Workplace Support and Service - Oriented Organisational Citizenship Behaviour: The Mediating Role Of Psychological Empowerment And Affective Commitment

Abstract The purpose of this study is to examine the mechanism underpinning the relationship between perceived supervisor support, perceived organisational support, and service-oriented organisational citizenship behaviour. The data was collected from 250 flight attendants working in airline companies, and structural equation model modelling using M-plus 7.0 was employed to test the hypotheses. This research provides evidence for the association between psychological empowerment, affective commitment, and service-oriented organisational citizenship behaviour. Additionally, perceived organisational support, psychological empowerment, and affective commitment were found to mediate the relationship between employees’ perceptions of the support from their supervisor and their service-oriented citizenship behaviour. In addition to contributing to the current literature, this research also suggests important implications for managers and practitioners in airlines.


Introduction
The service industry is continuously transforming (Beverungen et al., 2020;Kylkilahti & Autio, 2020), and many organisations are transitioning from providing services to enhancing the satisfaction and productivity of the customers (Sezgen et al., 2019). In terms of the aviation industry, researchers have focused on improving airlines' performance in order to boost customer experiences (Jiang & Zhang, 2016;Park et al., 2019;Tsafarakis et al., 2018;Yang et al., 2019). Currently, the performance of an organisation is not only determined by the input index (employees' performance, suitable procedures, etc.) but by the opinions of the customers (Parveen et al., 2015). Indeed, to effectively address the growing demands of passengers (Suh & Ryerson, 2019;Wang et al., 2018), flight attendants must surpass their ordinary tasks to enhance customer service further (Shin & Hur, 2019;Trisia & Sakapurnama, 2016). Therefore, out-of-role behaviours such as service-oriented organisational citizenship behaviour (service-oriented OCB) is vital for ensuring customer satisfaction in the aviation industry (Seo & Kim, 2018).
The concept of general OCB was first defined by Bateman and Organ (1983) as the unrestrained work behaviours of employees. Organ (1988, p. 4) enhanced the specificity of the definition to "behaviour(s) of a discretionary nature that are not part of the employee's formal role requirements, but nevertheless promote the effective functioning of the organisation". In relation to the service industry, Hogan et al. (1985) proposed the concept of service-oriented OCB based on this original concept, with service-oriented OCB representing active and proactive behaviours of service through which service personnel can provide high quality services to satisfy customer requirements in an enthusiastic and courteous manner. Overall, service-oriented OCB emphasises employees loyalty to the organisation, enthusiastic customer service, and altruistic actions, whereas general OCB focuses mainly on out-of-role behaviours of employees inside the organisation. Therefore, service-oriented OCB is more suitable for understanding and examining frontline employees in the aviation industry.
Several studies investigating service-oriented OCB have been conducted in the service industry (Cha & Borchgrevink, 2018;Chen, 2016;Tang & Tsaur, 2016). Indeed, some scholars have reported effects of organisational support on OCB (Tang & Tsaur, 2016;Yadav & Rangnekar, 2015). However, the mechanism that may link workplace support factors (e.g., perceived supervisor support, perceived organisational support) to service-oriented OCB have still not been comprehensively studied (Tang & Tsaur, 2016). As a result, research regarding out-of-role behaviours of employees is limited, especially in the aviation sector.
The current study contributes to addressing the literature gap regarding service-oriented OCB in multiple ways. Firstly, to our knowledge, this represents the first research to explore the link between workplace support and service-oriented OCB via the factors of affective commitment and psychological empowerment in the aviation sector. Secondly, there does not appear to be any previous research focusing on psychological empowerment and affective commitment as mediators of the relationship between workplace support and service-oriented OCB. In summary, this is the first study exploring a holistic model of workplace support, affective commitment, psychological empowerment, and service-oriented OCB. In addition to enriching the literature regarding service-oriented OCB, the results of this research may be useful for informing managers who aim to improve the aviation system and enhance passenger satisfaction.

