In the past decades, there were substantial researches on transformational leadership theory. According to Burns (1978), transformational leader transcends goals from short-term to higher order intrinsic needs. Scholars further proposed that there are two different viewpoints on leadership literatures. The first viewpoint is about leader-focused which attempts to recognize specific leader behaviours directly related to group, individual, or organizational performance outcomes (Howell & Hall-Merenda, 1999). Examples of such viewpoint include transformational leadership. In contrast, the second one is more relationship-based which focuses on the one-on-one leader-follower reciprocal relationships (Wang, Law, Hackett, Wang & Chen, 2005). The example is leader-member exchange (LMX) theory. According to Howell and Hall-Merenda (1999), in leader-focused research, an implied leader-follower relationship is essential to the relation between leader's behaviour and follower's response. The assumption is that the leader-follower relationship's quality through which transformational leaders' behaviours influence follower performance.
Moreover, trust has become a significant topic in management, ethics, sociology, psychology, and economics (Colquitt, Scott & LePine, 2007). Researches showed that transformational leaders are trustworthy and consequently they are associated with trust (Grosvenor, 2005), as well as trust is a vital element of the social exchange literature for two reasons (Colquitt et al., 2007): social exchange relationships have to be developed in the presence of trust (Blau, 1964) and lots of the trustworthiness facets help create social exchange relationships. Besides, Bartram and Casimir (2007) argued that there is an increasing number of works that illustrates the significance of trust in the leader as a mediating effect of leadership effects on followers. Since prior studies (e.g., Gerstner & Day, 1997; Deluga, 1992) focused only on the direct relationship between transformational leadership and LMX, and given the importance of trust in leadership, this paper therefore examines how trust in the transformational leaders relates to LMX. Furthermore, similar to trust, LMX to relates to numerous positive outcomes such as organizational citizenship behaviours (OCB) (Ilies, Nahrgang & Morgeson, 2007). Hence, this paper provides a concurrent analysis of the mediator of trust in the leader and LMX on the relationship between transformational leadership and OCB.
Transformational Leadership
Transformational leader behaves as a role model (Avolio and Bass, 2004) and "enables followers to transcend their own self-interests for a collective higher purpose, mission, or vision and to exceed performance expectations" (Howell & Hall-Merenda, 1999: 681). The four dimensions of transformational leadership are: "inspirational motivation (i.e. the degree to which the leader articulates a vision that is appealing and inspiring to followers; challenges followers with high standards, communicate optimism about future goal attainment, and provide meaning for the task at hand), idealized influence (i.e. the degree to which the leader behaves in admirable ways that cause followers to identify with the leader), intellectual stimulation (i.e. the degree to which the leader challenges assumptions, takes risks, and solicits followers' ideas), and individualized consideration (i.e. the degree to which the leader attends to each follower's needs, acts as a mentor or coach to the follower to fully develop his or her capabilities., and listens to the follower's concerns and needs)" (Judge & Piccolo, 2004: 755).
Leader-Member Exchange Theory
The principle of LMX is that leaders develop a different style of relationship with each follower (Graen & Scandura, 1987). Originally, Blau (1964) and Dienesch & Liden (1986) stated that LMX theory is evolved from social exchange theory, which proposes that followers have obligations to reciprocate high-quality social relationships and this dyadic relationships develop over a period of time through a cycle of exchanges. According to Dansereau, Graen and Haga (1975), high-quality LMX relationships are characterized by trust, support and reciprocal influence, whereas low-quality LMX relationships are those based strictly on employment contracts. During high-quality LMX relationships, leaders encourage followers to exert extra efforts (Graen & Uhl-Bien, 1995). In addition, followers often interact closely with their leaders so as to receive the support and consideration from leaders. They thereby perform their works that exceed formal contract (Wayne, Shore, & Liden, 1997). Study further found that LMX positively influences different outcomes such as objective performance, satisfaction with supervision and organizational commitment (Gerstner & Day, 1997).
Trust
From a model of organizational trust developed by Mayer, Davis & Schoorman (1995), trust consists of the trustor and trustee's characteristics. Trust is defined as the willingness of a trustor to be vulnerable to the actions of a trustee based on the anticipation that the trustee will fulfill his or her promised deed. Since different people have different predispositions to trust where some are less willing to trust than others, trustor will therefore judge the trustees' benevolence, ability and integrity. "Benevolence is the extent to which a trustee is believed to want to do good to the trustor, aside from an egocentric profit motive. Ability refers to a group of skills, competencies and characteristics that enable a party to have influence within some specific domain, and integrity involves the trustor's perception that the trustee adheres to a set of principles that the trustor finds acceptable" (Mayer et al., 1995: 717). The trustor will trust the trustee if the trustee has high benevolence, ability and integrity.
