Activators of Airline Customers’ Sense of Moral Obligation to Engage in Pro-Social Behaviors: Impact of CSR in the Korean Marketplace

This study was designed to better comprehend airline customers’ purchase and pay intention formation by involving perceived airline corporate social responsibility (CSR), emotional factors, volitional factors, moral obligation, and brand involvement as key concepts. A survey methodology with quantitative data analysis was used. Our empirical results revealed that perceived CSR contributed to eliciting positive and negative emotions, brand attitude, and social norm. These variables significantly activated a sense of obligation to take pro-social actions. In addition, brand involvement acted as a significant moderator in the moral obligation and pay intention relationship. The adequateness of the higher-order structure of perceived CSR was verified.


Introduction
For the past several decades, with the growing increase in customers' concern for unethical business issues, corporate social responsibility (CSR) has been one of the most predominant agenda items in the business society [1][2][3]. Recent studies have indicated that an increasing number of customers react to a company's CSR initiatives, practices, and promotions when purchasing a product/service, consuming it, and making a post-purchase decision [2][3][4][5][6]. Given the growing need for a firm's responsible business in society, CSR initiatives, activities, and promotions are recently considered as essential constituents of the firm's business success not only in the hospitality/tourism sector but also in the entire business sector [6][7][8].
The impact of a company's CSR on customer responses is especially considerable in the airline industry [8][9][10], as this industry connects different countries/locations/cultures, consumes natural resources excessively, deals with intangible products, and inevitably causes an environmental impact [11,12]. Indeed, various societal/environmental issues are unavoidable in the airline sector [8,13]. Nowadays, many airline companies have accordingly centered on CSR as a tool for their marketing and customer increase/retention strategy in the competitive marketplace [6,8]. It is indisputable that CSR substantially affects airline passengers' diverse behaviors and decisions [8,9].
Studies in the existing literature have investigated the links between CSR and its outcome variables, such as favorable attitude toward the firm, emotion/affect, social/personal norms, image, behavioral intentions, and loyalty [2,4,14,15]. Such variables in these studies were a significant function of patrons' perceived CSR. However, research investigating the entire volitional process as an outcome of perceived CSR has been rarely conducted. Little research has also considered both positive and negative emotion dimensions as dependent variables of perceived CSR. In addition, the normative process (or norm activation process) has hardly been integrated into the extant CSR literature. Furthermore, brand involvement has long been regarded as a crucial constituent in clearly explicating customer behaviors [16][17][18]. These researchers agreed that the magnitude of the association between customer behavioral intention and its direct predictors is fortified or enervated based on the level of customer brand involvement. Nonetheless, the existing CSR research in consumer behavior and tourism has hardly tested the possible role of brand involvement as a moderator.
The current study is an empirical endeavor to fill these research gaps in the existing literature, and attempts to provide a clear explanation of airline passengers' behavioral intention formation via evaluating the role of perceived airline CSR, emotional process, volitional process, normative process, and involvement. Specifically, the research objectives are designed (1) to test the possible theoretical relationships among perceived CSR, positive and negative anticipated emotions, brand attitude, and social norm, (2) to inquire how such relationships contribute to activate passengers' sense of obligation to take pro-social actions, (3) to assess the moderating effect of brand involvement in the association between sense of obligation and behavioral intentions (purchase and pay), (4) to evaluate the adequacy of the second-order structure of perceived airline CSR, and (5) to examine the mediating role of emotional, volitional, and normative processes within the proposed theoretical framework. Therefore, the following sections are involved with the literature review of several conceptions mentioned (i.e., CSR, anticipated emotions, and volitional factors: brand attitude and social norm, brand involvement, and sense of obligation to take pro-social actions), research methodology and outcomes, as well as the final conclusion compromising discussions, implications, limitations, and future research directions.

