchers have further elucidated the relationship among exposure to information, knowledge and interest by using statistical causal inference. There is research about the relationship between exposure to news and interest in politics, and it shows that, regardless of whether it is soft news or hard news, interest in politics and the desire for knowledge are aroused when the time spent viewing the news increases. The positive influence of the amount of media contact on interest and knowledge has also been proved [42]. Similar results have been shown in the field of education, indicating that interest in and knowledge of a subject increases with the amount of media contact [43]. Thus, the following three hypotheses are included.

Hypothesis 7 (H-7). 

The frequency of viewing SDGs advertisements positively influences ethical knowledge.

Hypothesis 8 (H-8). 

The frequency of viewing SDGs advertisements positively influences ethical interest.

Hypothesis 9 (H-9). 

Ethical knowledge positively influences ethical interest.

Last, to enhance the model to better fit the real purchase situation, perceived cost and perceived quality, as mentioned in Section 2.2, are introduced into the model in this study as external stimuli other than SDGs advertisements. Similar to prior research, in this study, it is assumed that consumers’ perceived monetary and time costs are factors that discourage ethical purchase behavior and are likely to have a negative impact on their feasibility assessment. Moreover, although in previous research the mental cost of the embarrassment of buying ethical products is considered a factor of the perceived cost [35], it is combined with unethical behavior acceptance in this study. Embarrassment is referred to as a self-conscious emotion because it is triggered by events that undermine or reinforce one’s self-image, and because it occurs only in the real or imagined presence of others [44]. It is thus appropriate to include it in the internal decision-making process and as part of unethical behavior acceptance, which is influenced by subjective norms as well.

Besides that, social learning theory proposes that new behaviors can be acquired by observing and imitating others in the same society [45]. As the perception that a specific behavior is expected by society becomes stronger, the sense of security that an individual feels when they will not be criticized when performing it in the same way also becomes stronger. Therefore, it is reasonable to assume that the subjective norm is determined by the behaviors of acquaintances and are negatively correlated with unethical behavioral acceptance.

On the other hand, the perceived quality of ethical products varies widely depending on the type and nature of the product. In a general model for ethical consumption, using the factor ‘perceived quality’ as a general impression of all ethical products in a survey-based study might be inappropriate, and perceived quality is better converted to a psychological attribute of consumers as the ‘pursuit of quality’. It is also not difficult to imagine that people who always pursue high-quality products believe that they will not be blamed for their purchase behavior, even though the products that they buy are not generally considered ethical, with the reason that the pursuit of quality regardless of the ethical impact of the product is human rationality.

Hypothesis 10 (H-10). 

Perceived cost negatively influences feasibility assessment.

Hypothesis 11 (H-11). 

Subjective norms negatively influence unethical behavior acceptance.

Hypothesis 12 (H-12). 

The pursuit of quality positively influences unethical behavior acceptance.

In summary, bringing together all hypotheses mentioned previously, an integrative ethical consumption model is proposed as shown in Figure 3.

3. Methodology and Measurement

3.1. Methodology

To analyze the influence of SDGs advertising on consumers’ ethical consumption intention, a theoretical model using Toyoda’s ethical consumption model as its basis but including important determinants of rational consumption and SDGs advertising is established. After that, a survey design is implemented based on past relevant research, prior to online data collection. In the end, a factor analysis is first carried out to ensure the correlations between predictor variables are not significant enough to affect the hypothesized construction of the model, and then a structural equation modeling analysis is conducted to examine the structural relationships of the hypothesized model. More meaningful findings for corporations to execute their SDGs strategy are also elaborated in further observation.

3.2. Measurement

To provide empirical evidence to prove the hypotheses in the proposed model, a survey was developed, and the survey data were simply categorized into two groups: ‘consumer demographic information’ and ‘attitudes and intentions toward the SDGs and ethical consumption’.

First, regarding ‘consumer demographic information’, there are five consumer attributes that were taken as control variables in this study because they were proved to be important to the decision making of ethical behaviors [27], namely ‘gender’, ‘age group’, ‘household income’, ‘final educational level’ and ‘residential area’. To ensure that there were sufficient samples in each subgroup for analysis, the categorization was simplified, and every attribute only contained up to three subgroups. In a contemporary society that emphasizes inclusivity, this study would have benefitted from including additional genders to better understand consumers. However, considering that a greater number of gender categories potentially results in increased complexity when conducting a stratified analysis, as a result, only the options of ‘male’ and ‘female’ were utilized. Similarly, because Japan has undergone significant events in recent decades, it may have had a profound impact on consumer behavior across different age groups. Despite the potential value of exploring this phenomenon in depth, gathering data on the elderly presents a challenge due to research limitations during the pandemic. As a result, to maintain an adequate sample size and avoid excessive categorization, this study divided subgroups based on the average age of individuals with different work statuses, namely ‘studying’ (~20s), ‘working’ (30s~50s) and ‘retired’ (60s~).

Second, there are eleven determinants in the group ‘attitudes and intentions toward the SDGs and ethical consumption’. Unlike other prior research, all the scale items used a six-point scale, which ranged from 1 = ‘Not Applicable’ to 6 = ‘Applicable’. The reason for choosing the six-point scale was that there is a tendency that the Japanese are most likely to use the midpoint (or ‘neither agree nor disagree’) on scales when answering a survey [46], which reduces the analysis’s reliability. For those analyses that highly rely on correlations, such as regression analysis and structural equation modeling, it is imaginable that the error caused by this tendency would be relatively high. Thus, a six-point scale without a midpoint is effective in eliminating this problem, though respondents might have felt extra burdened to complete the survey.

