Relationship between leadership styles and dimensions of employee organizational commitment : A critical review and discussion of future directions

Purpose: The aim of this work is the study and the discussion of the relationship between leadership styles and organizational commitment dimensions. Both styles of leadership known as transformational and transactional styles differ in the process by which the leader motivates his subordinates. Organizational commitment defined by its three types (Affective, Normative and Continuance) measures the strength of an individual identification with and involvement in the organization. Design/methodology/approach: An extensive literature research has been done in order to increase our understanding of leadership and organizational commitment as well as the relationship between these two concepts. Findings: The present study of the relationships between leadership styles and organizational commitment has shown how leadership dimensions can influence employee organizational commitment. Although there is considerable research available suggesting that transformational leadership is positively associated with organizational commitment in a variety of organizational settings and cultures, there has been little empirical research focusing on the precise ways in which style of leadership impacts employee organizational commitment. Originality/value: Some critics about previous empirical and theoretical studies will


Introduction
Leadership has been always a crucial issue since organizations and companies are permanently in a constant struggle to be increasingly competitive.Leadership is an important function of management which helps to maximize efficiency and to achieve organizational goals.The word leadership has been described in terms of the position, personality, responsibility, influence process; instrument to achieve a goal, behaviors (Limsila & Ogunlana, 2007).Most definitions have a common theme of directing a group towards a goal.Therefore, the leadership can be broadly defined as the relationship between an individual and a group built around some common interest wherein the group behaves in a manner directed or determined by the leader (Shastri, Shashi Mishra & Sinha, 2010).Leaders can influence the behavior of their followers through the use of different styles, or approaches, to managing others.For the past three decades, a pair of predominant leadership styles (transactional and transformational leadership) has received a significant amount of attention.
On the other hand, employee commitment has long been a topic of interest to organizational researchers (Meyer, Allen & Smith, 1993;Meyer & Allen, 1991, 1984;Mathieu & Zajac, 1990;Mowday, Porter & Steers, 1982).One of the main reasons for its popularity is that organisations have continued to find and sustain competitive advantage through teams of committed employees.Many researchers found that an organization's success is determined, in part, by having a high degree of organizational commitment (Jassawalla & Sashittal, 2003;Brooks, 2002;McElroy, 2001).Organizational commitment has attracted considerable attention in theory and research because of its attempt to understand and clarify the intensity and stability of employee dedication to work organizations (Eisenberger, Fasolo & Davis-Lamastro, 1990).Research literature states that organizational commitment is defined as a subordinate's identification with the mission, goals, and vision of the organization.According to Eisenberg, Monge and Miller (1983), organizational commitment has been defined in a variety of ways.
Most theorists, however, include one or more of the following three attitudinal elements as an integral part of their definition: -27-Intangible Capital -http://dx.doi.org/10.3926/ic.476 • a strong belief in and acceptance of the organizations goals and values; • a willingness to exert considerable effort on behalf of the organization, and • a strong desire to maintain membership in the organization.Generally, higher or lower levels of commitment have been shown to be a major driver of employees staying with or leaving an organization (Shaw, Delery, Jenkins & Gupta, 1998).
Employee commitment reflects the quality of the leadership in an organization (Stum, 1999).
Organizational commitment provides a broad measure of the effectiveness of leadership which offers a way to further explore the subject of the relationship between leadership and commitment.However, organizations are always looking for the committed human resources in order to achieve its strategic objectives.Specifically, supervisors have the responsibility to emphasize to their subordinates their link and contribution to the success of the organization and to understand the significance of building a positive relationship with their respective subordinates to enhancing the subordinate's commitment to the organization (Truckenbrodt, 2000).
In the present paper, an extensive bibliographic research about leadership and organizational commitment has been done.The main objective is to study and discuss the relationship between leadership styles and dimensions of organizational commitment.This study has allowed to highlight and propose some areas for future research.

