Promoting Shared Leadership

Relationship Between Vertical Leadership and Shared Leadership

Shared leadership—a process in which “group members actively and intentionally shift the role of leader to one another as necessitated by the environment or circumstances in which the group operates” (Pearce et al., 2010, p. 151)—is distinguished from vertical leadership, where influence on the team members and their actions stems from only one formally appointed leader (Fitzsimons, James, & Denyer, 2011; Hmieleski et al., 2011; Mehra et al., 2006; Pearce & Sims, 2002; Pearce et al., 2008). Yet shared leadership is not mutually exclusive of vertical leadership (Pearce & Sims, 2002). The shifting role of the leader is believed to complement vertical leadership and to further strengthen teamwork and augment team performance (Ensley et al., 2006; Hoch & Dulebohn, 2013; Pearce & Sims, 2002; Ramthun & Matkin, 2012). Both factors have been shown to have positive effects on teamwork outcome measures, such as effectiveness (Burke et al., 2006; Pearce & Sims, 2002; D. Wang et al., 2013; Zaccaro, Heinen, & Shuffler, 2009), financial performance (Burke et al., 2006; Carson et al., 2007; Ensley et al., 2006; Mehra et al., 2006; Small & Rentsch, 2010), and innovation (Hoch, 2013; Jung, Chow, & Wu, 2003). However, the extent that vertical and shared leadership are interconnected has yet to be clarified (Hoch, 2013; Pearce & Sims, 2002).

Opponent theories about the relationship between shared and vertical leadership exist. On the one hand, team members might notably take the lead when the formal team leader does not take leadership actions (Pearce & Sims, 2002). On the other hand, it has been suggested that vertical leadership may encourage shared leadership behavior (Pearce & Sims, 2002). In line with the latter postulation that assumes a positive relation of vertical and shared leadership behavior, several assumptions about positive influences of vertical leadership on shared leadership have been proposed (e.g., Bligh, Pearce, & Kohles, 2006; Cox et al., 2003; Hoch, 2013; Houghton, Neck, & Manz, 2003; Neck & Houghton, 2006; Pearce & Manz, 2005; Pearce & Sims, 2002). For example, it has been argued that vertical leaders can demonstrate relevant leadership behavior, which can then more easily be picked up by team members (Pearce & Manz, 2005; Pearce & Sims, 2002). This is in line with social cognitive theory (Bandura, 1977), suggesting that vertical leaders can act as role models for team members (Pearce & Manz, 2005; Pearce & Sims, 2002). It has also been argued that different effective leadership behaviors will directly encourage the development of shared leadership (Carson et al., 2007; Hoch, 2013). In fact, organizing and structuring the team’s work, offering employees possibilities for high participation and involvement, allowing employees to have an impact on their environment, encouraging initiative and innovational thinking while also providing social support and resources to team members when necessary, all have previously been argued and shown to be crucial for shared leadership (Carson et al., 2007; Cox et al., 2003; Hoch, 2013). As effective vertical leaders have been found to demonstrate these behaviors (e.g., Fleishman, 1953; Judge & Piccolo, 2004; Morgeson, DeRue, & Karam, 2010; Yukl, Gordon, & Taber, 2002), this is another way how they could possibly positively influence the development of shared leadership.

Initial empirical findings generally have supported a positive relationship between vertical and shared leadership (Ensley et al., 2006; Hoch, 2013; Pearce & Sims, 2002). Pearce and Sims (2002), and Ensley et al. (2006), have found positive correlations between vertical leadership behavior and shared leadership. Likewise, Carson et al. (2007) found team member coaching, defined as motivational and consultative behaviors provided by an external team leader, to be an important antecedent of shared leadership. A recent study of 43 work teams focused on specific types of vertical leadership (i.e., transformational and empowering leadership) and found a direct, positive relationship between them and shared leadership assumed by the team (Hoch, 2013).