Perceived CSR and Its Impact
Since a variety of ethical/legal/philanthropic/economic issues concerning the associations among business, society, and the public good have been raised/addressed in diverse consumer behavior sectors, CSR embracing these issues has received considerable attention from business practitioners, stakeholders, academics, and policy-makers [1,3]. In the consumer behavior literature, CSR includes a variety of actions reflecting company/business commitment to societal obligation, placing specific emphasis on customers' perception of such behaviors [2,14,19]. This perception is described as perceived CSR [2]. Lacey et al. [14] defined perceived CSR as patrons' assessment of how well a corporation meets its stakeholders' and patrons' expectations and societal obligation by practicing various voluntary actions that are beneficial to the society. A company that values and actively invests in corporate social responsibility activities will affect the patron's consumption actions through its positive corporate reputation and image, which in turn is conducive to maintaining and improving the overall financial income and advantageous market share [20]. Montiel and Delgado-Ceballos [21] emphasized that CSR is a crucial mainstay of stimulating corporate sustainability and achieving the balance between society, environment, and economy. Practicing responsible business activities is rapidly becoming a vital agenda in the business society as well as the entire society [3]. More recently, the practice of corporate social responsibility in the airline industry has also attracted considerable attention [20,22]. The airline companies attempt to seek sustainable development by staying close to environmental and social expectations through communicating with the stakeholders and turning these expectations into practical strategies [22], such as the utilization of eco-friendly and energy-saving fuels. According to Carroll [19], social responsibility becomes reality only when more companies and practitioners become moral and ethical in doing their business.
Many researchers in diverse contexts agree that CSR comprises major indicators, such as ethical responsibility, philanthropic responsibility, legal responsibility, and economic responsibility [4,5,10,19,23]. Ethical responsibility is about doing business in a manner consistent with societal expectations and ethical/moral norms adopted by a society [5,19]. Philanthropic responsibility is relevant to doing business that is compatible with the philanthropic expectations of a society, meeting its charitable expectations [10,23]. A key aspect of legal responsibility is related to doing business that is fulfilling its legal obligation [10,19]. Lastly, economic responsibility is concerned about maintaining a highly competitive position in the marketplace and a strong level of operational efficacy [5,19]. In sum, CSR and its major facets signify that a company should have responsibilities to be a respectful corporate citizen improving the public's quality of life, be ethical and moral, comply with laws and regulations, and have a competitive economic performance.
Numerous researches in the extensive tourism and consumer behavior literature have examined the influence of CSR on customer responses and behaviors [5,7,9,10,20]. Likewise, in the context of airline industry, Han et al. [20] and Seo et al. [22] verified that environmental corporate social responsibility plays a significant role in increasing customers' perceived quality, emotional attachment, and eliciting the positive customer behaviors (e.g., spontaneous word-of-mouth), which contributes to a high level of trust, brand involvement (e.g., brand respect and love) and customer commitment/attachment to a certain company [24,25]. Su et al. [7] inspected the customer intention generation process in the hotel sector and expressed that perceived CSR induces in customers positive affective/emotional responses and a favorable attitude for the company, helping it earn respect from customers. Palihawadana et al. [5] investigated the effect of customer CSR perception. Their empirical evidence revealed that customers' perception of a firm's CSR activities elicits a positive assessment of the product/service. According to these researchers, whether individuals have a positive/negative evaluation of a firm and its products and have a favorable/unfavorable attitude toward the firm and its products can be dependent on the nature of the CSR activities that the firm practices [5,7]. This notion is consistent with Chen et al.'s [9] and Ilkhanizadeh and Karatepe's [10] indication that patrons' perception regarding a company's broad range of CSR practices is an influential factor on their emotional process and attitudinal/volitional process, which eventually affect their behavioral intentions/loyalty for the company. Han et al. [25] indicated that customers who care more about environment concerns show an intensive interest in valuing social influence and supporting those companies with a sense of social responsibility. In another words, when a company is active in ethical, philanthropic, legal, and economic CSR practices, customers' cognitive and affective evaluations of the company and attitude toward it are favorable [2,4,7,10].

Impact of Anticipated Emotions
Customers experience positive and negative feelings when performing a certain action, and they also anticipate favorable and unfavorable emotions that they will experience when conducting such actions [26][27][28]. Perugini and Bagozzi [28] declared that anticipated emotions indicate these expected forms of emotions that they will experience by doing so, including positive and negative facets. In the pro-social behavior literature, positive anticipated emotion often is comprised of pride, accomplishment, confidence, and worth, and negative anticipated emotion often encompasses guilty, remorseful, sorry, bad, and ashamed feelings [29][30][31]. In diverse situations, individuals are likely to take the affective consequences into consideration prior to conducing a behavior [28,32]. Richard et al. [32] thus elaborated anticipated emotions as anticipated post-behavioral affective responses. Undoubtedly, both positive and negative anticipated emotions have long been regarded as vital factors in expounding customers' decision-making process and behaviors [27].
A number of researches in the behavior literature have examined the role of positive and negative anticipated emotions in explicating individuals' pro-social/pro-environmental behaviors [27,29,31]. Bamberg et al. [29] examined individuals' pro-social behaviors. They discovered that both positive and negative anticipated feelings are significantly associated with a sense of moral obligation to take pro-social actions. More recently, in the convention tourism context, Han et al. [27] found that positive and negative anticipated emotions act as affective triggers of moral norm. Their findings are aligned with Onwezen et al.'s [31] research that demonstrated the significant associations between anticipated emotions and personal norm. Results in these studies support that individuals' sense of obligation to take pro-social actions is a significant function of anticipated emotions.

