Introduction

How do organizations enhance employee work performance? In particular, previous studies have demonstrated the importance of maintaining the employee-organization relationship (EOR) to improve the social and economic exchanges within an organization. Researchers such as Pfeffer (1998) and Chadwick and Flinchbaugh (2021) have shown how effective HRM implementation leads to firm’s competitive advantage. Cook et al. (2016) added that HRM implementation can also positively impact organizational performance during recessions. Over the past decade, the research on employee work performance has also focused on social exchange theory (Blau, 1964), and principally on the overarching notion that employees respond according to the treatment they receive. This social exchange impacts employees’ counterproductive behavior for psychological contract breach (Griep & Vantilborgh, 2018), enhances employees’ extra-role behavior for psychological contract fulfillment (Kiazad et al., 2019) and increases employees’ perception of justice with less bullying reactions (Salin & Notelaers, 2020).

Researches (i.e., Blau, 1964; Chadwick & Flinchbaugh, 2021; Pfeffer, 1998) have also found the significance of social exchange theory with regard to the EOR but these findings explained that employees’ psychological experience tended to produce inconsistent results. To elaborate on this exchange mechanism, Wang et al. (2020) and Cropanzano and Mitchell (2005) have suggested a further exploration of the specific perceptions or processes involved in shaping employee responses. For example, Buchan et al. (2002) suggested that the trust between employees and an employer is reciprocated. Shin et al. (2012) found that organizational inducements and resilience implementation lead employees’ commitment to organizational change. The exchange relationship in this respect refers to the mutual obligations that the respective participants develop (Buchan et al., 2002; Gardner et al., 2020).

In most cases, the exchange partners trust each other to reciprocate the benefits mutually, thereby forming a psychological contract, such as in the case of an employee and an employer. However, research across firms has not produced conclusive and consistent results with regard to the psychological contract underpinning social exchange theory. For example, Bordia et al. (2017) noted that resource availability might affect psychological contract fulfillment. Dulac et al. (2008) addressed that employees’ perceptions have various interpretations for psychological contracts in the social exchange relationship, and the strength of an HRM system might affect employee perceptions of employer obligation fulfillment (Bowen & Ostroff, 2004; Ostroff & Bowen, 2016). Gardner et al. (2020) further suggested that psychological ownership shows a complement to the social exchange effect of psychological contract fulfilment to employee outcomes. The above-mentioned studies address the inconsistent results of the social exchange mechanism and show a gap in the knowledge of the actual workings of the psychological contract in EOR. Thus, the findings related to psychological contracts, mainly based on social exchange theory, may not suffice in the maintenance of firms’ EOR.

Some studies also implore organizations to focus on employees’ individual exchange ideology such as sustainability-based ideology infused psychological contracts and employees’ exchange ideology for better performance (Ahn et al., 2018; Dixon-Fowler et al., 2020). The underlying assumption is that people with a strong exchange orientation are more likely to reciprocate generous behavior (Bankins, 2015; Gardner et al., 2020). This is consistent with the view in which employees believe that their organization will not exploit their loyalty but will instead reward it (Buchan et al., 2002; Shin et al., 2012). A trust relationship is getting much attention regarding the increase in the likelihood of exchange partners fulfilling their obligations, and in anticipation of the reciprocation of such efforts, thus constituting the fulfillment of the psychological contract (Vogelgesang et al., 2021). Similarly, according to expectancy theory, the perception of the likelihood that the effort made towards required behaviors will secure desired outcomes, motivates individuals toward these behaviors (Hackman & Lawler, 1971; Vroom, 1964). Thus, an individual’s exchange belief or expectation strengthens the social exchange relationship between employees and organizations (Andrews et al., 2003; Dixon-Fowler et al., 2020). Despite the extensive validation of psychological contracts through the social exchange mechanism, the role of exchange belief underlying the fulfillment of the psychological contract remains largely unknown. Inquiry about this relationship suggests the following research questions: What factors enhance exchange belief? How does exchange belief affect employees’ affective reactions in an organization?