However, the few empirical studies on the relationship between vertical and shared leadership suffer from limitations because shared and vertical leadership were commonly assessed by asking team members to rate both types of leadership (Ensley et al., 2006; Hoch, 2013; Pearce & Sims, 2002). Team members, however, may not be able to differentiate between shared and vertical leadership when rating both at the same time (Pearce & Sims, 2002). Therefore, the high correlations between them found in those studies may have to be interpreted carefully. The current study uses different data sources to assess the relationship between vertical and shared leadership. It assesses leaders’ ratings on their own vertical leadership behaviors and team members’ ratings on shared leadership to test the following hypothesis:

The Role of Behavior Modeling and Leader Prototypicality for Shared Leadership

Out of the limited number of studies on the association between vertical and shared leadership, strong correlations between the two types of leadership were reported by Pearce and Sims (2002), but only moderate correlations were reported in other studies (Ensley et al., 2006; Hoch, 2013). To understand under which circumstances the relationship between vertical and shared leadership may be strong or moderate, conditions or mechanisms that influence the relationship should be identified.

As mentioned above, one explanation for the positive relationship between vertical and shared leadership is that team leaders may be able to demonstrate leadership behavior which can then be picked up by team members (Pearce & Manz, 2005; Pearce & Sims, 2002). This argument follows the often formulated assumption that team leaders may serve as a behavioral role model for team members (Gardner, Avolio, Luthans, May, & Walumbwa, 2005; Hogg, van Knippenberg, & Rast, 2012; Kalshoven & Den Hartog, 2009; Sims & Manz, 1982; van Ginkel & van Knippenberg, 2012), which has its roots in social cognitive theory (Bandura, 1977).

Also in line with the concept of social cognitive theory, it can be further assumed that the likeliness that an observer (i.e., the team member) will copy behavior demonstrated by a model (i.e., the team leader) is enhanced when he or she identifies with the model (Bandura, 1977). A team leader can represent his or her team in terms of attitudes, behavior styles, and personal characteristics, thus representing a prototype for the team with which followers can identify, referred to as leader prototypicality (Hogg et al., 2012; Kalshoven & Den Hartog, 2009; Seppälä, Lipponen, & Pirttilä-Backman, 2012). It could therefore be argued that leader prototypicality may enhance the likeliness that team members will pick up leadership behavior demonstrated by their team leader. Moreover, whereas leader prototypicality has not yet been evaluated in the context of shared leadership, its relevance for team processes has previously been studied in other research areas (Ullrich, Christ, & van Dick, 2009; B. van Knippenberg, van Knippenberg, De Cremer, & Hogg, 2005; D. van Knippenberg, 2011). In those studies, it was argued that prototypical leaders display normative behaviors that can influence attitudes in followers (Kalshoven & Den Hartog, 2009) and that team members perceive prototypical leaders as more group-oriented and attractive (Kalshoven & Den Hartog, 2009). Consequently, team members are more favorable and supportive of their leader’s behavior (Hogg et al., 2012; Ullrich et al., 2009; B. van Knippenberg & van Knippenberg, 2005). It has also been argued that prototypical team leaders are able to motivate followers to act in the team’s best interests (D. van Knippenberg, 2011). Motivation, in turn, is assumed to be essential when team members are given the opportunity to share leadership behaviors which are beneficial for the team (Carson et al., 2007; Pearce & Sims, 2002).

Given the conclusions drawn from social cognitive theory and empirical findings on the influence of leader prototypicality on team member attitudes and behaviors drawn from other research areas, we assume that team members will be particularly likely to pick up effective leadership behavior, as demonstrated by their team leader, when they perceive their team leader to be prototypical of the team.

Empowerment and Its Relation to Shared Leadership

As mentioned earlier, a recent study already provided indications that vertical leaders may empower team members, which could facilitate shared leadership (Hoch, 2013). At the same time, previous discussion has stressed the importance of differentiating between vertical leadership actions as one type of shared leadership antecedent and team member attributes as intrinsic states as a second type (Carson et al., 2007; Cox et al., 2003; Hoch, 2013; Hoch & Dulebohn, 2013; Seers et al., 2003). Independent of how vertical leaders’ actions may influence shared leadership development, this study therefore strives to evaluate whether the way team members psychologically feel empowered as an intrinsic component may enhance their likeliness to engage in shared leadership.

