The employee perspective on HR practices: A systematic literature review, integration and outlook

With the growing number of studies investigating employee perceptions of HR practices, the field of SHRM is challenged with monitoring how cumulative insights develop. This paper presents a systematic review on employee perceptions of HR practices in terms of 1) how they are examined (as an antecedent, mediator, or outcome), 2) the theoretical perspectives that explain this construct, and 3) the type of conceptualizations of employee perceptions of HRM that have been used in the extant SHRM research. The findings illustrate how scattered current approaches are in terms of how employee perceptions of HRM have been examined. In addition, a range of theoretical frameworks that advocate and support the employee perspective on HRM have been used, showing that a single perspective on employee perceptions of HRM seems infeasible. Finally, a variety of descriptive and evaluative conceptualizations have been used. Recommendations and avenues for future research to gain a more comprehensive understanding of employee perceptions of HRM are provided.


Introduction
Using the SHRM process model (Nishii & Wright, 2008), researchers within the field of SHRM describe the process of the development, implementation, and perceptions of HR policies and practices, from different stakeholders, and how these work towards organizational performance. A key feature in this model is the particular attention devoted to the potential differences between the intended and developed HR practices by management, the actual or implemented HR practices by linemanagement, and the perceived HR practices by employees (Nishii & Wright, 2008). Based on the work of Bowen and Ostroff (2004) and Nishii and Wright (2008), the role of employees when investigating these relationships has received increasing attention, i.e. 40% of the studies in the last four years included employee perceptions of HR practices when studying the relationship between HRM and performance (Beijer et al., 2019). This has resulted in a wide range of conceptual models in which employee perceptions of HR practices have been researched (Wang et al., 2020). These studies have shown that it is employees' perception of HR practices that influences employee behavior, rather than manager-rated implemented HR practices, demonstrating the importance of investigating the employee perspective on HR practices (Den Hartog et al., 2013;Jensen et al., 2013;Kehoe & Wright, 2013).
With the growing number of studies investigating employee perceptions of HR practices, the field of SHRM is challenged with monitoring how cumulative insights have developed. Extant SHRM literature has examined the employee perspective on HRM using different theoretical angles, resulting in a variety of conceptual models studied that include employee perceptions of HRM as an antecedent, mediator, or outcome (Beijer et al., 2019;Wang et al., 2020). In addition, there is a lack of transparency in the conceptualizations that are used to capture employee perceptions of HR practices. This is problematic, as it has been argued that different conceptualizations of employee perceptions of HR practices could have differential relationships with both actual HR practices and outcomes (Beijer et al., 2019;Boon et al., 2019;Wang et al., 2020). To date, we lack a systematic overview of how employee perceptions of HRM have served as an antecedent, mediator, and outcome, the theoretical perspectives that advocate the employee perspective on HRM, and the conceptualizations used to examine employee perceptions of HR practices. As such, it is important and timely to review progress and to identify areas for improvement in the application of the employee perspective in HR research.
Therefore, the objective of this study is three-fold. First, we look back and map how employee perceptions of HRM are examined (as an antecedent, mediator, or outcome) in the extant SHRM literature. Second, we identify the key theoretical frameworks and perspectives that advocate and support the employee perspective on HRM used in the extant SHRM literature. Third, we analyze how employee perceptions of HR practices are conceptualized and operationalized in empirical research. Based on this review, we look ahead, and offer important ways in which the application of the employee perspective on HR practices can contribute to a more complete understanding of the impact of actual HRM on employee and organizational outcomes.
We extend prior recent reviews on the employee perspective of HRM (Beijer et al., 2019;Wang et al., 2020). Beijer et al. (2019) offered an in-depth review on the conceptualization of employee perceptions of HR practices. Our review builds on, but goes beyond Beijer et al. (2019), by paying attention to, not only the conceptualization of employee perceptions of HRM, but also to how employee perceptions of HRM can serve as an antecedent, mediator, or outcome in SHRM research, and we map the theoretical perspectives used to explain this construct in the extant HRM research. Second, we build on the review by Wang et al. (2020) but extend their work by mapping and integrating the literature on how employee perceptions of HR practices are conceptualized, what type of theoretical perspectives have been used, as well as how this construct has been measured. On the basis of this, we formulate recommendations for future research that we suggest are central to a deeper understanding of how employees perceive HRM.
Below, we first provide an overview of how employee perceptions of HRM are conceptualized (as an antecedent, mediator, or outcome), drawing from the SHRM process model (Nishii & Wright, 2008). We then identify and elaborate on the key theoretical frameworks that advocate and support the employee perspective on HRM and describe different types of conceptualizations that have been used in the extant SHRM research. Next, we review extant empirical SHRM literature on these three components and present an integration of our findings. Finally, we offer recommendations for future research concerning employee perceptions of HRM.
1. Employee Perceptions of HRM as an Antecedent, Mediator, or Outcome Nishii and Wright (2008) developed the SHRM process framework to unravel the link between HRM and performance to shed light on the processes through which HR practices impact organizational performance (Jiang et al., 2013). The starting point of the SHRM process model is the concept of variation. The model makes a distinction between HR practices as intended HR practices, i.e. the practices that an organization develops on paper, the implemented or actual HR practices implemented by linemanagers, and the HR practices as experienced by employees (Nishii & Wright, 2008). Regarding the employee perspective on HR practices, the SHRM process model proposes that such perceptions may be different from the implemented HR practices by line-management.
According to the SHRM process framework, employee perceptions of HRM can serve as an antecedent, mediator, or outcome variable. That is, employee perceptions of HRM are included as antecedent to predict employee reactions, such as employees' attitudes and behaviors (Liao et al., 2009). Furthermore, employee perceptions of HRM are included as mediator in the SHRM process framework. More specifically, the SHRM process framework argues that how management implements HR practices, influences how employees rate them (i.e. actual versus perceived HRM). Therefore, it is implied that employee perceptions of HRM act as a mediating mechanism in the relationship between manager-rated HRM and employee attitudes and behaviors (Nishii & Wright, 2008). Finally, employee perceptions of HRM can also be seen as an outcome variable that is predicted by the actual HR practices.
2. Theoretical perspectives that explain the employee perspective on HRM Key theoretical perspectives that advocate and support the employee perspective on HRM will now be discussed. We have classified the theoretical perspectives into three types depending on their focus. The first set of theoretical perspectives focus on the exchange relationship between the individual and the organization. These perspectives draw from the exchange relationship between the organization and employee, and focus on the perspective that organizations offer inducements (i.e. HR practices) to their employees and that based on how employees perceive these inducements, they contribute to the organization (Takeuchi et al., 2007). Second, a set of theoretical perspectives that focus on how the organization communicates with their employees are identified. These theoretical perspectives highlight the more top-down focus from organizations towards its employees. Finally, a number of theoretical perspectives focusing on explaining employee well-being based on occupational health psychology literature is distinguished. These theoretical perspectives focus on the impact that HR practices have on individual well-being and pay explicit attention to the potential negative effects of HRM on employee health well-being (Jackson et al., 2014;Jiang et al., 2013). An overview of the theoretical perspectives in each of the three categories can be found in Figure 1.