Additionally, ethical purchase behavior significantly depends on the type of contributions that a corporation can make and the interests of consumers [27]. To further prove that the same tendency happens in this study, the types of product contributions were taken into account when thinking of the questions for the six related determinants, including ethical interest, objective intention, attitudes toward ethical consumption, the frequency of viewing SDGs advertisements, ethical knowledge and ethical purchase intention. A six-point scale ranging from 1 = ‘Not Applicable’ to 6 = ‘Applicable’ was adopted for these determinants. In this case, as there is no midpoint, a score of 4 or above can be considered as indicating that respondents certainly possess the attribute. Regarding the types of product contributions and consumer interests, they were simply categorized into the five Ps (‘People’, ‘Planet’, ‘Prosperity’, ‘Peace’ and ‘Partnership’) [47] to improve respondents’ understanding of the survey questions. For the purpose of reducing the number of questions, ‘Peace’ and ‘Partnership’ were combined into one single category, as these two concepts have a lot in common, such as mutual respect and cooperation without boundaries. Concrete examples of each type of contribution are brought up in the survey.

The major constructs that were used in this study and its measured items and references are given in

Table A1. Measures and references.

Determinant	Operational Definition	Item		References
Ethical interest (EI)	Interest in four categories of SDGs, integrating a sense of efficacy, responsibility and social awareness	ei1	I am interested in environmental issues such as marine litter and global warming.	[22,27,28]
		ei2	I am interested in the problems faced by minorities such as the disabled and homosexuals in society and issues of cultural diversity.
		ei3	I am interested in equity in the world, peaceful relations between nations, international and regional communication, etc.
		ei4	I am interested in the poor and their health and educational problems.
Objective intention (OI)	Intention to contribute to the SDGs	oi1	I want to contribute in some ways to solving environmental problems such as marine litter and global warming.	[33]
		oi2	I want to contribute in some ways to the realization of a culturally diverse society in which everyone can live in peace without being discriminated against.
		oi3	I want to contribute in some ways to the prevention of injustice and unfair practices, to peace-building in countries and to the promotion of people-to-people communication.
		oi4	I want to contribute in some ways to ensuring basic health, education and living standards for the poor.
Attitudes toward ethical consumption (AT)	Attitudes toward purchasing products with social and environmental contributions	at1	It is good to buy products that consume fewer resources and produce less waste and CO2 (e.g., recyclable goods, energy-efficient goods, etc.).	[22,28,33]
		at2	It is good to buy products that contribute to the promotion of equality, non-discrimination and the advancement of cultural diversity and enrichment (e.g., products that are minority-friendly, products for which part of the profits is donated to promote artistic and cultural activities, etc.).
		at3	It is good to buy products that follow legal compliance and promote international and regional communication (e.g., products produced by suppliers that are selected based on clear criteria, products produced in cooperation between local consumers and producers, etc.).
		at4	It is good to buy products that support the health, education and quality of life of the poor (e.g., products for which part of the profits is donated to school meals and educational support activities for children in poor areas).
Subjective norm (SN)	Expectations from social interpersonal relationships	sn1	Sometimes I think about how my actions are perceived by others.	[22,26,28,33]
		sn2	Buying socially and environmentally friendly products is expected by the public.
		sn3	It is my duty as a consumer to buy socially and environmentally friendly products.
Pursuit of quality (PQ)	The tendency to prioritize the desirable quality of a product over other factors when purchasing	pq1	Quality is more important than other factors such as price and social significance.	/
		pq2	As long as the product is of good quality, I don’t mind if the environmental burden increases.
		pq3	Regardless of the production process, origin, etc., I will give priority to good-quality products.
Unethical behavior acceptance (BA)	Sense of security that one believes when they will not be blamed when purchasing unethical products	ba1	Performing ethical consumption does not necessarily mean that the person is committed to social and environmental issues.	[33]
		ba2	People are not condemned by others for being indifferent to social and environmental issues.
		ba3	Few people buy ethically.
Perceived cost (PC)	Time and monetary evaluation of the feasibility of ethical purchase behavior	pc1	It takes more time to identify environmentally and socially friendly products.	/
		pc2	Environmentally and socially friendly products are more expensive than general products.
		pc3	It is relatively time-consuming to buy environmentally and socially friendly products.
Feasibility assessment (FA)	Temporal, financial and spiritual assessment of the feasibility of ethical purchase behavior	fa1	I have enough time to buy environmentally and socially friendly products.	[33]
		fa2	I don’t feel embarrassed buying environmentally and socially friendly products.
		fa3	It is financially affordable for me to buy environmentally and socially friendly products.
Frequency of viewing SDGs advertisements (FQ)	Perceived frequency of viewing SDGs advertisements published by corporations	fq1	Information on corporate environmental activities is well disclosed.	/
		fq2	Information on promoting corporate diversity, the collaboration between consumers and producers and improving employee welfare is well disclosed.
		fq3	Information on corporate international communication activities and deterrence against fraudulent activities is well disclosed.
		fq4	Information on corporate human rights activities and poverty support activities is well disclosed.
Ethical knowledge (EK)	Perception of having sufficient knowledge about society and the environment	ek1	I have sufficient knowledge of environmental issues such as marine debris and global warming.	/
		ek2	I have sufficient knowledge of the problems faced by minorities such as the disabled and homosexuals in society and of issues of cultural diversity.
		ek3	I have sufficient knowledge of equity in the world, peaceful relations between nations, international and regional communication, etc.
		ek4	I have sufficient knowledge of the health and educational problems faced by the poor.
Ethical purchase intention (PI)	The intention to preferentially buy products that contribute to society and the environment	pi1	I want to buy products that consume fewer resources and produce less waste and CO2 (e.g., recyclable goods, energy-efficient goods, etc.).	[22,28,33]
		pi2	I want to buy products that contribute to the promotion of equality, non-discrimination and the advancement of cultural diversity and enrichment (e.g., products that are minority-friendly, products for which part of the profits is donated to promote artistic and cultural activities, etc.).
		pi3	I want to buy products that follow legal compliance and promote international and regional communication (e.g., products produced by suppliers that are selected based on clear criteria, products produced in cooperation between local consumers and producers, etc.).
		pi4	I want to buy products that support the health, education and quality of life of the poor (e.g., products for which part of the profits is donated to school meals and educational support activities for children in poor areas).