Focusing on these key questions, we argue that the psychological contract strength, resulting from an individual employee’s exchange belief, contributes directly to employee behaviors and the desired work outcomes. In other words, employees would be more likely to perform a desired behavior when they strongly believe in the employer’s assurance concerning the expected outcome and rewards. In addition, consistency in human resource (HR) practice creates favorable conditions for organizations to enhance the strength of their psychological contract (Bowen & Ostroff, 2004; Kutaula et al., 2020; Ostroff & Bowen, 2016). We thus advocate a synthesis of the social exchange and expectancy theories, which calls for the explicit consideration of the psychological contract strength and the shedding of light on the key factors that increase the strength thereof. As such, this study responds to the call of Wang et al. (2020) for further clarification of the EOR “black box” and the role of employees’ expectations in an exchange relationship. We further address the inquiry of Wang et al. (2020) in clarifying the role of the psychological contract strength and identifying the key factors that enhance it in the employment relationship. We thus differ from many extant studies, which focus either on EOR through the social exchange mechanism (i.e., Rhoades & Eisenberger, 2002; Shore et al., 2006) or the conceptual idea of employee expectations (i.e., Birtch et al., 2016; Cropanzano & Mitchell, 2005). More specifically, we examine how HR practice consistency affects employee commitment by enhancing the psychological contract strength. This corresponds to the influence of the employee exchange belief on the EOR, which requires further investigation.

Perceiving this research gap and given the limitations of the extant research, we obtained 226 data from 50 medium to large companies. These are firms with over 200 employees (OECD, 2005) in both the manufacturing and service industries in Taiwan. We used these data to test the mediation effect of the psychological contract strength in the relationship between HR practice consistency and organizational commitment.

Overall, this study makes three contributions to the extant literature. First, we enrich social exchange theory (Blau, 1964) by merging the concepts of employee exchange belief and expectancy theory (Hackman & Lawler, 1971; Vroom, 1964) to elucidate the aforementioned EOR “black box” and to identify the significance of the psychological contract strength. Our mediating hypothesis suggests that the psychological contract strength mediates the relationship between HR practice consistency and organizational commitment. This study also contributes to the research on psychological contracts and argues that employees would be motivated toward the desired behavior if they strongly believed their efforts produced the expected outcome or rewards. Moreover, this study identifies the key role that employee exchange belief plays in a successful exchange relationship between employees and their organizations. Additionally, this study enriches human resource management (HRM) studies by identifying the necessity of HR practice consistency for creating favorable conditions that enhance the psychological contract strength.

This paper also contributes empirically in collecting data from ethnic Chinese participants in Taiwan. We used this unique dataset to examine HRM development, and employee attitude and behavior in medium to large companies in a prominent developing economy (Ahlstrom et al., 2001; Chen & Ahlstrom, 2017). The empirical evidence presented in this study supports the significance of psychological contract strength, characterized by the intensity of employee exchange belief (e.g., Buchan et al., 2002; Shin et al., 2012). More specifically, organizations that strengthen their employees’ exchange belief succeed in eliciting the desired outcomes and behaviors. Additionally, we studied the concept of psychological contract strength using a fine-tuned conceptual analysis and survey instrument. Finally, the concept of psychological contract strength presented in this study has a practical application in that it could increase employer awareness to enhance employee exchange belief for strengthening the EOR and psychological contract. Thus, they could better ensure the expected outcomes and behaviors of the employees, through consistency in their HR practices.

Theory and hypotheses

Psychological contracts and contract strength

The psychological contract is the key mechanism in the relationship between employers and employees. Unlike formal or implied contracts, a psychological contract is inherently perceptual, involving the interpretation of a promissory contract (Deas & Coetzee, 2021; Tekleab et al., 2013). A psychological contract refers to an individual’s expectations about the terms and conditions of a reciprocal exchange agreement between that person and another party, such as that of an employee and an employer (Rousseau, 1989). Psychological contracts contain different forms of obligations, including transactional, relational, and training components (Jensen et al., 2010; Karagonlar et al., 2016; Rousseau, 2001).