Styles of leadership
The leadership literature considers two styles of leadership: transformational and transactional.
To motivate employees, the transactional leader uses tangible rewards (e.g., money and status) while the transformational uses intangible rewards (e.g., personal growth, self-esteem, and professional values).Burns (1978) first introduced the concepts of transformational and transactional leadership in his treatment of political leadership, but this term is now used in organizational psychology as well.Bass (1985) extended the work of Burns (1978) by explaining the psychological mechanisms that underlie transformational and transactional leadership.

Transformational leadership
Transformational leadership has been considered as the most prominent topic in the research and theories of leadership (Bass, 1998;Pawar & Eastman, 1997).Burns (1978) defined transformational leadership as the process of pursuing collective goals through the mutual tapping of leaders' and followers' motive bases toward the achievement of the intended change.Transformational leadership can be seen when "leaders and followers make each other to advance to a higher level of moral and motivation" (Burns, 1978).Bass (1985) built on Burns (1978) work and described transformational leadership as a style of leadership that transforms followers to rise above their self-interest by altering their morale, ideals, interests, and values, motivating them to perform better than initially expected.Bass (1990b) asserted that transformational leadership "occurs when leaders broaden and elevate the interests of their employees, when they generate awareness and acceptance of the purposes and mission of the group, and when they stir their employees to look beyond their own self-interest for the good of the group" (Bass, 1990b, pp. 21).Bass (1985) depicted transformational leadership as comprising four distinct factors: charisma, inspiration, individualized consideration and intellectual stimulation.Charisma is shown by leaders who act as role models, create a sense of identification with a shared vision, and instill pride and faith in followers by overcoming obstacles.This dimension is also known as idealized influence and could be further divided into two sub-factors -idealized influence attributed and idealized influence behavior.Inspiration is defined as inspiring and empowering followers to enthusiastically accept and pursue challenging goals and a mission.Individualized consideration consists of behaviors such as communicating personal respect to followers by giving them specialized attention, by treating each one individually, and by recognizing each one's unique needs.Finally, leaders who consider old problems in new ways, articulate these new ideas, and encourage followers to rethink their conventional practice and ideas are said to be intellectually stimulating.
Later, Rafferty and Griffin (2004) re-examine the theoretical model developed by Bass (1985) to identify five dimensions of transformational leadership: vision, inspirational communication, supportive leadership, intellectual stimulation and personal recognition.
• Vision is one of the five elements that contribute to charisma (Weber, 1968).As opposed to the broader construct of charisma or idealized influence proposed by Bass and his colleagues, vision is the expression of an idealized picture of the future based around organizational values.Vision results in the internalization of organizational values and goals that encourages individuals to adopt desired behaviors (McClelland, 1975).House (1977) defined vision as a transcendent ideal that represents shared -29-Intangible Capital -http://dx.doi.org/10.3926/ic.476values and argued that charismatic leaders demonstrate a number of behaviors, including articulating an ideology that enhances goal clarity, task focus, and value congruence.
• Inspirational communication is the expression of positive and encouraging messages about the organization and statements that build motivation and confidence.Inspiration refers to "the extent to which a leader stimulates enthusiasm among subordinates for the work of the group and says things to build subordinate confidence in their ability to perform assignments successfully and attain group objectives" (Yukl, 1981, pp. 121).
Inspirational leaders use appeals and emotion laden statements to arouse followers' emotions and motivation.
• Supportive leadership is a component of individualized consideration leadership construct.Individualized consideration occurs when a leader has a developmental orientation towards staff and displays individualized attention to followers and responds appropriately to their personal needs (Bass, 1985).As opposed to broader construct of individualized consideration, supportive leadership means expressing concern for followers and taking account of their individual needs.Supportive leaders direct their behavior toward the satisfaction of subordinates' needs and preferences, display concern for subordinates' welfare, and create a friendly and psychologically supportive work environment (House, 1996).
• Intellectual stimulation is enhancing employees' interest in and awareness of problems and increasing their ability to think about problems in new ways (Bass, 1985).
Intellectual stimulation increases followers' abilities to conceptualize, comprehend, and analyze problems and improve quality of solutions (Bass & Avolio, 1990).
• Personal recognition is the provision of rewards such as praise and acknowledgement of effort for achievement of specified goals.Personal recognition occurs when a leader indicates that he or she values individuals' efforts and rewards the achievement of outcomes consistent with the vision through praise and acknowledgment of followers' efforts.