Literature review
Service-oriented organisational citizenship behaviour Bettencourt et al. (2001) defined service-oriented organisational citizenship behaviour (serviceoriented OCB) as type of out-of-role behaviour of employees towards customers, which includes three key aspects: (1) loyalty, (2) participation, and (3) service delivery. Employees who show service-oriented OCB tend to be loyal to the image of the organisation and aim to promote the organisation to the customer. Moreover, these employees actively participate in their job and are willing to listen to their colleagues in order to provide the best service for customers. Finally, by adopting service-oriented OCB, employees behave in a conscientious manner when serving customers (Bettencourt et al., 2001). Therefore, service-oriented OCB systems benefit the organisations by enabling them to maintain quality and customer satisfaction (Kloutsiniotis & Mihail, 2020).
Most previous studies in the service field have concentrated on general OCB (Kim et al., 2020;Motalebi & Marşap, 2020;Ocampo et al., 2018;Qiu et al., 2019;Zhang & Xu, 2019). Furthermore, in terms of aviation service, scholars have mainly focused on technical problems, such as passenger safety, risk, etc. (Cao et al., 2018;Gerstle, 2018;Ni et al., 2019;Patriarca et al., 2019;van Gasteren et al., 2019). Furthermore, there is less research examining the factors that can develop the proactive behaviour of flight attendants, frontline employees who directly affect passenger satisfaction (Gibbs et al., 2017). In service organisations, especially in airline industry, support from the organisation helps employees to deliver excellent service (Limpanitgul et al., 2013), but only few studies have examined these interpersonal relationships (Yoon et al., 2004). Therefore, in this framework, the present study aims to investigate the mechanism underpinning the relationship between workplace support and service-oriented OCB in the airline industry.

Psychological empowerment, affective commitment, and service-oriented OCB
The term "employee empowerment" was introduced by the research of Herzberg et al. (1959), which focused on enhancing the control and decision-making abilities of employees. Over time, this term has been re-appraised from a psychological perspective and revised as psychological empowerment concept (Conger & Kanungo, 1988). Psychological empowerment is a motivation construct comprising four aspects: meaning, competence, autonomy, and impact (G. M. Spreitzer, 1995). Importantly, work environments or other specific contexts rather than personality traits can shape psychological empowerment levels (Bandura, 1989;Thomas & Velthouse, 1990).
Several studies have linked psychological empowerment to out-of-roles behaviours (Singh & Singh, 2019;Thakre & Mathew, 2020;Turnipseed & VandeWaa, 2020). For instance, psychological empowerment encourages employees to go beyond their job description without the need for any benefits (G. Spreitzer, 2007). Specifically, this personal choice is regarded as OCB (Turnipseed & VandeWaa, 2020). This study proposes that psychological empowerment may activate the serviceoriented OCB of flight attendants. In summary, flight attendants with high levels of psychological empowerment may go beyond their daily tasks and be more willing to assist their customers in order ensure excellent service.
In high pressure working environments such as aviation (Lee & Hyun, 2016), flight attendants often work both day and night shifts and must on occasion cope with aggressive passengers (McLinton et al., 2020). Furthermore, flight attendants work in groups as cabin crew (Mahony et al., 2008) and may often experience group conflict due to the diversity of the work force (De Dreu & Weingart, 2003). As a result, OCB in providing service is necessary to ensure the effectiveness and efficiency of work teams (Lee et al., 2018). Based on social exchange theory, the emotions of employees also play an important role in increasing their voluntary behaviours (Lee et al., 2018). In particular, when there are high-quality relationships between employees and their organisation, those who have strong emotional attachment are more likely to engage in OCB as a form of repayment. Indeed, many researchers have confirmed that employees' affective commitment can enhance their OCB (Ahmad et al., 2020;Khaola & Rambe, 2020;Liu et al., 2019) across various organisational settings (Lee et al., 2018). Therefore, in this study, it is assumed that the affective commitment of flight attendants may lead to them showing service-oriented OCB. Based on the discussions above, we propose certain hypotheses:

Psychological empowerment as a mediator
When employees feel that their organisation or supervisor values their contributions and wellbeing, they perceive organisational or supervisor support at work (Eisenberger et al., 1986). This support at work may be shown through strong exchange relationships between employees and the organisation and its representatives (Ertürk, 2010). Those employees who perceive this support from the organisation are also likely to feel a sense of psychological empowerment (Maan et al., 2020). In turn, this psychological empowerment supports employees to engage in voluntary behaviour to assist their colleagues or to be involved in activities that benefit the organisation (Maan et al., 2020). Many researches in the service industry have also confirmed that employees with high psychological empowerment go beyond their responsibilities to serve customers better (Abdulrab et al., 2018;C. F. Chiang & Hsieh, 2012;Singh & Singh, 2019;Taylor, 2013;Thakre & Mathew, 2020). Therefore, in this study, it is expected that psychological empowerment may mediate the relationship between employees' perceptions of workplace support (perceived supervisor support, perceived organisational support) and service-oriented OCB. As a result, we propose the following hypotheses: H 1b : Psychological empowerment mediates the positive relationship between perceived supervisor support and service-oriented OCB H 1c : Psychological empowerment mediates the positive relationship between perceived organisational support and service-oriented OCB

Affective commitment as a mediator
Prior studies have found that high levels of perception of support from supervisors or the organisation result in high levels of affective attachment to the organisation (Gaudet & Tremblay, 2017; Montani et al., 2012;Nichols et al., 2016;Tremblay et al., 2019;Wong & Wong, 2017). The concept of affective commitment is defined as "emotional attachment to, identification with and involvement in the organisation" (Meyer & Allen, 1991, p. 67). Based on organisational support theory (Armeli et al., 1998), perceived organisational support may fulfil employees' socioemotional needs by providing them with emotional support, thus increasing their levels of affective commitment. Furthermore, employees with high levels of affective commitment may have more positive work attitudes and a higher likelihood of engaging in OCB (Meyer et al., 2002). This study proposes that the relationship between perceived organisational support and service-oriented OCB may be explained by the mediating effects of affective commitment.
Perceived supervisor support is defined as the belief of employees that their supervisor cares about them and values their contributions (Eisenberger et al., 2002). Tekleab and Chiaburu (2011) stated that employees may act reciprocally towards their organisation when they receive support from both their supervisors and the organisation itself. Moreover, employees who receive support from their supervisor often also perceive organisational support (Eisenberger et al., 1986), and it is important to note that perceived supervisor support can affect affective commitment (Li et al., 2018;Stinglhamber & Vandenberghe, 2003), thus leading to out-of-role behaviours. Based on the discussions above, we propose the following hypotheses: H 2b : Affective commitment mediates the positive relationship between perceived supervisor support and service-oriented OCB.
H 2c : Affective commitment mediates the positive relationship between perceived organisational support and service-oriented OCB.

Perceived organisational support as a mediator
Research has found that it takes some time for support at the workplace to influence the positive outcomes of employees (Choi, 2006;Stinglhamber & Vandenberghe, 2003). These results are consistent with a meta-analysis from Eisenberger et al. (2002) reporting that employees who continually receive support from their direct supervisor need time to establish a perception that this support comes from the organisation, which then eventually influences their outcome behaviours. Importantly, employees who perceive high levels of organisational support may have good fulfilment of their socio-emotional needs. Indeed, in our study, we consider that fulfilling these needs results in affective commitment (Baran et al., 2012). Moreover, the theory of organisational support focuses on the relationship between the employer and the employee (Baran et al., 2012), and this exchange relationship facilitates employees' psychological empowerment (Ertürk, 2010). Therefore, in this study, we hypothesise that perceived organisational support mediates the relationship between perceived supervisor support and the factors of psychological empowerment and affective commitment.

Research model
The research model developed based on the literature review and hypotheses is illustrated in Figure 1.

Sampling
This data for this study was collected in airports in Vietnam using a snowball sampling method, as we did not know sampling frame nor recruit the participants in advance (Hendricks & Blanken, 1992). With the agreement of the airport managers, we sent questionnaires to flight attendants and asked them to recruit other participants for the study from their colleagues.
During the questionnaire development in the initial stage of the survey procedure, we translated our questions into Vietnamese language and discussed them with specialists in the aviation field to develop a questionnaire that was accessible for the flight attendants. After the questionnaire was completed, it was re-translated into English for comparison to ensure accuracy between the two versions (Mullen, 1995).
With the help of the managers of the Vietnam Aviation Academy, 250 valid responses were collected from flight attendants working at airlines in Vietnam. The majority of the flight attendants were aged 24 to 30 years old (52.4%), held a 4-year college degree (55.2%), had a job tenure below 1 year (48%), and were working as cabin attendants (78.8%; the others worked as assistant pursers and pursers).