Impact of Volitional Factors
A clear comprehension of individuals' pro-social decisions and behavior undoubtedly requires both independent and combined roles of attitude toward the behavior and social norm [31,33]. Researchers have described these two concepts as volitional factors [28,34]. The efficacy of socio-psychology theories is enhanced by including dimensions such as attitude and social norm [34]. The concept of attitude and social norm in social psychology was established by Ajzen and Fishbein [35] and Ajzen [33], who asserted that individuals' decision-making process and behavior heavily depend on a volitional process. The key aspect of this volitional process is attitudinal and social dimension [28,33]-that is, when making a choice, individuals' decisions for a specific action forms based on attitudinal and social influence. While attitude refers to individuals' favorable/unfavorable tendency to react in a consistent manner to a certain behavior/product/brand [34,35], social norm indicates the level of social pressure that individuals perceive when making a decision of acting or not acting pro-socially [27].
The importance of volitional factors in the pro-social decision-making process and behavior has been uncovered in diverse social behavior and a tourism context [27,34,36]. In examining customers' underwater behavior, Ong and Musa [36] found that one's social norm exerts a significant effect on their sense of obligation to take pro-environmental actions, and in turn, this personal norm determines their behavior. In the tourism context, Han and Hyun [34] demonstrated that travelers' attitude toward the behavior and social norm play a crucial role in activating their sense of moral obligation, which in turn generates their intention to purchase a socially responsible tourism product. Within one robust theoretical framework, Han et al. [27] investigated individuals' pro-social intention formation in the environmentally responsible convention context. Their findings revealed that international convention travelers' cognition exerted a significant influence on moral norm, and social norm and attitude were vital and proximal determinants of moral norm. In their research, volitional process encompassed attitude and social norm. In these studies discussed above, moral obligation significantly mediated the impact of social norm and attitude on pro-social intentions.

Impact of Brand Involvement
Brand/product involvement is a vital concept in tourism and consumer behavior research [37][38][39]. Involvement refers to individuals' concentration and interest level stimulated by a specific consumption action/experience [38]. The major aspect of involvement comprises customers' absorption, deep engagement, and immersion [40,41]. When customers' level of involvement is high for a specific brand, they often become entirely absorbed and deeply engaged in the consumption activity of the brand's products/services [42] and have an enduring perception of the criticality of the brand and its products/services [37,38].
Involvement has been regarded as a key component in enlightening why people respond favorably/unfavorably to a tourism/leisure/hospitality service offering [16,18].
In general, when customers are involved, they should participate in a series of behaviors, such as active search, broad choice process, active information processing [17]. Csikszentmihalyi [43] demonstrated that people who have a higher involvement with a tourism/leisure activity (e.g., mountain climbing) would perceive the activity as entertaining and participate in extra activities related to climbing. Wakefield and Blodgett [18] discovered that the degree of involvement with a tourism activity has a powerful impact on customers' excitement and re-patronage intention formation. Likewise, in hedonic service consumption, Hightower et al. [44] declared that perpetual involvement significantly and positively affects customers' emotion and decision-making process. Kim et al. [45] indicated that food involvement is significantly associated with customer loyalty formation in food festivals. Moreover, in the cruise tourism context, Han and Hyun [38] demonstrated that the relationships among traveler motivations, satisfaction, and loyalty are influenced by the product involvement level. In their research, the associations were found to become stronger when the customer-perceived level of involvement was high. These empirical studies support the moderating role of involvement in the tourism/leisure product consumption situation. These outcomes are consistent with Buchanan's [46] suggestion that high perceived significance of a consumption activity to an individual positively influences their internal and external responses toward it. This suggests that involvement is a vital variable because of its effect on customer responses and the decision-making process [16]. Consequently, involvement can be identified as a momentous clarification for customers' behaviors in tourism.

Sense of Obligation to Take Pro-Social Actions and Its Impact
A sense of obligation to take pro-social actions is interchangeably used with moral norm, personal norm, and moral obligation [30]. This concept refers to a patron's feeling of strong moral responsibility that they experience when practicing a particular pro-social action related to product/service consumption [27,47]. According to Klöckner and Matthies [48] and Han [30], this concept is pertinent to customers' conviction that behaving in a certain way is correct or incorrect. They agreed that the core aspect of the sense of obligation to take pro-social actions is thus internalization. The general assumption of the norm activation process (i.e., activating patrons' sense of obligation) in existing norm-related theories is that customers' pro-social decisions/behaviors are elicited by a sense of obligation to make the decisions or take the actions, and this moral norm is activated through diverse cognitive, volitional, and emotional processes [30,31,47,48]. Consistently, the direct impact of the sense of obligation on traveler behavioral intentions (e.g., visit/buy intention, pay intention, recommendation intention) has been demonstrated in many recent empirical studies [27,31,34,48].