Generally, two aspects of empowerment can be distinguished, namely social–structural empowerment and psychological empowerment (Schermuly, Meyer, & Dämmer, 2013; Spreitzer, 2008). Social–structural empowerment refers to democratic structures within an organization that provide employees at a lower hierarchical status with information, support, and resources, giving them the means to voice their opinions, make decisions, and take actions on processes (Spreitzer, 2008). Initial empirical findings have indicated a positive effect of structural empowerment on shared leadership. Carson et al. (2007) reported that voice—defined as the “degree to which a team’s members have input into how the team carries out its purpose” (Carson et al., 2007, p. 1222)—to be an important antecedent of shared leadership. Similarly, empowering leadership in which the team leader encourages independent action and goal setting from the team members (Pearce & Sims, 2002) was shown to be positively related to shared leadership (Hoch, 2013).

The relationship between psychological empowerment and shared leadership has been discussed only theoretically (Hoch & Dulebohn, 2013). Psychological empowerment has been defined as an intrinsic motivation (Conger & Kanungo, 1988; Thomas & Velthouse, 1990) that is characterized by people feeling more in control of their work, and which compels them to take action (Spreitzer, 2008). The construct is generally considered to include four aspects: (a) Meaningfulness, referring to the extent to which work is important and worthwhile; (b) competence belief, as the extent to which workers believe that they can be effective; (c) impact, as the extent to which workers believe that their work will make a difference; and (d) self-determination/autonomy, which refers to the extent to which people believe that they independently make decisions and take action. Psychological empowerment has been shown to positively influence innovative behavior (Schermuly et al., 2013), enhance work effectiveness, and work satisfaction (Spreitzer, 1997), increase commitment (Liden, Wayne, & Sparrowe, 2000) while reducing fluctuation intentions (Koberg, Boss, Senjem, & Goodman, 1999), and facilitate organizational citizenship behavior (Seibert et al., 2011).

Engaging in shared leadership behavior can be viewed as voluntary behavior (Carson et al., 2007) which goes beyond what is classically required from team members. Thus, it can be assumed that each team member needs to feel personally empowered to engage in shared leadership.

Fair Reward and Shared Leadership

Fair reward is considered to be an interpersonal supporting factor within a team (Burke et al., 2006; Hoch & Dulebohn, 2013), which cannot only be provided by vertical leaders, but also by fellow team members (Hogg et al., 2012; Siegrist, 2002). It has previously been argued that supporting factors should be considered as a third type of shared leadership antecedents when aiming at exploring different starting points for facilitating shared leadership (Hoch & Dulebohn, 2013). Therefore, fair reward, which has already been identified to successfully enhance various performance criteria (e.g., Burke et al., 2006; Colquitt, Conlon, Wesson, Porter, & Ng, 2001) is included as a third antecedent of shared leadership in this study. We assessed whether fair reward as an extrinsic incentive may also contribute to the prediction of shared leadership, beyond the effects of vertical leadership and intrinsic components.

Apart from financial rewards, such as salary increase and bonuses or career options, appreciation from the leader and colleagues is an important extrinsic motivator. Several studies have shown that when financial reward and appreciation are considered fair in terms of personal investment in relation to rewarding outcome, they are positively related to teamwork outcome. For example, fair rewards have been shown to be associated with higher job performance (Burke et al., 2006; Feuerhahn, Kühnel, & Kudielka, 2012), enhanced creativity processes (Kahai et al., 2003), deeper coworker trust (Ferrin & Dirks, 2003), and increased commitment (Dulebohn & Martocchio, 1998), motivation, and organizational citizenship behavior (Colquitt et al., 2001). Fair rewards are therefore an incentive for active participation in work processes and initiative at the work place (Spreitzer, 1995). Studies have shown the importance of individual reward in motivating team members for personal initiative (Kahai et al., 2003). Given that shared leadership requires voluntary actions intentionally taken by each team member (Carson et al., 2007; Mehra et al., 2006), team members should feel fairly rewarded for their personal contributions to engage in leadership (Hoch & Dulebohn, 2013). However, this assumption, to the best of our knowledge, has not yet been empirically studied.

Studies have shown the importance of individual reward in motivating team members for personal initiative (Kahai et al., 2003). Given that shared leadership requires voluntary actions intentionally taken by each team member (Carson et al., 2007; Mehra et al., 2006), team members should feel fairly rewarded by their supervisor and colleagues for their personal contributions to engage in leadership (Hoch & Dulebohn, 2013). However, this assumption, to the best of our knowledge, has not yet been empirically studied.