Transactional leadership
Transactional leadership is the second style identified in the literature.Transactional leadership (Bass, 1985;Burns, 1978) refers to a dynamic exchange between leaders and their subordinates, in which the leader establishes specific goals, monitors progress, and identifies -30-Intangible Capital -http://dx.doi.org/10.3926/ic.476rewards that can be expected upon goal achievement.It involves an exchange process between the leader and the followers, intended to increase followers' compliance to the leader and to the organizational rules (Yukl, 1998).Bass (1985) characterized the transactional leader as one who operates within the existing system or culture, has a preference for risk avoidance, pays attention to time constraints and efficiency, and generally prefers process over substance as a means for maintaining control.Bass model of leadership (1990a) includes three dimensions: contingent reward, management-by-exception, and laissez-faire, or nonleadership behavior.
• Contingent reward relates back to earlier work conducted by Burns (1978) where the leader assigns work and then rewards the follower for carrying out the assignment.
Leaders transact with followers by rewarding effort contractually, telling them what to do to gain rewards, punishing undesired action, and giving extra feedback and promotions for good work (Bass, 1985).Bass (1985) emphasized that by providing contingent rewards, a transactional leader might inspire a reasonable degree of involvement, loyalty, commitment and performance from subordinates.
• Management-by exception (MBE): In general, is the degree to which the leader takes corrective action on the basis of results of leader-follower transactions (Judge & Piccolo, 2004).Is when the leader monitors the follower, and then corrects him/her if necessary.
Leaders transact with followers by intervening only when followers deviate from expectations, giving negative feedback for failure to meet standards.Based on the timing of the leader's interventions a distinction is often made between active and passive management-by-exception (Bass & Avolio, 1993;Hater & Bass, 1988).MBE-P includes waiting passively for errors to occur and then taking corrective action.The leader relies heavily on passive management-by-exception, intervenes with his or her group only when procedures and standards for accomplishing tasks are not being met (Bass, 1990a).MBE-A may be necessary when safety is an issue.The leader watches and searches for deviations from rules and standards, takes corrective action (Bass, 1990a).In the more active form of management-by-exception leaders try to anticipate mistakes or problems.
• Laissez-faire leadership is a contrast to the active leadership styles of transformational and transactional leadership.It is virtually an avoidance of leadership behaviors, when an individual avoids making decisions and demonstrates a passive indifference to both tasks and followers.Leadership behaviors are ignored and no transactions are carried out.Leaders who score high on laissez-faire leadership avoid making decisions, hesitate in taking action, and are absent when needed (Judge & Piccolo, 2004).