.

3.3. Data Collection and Sample Characteristics

There was no designated target population in this study, as SDGs advertisements and ethical consumption are not limited to a certain group of people. To effectively access random consumers with different backgrounds across Japan, an online anonymous survey was conducted between 13 September 2021 and 14 September 2021, and participants were recruited via Questant (Macromill, Inc., Tokyo, Japan), a cloud-based paid survey service. A total of 350 samples were collected, and only 302 of them were, at the end, considered valid. In this study, a ‘valid sample’ is defined as a ‘sample in which no single option is selected in more than 80% of questions in the survey’. The purpose of this is to minimize the negative effect on survey reliability caused by the perfunctory online response. The profiles of the respondents were as follows: 63.2% of respondents were male, 57.9% of them were in the 30s–50s age group, 35.4% of them answered that their household income is around 4000 k–8000 k, 57.9% of them were minimum undergraduate degree holders, and 51.3% of them lived in urban areas. A more exact percentage of each variable or category is given in

Table 1. Demographic characteristics of respondents.

Variable	Category	Frequency	(%)
Gender	Male	191	63.2
	Female	111	36.8
Age Group	~20s	45	14.9
	30s–50s	175	57.9
	60s~	81	27.2
Household Income (JPY/Year)	~4000 k	96	31.8
	4000 k–8000 k	107	35.4
	8000 k~	57	18.9
	Not answered	42	13.9
Final Educational Level	Undergraduate or more	175	57.9
	High school diploma or less	124	41.1
	Not answered	3	1.0
Residential Area	Urban areas	155	51.3
	Non-urban areas	147	48.7

Regarding household income in USD based on the average exchange rate in 2022 (JPY/USD = 0.0073431), 4000 k JPY is equivalent to around 29.4 k USD, and 8000 k JPY is equivalent to around 58.7k USD

.

4. Empirical Results

To examine the reliability and validity of this study, the statistical analysis consisted of three stages. The first was to conduct a confirmatory factor analysis using the maximum likelihood estimation method to verify the validity of the latent determinants that compose each item. The second stage was to test the proposed hypotheses that are included in the model through the SEM technique, and to prove the validity of the model structure as a whole. In the last stage, a stratified sampling method was also used to group samples by various consumer demographic characteristics and to further observe if there is a significant difference between consumer groups. In this statistical analysis, IBM SPSS Statistics version 27 and IBM SPSS AMOS version 26 were used for calculations.

4.1. Confirmatory Factor Analysis

The factor loadings, Composite Reliability (CR), Average Variance Extracted (AVE) and Cronbach’s alpha (Cα) for each determinant were calculated as the key judgment on convergent validity and construct validity, and the results are shown in

Table 2. Descriptive, reliability and convergent validity.

Determinant	Items	Mean	SD	Factor Loading	AVE	CR	Cα
Ethical interest (EI)	ei1	3.82	1.129	0.746	0.526	0.822	0.822
	ei2	3.36	1.123	0.682
	ei3	3.46	1.074	0.754
	ei4	3.59	1.216	0.718
Objective Intention (OI)	oi1	3.78	1.046	0.836	0.671	0.867	0.896
	oi2	3.86	1.099	0.824
	oi3	3.66	1.068	0.820
	oi4	3.52	1.108	0.796
Attitudes toward ethical consumption (AT)	at1	4.10	1.102	0.831	0.724	0.916	0.916
	at2	3.75	1.074	0.865
	at3	4.01	1.064	0.866
	at4	3.98	1.064	0.842
Subjective norm (SN)	sn1	3.65	1.110	0.511 (Dropped)	0.511	0.670	0.670
	sn2	3.81	1.073	0.775
	sn3	3.45	1.092	0.655
Pursuit of quality (PQ)	pq1	3.68	0.999	0.755	0.445	0.598	0.597
	pq2	2.84	1.003	0.410 (Dropped)
	pq3	3.66	0.933	0.565
Unethical behavior acceptance (BA)	ba1	3.85	1.135	0.684	0.428	0.598	0.597
	ba2	3.73	1.075	0.441 (Dropped)
	ba3	4.08	1.161	0.623
Perceived cost (PC)	pc1	3.97	1.005	0.643	0.490	0.653	0.652
	pc2	4.33	0.994	0.583 (Dropped)
	pc3	3.85	0.948	0.753
Feasibility assessment (FA)	fa1	3.16	1.135	0.800	0.576	0.729	0.728
	fa2	4.43	1.075	0.398 (Dropped)
	fa3	2.82	1.161	0.716
Frequency of viewing SDGs advertisements (FQ)	fq1	3.18	0.986	0.798	0.677	0.888	0.888
	fq2	3.13	0.984	0.825
	fq3	3.08	1.012	0.838
	fq4	3.11	1.048	0.829
Ethical knowledge (EK)	ek1	3.27	1.010	0.791	0.623	0.861	0.861
	ek2	3.26	0.992	0.730
	ek3	3.10	1.025	0.830
	ek4	3.11	1.001	0.802
Ethical purchase intention (PI)	pi1	3.73	1.125	0.824	0.689	0.899	0.898
	pi2	3.49	1.105	0.835
	pi3	3.54	1.055	0.860
	pi4	3.55	1.122	0.800

.