Measures
All items in the study questionnaire were measured on a 5-point Likert scale from 1 (strongly disagree) to 5 (strongly agree).

Perceived supervisor support
Perceived supervisor support was measured using 3 items by Eisenberger et al. (2002). This scale was designed to examine the perceptions of employees regarding support from their supervisors. An example item is "My supervisor strongly considers my goals and values". In the current sample, the Cronbach's alpha of the scale was 0.96.

Perceived organisational support
The six items measuring perceived organisational support were adopted from Eisenberger et al. (1986). These items were used to measure the overall perceptions of employees regarding the level of care of their organisation (e.g., "My organisation really cares about my well-being"). In the current sample, the Cronbach's alpha of the scale was 0.92.

Psychological empowerment
Psychological empowerment was assessed using the psychological empowerment questionnaire (G. M. Spreitzer, 1995). This scale examines four aspects of psychological empowerment, including meaning, competence, autonomy, and impact. The data in this study gave a Cronbach's alpha of 0.70.

Affective commitment
The construct of affective commitment was estimated using six items adopted from Meyer and Allen (1999), Mowday et al. (1979), and Rhoades et al. (2001). An example item is "I feel a strong sense of belonging to my organisation". In this study, this scale gave a Cronbach's alpha of 0.93.

Service-oriented organisational citizenship behaviour
We assessed out-of-role behaviours of flight attendants when performing their services using a 5-item scale from Bettencourt and Brown (1997). A sample item is "Voluntarily assists customers even if it means going beyond job requirements". This scale in our study gave a Cronbach's alpha of 0.91.

Data analysis
The Cronbach's alpha values were used to assess the reliability of the measures. Following this, the Person's r values were calculated to test the correlations between constructs (Table 1). The model fit was assessed using indices: χ2 ratio < 3 (Byrne, 2013), TLI and CFI > 0.9 (Tabachnick & Fidell, 2001), and SRMR and RMSEA < 0.8 (Graves et al., 2013;Mathieu & Taylor, 2006). The direct and mediation effects were examined through path analysis with SEM. The mediating effects of perceived organisational support, psychological empowerment, and affective commitment were tested with the bootstrapping method (5000 samples, percentile 95% CI; Shrout & Bolger, 2002). All of results were processed with MPlus 7.0.

Preliminary analysis
The results of the confirmatory factor analysis showed a good fit between the hypothesised five factor model and the data (χ2/df = 2.38; TLI = 0.92; CFI = 0.93; SRMR = 0.04; RMSEA = 0.07). The hypothesised model had a better fit with the data than other alternative models. Moreover, all alternative models were found not to fit with the data, such as the four-factor model combining perceived supervisor support and perceived organisational support, the three-factor model combining perceived supervisor support, perceived organisational support, and affective commitment, the two-factor model combining perceived supervisor support, perceived organisational support, affective commitment, and psychological empowerment, and the one-factor model combining all variables (Table 1).

Descriptive and correlational statistics
The correlation values in Table 2 show statistical support for the total mediation model rather than the partial mediation model (Preacher & Hayes, 2004). The results demonstrate a relationship between perceived supervisor support and service-oriented OCB (H 1b , H 2b ), as well as between perceived organisational support and service-oriented OCB (H 1c , H 2c ), via psychological empowerment and affective commitment.