The transactional component emphasizes short-term and narrowly-focused economic exchanges between an employer and employees whereas the relational component refers to open-ended socio-emotional obligations (Rousseau & McLean Parks, 1993) such as trust and good faith as well as loyalty (Rousseau, 1990). Training constitutes a third form of obligation and relates to employee development and future opportunities (e.g., Coyle-Shapiro & Kessler, 2000; Kickul & Lester, 2001). From an employee’s perspective, the psychological contract includes what they expect, in terms of their employer’s obligations, in exchange for their commitment and contributions to the organization goals (Turnley et al., 2003; Wang et al., 2020; Webster & Adams, 2010).

Individual “beliefs” regarding an exchange agreement between an employer and an employee play a key role in forming the psychological contract. Expectancy theory (Vroom, 1964) argues that individuals’ work motivation and performance depends on the perceived likelihood of specific outcomes associated with the act and the perceived value related to these outcomes (Feather & Newton, 1982; Fishbein, 1963). Warshaw and Davis (1985) similarly proposed the construct of behavioral expectation, which states that individuals execute the desired behavior when they estimate a high probability of the achievement of expected goals. Following this line of reasoning, this study argues that employees are more likely to espouse the expected job attitudes and behaviors when they perceive an increased likelihood of the employer’s fulfillment of the psychological contract. Hence, this study highlights the likelihood of psychological contract fulfillment as psychological contract strength, defining it as an employee’s assessment of the likelihood of an employer’s fulfillment of their obligations.

This study adopts expectancy theory as the theoretical basis for explaining the significance and effect of the psychological contract strength (Vroom,1964). That work holds that individuals would perform a particular action when they expected their actions to incur a desired outcome. Further, Hackman and Lawler (1971) noted that the perceived likelihood that the effort expended toward a particular behavior would lead to the successful accomplishment of a goal, resulted in the expected outcomes or rewards. Rousseau (2001) claimed that employees might frame their expectations of the psychological contract during their first employment, or even earlier, during the recruitment process. Employees exhibit the desired behavior or deviant behaviors after perceiving the fulfillment or breach of a psychological contract (Gardner et al., 2020; Griep & Vantilborgh, 2018; Karagonlar et al., 2016; Solinger et al., 2016). Drawing on expectancy theory, this study argues the significance of the psychological contract and addresses how employees would be willing to exert particular efforts when they perceive the likelihood that such efforts will produce the expected outcomes or rewards. In other words, it is expected that employees will perform the job behaviors better as the strength of the psychological contract increases.

HR practice consistency

The logical foundation of strategic human resource management (SHRM) studies is HR practice consistency which noted that HR practices should complement one another to create effective HR systems and to enhance organizational performance. For example, Becker and Gerhart (1996) suggested that the HR system contributes directly to organizational goals. Lepak and Snell (1999) further developed HRM systems and architecture based on different employment mode. Chen et al. (2016) added that HRM consistency from a systematic perspective yields particular employees’ expected role performance. Wright and Snell (1998) further noted that such an alignment among an organization’s HR practices occurs when all the practices promote the same organizationally relevant outcomes consistently.

Previous studies regarding HR practices and systems have focused on aligning complementary practices, implying the necessity of consistency (Bowen & Ostroff, 2004; Ostroff & Bowen, 2016). Even though consistency in HR practice is a crucial point that previous SHRM studies have addressed, few scholars have attempted to define it or the associated approaches. According to Baron and Kreps (1999), firms achieve this consistency when they implement HR practices fairly and reasonably over time. They suggest that there are three types of consistency: treatment, temporal, and complementary consistency. Treatment consistency occurs when different employees are all subject to the same HR practices, without any significant variations in their treatment (Baron & Kreps, 1999; Marchington et al., 2011). Temporal consistency refers to the similar treatment of an individual worker over time (Baron & Kreps, 1999; Marchington et al., 2011). Complementary consistency occurs when an individual employee perceives that an HRM system is sending consistent and complementary messages, that the employer might consult them about some decisions, and then pay them in the upper quartile of the range, while providing opportunities for promotion (Kepes & Delery, 2007).

Prior SHRM studies have emphasized the importance and benefits of consistent HR practices. For example, HR practices that consistently focus on systematic perspectives can better support organizational performance outcomes and increase the firm’s competitive advantages (Becker & Gerhart, 1996; Paauwe & Boon, 2018) and thus lead to better organizational performance (Wood, 2018) and employee performance (Chen et al., 2016) as well as availability and effectiveness of human resources (Hauff et al., 2017). In contrast, inconsistency can lead to perceptions of unfair treatment and tension among employees, fostering a competitive climate within an organization and contributing to negative performance outcomes (Kuvaas, 2008; Rubery et al., 2009).