The relationship between transactional and transformational leadership
According to Burns (1978), the difference between transformational and transactional leadership is what leaders and followers offer one another.Transactional leadership occurs when one person takes the initiative in making contact with other for the purpose of an exchange of valued things.Both parties acknowledge the power relationships of the other and together they continue to pursue their respective purposes.The people are not bound together by a mutually similar purpose.In contrast, transformational leadership occurs when one or more persons engage with one another and they increase their levels of motivation and morality.The power base, in this instance, mutually supports a common purpose.This latter form of leadership seeks to "raise the level of human conduct and ethical aspiration of both the leader and led, and thus it has a transforming effect on both" (Burns, 1978, pp. 20).
Burns' view is that transformational leadership is more effective than transactional leadership, where the appeal of the latter is to more selfish concerns.An appeal to social values thus encourages people to collaborate, rather than working as individuals (and potentially compete with one another).He also views transformational leadership as an ongoing process rather than the discrete exchanges of the transactional approach.Burns contrasted transactional and transformational leadership, believing that they lie at opposite ends of a continuum (Bass, 1990a;Yukl, 1989).Burns theorized that transforming and transactional leadership were mutually exclusive styles, an individual can display transformational leadership or transactional leadership, but not both.
Other leadership scholars (e.g., Avolio, Bass & Jung, 1999;Bass, 1999Bass, , 1998Bass, , 1985;;Bycio, Hackett & Allen, 1995;Bass & Avolio, 1993;Waldman, Bass & Yammarino, 1990;Conger & Kanungo, 1988) hold a different view, arguing that these styles are not competing, but complementary.For example, Conger and Kanungo (1988) suggested that leaders who rely on contingent rewards (a dimension of transactional leadership) and charisma (a dimension of transformational leadership) may be most successful in empowering their subordinates.Avolio et al. (1999) believe, and have empirically supported the contention, that effective leaders engage in both transformational and transactional behaviors.Similarly Bass (1985) argued that transformational leadership enhances or augments the effects of transactional leadership and that all leaders display leadership styles though to different degrees.Leaders are capable of being both transformational and transactional.In this sense, both styles are regarded as integrated by recognizing that both may be linked to the achievement of desired goals and objectives; their primary difference resides in the process by which the leader motivates subordinates and the types of goals set (Hater & Bass, 1988).Bass (1985) has depicted transactional leadership as being based on material/economic exchange and transformational leadership as being based on social exchange.Bass believes that every leader displays each of the aforementioned styles to some extent; he calls this the "Full Range of Leadership Model" (Bass, 1998, pp. 7).
Although some studies suggest that outstanding leaders display both transformational and transactional styles, it seems that transformational leadership can be more effective than transactional leadership in many cases (for a review, see Limsila & Ogunlana, 2007;Judge & Piccolo, 2004;K.B. Lowe, Kroeck & Sivasubramaniam, 1996).

Impact of transformational leadership on followers
After more than 20 years of accumulated research evidence, there is little doubt that transformational leadership behaviour is related to a wide variety of positive individual and organizational outcomes (Bommer, Robert, Rubin & Baldwin, 2004).However transformational leadership is important since it has a significant influence on the work attitudes and behaviours of followers.Among the principal outcomes of the transformational leadership on follower found in the literature we can mention: • Follower job satisfaction: Job satisfaction was defined by Locke (1976) as "a pleasure or positive emotional state resulting from the appraisal of one's job or job experience" (Locke, pp. 1297).Transformational leadership is positively associated with follower job satisfaction.In fact, it has been established that job satisfaction is higher among employees whose leaders emphasize consideration, support, and concern for their followers (Rafferty & Griffin, 2006;Walumbwa & Lawler, 2003;Allen & Meyer, 1990).
• Follower job performance: Transformational leadership is positively associated with job performance (Bono & Judge, 2003).Walumbwa and his colleagues (Walumbwa, Avolio & Zhu, 2008) found that supervisor-rated task performance was higher when leaders demonstrate transformational leadership behaviours more frequently as evaluated by their respective followers.However, transformational leadership theory suggests that transformational leadership is related not only to individual follower performance but also to performance at the group and organization levels.DeGroot, Kiker and Cross (2000) suggest that charismatic leadership is more effective at increasing group performance than at increasing individual performance.
• Follower creativity: Preliminary field studies have found significant relationships between transformational leadership and subordinate creativity in Korean research and development departments (Shin & Zhou, 2007, 2003).P. Wang and Rode's results from multi-level linear modeling analyses indicated that transformational leadership is not -33-Intangible Capital -http://dx.doi.org/10.3926/ic.476directly related with employee creativity.However the three-way interaction between transformational leadership, employee identification with leader and innovative climate is associated with employee creativity (P.Wang & Rode, 2010).

Organizational Commitment
Commitment is a force that binds an individual to a course of action that is of relevance to a particular target (Meyer & Herscovitch, 2001).Although various definitions have emerged in the literature, the most common approach has defined organizational commitment as "the strength of an individual's identification with and involvement in a particular organization" (Porter, Steers, Mowday & Boulian, 1974, pp. 604).Organizational commitment has an important place in the study of organizational behaviour.This is partly due to the large number of works that have found relationships between organizational commitment and attitudes and behaviours in the workplace.Batemen and Strasser (1984) state that the reasons for studying organizational commitment are related to: • "employee behaviours and performance effectiveness, • attitudinal, affective, and cognitive constructs such as job satisfaction, • characteristics of the employee's job and role, such as responsibility and • personal characteristics of the employee such as age, job tenure" (Batemen & Strasser, 1984, pp. 95-96).Meyer and Allen (1991) and Allen and Meyer (1990) identified three separable components reflecting:

Components of organizational commitment
• a desire (affective commitment), • a need (continuance commitment), and • an obligation (normative commitment) to maintain employment in an organization.
The three-component model developed by Meyer and Allen has been subjected to the greatest empirical scrutiny and has arguably received the greatest support (For a review, see Meyer, Stanley, Herscovitch &Topolnytsky, 2002 andMeyer &Allen, 1997).Meyer and Allen (1991) argued that one of the most important reasons for distinguishing among the different forms of organizational commitment was that they have very different implications for behaviour.
Although all three forms tend to bind employees to the organization, and therefore relate negatively to turnover, their relations with other types of work behaviour can be quite different (Meyer et al., 2002).
• Affective commitment (AC) entails an acceptance and internalization of the other party's goals and values, a willingness to exert effort on their behalf and a strong emotional attachment to them (Allen & Meyer, 1990;Mowday, Steers & Porter, 1979).
Employees who are affectively committed to the organisation will probably carry on working for it because they want to (Meyer & Allen, 1991).
• Normative commitment (NC) entails perceived obligations to maintain employment memberships and relationships.In exchange for employment, employees feel compelled to reciprocate with loyalty and commitment that derive from morality and value-driven principles based on reciprocity norms and socialization practices (Meyer & -35-Intangible Capital -http://dx.doi.org/10.3926/ic.476 Herscovitch, 2001)."Employees with a high level of normative commitment feel that they ought to remain with the organization" (Meyer & Allen, 1991, pp. 67).
• Continuance commitment (CC) involves appraisals of personal investments tied to one's current employment and the availability of employment alternatives (Meyer & Allen, 1984).Continuance commitment "refers to the awareness of the costs associated with leaving the organization" (Meyer & Allen, 1991, pp. 67).Individuals with high continuance commitment remain with their organizations because they perceive the costs of leaving to be too great.This type of commitment indicates that employees remain because they have too much time invested (Meyer & Allen, 1991).Becker (1960) originally proposed that people engage in consistent lines of behaviour because of the inducements (side bets) to do so.Employers offer a variety of such inducements to retain employees, including job status, seniority and benefits.Further, employees often desire to avoid the social and economic costs of leaving (e.g., relocation costs, disrupted social networks).CC strengthens as these side bets accumulate, rendering employees more likely to stay with the organization.Meyer and Allen (1991) also indicate that individuals whose most important connection to the organisation is based on continuance commitment stay because they need to.
• Commitment due to a lack of alternative employment opportunities (CC: LoAlt) reflected commitment based on few existing employment alternatives.This commitment refrains the individual from leaving the organization, due to the perceived lack of more desirable employment opportunities.
• Perceived sacrifice of investments associated with leaving the organization CC: HiSac) related to fear of losing benefits acquired by the organization during the years of work.This commitment is driven by the perception of loosing the investments done in the targeted organized if it is abandoned by the individual.

Outcomes of organizational commitment
The interest of researchers in the construct of organizational commitment can be understood in relation to its links with desirable work outcomes.There seems to be a consensus that employees' organizational commitment influences their work attitudes and behaviors.Several decades of research demonstrate that organizational commitment can have positive consequences for the organization and the individual employee (O 'Driscoll, Pierce & Coghlan, 2006;Riketta & van Dick., 2005;Meyer et al., 2002;Mathieu & Zajac, 1990).