Research Model and Hypothesized Relationships
The proposed model is exhibited in Figure 1. It includes perceived airline corporate social responsibility (ethical, philanthropic, legal, and economic), positive and negative anticipated emotions, brand attitude, social norm, sense of obligation to take pro-social actions, purchase intention, and pay intention, containing 10 research hypotheses (Hypothesis 1-Hypothesis 10). The model also encompasses the concept of brand involvement as a moderator (Hypothesis 11a and Hypothesis 11b). Two identical models for high and low brand involvement groups were developed.

Hypothesis 5 (H5).
Positive anticipated emotion significantly affects a sense of obligation to take pro-social actions.
Hypothesis 6 (H6). Negative anticipated emotion significantly affects a sense of obligation to take pro-social actions.

Hypothesis 7 (H7).
Brand attitude significantly affects a sense of obligation to take pro-social actions.

Hypothesis 8 (H8).
Social norm significantly affects a sense of obligation to take pro-social actions.

Hypothesis 9 (H9).
A sense of obligation to take pro-social actions significantly affects purchase intention.

Hypothesis 10 (H10).
A sense of obligation to take pro-social actions significantly affects pay intention.
Hypothesis 11a (H11a). Brand involvement significantly moderates the relationship between a sense of obligation to take pro-social actions and purchase intention.
Hypothesis 11b (H11b). Brand involvement significantly moderates the relationship between a sense of obligation to take pro-social actions and pay intention.

Measurement Instrument
Constructs were measured using items taken from prior studies [5,19,23,26,28,30,31,33,49]. The adopted measures were altered to the current research context. While brand attitude was measured with a seven-point semantic differential scale (i.e., bad (1)/good (7)), the other constructs were measured by means of a seven-point Likert scale (i.e., strongly disagree (1)/strongly agree (7)). Firstly, the four dimensions of perceived airline corporate social responsibility were measured, five measurement items were used to assess ethical responsibility (e.g., "It is important for an airline to perform in a manner consistent with expectations of societal mores and ethical norms"). Philanthropic responsibility was evaluated by five items (e.g., "It is important for an airline to perform in a manner consistent with the philanthropic and charitable expectations of society"). Five items were utilized to determine legal responsibility (e.g., "It is important for an airline to comply with various international, governmental, and local regulations"). Economic responsibility was measured through four items (e.g., "It is important for an airline to maintain a strong competitive position"). Subsequently, the additional constructs were evaluated, four items for positive anticipated emotion (e.g., "proud") and five items for negative anticipated emotions (e.g., "guilty") were used. Brand attitude was assessed through five items (e.g., "For me, using an airline that actively practices and promotes CSR activities is bad (1)/good (7)"). Three items were used to analyze social norm (e.g., "Most people who are important to me think I should use an airline that actively practices and promotes CSR activities"). A sense of obligation to take pro-social actions was assessed by four items (e.g., "I feel an obligation to choose an airline that actively practices and promotes CSR activities when I travel in the future"). Moreover, brand involvement was measured with three items (e.g., "I feel my strong involvement in an airline that actively practices and promotes CSR activities"). Further, three items and two items were exploited to assess purchase intention (e.g., "I plan to use an airline that actively practices and promotes CSR activities when I travel in the future") and pay intention (e.g., "I am willing to pay more for an airline that actively practices and promotes CSR activities"), respectively.
Overall, the survey questionnaire contained three sections encompassing these measurement items, research depiction, and demographic questions related to background information (e.g., age, gender, education, income). The original version of the questionnaire was improved through a pre-test with academics and airline practitioners. Lastly, it was perfected through an expert review. An integral measurement list of all constructs can be seen in Appendix A, Table A1.