Prior studies have also suggested that HR practices should take on a more systematic perspective since HRM system should exert synergistic effects than the single HRM practices (Chadwick & Flinchbaugh, 2021; Jiang et al., 2012). Speculatively, a system of interrelated practices can have more influence on the performance of the organization compared to the application of piecemeal practices (Bowen & Ostroff, 2004; Delery & Shaw, 2001; Hauff et al., 2017; Ostroff & Bowen, 2016) and HRM system has much more variance explained on outcomes (Dyer & Reeves, 1995). According to Baron and Kreps (1999), consistency in HR management involves three interrelated considerations: employees, practices, and time. Coherent HRM should involve synergetic approaches, rather than focusing on individual issues (Hauff, 2021; Rock & Palmer, 1990). Based on the extant SHRM research and the systematic HR perspective, we argue that HR practices consistency should involve three interrelated considerations of treatment, temporal, and complementary. These practices should inform each other, be coherent, and be oriented toward systematic consistency to influence individual performance significantly.

Organizations that maintain consistent and well-structured HR practices tend to better fulfill their obligations as employers and build mutual exchange relationships with their employees. Such organizations develop high-quality mutual investment relationships (Hall, 1996). The employees of such organizations tend to contribute to their employers’ goals, thus satisfying their own needs. Furthermore, these organizations can establish such mutual and consistent expectations while rewarding employees and sustaining relationships by reciprocating desired behaviors such as employee expected performance (Akhtar, 2019), affective commitment (Bos-Nehles & Meijerink, 2018; Stein & Min, 2019), and work engagement (Meijerink et al., 2020). As expectancy theory predicts, individuals perform a particular action when they expect their action to produce a specific outcome (Vroom, 1964). Consistency in HR practice can create favorable conditions for employees to expect specific outcomes associated with their actions enhancing performance (Wang et al., 2008). Bowen and Ostroff (2004) noted that consistent HRM develops a perceived cause effect relationship in reference to the management desired behaviors and associated employee expectations (Ostroff & Bowen, 2016). Hauff et al. (2017) suggested that consistent HRM develops the conditions of availability and effectiveness of human resources. Further, Dello Russo et al. (2018) addressed that consistent HRM creates a strong situation for employees’ expectations to their employer. Employees will have a strong belief regarding their employers’ obligations in the condition of HR practice consistency. Therefore, we hypothesize:

  • Hypothesis 1: HR practice consistency is positively related to psychological contract strength.

Organizational commitment

Organizational commitment refers to the acceptance and adoption of the organizational goals and values, the willingness to exert considerable effort on behalf of the organization, and a definite desire to maintain organizational membership (Porter et al., 1974). Three distinct dimensions originally defined it: affective, continuance and normative commitment. However, studies (e.g., Ferris & Aranya, 1983; Mowday et al., 1982; Randall et al., 1990) reported the appropriateness of a single common underlying construct of organizational commitment that focuses on the affective component. Additionally, while later studies indicated the possibility that organizational commitment might have two dimensions, these two factors exhibited a high correlation (Angle & Perry, 1981; Meyer & Allen, 1984). Since this study examines employees’ affective reaction, we adopt single dimension of organizational commitment. Prior studies have documented the positive relationship between HR practices and organizational commitment (Wright & Kehoe, 2008). Dyer and Reeves (1995) posited that HR practices impact employees’ affective reactions such as job satisfaction and organizational commitment. Several studies provide the empirical evidence for HR practices and organizational commitment in various context such as the software professionals (Paul & Anantharaman, 2004), frontline employees in service industry (Browning, 2006; Wright et al., 2005).