Theoretical perspectives from an exchange relationship perspective
The Social Exchange Theory (hereafter referred to as SET) provides a framework for understanding the quality of exchange relationships at the individual level as well as the level of the organization (Blau, 1964). The norm of reciprocity within these exchange relationships is central in this theory. According to this theory, social exchanges can be seen as actions which are voluntary. These actions may be caused by how an organization treats their employees (Gould-Williams & Davies, 2005). Based on how the organization treats their employees, it is argued that employees who receive benefits feel required to respond in kind (Blau, 1964). In particular with regard to HR practices, SET is helpful in explaining how HR practices can motivate employees, as the exchange of resources and benefits is shaped by the social relationship (Jiang, 2016;Jiang & Li, 2018;. The psychological contract is a kind of social exchange relationship between an employer and employee, which represents the beliefs, informal commitments and perceptions that exists between an employer and employee (Rousseau, 1989). A psychological contract is a relationship between an employer and an employee where both parties have undescribed mutual expectations (Rousseau, 1989). The set of obligations and promises are represented in this contract. In addition, the psychological contract addresses whether these commitments and promises made between the two parties are actually fulfilled Rousseau, 1989).
Closely related to perceptions of social exchange, breach and expectations, is the equity theory (Adams, 1965). This perspective is used to evaluate fairness and focuses not so much on the outcomes itself but more on whether the outcomes are perceived as fair . In order to determine the extent to which the outcome was perceived as fair, one takes into consideration the ratio of the input and outcomes. This ratio provides the employee with information in terms of equality or inequality .
Person-environment (P-E) fit focuses on the match between a person and particular characteristics from the environment (Kristof-Brown   al., 2005). Examples of personal characteristics are the needs, values, and goals a person has. On the other hand, characteristics from the environment include intrinsic and extrinsic rewards, the demands of a job, and cultural values, among others (Kristof-Brown et al., 2005). Research has shown that a fit between the person and the environment results in benefits for both the individual and the organization, and positively impact employee attitudes and behaviors (Boon et al., 2011;Kristof-Brown et al., 2005;.