Data Collection and Sample Background Information
An online survey was conducted to collect the data. With the use of an online marketing research firm's survey system, a survey invitation e-mail was sent to general airline customers who were selected from the firm's database in a random manner. Undoubtedly, airline customers normally arrange their travel matters (e.g., fare search, bookings, and flight details) through the major online mediums/platforms, especially in South Korea. On the other hand, the online survey also provided the convenience for potential respondents to complete the survey within their available time, thereby increasing the response quality. In consequence, the invitation e-mail, including a brief research description and the introductory letter of the survey, was sent by the system. In addition, the survey invitation e-mail contained the link leading to the survey questionnaire. The potential respondents were asked if they had experience with an airline within the past one year. Only those who had such experience were requested for survey participation. In order to reduce the unengaged responses, a suggested method was employed to discard the cases with standard deviation values below 0.5 [50]. Through the process described above, a total of 375 valid responses remained. The average time of completing the survey was about 10.5 minutes. The further data analysis was conducted with these 375 cases. The data collection was done in the middle of March, 2018 for a one-week period.
Sample characteristics and background information were investigated. Among 375 airline customers, 191 respondents (50.9%) were male customers, and 184 (49.1%) were female customers. The participants' mean age was 39.87 years, ranging from 20 years old to 60 years old. About 18.1% answered that their most recent airline use was within the last one month, 52.8% responded within the last three months, and 79.5% reported within the last six months. Additionally, every participant's most recent airline use was within the past 12 months. Regarding the frequency of airline use within the past five years, 23.2% indicated 1-3 times, 25.1% reported 4-5 times, 26.7% indicated 5-9 times, and 25.1% indicated 10 times or more. Most participants were highly educated. About 65.1% reported that they had a college degree, 13.3% reported a graduate degree, 11.5% reported a two-year college degree, and 10.1% reported a high school diploma or less. With regard to the participants' income, about 47.2% indicated that their annual income was between $40,000 and $84,999, followed by an income of $39,999 or less (39.2%), and an income of $85,000 or more (13.6%).

Confirmatory Factor Analysis
A measurement model assessment was conducted. Our results from a confirmatory factor analysis with a maximum likelihood examination method indicated that the goodness-of-fit statistics for the measurement model were acceptable: χ 2 = 1826.375, df = 877, χ 2 /df = 2.124, p < 0.001, RMSEA = 0.055, CFI = 0.930, IFI = 0.931, TLI = 0.921. Details regarding the measurement model assessment results are shown in Table 1. All items were significantly loaded to their relevant latent construct (p < 0.01). Composite reliability (CR) was estimated, the values fell between 0.840 and 0.939. All composite reliability values exceeded the criterion of 0.70 suggested by Hair et al. [51], which implies strong internal consistency among the items for each study construct. Average variance extracted (AVE) was estimated for the assessment of convergence validity. Our findings revealed that all AVE values exceeded the minimum criterion of 0.500 suggested by Hair et al. [51], ranging between 0.595 and 0.837. As displayed in Table 1, the correlations (squared) between variables were all below than the AVE values. Consequently, convergent and discriminant validity of the measures was evident. In addition, the standard deviation (SD) of all measurement constructs was also calculated, ranging from 0.901 to 1.315.

Structural Model Evaluation
A structural model evaluation was performed. A structural equation modeling employing the maximum likelihood examination method was executed to estimate the proposed model. The goodness-of-fit statistics revealed that the model had an adequate fit to the data (χ 2 = 2115.811, df = 803, χ 2 /df = 2.635, p < 0.001, RMSEA = 0.066, CFI = 0.899, IFI = 0.899, TLI = 0.891). The results of the structural model estimation along with hypotheses testing results are presented in Figure 2 and Table 2 in detail. As reported in Figure 2, our results regarding the higher-order model for perceived airline CSR showed that the four lower-order dimensions (ethical responsibility, philanthropic responsibility, legal responsibility, and economic responsibility) and the higher-order global factor (perceived airline CSR) were positively and significantly associated. The values of coefficients (standardized) for such associations were 0.731 (ethical responsibility), 0.782 (philanthropic responsibility), 0.652 (legal responsibility), and 0.351 (economic responsibility), respectively. The relationships were all significant at p < 0.01. The first-order dimensions of ethical responsibility (R 2 = 0.535), philanthropic responsibility (R 2 = 0.612), legal responsibility (R 2 = 0.425), and economic responsibility (R 2 = 0.123) were in general satisfactorily accounted for by the higher-order construct of perceived airline CSR. Hence, it was evident that the four lower-order dimensions of perceived airline CSR significantly belong to one global latent construct within the proposed theoretical framework.
The hypothesized associations were evaluated. First, the proposed influence of perceived airline CSR was assessed. Our results revealed that perceived airline CSR exerted a significant impact on positive anticipated emotion (β = 0.824, p < 0.01), negative anticipated emotion (β = 0.471, p < 0.01), brand attitude (β = 0.553, p < 0.01), and social norm (β = 0.742, p < 0.01), which supported Hypotheses 1, 2, 3, and 4. Perceived airline CSR explained about 67.8%, 22.2%, 30.6%, and 55.1% of the variance in positive anticipated emotion, negative anticipated emotion, brand attitude, and social norm, respectively. The hypothesized impact of these emotional factors and volitional factors on the sense of obligation to take pro-social actions was examined. As expected, the results revealed that positive anticipated emotion (β = 0.296, p < 0.01), negative anticipated emotion (β = 0.120, p < 0.01), brand attitude (β = 0.078, p < 0.05), and social norm (β = 0.575, p < 0.01) had a significant impact on the sense of obligation to take pro-social actions. Therefore, Hypotheses 5, 6, 7, and 8 were supported. These variables, along with perceived airline CSR, accounted for about 78.6% of the variance in the sense of obligation to take pro-social actions. Then, the outcomes from structural analysis verified that purchase intention (β = 0.731, p < 0.01) and pay intention (β = 0.767, p < 0.01) were a significant function of the sense of obligation to take pro-social actions, thus supporting Hypotheses 9 and 10. This moral norm explained about 53.4% and 58.9% of the total variance in purchase intention and pay intention, respectively.