Sampling Procedure and Participants

Participation was achieved via direct solicitation (i.e., presenting the study at university and business conferences, and handing out information leaflets) and by snowball sampling via the Internet (i.e., by contacting friends and family via emails, the university website, and social media, and asking them to forward information about the study to team leaders or members they knew). Team leaders interested in participating with their teams were asked to arrange a short telephone interview with us. We conducted 130 telephone interviews, from which we assessed whether the team fulfilled the following inclusion criteria: (a) Teams were required to consist of at least three team members and one formally assigned team leader. Teams without a designated leader were excluded because of the study’s focus on the effect of vertical leadership on shared leadership. (b) All team members were required to work within a formal working contract in an organization located in Germany. No constraints were placed on type of profession, the industrial sector, or size of enterprise. The leaders from the 104 qualifying teams were provided with a link and login data to an online survey. They were asked to forward a separate team member survey link and login data to their staff. Responses from team members and their team leader were matched using the login data. Data were included in the final sample when at least half of the team (Hiller, Day, & Vance, 2006) and a minimum of three team members per team, plus their assigned leader, had participated.

Our final sample included 328 team members nested in 67 teams, with 67 team leaders. An average of 4.89 team members participated (SD = 2.87) who were, on average, 39.25 years old (SD = 12.31). Among them, 65.5% were female, 31.5% were male, and 3.0% did not specify their gender. Team leaders were, on average, 45.34 years old (SD = 8.34); 51.8% were female and 48.2% were male. The majority of teams worked in the social sector (58.2%), the services sector (22.0%), or the industrial sector (14.3%). Most team members (80.0%) had been working in their team for at least a year, and 37.8% worked in their teams for more than 5 years. Most team leaders (80.0%) had been leading their team for at least a year, and 37.2% led their team for more than 2 years.

Measures

We used a 6-point Likert-type scale ranging from 1 (does not apply at all) to 6 (fully applies) for all scales in the study.

Levels of Analysis

According to our theoretical assumptions, psychological empowerment as an intrinsic state, and perceptions of being individually and fairly rewarded, were conceptualized at the individual (team member) level. Furthermore, given that team members could have different opinions about their group’s prototype (Hogg et al., 2012), leader prototypicality was also modeled at the individual level. In contrast, team leaders’ ratings on their own vertical leadership were included as a team level predictor because the vertical leadership of the team leader influences the team as a whole. Thus, with individual-level antecedents predicting individual-level shared leadership and team-level antecedents predicting team-level shared leadership (Preacher, Zyphur, & Zhang, 2010), shared leadership was analyzed on the individual and the team level. Each team member’s team tenure was assessed on the individual level and team size was assessed on the team level. Figure 1 represents our theoretical model and the levels on which each factor is located in our analyses.

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Figure 1.

Hypotheses and levels of analysis.

Aggregation Issues

As described above, shared leadership was assessed at the individual level. To test our multilevel model, which includes shared leadership as an outcome variable at both the individual and the team level (Figure 1), we calculated the interrater agreement index r_wg(J), the intraclass correlation ICC(1), the group mean reliability ICC(2), and F tests indicating significant differences between average team scores, to justify the aggregation of shared leadership to the team level.

The average interrater agreement for shared leadership was r_wg(J) = .97 (SD = .07), indicating a very strong agreement (LeBreton & Senter, 2008). The ICC(1) for shared leadership was .24 and the ICC(2) was .61, F(66, 261) = 2.61, p < .001. The ICC(1) values indicate that a considerable part of the variance of shared leadership is explained by team membership (Bliese, 2000). The ICC(2) value is also above the required cut-off value of .60 (Glick, 1985). Therefore, using shared leadership not only at the individual, but also at the team level, is justified.