Trust in Transformational Leader
In leader-follower relationships, trust is important and is the core that causes the followers to identify with the leader, accordingly, leaders need to be trusted by their followers so as to develop a high-quality relationship (Nanus, 1989). Boies and Corbett (2005) showed that transformational leadership correlates with followers' perceptions of ability, benevolence and integrity, and Bass (1990) posited that transformational leader is connected with trust in the leader. To support, Bartram and Casimir (2007) further examined that transformational leadership correlates closely with trust because leader's commitment to the vision indicates that the leader's words are consistent with his or her actions and thus builds integrity (Kouzes & Posner, 1993). Also, leader advocates and embodies shared values makes followers to identify with (Bennis & Nanus, 1997; Jung & Avolio, 2000). Besides, transformational leader has a higher level of self-confidence and therefore is perceived as capable of performing leadership role in terms of having the aptitude to achieve the shared vision, which in turn helps developing trust (Whitener, Brodt, Korsgaard & Werner, 1998). Furthermore, individualized consideration causes the followers believe that the leader cares about them by acting as a mentor or coach who concerns followers' needs for achievement, which is crucial for trust (Kark & Shamir, 2002).
Bartram and Casimir (2007) demonstrated that trust in the leader facilitates high levels of satisfaction with the leader and followers' performance. The followers will trust the leader if they believe the leader has integrity, is competent and concerns about their welfare. Hence, they will satisfy with the leader and in turn increasing their performance. Because transformational leadership necessitates trust in the leader due to the changing status quo and trust in the leader leads to various outcomes such as satisfaction, performance and OCB (Jung & Avolio, 2000), thus, trust is an important mediating variable regarding the relationship between transformational leadership and various outcomes.
Benevolence as a Mediator between Transformational Leader and Leader-Member Exchange
According to Gomez & Rosen (2001), the followers are more likely to rate their leader-follower relationships as high quality as a result of high level managerial trust. Likewise, in order to develop high-quality LMX relationships, leaders must foster trust (Grosvenor, 2005).
Grean & Uhl Bien (1995) demonstrated that LMX relationship starts out at low-quality status and move to high-quality status since leader and members get to familiar with each other over time and thereby are able to assess each other in the process. Despite Boies and Corbett (2005) proposed that ability and integrity are significant predictors of trust that mediate the relationship among transformational leadership and trust, benevolence is regarded as the only one factor that is relational in LMX theory because it includes the trustee's (leader's) personal social relationship with the trustor (follower) (Bartram & Casimir, 2007). According to Mayer et al. (1995), "the effect of perceived benevolence on trust will increase over time as the relationship between the parties develops" (p.722). Moreover, high-quality LMX relationships are characterized by mutual responsibility, which is more or less the same as the concept of benevolence, given that they both involve non negative actions towards others (Grosvenor, 2005). The notion is that a follower can only judge whether his or her leader is benevolent based on personal interactions over times. So, the LMX's quality has a positive relationship with leader's benevolence.
In addition, there is a significant correlation between trust in the leader and the followers' perceptions of leader's benevolence (Gill, Boies, Finegan & McNally, 2005) and the followers assess their leader's trustworthiness on a sense of benevolence. Grosvenor (2005) further examined that leader's benevolence relates to high-quality LMX relationship and leader's benevolence relates to trust in the leader. Therefore, leader's benevolence can be seen as an important component between LMX and trust. It is consistent with Gomez's and Rosen's (2001) result that trust (in the leader) relates to high-quality LMX relationships.
Furthermore, previous research (Bass, 1990) and this paper have examined that transformational leadership associates with trust and it is positively related to leader's benevolence (Boies & Corbett, 2005) because transformational leaders concern followers and are supportive through individual consideration. Hence, to include the above mechanisms, trust (i.e. with the mediating effect of benevolence) acts as a mediator between transformational leadership and high-quality LMX relationship.
Leader-Member Exchange and Organizational Citizenship Behaviours
Studies (e.g., Wayne et al., 1997; Scandura & Schriesheim, 1994) have demonstrated that LMX positively predicted follower performance (task performance and OCB). However, this paper only focuses on OCB because LMX and OCB share similar notion.