To begin, according to the result, most of the factor loadings were over 0.5, and this means that the corresponding items were considered contributable enough to the determinants, confirming that the model measures had construct validity at a certain level. Those items with factor loadings less than 0.5, namely pq2, ba2 and fa2, were dropped. Moreover, except for the ‘pursuit of quality’ and ‘unethical behavior acceptance’, the composite reliability for each factor exceeded 0.6, which is often considered the threshold score criteria, and the composite reliabilities of the two exceptions were 0.598, which is extremely close to the threshold. This proved that convergent validity was established. Regarding another indicator of convergent validity, Average Variance Extracted (AVE) was also confirmed in this analysis, and most of the determinants reached the threshold of 0.5 except the ‘pursuit of quality’, ‘unethical behavior acceptance’ and ‘perceived cost’. This could be improved via better question design. Last, the Cronbach’s alphas of most determinants ranged between 0.652 and 0.916, which is considered adequate for a measure’s internal consistency, and Cronbach’s alphas of the ‘pursuit of quality’ and ‘unethical behavior acceptance’ were only 0.597. Although the AVE of the ‘pursuit of quality’, ‘unethical behavior acceptance’ and ‘perceived cost’ did not meet the recommended threshold, the CR and Cα values were found to be close to 0.6. Therefore, these determinants were retained in the model. However, it is undeniable that there were some concerns about reliability, and improvement is desired in future research.

To investigate possible collinearity issues in the proposed model, the standardized coefficients between each determinant were also examined, and the results are shown in

Table 3. Standardized coefficients among the measured determinants.

	1	2	3	4	5	6	7	8	9	10	11
1. Ethical interest (EI)	-
2. Objective intention (OI)	1.005	-
3. Attitudes toward ethical consumption (AT)	0.824	0.880	-
4. Subjective norms (SN)	0.920	0.930	0.871	-
5. Pursuit of quality (PQ)	0.206	0.232	0.276	0.265	-
6. Unethical behavior acceptance (BA)	0.210	0.265	0.311	0.255	0.570	-
7. Perceived cost (PC)	0.280	0.255	0.295	0.360	0.294	0.854	-
8. Feasibility assessment (FA)	0.831	0.810	0.704	0.804	0.433	0.205	0.158	-
9. Frequency of viewing SDGs advertisements (FQ)	0.723	0.711	0.516	0.700	0.354	0.074	0.055	0.675	-
10. Ethical knowledge (EK)	0.837	0.745	0.505	0.678	0.308	0.279	0.243	0.703	0.744	-
11. Ethical purchase intention (PI)	0.898	0.926	0.858	0.908	0.259	0.146	0.261	0.784	0.689	0.633	-

. Almost all the values did not exceed 1.0, and thus, the collinearity issue does not happen in the proposed model.

However, what is notable is that the coefficient between ‘ethical interest’ and ‘objective intention’ was larger than 1.0, and it is sometimes referred to as ‘Heywood cases’. Standardized coefficients over 1.0 are not necessarily invalid [48], and this might sometimes indicate that there is a correlation that is approximately near the possible maximum, that a high degree of multicollinearity occurs in the data, that some unreasonable constraints have been set in the model, etc. This issue can be also attributed to inadequate reliability, and in response to this, larger samples, factors with more items (or indicators) and more reliable measures are preferable, which can be helpful to prevent the same issues from happening [49].

4.2. Validation of Structural Equation Model

In this study, Path analysis was implemented to test the hypotheses and

Table 4. Structural equation modeling (SEM) results.

Hypothesis	Relationship	β	Result
H-1	Subjective norm (SN) → Ethical purchase intention (PI)	0.262 ***	Valid
H-2	Attitudes toward ethical consumption (AT) → Ethical purchase intention (PI)	0.778 ***	Valid
H-3	Feasibility assessment (FA) → Ethical purchase intention (PI)	0.204 ***	Valid
H-4	Objective intention (OI) → Attitudes toward ethical consumption (AT)	0.877 ***	Valid
H-5	Unethical behavior acceptance (BA) → Feasibility assessment (FA)	0.699 ***	Valid; Inverse relationship
H-6	Ethical interest (EI) → Objective intention (OI)	0.966 ***	Valid
H-7	Frequency of viewing SDGs advertisements (FQ) → Ethical knowledge (EK)	0.742 ***	Valid
H-8	Frequency of viewing SDGs advertisements (FQ) → Ethical interest (EI)	0.308 ***	Valid
H-9	Ethical knowledge (EK) → Ethical interest (EI)	0.546 ***	Valid
H-10	Perceived cost (PC) → Feasibility assessment (FA)	–0.115 **	Valid
H-11	Subjective norm (SN) → Unethical behavior acceptance (BA)	0.907 ***	Valid; Inverse relationship
H-12	Pursuit of quality (PQ) → Unethical behavior acceptance (BA)	0.593 ***	Valid

β, the standardized path coefficient; **, p < 0.05; ***, p < 0.01.

shows if each relationship between determinants in the proposed model is validated by the statistical data or not. To measure the fitness of the proposed model, the Comparative fit index (CFI) and Root-mean-square error of approximation (RMSEA) are also used. Although the CFI is 0.836 which is slightly less than the good fit value of 0.9, the RMSEA is 0.086 which is less than 0.1 and all coefficients were significant (p < 0.05). Based on this reason, the model fit is considered marginally acceptable and there is no significant discrepancy between the measurement and the hypothesized model.

According to the result, all the relationships were proven to be significant at least at the p < 0.05 level. The core concept of Toyoda’s model was proved again; attitudes toward ethical consumption, subjective norms and feasibility positively influence ethical purchase intention, and objective intention positively influences the attitude. On the other hand, the frequency of viewing SDGs advertisements positively influences both ethical knowledge and ethical interest, and ethical knowledge has a further positive effect on ethical interest, which also positively stimulates objective intention.