Hypothesis Testing

To test our multilevel assumptions, we used Mplus version 6.12 (Muthén & Muthén, 2010). The maximum likelihood estimator with robust standard errors and full-information maximum likelihood was used. All values were z standardized before they were entered into the regression models (cf., Brodbeck, 2001; Fay, Borrill, Amir, Haward, & West, 2006). First, team size (team level) and team tenure (individual level) were added as control variables to a multilevel regression model. None of the control variables were significantly related with shared leadership. As indicated by the R² values, the amount of variance in shared leadership explained by the control variables was 1.3% at the individual (R² = .013) and 0.1% at the team level (R² = .001). Hence, the direct effect of vertical leadership (team level, Hypothesis 1), psychological empowerment (individual level, Hypothesis 3) and feelings of being fairly rewarded (individual level, Hypothesis 4) on shared leadership were modeled. As indicated by the R² values and changes in the R² values, the amount of explained variance was 25% at the individual (R² = .251, ΔR² = .238) and 2.4% at the team level (R² = .024, ΔR² = .023).

The results of the multilevel regression models are displayed in Table 2. Consistent with Hypotheses 3 and 4, we found a significant, positive effect of empowerment (B = .26, SE = .06, p < .001) and fair reward (B = .36, SE = .05, p < .001) on shared leadership. However, the direct effect of vertical leadership on shared leadership could not be confirmed (B = −.07, SE = .20, p = .72). Thus, the assumption that vertical leadership is positively linked to shared leadership (Hypothesis 1) could not be supported.

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Table 2.

Results of Multilevel Modeling Analyses Predicting Shared Leadership.

	Model 1		Model 2
	Estimate	SE	Estimate	SE
Individual level
Team tenure	−.08 (−.08)	.05 (.05)	−.07 (−.07)	.05 (.05)
Psychological empowerment	.26** (.24**)	.06 (.05)	.23** (.21**)	.06 (.05)
Reward	.36** (.34**)	.05 (.06)	.31** (.30**)	.06 (.06)
Leader prototypicality			−.16* (.15*)	.06 (.05)
Team level
Team size	.14 (.05)	.18 (.07)	.14 (.05)	.17 (.07)
Vertical leadership	−.07 (−.02)	.20 (.06)	−.12 (−.04)	.19 (.06)
Cross levels
Vertical leadership * leader prototypicality			.15* (.14*)	.05 (.04)
Random effects
Intercept	−.03 (−.01)	.19 (.06)	−.03 (–.01)	.18 (.06)

Note. Individual level: N = 328; team level: N = 67. Unstandardized model results in parentheses.

**

p< .001. *p < .01 (all 2-tailed).

We further hypothesized a moderating effect of leader prototypicality on the relationship of vertical and shared leadership (Hypothesis 2). To test this assumption, we added to our model the effect of the interaction term of leader prototypicality and vertical leadership, and the direct effect of leader prototypicality on shared leadership. In comparison to the model only including direct effects, this adaptation led to a small increase of explained variance at the individual level (R² = .301, ΔR² = .050) and at the team level (R² = .033, ΔR² = .009). Moreover, the Akaike information criterion (AIC) and the Bayesian information criterion (BIC) were assessed to compare the models. These were lower for the multilevel regression model including the moderator variable (AIC = 812.30, BIC = 818.32) than for the model only including direct effects on shared leadership (AIC = 839.25, BIC = 844.15) or the model only including control variables (AIC = 911.91, BIC = 914.97). Thus, the final multilevel moderation model should be selected (Geiser, 2012).

The results indicate a significant moderator effect (B = .16, SE = .06, p < .01). Figure 2 displays the significant interaction effect. Team members who perceived their supervisors as prototypical (sample mean +1 SD) engaged in more shared leadership behavior when their supervisors showed more vertical leadership behavior. In contrast, a negative relationship of vertical and shared leadership was found for team members who did not perceive their supervisor as prototypical (sample mean −1 SD). Following the methods described in Bauer and Curran (2005), we used the Johnson–Neyman technique to evaluate interactions in a multilevel model. In contrast to the pick-a-point approach, the Johnson–Neyman technique allows for the identification of the region of significance for the effect of vertical leadership on shared leadership (Bauer & Curran, 2005; Hayes, 2013). The boundaries to the region of significance found in our study indicate a significant, positive relationship of vertical and shared leadership when—on a scale of 1 to 6—leader prototypicality is higher than 5.59. A significant, negative relationship of vertical and shared leadership was found when leader prototypicality was lower than 3.70 and no significant relationship of vertical and shared leadership were found for values of leader prototypicality between 3.70 and 5.59. Despite the negative link of vertical and shared leadership for team members who perceived low leader prototypicality, the significant interaction effect and the positive link between vertical and shared leadership for team members who rated their team leader as highly prototypical support Hypothesis 2.