Structural Invariance Model
A baseline model evaluation was conducted. A total of 375 cases were divided into high and low brand involvement groups based on the K-means cluster analysis results. The high brand involvement group contained 247 cases, whereas the low group encompassed 128 cases. The outcomes of the baseline model evaluation comprising these two groups are displayed in Table 3 and Figure 2. The goodness-of-fit statistics were, in general, acceptable (χ 2 = 3357.809, df = 1637, χ 2 /df = 2.051, p < 0.001, RMSEA = 0.053, CFI = 0.851, IFI = 0.852, TLI = 0.843). Thus, an empirical comparison between this model and a nested model was employed by using a chi-square difference test. A particular link of interest was restricted to be equal between high and low brand involvement groups.

Structural Invariance Model
A baseline model evaluation was conducted. A total of 375 cases were divided into high and low brand involvement groups based on the K-means cluster analysis results. The high brand involvement group contained 247 cases, whereas the low group encompassed 128 cases. The outcomes Sustainability 2020, 12, 4334 12 of 17 of the baseline model evaluation comprising these two groups are displayed in Table 3 and Figure 2. The goodness-of-fit statistics were, in general, acceptable (χ 2 = 3357.809, df = 1637, χ 2 /df = 2.051, p < 0.001, RMSEA = 0.053, CFI = 0.851, IFI = 0.852, TLI = 0.843). Thus, an empirical comparison between this model and a nested model was employed by using a chi-square difference test. A particular link of interest was restricted to be equal between high and low brand involvement groups. Table 3. Baseline model and nested model assessment, chi-square test. The outcomes from the chi-square test indicated that the association between sense of obligation to take pro-social actions and purchase intention was not significantly different between high and low groups (∆χ 2 (1) = 0.001, p > 0.05). Thus, the hypothesized moderating effect of brand involvement on such association was not supported (Hypothesis 11a). Yet, the outcomes of the structural invariance assessment revealed that the relationship strength between a sense of obligation to take pro-social actions and pay intention was significantly different across high and low brand involvement groups (∆χ 2 (1) = 4.133, p < 0.05). Accordingly, the assumed moderating influence of brand involvement on such a relationship was established (Hypothesis 11b).

Summary of the Study
This study was an endeavor to build a sturdy conceptual framework elaborating passenger purchase and pay intention formation by considering the intricate interrelationships among perceived airline CSR, emotional factors, volitional factors, and moral obligation. The particular moderating role of passenger brand involvement was also investigated. Findings from the structural equation modeling wholly supported the hypothesized associations. The hypothesized moderating impact of brand involvement on pay intention generation process was also supported. The proposed theoretical framework encompassed a satisfactory level of capability in predicting passenger intentions, since its accountability for the variance in passenger purchase and pay intentions was 53.4% and 58.9%, respectively. Each study construct had an important role directly/indirectly contributing to the increase in passenger purchase and pay intentions. The strength of the relationship between sense of obligation to take pro-social actions and pay intention was moderated by brand involvement. In sum, the theoretical framework of the present research explicitly explains the complicated psychological process of how perceived airline CSR results in passengers' positive decisions for a socially responsible airline. In recent years, airline management has encountered increasingly demanding/sophisticated patrons and faced growing competition. In this severely challenging marketplace, this study offers airline management clear understanding regarding the underlying mechanism of the airline passenger intention generation process. This research sufficiently informs airline researchers and practitioners of the specific role of perceived CSR, emotional process, volitional process, and normative process in inducing customer favorable behaviors for a socially responsibly airline that ultimately lead to an increased share of the market.