However, even though the relationships between ‘unethical behavior acceptance’ and ‘feasibility assessment’ (H-5), and between ‘unethical behavior acceptance’ and ‘subjective norm’ (H-11) are significant, the influence is inverse to the anticipated one. This means that unethical behavior acceptance is positively affected by subjective norms, and at the same time, it positively influences feasibility assessment as well. Moreover, the results show that the pursuit of quality exerts a positive influence on unethical behavior acceptance, and perceived cost has a negative impact on feasibility assessment.

4.3. Stratified Analysis

A total of 302 samples were further stratified according to several consumer demographic characteristics, namely ‘gender’ (Male, N = 191; Female, N = 111), ‘age group’ (~20s, N = 45; 30s–50s, N = 175; 60s~, N = 81), ‘household income’ (~4000 k, N = 96; 4000 k–8000 k, N = 107; 8000 k~, N = 57), ‘final educational level’ (Undergraduate or more, N = 175; High school diploma or less, N = 124) and ‘residential area’ (Urban areas, N = 155; Non-urban areas, N = 147). Because the target beneficiary group to which a consumer can contribute has a signification influence on ethical behavior [27], it is imaginable that the object of ethics has an important role in the decision-making process. Therefore, based on the four items (ei1–ei4) of ‘ethical interest’ in the survey, the data of those respondents who were interested in a specific object (rated 4 or above in the four items) were extracted as another sample group, ‘interested object of ethics’ (Planet, N = 206; People, N = 140; Prosperity, N = 173; Peace and Partnership, N = 157). Path analysis was implemented with stratified data groups, and the results are shown in

Table 5. Structural equation modeling (SEM) results stratified by gender.

Relationship	Male	Female
	β	β
H-1: Subjective norm (SN) → Ethical purchase intention (PI)	0.259 ***	N/A
H-2: Attitudes toward ethical consumption (AT) → Ethical purchase intention (PI)	0.817 ***	0.652 ***
H-3: Feasibility assessment (FA) → Ethical purchase intention (PI)	0.184 **	N/A
H-4: Objective intention (OI) → Attitudes toward ethical consumption (AT)	0.883 ***	0.859 ***
H-5: Unethical behavior acceptance (BA) → Feasibility assessment (FA)	0.703 ***	0.669 **
H-6: Ethical interest (EI) → Objective intention (OI)	0.971 ***	0.970 ***
H-7: Frequency of viewing SDGs advertisements (FQ) → Ethical knowledge (EK)	0.727 ***	0.774 ***
H-8: Frequency of viewing SDGs advertisements (FQ) → Ethical interest (EI)	0.392 ***	N/A
H-9: Ethical knowledge (EK) → Ethical interest (EI)	0.475 ***	0.698 ***
H-10: Perceived cost (PC) → Feasibility assessment (FA)	–0.189 ***	N/A
H-11: Subjective norm (SN) → Unethical behavior acceptance (BA)	0.806 ***	1.151 **
H-12: Pursuit of quality (PQ) → Unethical behavior acceptance (BA)	0.612 ***	N/A

β, the standardized path coefficient; **, p < 0.05; ***, p < 0.01; N/A, invalid relationship. Male, N = 191; Female, N = 111.

,

Table 6. Structural equation modeling (SEM) results stratified by age group.

Relationship	~20s	30s–50s	60s~
	β	β	β
H-1: Subjective norm (SN) → Ethical purchase intention (PI)	0.850 ***	N/A	0.510 ***
H-2: Attitudes toward ethical consumption (AT) → Ethical purchase intention (PI)	0.872 ***	0.888 ***	0.464 ***
H-3: Feasibility assessment (FA) → Ethical purchase intention (PI)	–0.565 **	0.01 ***	0.541 ***
H-4: Objective intention (OI) → Attitudes toward ethical consumption (AT)	0.817 ***	0.889 ***	0.857 ***
H-5: Unethical behavior acceptance (BA) → Feasibility assessment (FA)	1.079 **	0.636 ***	–0.400 **
H-6: Ethical interest (EI) → Objective intention (OI)	0.928 ***	0.979 ***	0.960 ***
H-7: Frequency of viewing SDGs advertisements (FQ) → Ethical knowledge (EK)	0.600 ***	0.798 ***	0.691 ***
H-8: Frequency of viewing SDGs advertisements (FQ) → Ethical interest (EI)	N/A	0.455***	N/A
H-9: Ethical knowledge (EK) → Ethical interest (EI)	0.661 ***	0.389 ***	0.707 ***
H-10: Perceived cost (PC) → Feasibility assessment (FA)	–0.476 ***	–0.188 **	0.324 **
H-11: Subjective norm (SN) → Unethical behavior acceptance (BA)	0.799 **	0.796 ***	N/A
H-12: Pursuit of quality (PQ) → Unethical behavior acceptance (BA)	N/A	0.823 ***	0.539 ***

β, the standardized path coefficient; **, p < 0.05; ***, p < 0.01; N/A, invalid relationship. ~20s, N = 45; 30s–50s, N = 175; 60s~, N = 81.

,

Table 7. Structural equation modeling (SEM) results stratified by household income.