Psychological empowerment
As displayed in Table 3 and Figure 2, psychological empowerment has a direct effect on serviceoriented OCB (0.47, p < .001), thus providing support for hypothesis H 1a . Psychological empowerment is influenced by both perceived supervisor support (0.19, p < .05) and perceived organisational support (0.25, p < .05). The inclusion model of the direct effects of perceived supervisor support on service-oriented OCB (χ2/df = 2.49) and of perceived organisational support on serviceoriented OCB (χ2 /df = 2.49) did not significantly improve our hypothesised model. Therefore, the data support a total mediation model from perceived supervisor support (Hypothesis H 1b ) and perceived organisational support (Hypothesis H 1c ) to service-oriented OCB. The indirect effect of perceived supervisor support on service-oriented OCB via psychological empowerment was .09 (p < .05), and the 5000 bootstrap sampling revealed a 95% confidence interval ranging from 0.01 to 0.24 (Table 4), which does not contain zero. Therefore, this result provides support for hypothesis H 1b that psychological empowerment has a mediating role in the relationship between perceived supervisor support and service-oriented OCB.
Finally, there was an indirect effect of perceived organisational support on service-oriented OCB via psychological empowerment (0.12, p < .05), and the 5000 bootstrap sampling result revealed a 95% confidence interval ranging from 0.05 to 0.36, which does not contain zero. Therefore, the results also supported hypothesis H 1c that perceived organisational support has an indirect effect on service-oriented OCB via psychological empowerment. Table 3 and Figure 2 demonstrate all the effects related to affective commitment. Affective commitment has a direct effect on service-oriented OCB (0.16, p < .001), which supports hypothesis H 2a . In turn, affective commitment is influenced by both perceived supervisor support (0.35, p < .05) and perceived organisational support (0.47, p < .01). Similarly, the inclusion model of the direct effects of perceived supervisor support or perceived organisational support on serviceoriented OCB did not significantly improve our hypothesised model. Therefore, there is statistical verification of a total mediation model from perceived supervisor support (hypothesis H 2b ) and perceived organisational support (hypothesis H 2c ) to service-oriented OCB. The indirect effect of perceived supervisor support on service-oriented OCB via affective commitment was .06 (p < .05), and the 5000 bootstrap sampling result revealed a 95% confidence interval ranging from 0.02 to 0.15 (Table 4), which does not contain zero. Overall, this result provides support for hypothesis H 2b that affective commitment has a mediating role in the relationship between perceived supervisor support and service-oriented OCB. An indirect effect of perceived organisational support on service-oriented OCB was also found (0.08, p < .05), and the 5000 bootstrap sampling revealed a 95% confidence interval ranging from 0.03 to 0.21, which does not contain zero. Therefore, the results also supported hypothesis H 2c that perceived organisational support has an indirect effect on service-oriented OCB via affective commitment.

Perceived organisational support
Perceived organisational support has a direct effect on affective commitment (0.47, p < .01) and psychological empowerment (0.25, p < .05), as illustrated in Table 3 and Figure 2. There was support for a total mediation model of the relationship between perceived supervisor support and affective commitment (χ2 /df = 2.55) via perceived organisational support, as well as for the model of the relationship between perceived supervisor support and psychological empowerment (χ2 /df = 2.53) via perceived organisational support. Therefore, there was statistical verification for partial mediation models via perceived organisational support from perceived supervisor support to psychological empowerment (hypothesis H 1d ) and from perceived supervisor support to affective commitment (hypothesis H 2d ). The indirect effect of perceived supervisor support on psychological empowerment via perceived organisational support was .18 (p < .05), and the 5000 bootstrap sampling revealed a 95% confidence interval ranging from 0.07 to 0.51 (Table 4), which does not contain zero. This result provided support for hypothesis H 1d that perceived organisational support has a mediating role in the relationship between perceived supervisor support and psychological  empowerment. Additionally, the indirect effect of perceived supervisor support on affective commitment via perceived organisational support was .34 (p < .01), and the 5000 bootstrap sampling revealed a 95% confidence interval ranging from 0.18 to 0.80 (Table 4), which does not contain zero. This result provided support for hypothesis H 2d that perceived organisational support has a mediating role in linking perceived supervisor support to affective commitment.