Attribution theory (Heider, 1958) also suggested a reference framework that individuals adopt to explain why events happen in their work environment and how outcomes are attributed to internal (routine) and external (random) sources, which influences their responses to an event. According to this notion, employees explain the HR practices consistency as an internal attribution of regular implementation of HR practices which strengthens the casual effect of HR practices and employees’ expected outcome behavior. Prior studies have noted the positive relationship between HR practices and organizational commitment (e.g., Browning, 2006; Wright & Kehoe, 2008). Further, organizations maintain consistent HR practices to strengthen the mutual and consistent expectations, reward employees, and sustain relationships by reciprocating desired organizational commitment (Blau, 1964; Bos-Nehles & Meijerink, 2018). Therefore, we hypothesize:

  • Hypothesis 2: HR practice consistency is positively related to organizational commitment.

Mediation effect of the psychological contract strength

HR practices are supported to develop employees’ organizational commitment (e.g., Browning, 2006; Wright & Kehoe, 2008). As we discuss above, the consistent HR practices creates favorable conditions for employees’ strong belief of employers’ obligations, in terms of psychological contract strength (Bowen & Ostroff,2004; Hauff, 2021; Paauwe & Boon, 2018). In addition, organizations maintain consistent HR practices to strengthen the attribution of regular HR practices implementation and employees’ desired affective reactions (Browning, 2006; Wright & Kehoe, 2008) which enhance employee commitment. Further, we argue that employees’ strong belief of employees’ obligation fulfilment strengthens the social exchange relationship by their reciprocated desired behaviors (Akhtar, 2019; Blau, 1964). In summary, this study proposes that the consistent HR practices lead the psychological contract strength which enhances the social exchange relationship for employees’ organizational commitment. Therefore, we hypothesize:

  • Hypothesis 3: The psychological contract strength positively mediates the relationship between HR practice consistency and organizational commitment.

Methods

Research design

This study focuses on the cross-level influence of HR practice consistency on the employees’ psychological contract strength and organizational commitment. The study regards HR practice consistency as an organizational-level variable, while considering the psychological contract strength and organizational commitment as individual-level variables. Figure 1 illustrates the research framework.

Fig. 1
figure 1

Conceptual framework

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Participants and procedures

To understand the abovementioned relationship, we invited five employees from 70 participating companies to complete the survey questionnaires. The 70 companies that participated in this study are middle to large companies all with over 200 employees. These companies are actors in the manufacturing and service industries of Taiwan. We selected medium to large enterprises for this study to ensure that the participating companies had operational HR functions.

We screened the potential participants based on predefined selection criteria. The study required participants to have been working in the current position for at least 2 years. The HR departments of the participating companies provided lists of employees who met the requirements, from which our research team randomly identified five employees.

Originally, we had 310 questionnaires from 70 companies returned, with equal representation from the manufacturing and service industries. We deleted 31 incomplete cases from 8 companies as invalid samples and excluded them from the analysis. In addition, to aggregate HR practice consistency from employee perception to organizational level, we calculate Rwg coefficient for inter-rate agreement before aggregation (James et al., 1993). Based on the cutoff criteria of 0.7, we deleted 53 employee cases from 12 company cases yielding a final sample of 226 employee cases in 50 companies. Of the valid sampled organizations, 22% were mangers and 78% were rank and file employees while 52% were manufacturers and 48% were in the service industry.

Measures

HR practice consistency

We adopted a 15-item scale from Chen et al. (2016) to measure HR practice consistency. The sample items are “Employees have equal internal opportunities for promotion,” “The management’s philosophy has not changed since I joined this company” and “Overall, the philosophy of each HR system is consistent with the others.” Thus, a high score for this measure indicates a relatively high level of HR practice consistency. The Cronbach’s alpha coefficient of overall HR consistency was .90. This showed that these measures exhibited a high level of internal consistency. We further conducted confirmation factor analysis (CFA) with Mplus and the CFA shows a reasonable measure that has a model chi-square of 445.16 (χ2/df = 4.95, CFI = 0.76, TLI = 0.71, SRMR = 0.08, RMSEA = .13).

Psychological contract strength

We adapted the set of items related to the psychological contract from Kickul (2001) in order to reflect its “strength.” We asked the participants to indicate the extent to which they believed their employer would deliver on each of their obligations. A sample item is “I believe that my employer will provide me the opportunity for personal growth.” The associated Cronbach’s alpha was .90, indicating high internal consistency. A high score for this measure indicates the relative strength of the psychological contract. We further conducted confirmation factor analysis (CFA) with Mplus and the CFA result shows a reasonable measure that has a model chi-square of 1582.94 (χ2/df = 5.29, CFI = 0.79, TLI = 0.78, SRMR = 0.06, RMSEA = .14).