Relationship	~4000 k	4000 k–8000 k	8000 k~
	β	β	β
H-1: Subjective norm (SN) → Ethical purchase intention (PI)	0.256 ***	0.425 ***	0.186 **
H-2: Attitudes toward ethical consumption (AT) → Ethical purchase intention (PI)	0.701 ***	0.825 ***	0.946 ***
H-3: Feasibility assessment (FA) → Ethical purchase intention (PI)	0.275 ***	N/A	N/A
H-4: Objective intention (OI) → Attitudes toward ethical consumption (AT)	0.285 ***	0.927***	0.916 ***
H-5: Unethical behavior acceptance (BA) → Feasibility assessment (FA)	N/A	–0.331 **	N/A
H-6: Ethical interest (EI) → Objective intention (OI)	0.949 ***	0.941 ***	0.985 ***
H-7: Frequency of viewing SDGs advertisements (FQ) → Ethical knowledge (EK)	0.743 ***	0.779 ***	0.629 ***
H-8: Frequency of viewing SDGs advertisements (FQ) → Ethical interest (EI)	0.335 ***	N/A	N/A
H-9: Ethical knowledge (EK) → Ethical interest (EI)	0.554 ***	0.629 ***	0.539 ***
H-10: Perceived cost (PC) → Feasibility assessment (FA)	N/A	0.427 ***	N/A
H-11: Subjective norm (SN) → Unethical behavior acceptance (BA)	0.236 ***	–0.424 ***	N/A
H-12: Pursuit of quality (PQ) → Unethical behavior acceptance (BA)	N/A	0.634 ***	0.720 ***

β, the standardized path coefficient; **, p < 0.05; ***, p < 0.01; N/A, invalid relationship. ~ 4000 k, N = 96; 4000 k–8000 k, N = 107; 8000 k ~, N = 57.

,

Table 8. Structural equation modeling (SEM) results stratified by final educational level.

Relationship	Undergraduate or More	High School/Diploma or Less
	β	β
H-1: Subjective norm (SN) → Ethical purchase intention (PI)	0.335 ***	0.244 ***
H-2: Attitudes toward ethical consumption (AT) → Ethical purchase intention (PI)	0.752 ***	0.820 ***
H-3: Feasibility assessment (FA) → Ethical purchase intention (PI)	0.261 ***	0.196 **
H-4: Objective intention (OI) → Attitudes toward ethical consumption (AT)	0.903 ***	0.828 ***
H-5: Unethical behavior acceptance (BA) → Feasibility assessment (FA)	N/A	0.554 ***
H-6: Ethical interest (EI) → Objective intention (OI)	0.958 ***	0.955 ***
H-7: Frequency of viewing SDGs advertisements (FQ) → Ethical knowledge (EK)	0.724 ***	0.757 ***
H-8: Frequency of viewing SDGs advertisements (FQ) → Ethical interest (EI)	N/A	0.450 ***
H-9: Ethical knowledge (EK) → Ethical interest (EI)	0.634 ***	0.442 ***
H-10: Perceived cost (PC) → Feasibility assessment (FA)	N/A	N/A
H-11: Subjective norm (SN) → Unethical behavior acceptance (BA)	0.247 **	0.713 ***
H-12: Pursuit of quality (PQ) → Unethical behavior acceptance (BA)	0.368 ***	1.185 ***

β, the standardized path coefficient; **, p <0.05; ***, p < 0.01; N/A, invalid relationship. Undergraduate or more, N = 175; High school diploma or less, N = 124.

,

Table 9. Structural equation modeling (SEM) results stratified by residential area.

Relationship	Urban Areas	Non-Urban Areas
	β	β
H-1: Subjective norm (SN) → Ethical purchase intention (PI)	0.279 ***	0.241 **
H-2: Attitudes toward ethical consumption (AT) → Ethical purchase intention (PI)	0.906 ***	0.608 ***
H-3: Feasibility assessment (FA) → Ethical purchase intention (PI)	N/A	0.376 ***
H-4: Objective intention (OI) → Attitudes toward ethical consumption (AT)	0.941 ***	0.794 ***
H-5: Unethical behavior acceptance (BA) → Feasibility assessment (FA)	0.884 ***	0.515 ***
H-6: Ethical interest (EI) → Objective intention (OI)	0.927 ***	0.743 ***
H-7: Frequency of viewing SDGs advertisements (FQ) → Ethical knowledge (EK)	0.666 ***	0.784 ***
H-8: Frequency of viewing SDGs advertisements (FQ) → Ethical interest (EI)	0.392 ***	N/A
H-9: Ethical knowledge (EK) → Ethical interest (EI)	0.483 ***	0.661 ***
H-10: Perceived cost (PC) → Feasibility assessment (FA)	N/A	N/A
H-11: Subjective norm (SN) → Unethical behavior acceptance (BA)	0.775 ***	1.171 ***
H-12: Pursuit of quality (PQ) → Unethical behavior acceptance (BA)	0.476 ***	0.743 ***

β, the standardized path coefficient; **, p < 0.05; ***, p < 0.01; N/A, invalid relationship. Urban areas, N = 155; Non-urban areas, N = 147.

and

Table 10. Structural equation modeling (SEM) results stratified by the interested object of ethics.

Relationship	Planet	People	Prosperity~	Peace and Partnership
	β	β	β	β
H-1: Subjective norm (SN) → Ethical purchase intention (PI)	0.377 ***	N/A	0.312 ***	0.332 ***
H-2: Attitudes toward ethical consumption (AT) → Ethical purchase intention (PI)	0.636 ***	0.728 ***	0.782 ***	0.743 ***
H-3: Feasibility assessment (FA) → Ethical purchase intention (PI)	0.227 ***	0.315 ***	0.211 ***	N/A
H-4: Objective intention (OI) → Attitudes toward ethical consumption (AT)	0.854 ***	0.879 ***	0.923 ***	0.917 ***
H-5: Unethical behavior acceptance (BA) → Feasibility assessment (FA)	0.684 ***	N/A	0.761 ***	N/A
H-6: Ethical interest (EI) → Objective intention (OI)	0.902 ***	0.918 ***	0.944 ***	0.920 ***
H-7: Frequency of viewing SDGs advertisements (FQ) → Ethical knowledge (EK)	0.652 ***	0.660 ***	0.761 ***	0.639 ***
H-8: Frequency of viewing SDGs advertisements (FQ) → Ethical interest (EI)	N/A	N/A	N/A	N/A
H-9: Ethical knowledge (EK) → Ethical interest (EI)	0.667 ***	0.195 ***	0.614 ***	0.518 ***
H-10: Perceived cost (PC) → Feasibility assessment (FA)	N/A	N/A	N/A	N/A
H-11: Subjective norm (SN) → Unethical behavior acceptance (BA)	0.711 ***	N/A	0.819 ***	N/A
H-12: Pursuit of quality (PQ) → Unethical behavior acceptance (BA)	0.584 ***	N/A	0.603 **	N/A

β, the standardized path coefficient; **, p < 0.05; ***, p < 0.01, N/A, invalid relationship. Planet, N = 206; People, N = 140; Prosperity, N = 173; Peace and Partnership, N = 157.