Theoretical perspectives that focus on organizational communication
In 2004, Bowen and Ostroff presented a framework demonstrating how a system of HR practices can stimulate employees to adopt desired behaviors and ultimately contribute to achieving organizational performance, also called HRM system strength. This model builds on the attribution theory of Kelley (1967), which aims to clarify how causal inferences are explained. These attributions are the people's beliefs about the motivations for the successes and failures that occur and which affect their individual expectations and behaviors (Martinko et al., 2007). Drawing from attribution theory, a strong HRM system involves that employees experience the HRM system as high in distinctiveness, consistency and consensus (Bowen & Ostroff, 2004). First, the degree to which the HR practices are easy to distinguish, so that they are not ambiguous, have legitimate authority, and individuals experience that they are relevant to an important purpose, is called distinctiveness (Bowen & Ostroff, 2004;Lepak & Boswell, 2012). Second, consistency refers to the realization of the impact of the HR practices over time (Kelley, 1967). Finally, consensus is about the alignment between the senders of messages communicated in HR practices (i.e. agreement between HR departments and line managers) and is also about the fairness of the HRM system (Bowen & Ostroff, 2004).
The construct of HR attributions is based on social attribution theory (Fiske & Taylor, 1991). According to this theory, people value the social context differently and based on the way they interpret this, they respond differently in terms of displayed attitudes and behaviors (Fiske & Taylor, 1991;. The motives as to why management adopts HR practices are called HR attributions . Related to the employee perspective on HR practices, research has shown that employees have different attributions about the motive(s) why the HR practices are implemented in organizations (Hewett et al., 2018;Shantz et al., 2016;Van De Voorde & Beijer, 2015).
The process of understanding the communication and the environment is understood through the lens of social information processing theory (Salancik & Pfeffer, 1978). This theory supports the assumption that the social environment in which employees operate influences their attitudes in organizations (Jiang & Li, 2018;Takeuchi et al., 2009). According to this theory, the social environment creates variation in individual perceptions regarding job characteristics and these experiences in turn influence individuals' attitudes and behavior. This notion is also reflected in HRM system strength, as the interpretations of the HR system influence the consensus across employees (Bowen & Ostroff, 2004;Wang et al., 2020). Finally, a related theory that focuses on the communication from the organization to employees, by sending signals to employees, is the signaling theory (Spence, 2002). According to this theory, HR practices that are offered by the organization affect how employees perceive the HR practices, due to the signals that managers use (Wang et al., 2020).

Theoretical perspectives from an occupational health perspective
The third category of theoretical perspectives focuses on explaining employee well-being. Drawing from the demand-control model (D-CM) (Karasek, 1979) and the job demands-resources (JD-R) model (Demerouti et al., 2001) HRM scholars (Jackson et al., 2014;Peccei et al., 2013;Van de Voorde & Boxall, 2014) have started to interpret HR practices by means of work demands and resources. Job demands, such as high workload and emotional demands, can be associated with reduced employee health well-being (Bakker et al., 2004). Job resources are aspects of the job that contribute to the employees' work goals and can buffer the negative well-being effects of work demands (Bakker et al., 2004). These resources can exist at different levels, such as the organizational level (e.g. job security), the level of social relations (e.g. getting support from coworkers), the job level (e.g. clarity in the job role) and the task level (e.g. autonomy in work) (Bakker et al., 2004).
In line with the D-CM and JD-R model, conservation of resources (COR) theory focuses on the investment, development and protection of resources. The underlying logic of this theory is that people are motivated to maintain and obtain new resources, since losing resources can lead to higher levels of stress (Halbesleben et al., 2014). According to Hobfoll (1989), resources are defined as "objects, personal characteristics, conditions, or energies that are valued by the individual" (p. 516). Examples of job resources are social, personal, material or energetic resources, such as HR practices (Hobfoll, 1989). Following the reasoning of the JD-R model and COR theory, implemented HR practices could be perceived as demands and/or resources by employees (Conway et al., 2016;Peccei et al., 2013) and could potentially also have negative effects on employee well-being (Jackson et al., 2014;Jiang et al., 2013).