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Figure 2.

Shared leadership as a function of vertical leadership for high and low prototypical leaders.

Practical Implications

Our findings can easily be transformed into advice for practitioners wishing to encourage shared leadership in their teams as different starting points could be identified. Whereas a recent study indicated that the development of shared leadership may also depend on situational factors (Ramthun & Matkin, 2014), the current study has provided different clues as to what practitioners can do under regular work circumstances in order to facilitate shared leadership. As team leaders can serve as a role model, demonstrating the desired behavior styles, the speculation that vertical leadership becomes less important when leadership is shared can be denied. Instead, training formal team leaders should be further encouraged (see also Hoch, 2013). It should be especially attractive for organizations because it is economically much more efficient than training leadership behavior in every individual.

However, at the same time, it is important that the team leader represents the team’s values and attitudes in order to reach high team leader prototypicality. If structures allow it, team members should be given the option to choose their team leader autonomously, rather than having the management appoint a formal leader. Research has provided evidence that emergent leaders are most likely those people who are seen to be most prototypical of a group (Hogg, 2001). Newly appointed leaders should strategize to engage in some projects likely to end in success because successful performance has been shown to increase perceptions of prototypicality (Giessner et al., 2009). Throughout the duration of the team’s existence, members should be frequently encouraged to think about common values and behavioral standards that apply to the team as a whole, including all members and the team leader. These collective actions are likely to contribute to a greater sense of group purpose and meaning. Encouraging and supporting team leaders’ efforts to live up to these collective standards could enhance leader prototypicality. Hence, shaping leaders’ behavior will, in turn, increase the likelihood that team members will adopt the demonstrated leadership styles.

When creating teams that are requested to take and share the lead throughout a project, teams should be composed of members who express a generally high perception of empowerment. In already existing teams, empowerment can be further enhanced by regularly reflecting with the team on its work and working structures, keeping the following principles in mind (e.g., see Maynard et al., 2012, for a review): (a) Emphasizing options for decision making, and providing access to resources and information can advance the team members’ autonomy and decision latitude (Elovainio, Kivimäki, Steen, & Vahtera, 2004; Logan & Ganster, 2007); (b) giving team members a chance to have a voice in decision making can further the feeling of having an impact on their environment (Carson et al., 2007; Seibert et al., 2011); (c) providing positive and constructive feedback for their actions and encouraging learning from mistakes can contribute to higher personal competence beliefs (Maynard et al., 2012; Schunk, 1991); and (d) putting the team members’ work into a larger frame that helps to explain the organizational mission, and letting team members participate in goal setting, can boost meaningfulness (Hon & Rensvold, 2006; Spreitzer, 1995).

A final practical implication of the study is that each team members’ behavior should be rewarded. Extrinsic rewards that are perceived to be fair are important for initiating behavior (Spreitzer, 1997) and for sustaining efforts (Judge & Piccolo, 2004). Rewards in organizations should include appropriate salaries and appreciation of personal efforts (Siegrist, 2002). The latter should not only be provided by team leaders, but also by fellow team members. All members of a team, not only the leader, should therefore be encouraged to reflect on the way appreciation is given and on how appreciation for extra effort could be further expressed, in order to motivate participation in sharing leadership. Team leaders should then follow through by providing contingent rewards, such as bonuses, when team members have effectively engaged in shared leadership behaviors.

Limitations and Future Research

As with all studies, the present study has several limitations. First, given that our data was cross-sectional, longitudinal effects could not be assessed. Thus, the reported results should therefore be interpreted carefully. Our selection of variables relied on previous discussion and research findings from related areas, from which we speculated about the directions of relationships (e.g., the way leaders lead their team influences members’ behavior; Judge, Piccolo, & Ilies, 2004; Yukl et al., 2002). The implied causal relationships, however, might work the other way around, and reciprocal relations seem likely (e.g., followers’ behaviors in turn influence leaders’ motivation to lead, or the extent to which they feel the need to lead). Assessing both directions could not be tested in the present study. The results only provide an initial empirical baseline, and we encourage future research to further analyze these findings in longitudinal studies.