OCB refers to discretionary behavior which is typically not compensated and rarely included in formal job descriptions. It enhances a psychological and social work environment that supports task performance (Ilies et al., 2007). As mentioned before, high-quality LMX relationship is characterized by high levels of trust, and also formal and informal rewards (Dienesch & Liden, 1986). This relationship includes the exchange of material and nonmaterial goods that are not stated in the formal job descriptions (Liden, Sparrowe, & Wayne, 1997). Additionally, leaders appeal to the higher-order needs of followers by getting them to replace their short-term personal interests by collective interests in high-quality LMX relationship (Graen & Uhl-Bien, 1995). Prior empirical studies (e.g., Hackett, Farh, Song, & Lapierre, 2003; Wang et al., 2005; Ilies et al., 2007) posited that to reciprocate high-quality LMX relationships, subordinates or followers are likely to go beyond their prescribed roles and engage in OCB with the aim to maintain an equitable social exchange. To simplify, followers will "pay back" their leaders by engaging in OCB that benefit the leader in high-quality LMX relationships (Liden et al., 1997). This relationship was supported by Hackett et al. (2003), who concluded that OCB is an important role in the reciprocal social exchange process of LMX.
Conclusion
This paper examines the mediating effects of trust as well as LMX on the relationship between transformational leadership and follower performance (i.e. OCB). Notwithstanding there are several studies integrate transformational leadership and LMX literatures, this paper attempts to expand the relationship by linking trust between transformational leadership and LMX.
With respect to Bartram and Casimir's (2007), and Boies and Corbett's (2005) result, transformational leadership is positively related to followers' perceptions of benevolence and had significant positive correlation with trust. "Benevolence creates an emotional attachment to the trustee, with caring and supportiveness nurturing a sense of positive effect" (Colquitt et al., 2007: 911). Grosvenor (2005) examined that leader's benevolence relates to trust in the leader, which is consistent with Colquitt et al.'s (2007) result that benevolence has significant unique relationships with trust. Supported by previous examinations, transformational leader is benevolent and therefore likely to trust by the followers.
Furthermore, benevolence is correlated with high-quality of LMX since both of them require a personal relationship between leader and follower that develops over time. Grosvenor (2005) demonstrated that leaders must foster trust to facilitate high-quality LMX relationships. In turn, the leader must be trusted by his or her followers so that they have a positive impression on the leader and consequently are willing to perform extra activities. Thus, it is not surprising that trust can be seen as a mediator between transformational leadership and high-quality LMX.
Although researches (e.g., Sosik, Avolio & Kahai, 1997) showed that transformational leadership is directly related to follower performance, this paper suggests that LMX mediates between transformational leadership and follower performance (i.e. OCB) for the reason that LMX is an important predictor of follower performance (Howell & Hall-Merenda,1999). Thus, this paper focuses on OCB as a result of high-quality LMX because OCB has a significant influence in the reciprocal social relationship (Hackett et al., 2003). In a high-quality LMX, followers reciprocate the transformational leader's supports and rewards by executing OCB that benefit the leader directly. And, since OCB goes beyond the formal reward system, the followers will be awarded informally through LMX (Ilies et al., 2007). Wang et al. (2005) argued that in high-quality LMX, transformational leaders stimulate followers by getting them to replace collective interests over individual interests. Followers who are motivated to achieve a collective vision intrinsically are more likely to accomplish extra role activities (Wang et al., 2005). The fact is that "LMX predicts OCB as strongly as it predicts task performance suggests that the benefits from high-quality LMX go beyond what has been suggested by the validity of LMX in predicting task performance alone" (Ilies et al., 2007: 273). These findings propose that the transformational leadership's effect on follower performance (i.e. OCB) is based on how each follower interprets and experiences these behaviours (Wang et al., 2005).
All in all, this paper integrates different scholars' ideas to present an indirect relationship between transformational leadership and OCB through the mediator of trust and LMX: transformational leader is benevolent and therefore fosters trust, and trust is related to high-quality LMX, and in turn enhances OCB. Future research is necessary in transformational leadership literature. First of all, this paper only focuses on individual level, further research should focus on the team level, to examine whether LMX and trust mediates between transformational leader and follower performance through the team variables such as team potency (Schaubroeck, Lam & Cha, 2007). Second, this paper does not examine the LMX effect on follower performance if the contextual variable (i.e. physical distance) (Howell & Hall-Merenda, 1999) is added in the relationship. Physical distance influences the leaders' behaviours and the quality of LMX. Distance reduces the chances for leaders to observe and/or supervise followers. Howell and Hall-Merenda (1999) argued that LMX influences follower performance regardless of close or distant condition whereas transformational leaders lead to high follower performance only in close situation or there is physical proximity. However, the results are tested independently, therefore, further research should examine the concurrent correlation between LMX and transformational leadership through the variable of physical distance, to see whether transformational leaders contribute higher follower performance in distant situation through the mediator of LMX.