Implications
Our study provides practitioners both in the airline and tourism industry with theoretical and practical implications. A particularly valuable point is the second-order construct of perceived airline CSR that adds important implications to the airline and tourism literature. Empirical evidence provided by this research revealed that the commonality under the ethical, philanthropic, legal, and economic first-order dimensions was satisfactorily extracted by their higher-order latent factor (perceived airline CSR), which indicates an adequacy of a comprehensive assessment of perceived airline CSR within the proposed theoretic framework. This result deepens the existing knowledge in the extant airline and tourism literature by offering an effectiveness of a hieratical approach that recognizes and assesses customer perception of CSR in a clear manner. Furthermore, the parsimonious second-order perceived CSR typology addresses airline practitioners and researchers' need for theorizing the intricate CSR constituents in a concise manner.
Philanthropic responsibility was identified as the strongest indicator of perceived airline CSR. This result implies that allocating monetary/non-monetary resources to philanthropic activities meeting charitable expectations of society is perceived as the most critical airline CSR by passengers. Ethical responsibility was found to be the second strongest indicator of perceived CSR. It is therefore important for airline practitioners to do their business ethically and morally, recognizing and respecting society's new/growing ethical and moral norms. Legal responsibility was identified as another critical indicator of perceived airline CSR. It is thus essential for airlines to fulfill legal obligations and become a law-abiding corporate citizen in the society. Lastly, economic responsibility was also found to be a significant indicator of perceived airline CSR. This finding implies that to maintain a competitive position in the marketplace keeping the firm consistently profitable is also perceived as an important airline CSR by passengers.
Furthermore, emotional factors (positive and negative) and volitional factors (brand attitude and social norm) were found to significantly enhance the sense of obligation to take pro-social actions and play a significant role in the formation of purchase and pay intentions for pro-social airlines. This result is consistent with the empirical findings of prior studies that emphasized the individual role of such constructs [27,31,34,48]. From the practical perspective, it is suggested that airline operators must center on the increase of customers' positive anticipated emotion and the decrease of their negative anticipated emotion and that airline practitioners should focus on inducing customers' positive attitude and social norms in order to stimulate their personal moral obligation efficiently. As evidenced in the present study, emotional and volitional factors were the direct and critical contributors of the sense of moral obligation to take pro-social actions. Thus, such endeavors for an increase in visitors' moral obligation will eventually contribute to boosting their pro-social decisions to purchase and pay for the airline that actively practices/promotes CSR activities.
Results of this research showed the predominant role of the sense of obligation to take pro-social actions within the proposed theoretical framework. Existing CSR studies in many contexts have overlooked the importance of individuals' moral obligation. This research is one of the very few studies to demonstrate the criticality of moral obligation in elaborating customer pro-social decision formation driven from customer CSR perception and identify the relative significance in determining such a decision as compared to emotional variables and volitional variables. Therefore, our finding regarding the role of the sense of obligation to take pro-social actions is both theoretically and practically meaningful. The present study further informs that such emotional and volitional factors are not the direct triggers of behavioral intentions, but the activators of the sense of obligation to take pro-social actions. This implies that if airline practitioners desire to see the maximum effect of their CSR efforts on customer positive responses for the company, activating customers' moral obligation should be the top priority, as such endeavors lead to enhanced purchase and pay intentions for the company.
Our results revealed that the link between a sense of obligation to take pro-social actions and pay intention was under the significant influence of brand involvement (∆χ 2 (1) = 4.133, p < 0.05). Specifically, the relationship was stronger in the high brand involvement group (β = 0.768, p < 0.01) than in the low brand involvement group (β = 0.669, p < 0.01). This finding implies that at a similar level of moral obligation for pro-social actions, customers who feel stronger involvement with a socially responsible airline brand build a stronger intention to pay more for the airline. Theoretically, this research suggests that brand involvement could be added as a significant factor in the activation process of passengers' moral obligation (moral norm) and pay intention formation in airline research. From the managerial perspective, building customer involvement in the airline would significantly benefit the airline operators, because, as our results indicate, highly involved customers are likely to activate their moral obligation to pay more for the airline that organizes and promotes CSR activities. Promotional messages that emphasize the efforts/outcomes of the airline's CSR activities (e.g., disaster relief effort, breast cancer awareness campaign, free breakfast program for low-income families, tree planting projects) may enhance passengers' involvement with a socially responsible airline.