Descriptive Versus Evaluative Conceptualizations of Employee Perceptions of HRM
Within research on employee perceptions of HR practices, a large amount of diversity exists in the type of perceptions that are investigated. More specifically, the conceptualization of what employee perceptions of HR practices actually constitute, and how these are measured, vary greatly from one study to the next (Beijer et al., 2019;Boon et al., 2019). For example, some studies investigate the perceived availability of HR practices, describing the offered HR practices that employees perceive in their work environment (e.g. Den Hartog et al., 2013). Other studies examine employees' satisfaction with the HR practices (e.g. Kinnie et al., 2005), the supportiveness of HR practices (Knies & Leisink, 2014), or the effectiveness of HR practices (Chang, 2005). Research concludes that "considerable idiosyncrasy exists in measures of perceived HR practices, coupled with a lack of transparency in how these measures are often reported in existing studies" (Beijer et al., 2019, p. 1).
Therefore, Beijer et al. (2019) suggest that employee perceptions of HR practices should be separated into two types of perceptions: descriptive and evaluative perceptions of HR practices. Descriptive perceptions are employee reports of the actual HR practices in place or the extent to which they are exposed to the HR practices. Evaluative measures refer to the positive or negative assessment of HR practices that employees are exposed to (Beijer et al., 2019;Wang et al., 2020). Furthermore, the research by Boon et al. (2019) distinguished between three different types of employee perceptions of HR practices according to level: collective employee perceptions (at the organization or group level), employee perceptions of the HR system (at the individual level), and employee attitudes towards the HR system (at the individual level). They argue that the (collective) employee perceptions of the HR system should focus on descriptive measures of HR practice perceptions, while employee attitudes towards the HR system should be investigated using evaluative measures (Boon et al., 2019). the start year for the analysis because, around this time, the employee perspective on HR practices started receiving more and more attention in research (Guest, 1999;Ostroff & Bowen, 2000).
A study had to meet the following criteria in order to be included in the review. First, we focus on research including multiple HR practices, as strategic HRM research has argued that an HR system or multiple HR practices have a stronger effect on outcomes compared to a single HR practice (Combs et al., 2006). In effect, this selection criterion means that we focus on studies that attempt to capture employee perceptions across a range of HR practices simultaneously, thus avoiding the single practices literature. Therefore, we selected studies that have investigated a combination of HR practices that enhance employees' abilities (e.g. training and development), their motivation (e.g. performance management and compensation), and provides them with the opportunity to participate (communication and information sharing, participation) (Appelbaum et al., 2000). The included HR practices are also among the most frequently studied HR practices in the SHRM literature (Boselie et al., 2005). Second, studies had to refer to a traceable, existing scale measuring employee perceptions of HR practices, or had to include the full measurement scale, in order to be able to directly evaluate in detail the conceptualization and measures used. Third, in order to review the theoretical perspectives and conceptualizations used, studies were only included if they addressed the theoretical perspective that explained the conceptualizations of employee perceptions of HRM at least in some detail. Fourth, in order to be able to evaluate and compare the different conceptualizations and measures of employee perceptions of HR practices, item content needed to apply to the HR practices level. Therefore, it has been argued that employees are best able to answer questions based on their own experiences at the HR practice level, rather than at HRM system level (Arthur & Boyles, 2007). Accordingly, studies pertaining to an evaluation of the whole HRM system (e.g. HRM system strength) were excluded (e.g. Alfes et al., 2019). Finally, only studies that included employee perceptions of HR practices as the focal construct were selected. Therefore, studies investigating employee perceptions of HR practices as a moderating variable for example (e.g. Trevor & Nyberg, 2008) were excluded.
The study selection was independently conducted by the first author, while having intensive contact with the other authors during this process. In terms of search criteria, the first author read all the abstracts of the articles published in the selected time period in the 11 journals. Initially, 145 studies were found based on the abstract. After the articles had been read in full, 100 studies were excluded because they did not meet (one of the) the selection criteria. In total, 45 studies that made use of employee perceptions of HR practices were ultimately included in the review. An overview of the selection process can be found in Figure 2. The second and third author coded half of the articles. After discussing a few discrepancies in coding between the three raters, they were able to agree.