Organizational commitment

We adopted the 15-item Organizational Commitment Questionnaire (OCQ) from Porter et al. (1974). One sample item is “For me, this is the best of all organizations for which to work.” The Cronbach’s alpha was .92, indicating a high internal consistency. Thus, a high score for this measure indicates a relatively high level of organizational commitment. We further conducted confirmation factor analysis (CFA) with Mplus and the CFA shows a reasonable measure that has a model chi-square of 344.43 (χ2/df = 3.83, CFI = 0.84, TLI = 0.82, SRMR = 0.06, RMSEA = .11).

Control variables

The employees’ years of service might influence their perception about organizational commitment (Cohen, 1993). Thus, we included individual employees’ years of service at the individual-level as control variables in this study. We measured all the survey items using 7-point Likert scales ranging from 1 (“very strongly disagree”) to 7 (“very strongly agree”).

Analysis

Considering the multilevel structure of the data, we applied multilevel modeling (MLM) using the aggregation approach to take into account the estimation of the between-group and within-group relationships (Preacher et al., 2010). Hypotheses were tested using Mplus. Regarding Hypotheses 1 and 2, the first model including the relationships of HR practice consistency, psychological contract strength, and organizational commitment, with controls of tenure was tested. HR practice consistency is an organization-level variable that does not vary within groups, the hypothesized relationships can occur only at the between-group level and therefore these relationships were modeled at the between-level. In addition, to test Hypothesis 3, we added a direct relationship between HR practice consistency and organizational commitment, as well as an indirect relationship via psychological contract strength in the second model. Hypothesis 3 proposed a cross-level relationship among HR practice consistency, psychological contract strength and organizational commitment in which the relationship between psychological contract strength and organizational commitment with the control of tenure were modeled at the within-group level. In addition, the indirect relationship via psychological contract strength was modeled at the between-group level. The Maximum-likelihood estimation was used in all analyses. We reported chi-square statistics and significance for all analyses. Before conducting multilevel analysis, we used the HLM null model to estimate the significance level of organizational commitment (τ00 = .24, σ2 = .52) and psychological contract strength (τ00 = .13, σ2 = .90). The results of ICC(1) coefficient indicated that appropriate levels of variance in organizational commitment (.31) and psychological contract strength (.12) existed among the groups (Bliese, 2000).

Results

Descriptive statistics and correlations

Descriptive statistics and correlations are provided in Table 1. The results in Table 1 shows that the value of skewness and kurtosis of all constructs in this study are acceptable for multilevel path analyses (Barbeau et al., 2019; Kim, 2013). The table shows that psychological contract strength is positively correlated to organizational commitment (.37, p < .01) and the control of tenure is positively correlated to organizational commitment (.17, p < .01). Hypothesis 1 proposed that HR practice consistency positively relates to psychological contract strength and Hypothesis 2 stated that HR practice consistency would positively relate to organizational commitment. The first model tests those hypotheses and Table 2 shows the results of those analyses. The first model fits the data at acceptable level (Browne & Cudeck, 1992; Lievens & Anseel, 2004), χ 2 (4) = 11.89; χ2/df = 2.97, CFI = .88, TLI = 0.73, SRMR = 0.05; RMSEA = .09. The results shown in Table 2 show that HR practice consistency is significantly positively related to both psychological contract strength (.25, p < .05) and organizational commitment (.66, p < .001). Thus, the higher HR practice consistency is, the higher employees’ psychological contract strength will be along with organizational commitment, thus supporting Hypotheses 1 and 2.