Discussion
This study explored the impacts and underlying mechanisms of flight attendants' perceptions of workplace support (supervisor and organisational on out-of-role behaviours directed towards the airline services. As expected, the results provide evidence for the significant influence of psychological empowerment and affective commitment on fostering OCB. Furthermore, perceptions of support from direct supervisors is a motivational factor that encourages flight attendant employees to go beyond their daily tasks by enhancing their emotional states. In turn, perceived organisational support has a mediating role connecting perceived supervisor support and the factors of psychological empowerment and affective commitment. Our research provides a useful contribution to the aviation industry in multiple ways. Firstly, this study addresses the call for further research into the mechanism of the relationship between perceived support and service-oriented OCB via the fulfilment of socio-emotional needs (i.e., affective commitment, psychological empowerment; Baran et al., 2012). With the increasing demand in the service industry (Bock et al., 2016), flight attendants must go beyond their daily tasks and be willing to help both their colleagues and passengers to ensure satisfaction and loyalty towards their organisation. The emotions of employees play an important role in voluntary tasks (Lee et al., 2018), and two key aspects of flight attendants' emotions, namely psychological empowerment and affective commitment, were found to have a positive impact on service-oriented OCB.
Secondly, psychological empowerment and affective commitment also have mediating roles in linking support in the workplace (perceived supervisor support and perceived organisational support) and OCB. Specifically, flight attendants who perceived support from both the organisation and their direct supervisors had higher psychological well-being and emotional commitment to their organisation. In terms of organisational support theory (Eisenberger et al., 1986(Eisenberger et al., , 2002, this increase in affective commitment leads to employees engaging in voluntary behaviours that increase organisational effectiveness as a way of reciprocating the support they perceive. Thirdly, we also confirmed that employees who have support from their direct supervisor tend to perceive this as representing a support policy at the organisational level. This effect then shapes both the affective commitment and psychological empowerment of flight attendants. Therefore, perceived organisational support has a mediating role linking perceived supervisor support to the factors of psychological empowerment and affective commitment. Overall, this study confirms and contributes to the related literature integrating the role of managers and contextual factors (e.g., Miao et al., 2018;Zhao & Zhou, 2021) to understand the mechanisms underpinning employees' out-of-role behaviours in the workplace.
Through enhancing understanding of the relationships between perceived supervisor support, perceived organisational support, psychological empowerment, affective commitment, and serviceoriented OCB, these findings highlight some important recommendations for managers and practitioners. Managers and direct supervisors of flight attendants should focus on creating a flexible working atmosphere and empowering flight attendants to perform daily tasks. These empowered employees are likely to experience psychological safety (Barrera, 2000) and, thus, be willing to go beyond their job descriptions to support colleagues and customers. Moreover, airlines should develop a system for empowering flight attendant using assigned support employees to address their needs in order to create a proactive and positive working conditions. Secondly, managers and practitioners should respect the diversity of flight attendants in order to better understand their well-being, as the emotional support (i.e., empathy) of employers to employees can activate affective commitment towards the organisation (Basuil et al., 2016;Yu-Ping et al., 2020). Additionally, employers should focus on providing non-financial rather than financial rewards, as this has a better effect on emotional value (F. F. Chiang & Birtch, 2008). Specifically, organisation should develop a supportive culture and focus on training pursers and assistant pursers, as they play a vital role in supporting employees to express OCB via affective commitment.

Limitations and future research
Our research has some limitations that provide suggestions for future research directions. Firstly, our data collection used a cross-sectional survey, which may contain bias (Podsakoff et al., 2012). Therefore, future research should design cross-lagged, longitudinal studies to resolve common method variance bias and single respondent bias. Secondly, our study focused on examining service-oriented OCB in the airline industry to obtain insights into how supervisor and organisational support can affect flight attendants. This research framework may be of interest to other industries should be applied to those in which the frontline employees directly impact customer perceptions of the organisation, such as healthcare, education, or public services. Thirdly, this study mainly focuses on psychological mediation mechanisms (i.e., psychological empowerment, affective commitment), so future studies could integrate the effects of other behavioural mechanisms, such as felt obligation or performance and reward expectancies (Baran et al., 2012). Fourthly, future studies should also consider the interactive effects that arise from group diversity in aviation services (De Dreu & Weingart, 2013;Mahony et al., 2008) at the individual level. Indeed, it is known that, in aviation service, the flight attendants are organised into groups, and the diversity of the group may directly affect the quality of service. Finally, this study used contextual factors (organisational support) as mediating mechanisms for the relationship between employee perceptions about supervisors and OCB. Therefore, further studies should consider re-testing the model with specific supportive leadership styles (e.g., servant leadership), as well as other contextual moderators (e.g., human resource management practices) and individual moderators (e.g., emotional intelligence, personality), to expand this stream of research