Limitations and Directions for Future Research
Despite its essential theoretical and practical meaning, the current study had several limitations. After all, this study was designed to be adequate in an airline setting. That is, the survey participants were airline customers. The generalization of our findings to other hospitality and tourism sectors (e.g., restaurant, hotel, and cruise) thus needs a caution, while testing the proposed framework in other hospitality and tourism contexts is worthy of reference for future research. In addition, anticipated emotions, volitional factors, and moral obligation were demonstrated to be significant mediators. This finding was in line with prior studies in social behavior and tourism that stressed the important mediating nature of emotional, volitional, and normative processes [27,28,30,31,48], which supports the view of anticipated emotions, attitude, social norms, and sense of obligation to take pro-social actions as a bridge mediating the relationship between perceived CSR and intentions to purchase and pay for the product/service of a socially responsible brand. Given this, for researchers, it is crucial to recognize that using positive and negative anticipated emotions, attitude, social norms, and a sense of moral obligation as complete mediators is efficient when building any conceptual framework comprising emotional, volitional, and normative processes in further CSR research. Furthermore, this study found a significant moderating impact of brand involvement. Nevertheless, the underlying motives of involvement were not explored. For the purpose of exploring the role of brand involvement further, future researchers are encouraged to identify the triggers of brand involvement through a qualitative approach and to empirically investigate the combined role of brand involvement and its triggers within our proposed theoretical framework.

Conflicts of Interest:
The authors declare no conflicts of interest. Table A1. Summarization of measurement items.

Perceived Airline Corporate Social Responsibility
Ethical responsibility It is important for an airline to perform in a manner consistent with the expectations of societal mores and ethical norms. It is important for an airline to recognize and respect new or evolving ethical/moral norms adopted by society. It is important for an airline to prevent ethical norms from being compromised in order to achieve corporate goals. It is important that good corporate citizenship be defined as doing what is expected morally or ethically. It is important for an airline to recognize that corporate integrity and ethical behavior go beyond mere compliance with laws and regulations.

Philanthropic responsibility
It is important for an airline to perform in a manner consistent with the philanthropic and charitable expectations of society. It is important for an airline to allocate some of their resources to philanthropic activities (e.g., fine/performing arts and sports). It is important that managers and employees of an airline participate in voluntary and charitable activities within their local communities. It is important for an airline to provide assistance to private and public educational institutions. It is important for an airline to assist voluntarily those projects that enhance a community's "quality of life".

Legal responsibility
It is important for an airline to perform in a manner consistent with the expectations of government and law. It is important for an airline to comply with various international, governmental, and local regulations. It is important for an airline to be a law-abiding corporate citizen. It is important that a successful airline be defined as one that fulfills its legal obligations. It is important for an airline to provide goods and services that at least meet minimal legal requirements.

Economic responsibility
It is important for an airline to perform in a manner consistent with maximizing earnings per share. It is important for an airline to be committed to being as profitable as possible. It is important for an airline to maintain a strong competitive position. It is important that a successful airline be defined as one that is consistently profitable.

Positive anticipated emotion
Imagine that you are traveling with an airline that actively practices and promotes CSR activities. How would you feel? Proud; Accomplished; Confident; Worthwhile.

Negative anticipated emotion
Imagine that you are NOT traveling with an airline that actively practices and promotes CSR activities. How would you feel? Guilty; Remorseful; Sorry; Bad; Ashamed.

Brand attitude
For me, using an airline that actively practices and promotes CSR activities is bad (1)/good (7). For me, using an airline that actively practices and promotes CSR activities is foolish (1)/wise (7). For me, using an airline that actively practices and promotes CSR activities is unpleasant (1)/pleasant (7). For me, using an airline that actively practices and promotes CSR activities is harmful (1)/beneficial (7). For me, using an airline that actively practices and promotes CSR activities is unattractive (1)/attractive (7).

Social norm
Most people who are important to me think I should use an airline that actively practices and promotes CSR activities. Most people who are important to me would want me to use an airline that actively practices and promotes CSR activities. People whose opinions I value would prefer me to travel with an airline that actively practices and promotes CSR activities.
Sense of obligation to take pro-social actions I feel an obligation to choose an airline that actively practices and promotes CSR activities when I travel in the future. Regardless of what other people do, because of my own values/principles, I feel that I should use an airline that actively practices and promotes CSR activities when I travel in the future. I feel that it is important to use an airline that actively practices and promotes CSR activities when I travel in the future. I feel it is important that an air traveler in general makes a decision to choose an airline that actively practices and promotes CSR activities when he/she travels in the future.