Table 1 Descriptive statistics and correlations
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Table 2 Results of multilevel path analysis
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Hypothesis 3 proposed a mediating effect of psychological contract strength in the relationship between HR practice consistency and organizational commitment at the between-group level. The second model tests this hypothesis and results are presented in Fig. 2. The second model fits the data at acceptable level (Browne & Cudeck, 1992; Lievens & Anseel, 2004), χ 2 (5) = 12.02; χ2/df = 2.40, CFI = .89, TLI = 0.81, SRMR = .05, RMSEA = .08. The results in Fig. 2 show that between groups, HR practice consistency significantly predicts psychological contract strength (.25, p < .05) when psychological contract strength is taken into account in between group level, HR practice consistency has slightly decreased the effect on organizational commitment (.60, p < .001) when compared to the effect in the first model (.66, p < .001). Psychological contract strength has a significant effect on organizational commitment (.24, p < .001). According to Preacher and Hayes (2004), the two conditions of mediation are required to be met including the significant direct effect and the indirect effect. For the first condition, the results supported hypotheses 2. Further, the indirect effect from HR practice consistency via psychological contract strength to organizational commitment is significant (.06, p < .05; 95%CI: .01 ~ .11). Thus, psychological contract strength partially mediates the relationship between HR practice consistency and organizational commitment thus providing partial support for hypothesis 3.

Fig. 2
figure 2

Two-level path model

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Discussion

Theoretical contributions

The main purpose of this study was to specify psychological contract strength and test how psychological contract strength affects EOR in an organization. The key findings in this study are discussed as follows. First, in consistent with the findings that HR practice consistency affects employees’ performance in positive way (e.g., Chen et al., 2016; Rubery et al., 2009), this study supports that HR practice consistency plays a key role affecting employees’ interpretation regarding EOR and their work outcomes. Based on the findings, we argue that consistent HR practices enhance employees’ psychological contract strength and employees’ organizational commitment. The second finding in this study is that employees’ psychological contract strength acts as a mediator in the cross-level relationship of HR practice consistency and organizational commitment. Our findings support employees’ psychological contract strength partially mediates this relationship.

In response to Wang et al.’s (2020) and Cropanzano and Mitchell’s (2005) call for clarification of the social exchange mechanism with respect to the EOR black box and more investigation on effect of employee exchange belief (e.g., Hackman & Lawler, 1971; Vroom, 1964), this article makes additional theoretical contributions. Extending the social exchange foundation regarding the relationship between the employees and the organization, this study further shows that enhancing employees’ beliefs with respect to the EOR can maintain the effect of social exchange. Additionally, this study identified psychological contract strength as a form of employee exchange belief to explain the mechanism in social exchange in the employment relationship. We incorporated the concept of “psychological contract strength” on the theoretical lens of the social exchange and expectancy theories to elaborate the significance of employee belief in constructing employees’ expectation on employers’ obligation fulfillment and in maintaining EOR, and further developing desired employee outcomes/behaviors. According to expectancy theory (Hackman & Lawler, 1971; Vroom, 1964), employees would be more willing to perform the desired behavior if they perceived the strong connection between their efforts and the expected outcomes or rewards. Our results are consistent with the findings of prior psychological contract studies that indicate that the social exchange mechanism supports EOR. Moreover, we argue that psychological contract strength plays a key role in enhancing the employee-organization exchange relationship by increasing the employees’ belief of their employers fulfilling their obligations (Andrews et al., 2003) while strengthening trust in the employer-employee relationships within the organization (Shin et al., 2012).

Our investigation also enriches the HRM literature by identifying the key role of HR practice consistency in increasing psychological contract strength and organizational commitment, which is consistent with prior research findings (i. e., Bowen & Ostroff, 2004; Chen et al., 2016; Ostroff & Bowen, 2016). Thus, we propose HR practice consistency as a key organizational characteristic regarding HR practice implementation to increase employee exchange belief with respect to employers’ obligation fulfillment. We advocate an integrative perspective involving the social exchange and expectancy theories by providing a fine-tuned analysis of the relationship among HR consistency, psychological contract strength, and organizational commitment.