Leadership styles and organizational commitment
Prior research suggests that work experiences, personal and organizational factors serve as antecedents to organizational commitment (Eby et al., 1999;Meyer & Allen, 1997;Allen & Meyer, 1996, 1990).One organizational factor that is considered a key determinant of organizational commitment is leadership (Mowday et al., 1982).Lee (2004) found out that transformational leadership correlates significantly with organizational commitment with samples of research and development professional in Singapore.Contrary, transactional leadership does not have significant relationship with organizational commitment.Hayward, Goss and Tolmay (2004) findings have further indicated that no correlation was found between transactional leadership and affective, normative and -37-Intangible Capital -http://dx.doi.org/10.3926/ic.476continuance commitment.Limsila and Ogunlana (2007) found that the leadership style mostly adopted and proving to be most suitable for Thai people is the transformational leadership.In addition, their result reveals that transformational leadership style is likely to generate commitment from subordinates while transactional and laissez-faire are not.
Essentially, the empirical and meta-analytic studies suggest that followers working with transformational leaders are more committed to their organizations and demonstrate fewer withdrawal behaviors (Walumbwa, Wang, Lawler & Shi, 2004;Bono & Judge, 2003;Walumbwa & Lawler, 2003;Barling, Weber & Kelloway, 1996).Transformational leaders have great ability to influence organizational commitment by promoting the values which are related to the goal accomplishment, by emphasizing the relation between the employees efforts and goal achievement and by creating a greater degree of personal commitment on part of both follower's as well as leaders for the achievement of ultimate common vision, mission and goals of the organization (Shamir, Zakay & Popper, 1998).Transformational leaders influence followers' organizational commitment by encouraging followers to think critically by using novel approaches, involving followers in decision-making processes, inspiring loyalty, while recognizing and appreciating the different needs of each follower to develop his or her personal potential (Avolio, 1999;Bass & Avolio, 1994;Yammarino, Spangler & Bass, 1993).This is further supported by Walumbwa and Lawler (2003) that transformational leaders can motivate and increase followers' motivation and organizational commitment by getting them to solve problems creatively and also understanding their needs.
Transformational leadership behaviour may encourage employees in both regular and irregular ways to develop stronger employee commitment (Bass, 1985).Although transformational leadership has been conceptually and empirically linked to organizational commitment, there has been little empirical research focusing on the precise ways in which style of leadership impacts employee organizational commitment.

Discussion
A multitude of studies have substantiated empirical results about leadership styles and the dimensions of organizational commitment.Hayward et al. (2004)  were also found.Other researchers such as Kent and Chelladurai (2001) posited that individualized consideration has positive relationship with both affective commitment and normative commitment.Similarly, positive correlations was found between intellectual stimulation and both affective commitment and normative commitment.Contrary to their hypotheses, Simosi and Xenikou (2010) found that transformational leadership did not explain how continuance commitment develops.Only the subscale of personal sacrifices was linked to transactional contingent reward.Rafferty and Griffin (2004) found conflicting empirical results en relation with continuance commitment.They hypothesized that personal recognition has a unique positive relationship with CC.Contrary to their expectations; personal recognition was significantly negatively associated with CC.Moreover, they found that vision displayed a unique negative association with CC (not hypothesized in their work).These results may be explained by focusing on the composition of the CC scale, which contains items measuring individuals' perceptions of their investments in the organization and the availability of alternative employment possibilities.
When the only rewards that are available for use by leaders are verbal encouragement or rewards of a personal nature, this may result in follower frustration as people do not feel that they are being adequately rewarded for performance.Increased frustration may lead individuals to evaluate alternative opportunities more positively, reducing CC to the organization (Rafferty & Griffin, 2004).Regarding the relationship between vision and CC, alternate expectations were consequently proposed: on the one hand, vision can be positively associated with continuance commitment as articulating an idealized picture of the future increases people's investment in the future of an organization.On the other hand, vision may be associated with a decrease in CC by empowering people and positively influencing their perceptions of the opportunities available to them (Rafferty & Griffin, 2004).
Most previous studies have been focused on the affective commitment dimension of organizational commitment.While a relationship between transformational leadership and affective organizational commitment has been empirically established (e.g.Castro, Periñan & Bueno, 2008;Felfe, Yan & Six, 2008;Metscher, 2005;Walumbwa et al., 2005Walumbwa et al., , 2004;;Dvir, Kass & Shamir, 2004;Bono & Judge, 2003;Meyer et al., 2002;W.A. Lowe, 2000;Bycio et al., 1995), the relationship between transformational leadership and employees' normative commitment has only been theoretically supported (Simosi & Xenikou, 2010).This may be explained by the extensive literature on the determinants of affective commitment, while there have been relatively few empirical investigations examining the antecedents of normative and continuance commitment.Despite the difficulties associated with the measurement of their antecedents, it is important to continue to investigate how continuance and normative commitment develop (Meyer et al., 2002).
Within a transformational leadership framework, the ability of leaders to properly implement transformational processes, such as intellectual stimulation, individualized consideration, individualized influenced attributed and individualized influence behavior in managing organization functions may lead to an increased organizational commitment (Simon, 1994).
Although direct effects model based study has provided significant findings, it does not sufficiently explain how and why transformational leadership style affect organizational commitment in dynamic organizations (Avolio et al., 2004;Bycio et al., 1995).