. In several groups, there were some relationships that were not supported by the results. As shown in Table 5, for example, relationships between subjective norms and ethical purchase intention, as well as feasibility assessment and ethical purchase intention, do not apply to females. More details and observations about those exceptions are elaborated in Section 5.3. However, as all the RMSEA in these groups was lower than the threshold of 0.9, the result is considered valid.

5. Discussion

5.1. Discussion of the Inverse Relationship

There are two proven relationships in the results that are opposite to the hypotheses: H-5, ‘unethical behavior acceptance’ → ‘feasibility assessment’ (−) and H-11, ‘subjective norm’ → ‘unethical behavior acceptance’ (−). To begin, H-5 assumes that consumers are generally morally lazy, which means that, under most circumstances, they avert or avoid moral efforts and exertion. In other words, as a specific unethical behavior feels more acceptable, they consider doing it to be more exhausting ethically. Surprisingly, the result reveals that people positively assess the feasibility of ethical purchases when they think that unethical behavior is tolerated. From the perspective of human ethics and the sense of a mission, it seems more rational and general to feel that it is easier or worthier to perform ethical behaviors, if unethical behaviors are even tolerated.

Next, H-11 assumes that customers act as described in social learning theory; people observe, model and imitate the behaviors, attitudes, and emotional reactions of others so that, if they think a specific behavior is expected by others, they tend to perform them in the same way. However, the result violates this hypothesis, showing that customers feel less obliged or feel that it is less necessary to purchase ethical products when they strongly perceive that the behavior is expected and already being executed by others. One of the explanations is that the bystander effect also occurs with regard to ethical purchase behavior. Hirose’s study consistently suggested that ethical behavior is positively influenced by a stronger subject norm. In contrast, this study presents a relatively novel and comprehensive perspective to comprehend the underlying mechanism and explore the potential negative effects of subject norms in the decision-making process.

5.2. Discussion of Groups with Different Interested Objects of Ethics

In the stratified analysis, Table 10 demonstrates that, regardless of the object of ethics, the influence of the frequency of viewing SDGs advertisements on ethical knowledge is relatively trivial for those respondents who were interested in ethical problems when compared to other groups. In addition, the frequency of viewing SDGs advertisements does not have a significant correlation with ethical interest. The reason for this is likely that the law of diminishing returns might also apply to SDGs advertising. In other words, although SDGs advertising has an outstanding effect on increasing customers’ ethical interest at the beginning, once the interest reaches a certain level, knowledge and interest can hardly increase regardless of how often the customers receive relevant information afterward.

From the same result, it is verified that the perceived cost does not have a significant correlation with feasibility assessment. One interpretation for this is that people with a certain level of ethical interest do not judge the feasibility of ethical purchase behavior by the price or time that they might need to spend on the products because they consider ethical factors as the top priority.

More importantly, Table 10 also makes it clear that viewing SDGs advertisements or even sales promotions is not as effective with the customer segment that is certainly interested in ethical problems when compared to other groups.

5.3. Discussion of Groups with Different Demographic Characteristics

Regarding the differences caused by demographic characteristics, there are two notable points in this study. First, when examining age groups, Table 6 reveals the following similarities between the group of individuals in their 20s or below and those in their 60s or above: (1) the correlation between the ‘frequency of viewing SDGs advertisements’ and ‘ethical knowledge’ is weaker than the average, (2) the correlation between ‘ethical knowledge’ and ‘ethical interest’ is stronger than the average, and (3) the correlation between ‘subjective norms’ and ‘ethical purchase intention’ is stronger than the average.

For point (1), the average standardized path coefficient of the ‘frequency of viewing SDGs advertisement’ and ‘ethical knowledge’ is 0.742. That of the group of 20s or below is 0.6, and that of the group of 60s or above is 0.691, which are both smaller than the average. Although there is still no sufficient evidence to explain the causes of the above observation, it is likely related to learning capability and cognitive skills that affect the conversion from advertisement information to internal knowledge. Regarding point (2), there is a chance that the lifestyle of people in the groups of ~20s and 60s~ is not as tough as that of the dominant working class, and thus they might be more capable of turning their knowledge into their interest, relatively with more time and mental capacity. Concerning point (3), it seems that they are more influenced by their peer groups and thus pay more attention to following the subjective norm.

Another interesting point is that Table 8 shows that the final education level is also a key element to determine ethical purchase behavior. First, the average standardized path coefficient between the ‘frequency of viewing SDGs advertisements’ and ‘ethical interest’ is 0.308. However, the coefficient is higher for individuals with lower educational backgrounds compared to the groups of people who graduated from high school or who hold a diploma, showing a coefficient of 0.45. Similarly, the relationship between the ‘frequency of viewing SDGs advertisements’ and ‘ethical knowledge’ is stronger with a standardized path coefficient of 0.757, compared to the average coefficient of 0.742. On the other hand, for individuals with at least a bachelor’s degree, the relationship between the ‘frequency of viewing SDGs advertisements’ and ‘ethical interest’ is not statistically significant, and the relationship between the ‘frequency of viewing SDGs advertisements’ and ‘ethical knowledge’ is even lower at 0.724. These findings suggest that individuals with lower educational backgrounds may have a greater interest in the content of SDGs and may perceive a higher level of knowledge gained from SDGs advertisements. This difference in perception may be due to the volume of knowledge acquired before, as knowledge gain is typically easier to perceive when the knowledge is new. Additionally, for individuals with a lower level of education, the relationship between the ‘pursuit of quality’ and ‘unethical behavior acceptance’ is unusually high with a standardized path coefficient of 1.185, which is higher than the average of 0.593. However, the relationship between ‘feasibility assessment’ and ‘ethical purchase intention’ is lower than others. This means that they tend to prioritize product quality and may not consider feasibility when assessing their ethical purchase intentions. One potential reason is that education level is associated with various personal abilities, such as self-discipline and endurance, which may influence an individual’s focus on short-term versus long-term benefits. Indeed, there should be more hidden factors behind this result, and further research is required.