Longitudinal studies would also offer the advantage of examining whether antecedents are differentially related to shared leadership at different stages of shared leadership development (Small & Rentsch, 2010). This could be of special relevance because previous findings have already suggested that shared leadership may be differently related to several antecedents over time and is more likely to occur in more mature teams (Small & Rentsch, 2010). At early stages of team development, where group identity is highly salient (Tajfel, 1970), prototypical team leaders’ behavior may be particularly influential on team members’ likelihood to engage in shared leadership behaviors. Psychological empowerment, however, is believed to develop after some time once team members have internalized options for participation that environmental structures, practices, and policies provide for them (Schermuly et al., 2013). Psychological empowerment may therefore be of special relevance at later stages of team development to initiate team members to start taking over leadership functions themselves. Finally, fair reward may, on the one hand, be an important incentive to start engaging in shared leadership at early stages of team development. On the other hand, it may be particularly relevant to motivate team members to continue their efforts once they have engaged in sharing leadership (e.g., Burke et al., 2006; Judge & Piccolo, 2004; Kahai et al., 2003; Kuvaas, 2006). Given that all these variables where related to shared leadership in our heterogeneous sample, conducting longitudinal studies to investigate these differential effects seems very promising.

A second limitation of this study is that even though vertical leadership was assessed from a different data source, all other measures only relied on self-report items. These measures were all rated by the same individual, which can cause common method bias (Podsakoff, MacKenzie, Lee, & Podsakoff, 2003). However, self-report questionnaires on standardized scales, such as those used in this study, are widely regarded as a valid data source when measuring psychological constructs (Spector, 2006), for example, identification with the leader, psychological empowerment, and feelings of being fairly rewarded. Furthermore, using self-report questionnaires is an expedient approach to present a first overview of possible relationships between different constructs of interest. Future studies could follow recommendations by including measures to assess aspects likely to influence common method bias, such as social desirability, into their studies, and then to partial its effect out of the relation between the predictors and shared leadership (Podsakoff et al., 2003).

Third, our sample consisted of teams coming from a large variety of professions. The statistically significant results speak for the generalizability of our findings. However, the number of teams within a given profession or industry was too small to draw conclusions at that level, and variation in organizational structures and task characteristics could not be controlled. Specific effects for these criteria and subgroups will need further exploration in future studies.

Fourth, we only collected data from teams with a classical team structure of one formally assigned leader to test our hypotheses. This method was important to clearly differentiate between vertical and shared leadership, to be able to assess the relationship between each type. Different dynamics, however, might apply for teams with no or multiple official team leaders.

Finally, several indirect effects of vertical on shared leadership have previously been proposed in literature. For example, vertical leaders have been argued to enhance perceptions of self-efficacy among team members, and thereby to foster their belief in being able to successfully perform shared leadership behavior (Bligh et al., 2006; Neck & Houghton, 2006; Pearce & Manz, 2005). Houghton et al. (2003) explained that vertical leadership actions, such as encouraging learning from mistakes, fostering initiative and creativity, and supporting decision making, were crucial for the development of self-leadership, which in turn facilitate participation in shared leadership. Similarly, our results provide evidence that team members’ perceived similarity to their team leader may influence the likeliness that they will mirror leader behavior demonstrated by their leader. This, in turn, could be explained in part by leader prototypicality affecting team members’ willingness to learn, and their motivation to assist the team leader. The evaluation of such mediating mechanisms would therefore clearly be an important research field for future studies in order to understand how exactly vertical leaders may foster shared leadership.

Conclusion

The present study supports the idea that factors on the team level and factors on the individual level independently influence shared leadership and present different strategies for facilitating shared leadership. First, shared leadership depends on the extent to which each team member personally feels empowered. Second, it is influenced by team members’ perception of being fairly rewarded by others for their contributions. Third, the official leader’s behavior influences shared leadership, but only when executed by prototypical leaders. When executed by non-prototypical leaders, the behavior diminishes shared leadership. This finding can generate fruitful hypotheses about other mechanisms that might influence the relationship between presumed antecedents and shared leadership. Furthermore, longitudinal studies are needed to confirm the causal relationship of our findings, and examine which factors may be of special relevance at different stages of shared leadership development.