Conclusions
The aim of this work was to study of the relationship between leadership styles and organizational commitment dimensions.Firstly, the contemporary leadership literature was studied and the two styles: transformational and transactional were detailed.Secondly, our literature study focused on organizational commitment identified with its three components affective commitment, continuance commitment, and normative commitment.The attention was focused then on showing the importance of the leadership behaviours in influencing employee commitment by different ways.Finally, some critics about previous empirical and theoretical studies will present and a number of areas for future research will highlight.
In order to revise and to generalize the results of the previous studies, the relationship between leadership styles and components of organizational commitment should be conducted in various cities, different cultures and at different organizational levels.This study can further be enhanced by considering the three dimensions of organizational commitment while considering the two sub-dimensions of continuance commitment and the dimensions of leadership styles.
There is substantial evidence that transformational leadership is positively related to employee organizational commitment.This was demonstrated in numerous studies which have applied a direct effect approach to examine the effect of transformational leadership on organizational commitment.However, the mechanisms by which transformational leaders influence their followers have not been studied in a systematic manner (Avolio et al., 2004), and several authors have suggested that greater attention should be paid to understand how these influential processes operate in transformational leadership (Kark & Shamir, 2002;Conger, Kanungo & Menon, 2000;Bass, 1999;Yukl 1999).Despite the lack of systematic research in this area, the future study will may focus on the possible mediating role of LMX, procedural justice, employee positive mood… -40-Intangible Capital -http://dx.doi.org/10.3926/ic.476

Limitations and recommendations for future research
In the majority of reported studies, transformational leadership has been considered as a single construct (Simosi & Xenikou, 2010;Castro et al., 2008, Walumbwa et al., 2005;Avolio et al., 2004).Defining and testing models that take into account the diverse dimensions of transformational and transactional leadership can allow us to gain a more precise understanding about how leadership enhances employee commitment.
Previous research has found contradictory findings about the relationship between transformational leadership and continuance commitment (Simosi & Xenikou, 2010;Rafferty & Griffin, 2004).Taking into account the two subdimensions of continuance commitment can allow us to test how does it relate to transformational leadership, and the relationship between transactional leadership and employee commitment.
One area that clearly requires additional research is the influence of vision on employees.
However, as Rafferty and Griffin (2004) mentioned, there is a clear need to more understand the theoretical nature of the relationship between vision and continuance commitment.Taking into account the two subdimensions of continuance commitment can allow us to test how it relate to vision The literature about the relationship between leadership and commitment has tested direct relationships between these two constructs.However, some studies draw on social exchange theory to define more elaborated models of the relationship between leadership and attitudinal outcomes (Asgari, Silong, Ahmad & Sama, 2008;Ngodo, 2008;H. Wang, Law, Hackett, Wang & Chen, 2005;Pillai, Schriesheim & Williams, 1999).In those models, constructs such as leader-member exchange (LMX), perceived organizational support and organizational justice act as mediating variables.Incorporating these variables in future research can allow us to gather a better understanding about the social of psychological mechanism that link leadership styles and followers organizational commitment.
noted that transformational leadership has moderate positive correlation with affective commitment.Low correlation coefficients between transformational leadership and normative and continuance commitment