6. Conclusions

With the integrative ethical consumption model, this study first provides statistical evidence to demonstrate that SDGs advertising can positively influence both consumers’ ethical knowledge and interest, which ultimately promotes their ethical consumption behavior. This finding is consistent with prior research that suggests the prioritization of awareness and interest, and it highlights the relationship among exposure to information, knowledge and interest [37,38,39,40,41,42,43]. Second, as indicated in the SEM analysis, ethical consumption is significantly influenced mainly by attitudes toward ethical consumption, followed by subjective norms and feasibility assessment. More specifically, the importance of these three factors is quantitively calculated; the influence of attitudes toward ethical consumption is approximately three to four times that of the other two factors. Finally, product-related determinants such as the ‘pursuit of quality’ and ‘perceived cost’ are emphatically introduced in this ethical consumption model, in the hope of reducing the blind spots in past research, which has normally overlooked the cruciality of those external stimuli.

Unlike previous studies that have delineated ethical consumption from rational consumption [25,35], this model integrates ethical, rational and SDGs advertising components to offer a more comprehensive understanding of ethical purchase behavior in the real world. As a result, this study contributes to quantifying the influence of SDGs advertising on consumers’ ethical purchase behavior. Consequently, as long as the profitability of SDGs advertising is somehow supported by objective evidence, corporations are more likely to have incentive and motivation to continue promoting their SDGs activities, establishing a more sustainable SDGs strategy that focuses not only on activity executions but also customer education.

Besides the contributions, there are also both theoretical and practical implications from this study. To begin, from a theoretical perspective, this study adopts the widely recognized TRA as the fundamental framework of the integrative model. However, this study expands upon this theoretical foundation by introducing determinants that influence rational purchasing decisions, resulting in a more comprehensive ethical consumption model that better reflects real-world shopping situations compared to previous models. Moreover, as the SDGs became one of the most concerned agendas in the current decade, this study demonstrates a way to apply this concept to academic research on ethical consumption or ethical behavior. Moreover, in the context of ethical consumption, communication with customers is relatively less emphasized compared to other factors, although some studies have been conducted on CSR communication, which explores the organizational process of anticipating stakeholders’ expectations of corporations’ CSR policies and employing various communication tools to disseminate pertinent information. This study focuses on SDGs advertising (ethical advertising) in the hope of exploring more potential contributions that ethical advertising can bring to society and corporations as well.

Regarding the practical implications of this study, the key takeaway is that SDGs advertising can not only enhance a corporation’s brand image but can also promote consumer ethical purchase behavior, ultimately resulting in increased revenue through sales activities, which could be more sustainable and practical for the whole business in terms of both profitability and reputation. Other than that, based on the real data collected from the Japanese market, this study analyzes and suggests differences in ethical consumption decision making among various consumer segments. Therefore, Japanese corporations can now have a better understanding of their target customers and their reactions after viewing SDGs advertisements, enabling the development of more effective advertising strategies soon. Consistent with optimal circulation for ethical market development, as depicted in Figure 2, corporations are limited in their resources to disseminate information into circulation. Therefore, the most critical task is to effectively target the appropriate audience with the right information to facilitate the continuation of circulation. The findings of this study are aligned with Figure 2, demonstrating that SDGs advertising can increase the intention to engage in ethical consumption. Alternatively, this study underscores the need for quantitative evidence to categorize consumers effectively and improve the information disclosure of SDGs activities. As outlined in Section 1.3, the personalization of content is crucial for enhancing customer engagement, which can lead to increased direct and indirect revenue. In light of this, this study offers further insight into understanding the connection between advertising and ethical purchase intention based on customer attributes.

Ultimately, it is essential to recognize several limitations of this study and identify potential areas for improvement in future research. First, the integrative model in this study is based on Toyoda’s model but is extended to some other academic aspects and elements, such as rational purchasing and advertising. It might be necessary to better clarify the relationships among those different aspects, and in particular, this study adopts a relatively novel point of view—the SDGs. Second, in terms of data collection, the sample size is relatively small, owing to limited time and financial resources, and it has likely not managed to adequately reflect the general population. The ideal case is to collect data from several channels to best eliminate sampling bias, which also potentially contributes to increased RMSEA of the model. However, under the current social situation, it was difficult to conduct a face-to-face paper survey, so an online survey became the best option, though the response bias can be expected to be more serious.

Furthermore, because the data in this study are limited to the Japanese market, the generalizability of the findings might be limited. To better understand the general situation of ethical consumption, cross-cultural or cross-regional research is preferable to further validate the proposed model and to see whether it applies to other countries as well. Last, even though SDGs advertising has been proven to positively promote ethical consumption, the findings do not provide insight into the specific mechanisms that underlie this positive impact. Future research could explore how consumers view SDGs advertisements and how to effectively implement advertising strategies. Before those questions are clear, corporations still have lots of concerns when considering if they should adopt SDGs advertising based on their business situation. Thus, it is also worth exploring the mechanism behind SDGs advertisements, particularly in the age of digitalization. This includes examining innovative communication methods and determining how to effectively employ them.