Empirical contributions

This study also contributed empirically to the extant research by collecting survey data from 226 employees in 50 medium to large companies in manufacturing and service industries in Taiwan. The results support the significance of psychological contract strength in explaining a better social exchange mechanism in the context of EOR. The empirical evidence supports the mediation effects of psychological contract strength and shows that implementing HR practice consistency enhances psychological contract strength and leads to increased organizational commitment. Prior studies suggested the potential significance and importance of employee exchange nature and characteristics such as employee exchange orientation, exchange ideology, and the reciprocity norm (e.g., Cropanzano & Mitchell, 2005; Eisenberger et al., 2004; Song & Gu, 2020) but few have stressed the concept of the exchange belief, which we conceptualized as psychological contract strength. Thus, this study extends this line of research to identify the importance of psychological contract strength and its mediating role in the relationship between HR practice consistency and organizational commitment. Consequently, the results provide crucial empirical evidence in support of the effect of employee exchange belief from an expectancy theory perspective and thus improve the explanation of the social exchange mechanism in EOR.

Practical contributions

Finally, in terms of contributions to practice, by introducing the concept of psychological contract strength, we suggest that organizations pay more attention to enhancing their employees’ exchange beliefs which implies the significance of employees’ perceptions and interpretations toward HR practices (Wang et al., 2020). Earlier studies have suggested employee perceptions affect work outcomes in an organization (e.g., Aryee et al., 2012; Wang et al., 2020). Based on this notion, we further suggest that employers should ensure that employees have a strong belief of their employers fulfil their obligations. This exchange belief enhances the social exchange relationship for the employees to connect their efforts related to desired behavior, with the expected outcomes or rewards (de la Rosa-Navarro et al., 2019; Witt et al., 2001). To enhance the psychological contract strength, we emphasize that organizations should put efforts toward creating a favorable condition for employees to strengthen the connections of expected specific outcomes associated with their actions (Bruton et al., 2000). To do so, organizations must deliver consistent HR practices so as to develop the favorable conditions for employees. More specifically, maintaining HR practice consistency is essential for organizations to increase employees’ psychological contract strength, which would eventually ensure the expected employee behaviors. The concept of psychological contract strength is a model example for organizations to exploit an exchange relationship by creating favorable conditions for employee exchange belief. This, in turn, develops the outcomes/behaviors that the organizations need to satisfy market demands and to outperform their competitors, thereby facilitating firm growth (Tomizawa et al., 2020).

Limitations and future research

This study carries certain limitations, which suggest avenues for future research. First, the moderately sized sample that resulted from the strict selection criteria may have limited the contributions of this study. However, our models supported all the hypotheses, indicating substantial implications. Future research could test the validity of the results using a larger sample. In addition, we collected the sample in Taiwan. Most of the extant HR-related studies occurred in the context of more developed economies. However, Taiwan is also an important development hub with respect to the mainland Chinese economy (Lin et al., 2021). Its enterprises are undergoing significant changes, especially in the context of EOR-related issues, adding significant value to the dataset (Uen et al., 2012). Future research could replicate this investigation in the major developed economies to investigate the related issues further.

In addition, the measures this study adopts are well developed measures from earlier studies. We conducted scale reliability and confirmatory factor analysis (CFA) with the data in this study to provide measure reliability and construct validity. The results show that those measures have high internal reliability and reasonable model fit which might be affected by the medium sample size in this study (Kyriazos, 2018). Future research could further validate those measures with different and bigger samples to provide more empirical evidences of measure validity.

Finally, there may be other important antecedents related to psychological contract strength and key employee outcomes/behaviors. Future studies could explore more factors of HRM systems (e.g., HR practice distinctiveness and consensus (Bowen & Ostroff, 2004; Ostroff & Bowen, 2016), which could help organizations increase the strength of their employee psychological contracts through understanding different factors related to organizational characteristics.

Conclusion

This study examined the psychological contract strength that derives from an employee’s belief in mutual exchange with regard to their employers’ obligation fulfillment. This study explores the role of the psychological contract strength in terms of the relationship between the HR practice consistency and organizational commitment. Data from 226 participants in 50 medium to large enterprises were collected from across the manufacturing and service industries in Taiwan. This study mainly explored the direct effect of HR practice consistency on psychological contract strength and further examined their influence on organizational commitment via the mediation effect of psychological contract strength. Our models supported all the hypotheses, and the empirical evidence showed much significance for HRM and psychological contract studies. In conclusion, this paper signifies that consistency in HR practice is key to creating increased employee exchange beliefs and is energized by the concept of the psychological contract strength which affects employees’ positive organizational commitment.