Description of the studies
The majority of selected studies were published in dedicated HR-focused journals, such as the International Journal of Human Resource Management (17) In terms of research design, 35 of the studies were cross-sectional, nine used a longitudinal design, and one study used a cross-sectional and a longitudinal study design. No qualitative research was included, as this line of studies did not meet the selection criteria, mostly due to a lack of inclusion of the exact interview questions in the papers. The majority of studies (38) investigated HR practices as a HRM index (e.g. high-commitment HR bundle or high-performance HR bundle). The other studies investigated the effects of separate HR practices (7).

Results
First, the results will be discussed per feature, i.e. how employee perceptions have been conceptualized, which theoretical perspectives have been used, and how they have been operationalized. Next, the integration of the different features will be described.
1. An Overview of how Employee Perceptions of HRM are Examined (as an Antecedent, Mediator, or Outcome) in Existing Empirical Studies As shown in Table 1, our analysis shows that the majority of studies (34) investigated employee perceptions of HRM as an antecedent. Most of these studies examined the effect of employee perceptions of HRM on individual or organizational performance outcomes (53%), while eight studies examined the effect on employee well-being outcomes and six studies on both outcome types. This table shows that ten studies have investigated the employee perspective of HRM as a mediator. Of these studies, the majority (70%) included employee perceptions of HRM as a mediating variable in the relationship between management-rated HRM and outcomes. Other management-related factors that are used as a predictor when employee perceptions of HRM are investigated as mediating mechanism are employee's perceptions of LMX (Bos-Nehles & Meijerink, 2018) and transformational leadership (Vermeeren, 2014). Finally, three studies investigated employee perceptions of HRM as an outcome variable. These studies investigated different types of antecedents in their research, namely the level of top-management HR cause-effect beliefs (Arthur et al., 2016), institutions (Garcia-Cabrera et al., 2018), and changes in financial performance and customer satisfaction . It should be noted that the study of Piening et al. (2013) included employee perceptions of HRM as an antecedent, mediator, and outcome and is therefore included in all three categories.
2. An Overview of Theoretical Perspectives that Advocate and Support Employee Perceptions of HRM Table 1 show that a variety of theoretical perspectives and frameworks are used to explain the concept of employee perceptions of Note. The variable in italics represents employee perceptions of HRM (as an antecedent, mediator, or outcome). Each new step in a path analytic chain is indicated with an arrow (⟶).

Results in
HR practices. The SHRM process framework is used in more than half of the studies (23 out of the 45 studies). From the theories drawing from an exchange perspective, only the social exchange theory is used (six studies). From the studies that included a theoretical perspective from a communication point of view, four studies used the social information processing theory, five studies the HRM system strength theory, and one study used HR attributions theory. In addition, from the theoretical perspectives that advocate and support employee perceptions of HRM using an occupational health perspective, three studies used the job demandsresources model and one used the job demand-control model. Finally, two other theoretical perspectives were used, the theory of reasoned action (one study) (Ajzen & Fishbein, 1980), and HR differentiation (one study). Table 2 illustrates the different approaches to how employee perceptions of HRM are operationalized. Results show that 18% of the studies included a conceptualization of employee perceptions of HRM that is descriptive and 27% of the studies included a conceptualization that is evaluative in nature. The other 55% of the studies included a mixture of descriptive and evaluative conceptualizations of employee perceptions of HRM. When analyzing all items that have been used in the measurement scales of the included studies, the results show that descriptive items are included in 33 studies. A descriptive item that relates to the perceived availability of HR practices is for example "The organization offers me the opportunity to participate in decision-making processes" (Boon et al., 2011). Furthermore, results of this analysis shows that a diverse range of evaluative items have been used too, of which the mental evaluation of HR practices is most often used (28 studies). An evaluative item that relates to a mental evaluation of HR practices is, for example the extent to which the HR practice is considered supportive. Such an example is "I experience the following HR practices as being implemented to support me: training and development" (Knies & Leisink, 2014). Next is a type of evaluation about the effectiveness of HR practices according to the employee (eight studies), fairness of the HR practice (seven studies), and satisfaction with the HR practices (five studies). Other types of evaluative conceptualizations are used as well (see Table 2). It should be noted that 25 studies included descriptive as well as evaluative, or a mixture of different evaluative items in their measure of employee perceptions of HRM.

An Overview of Conceptualizations of Employee Perceptions of HR Practices
Integrating the theoretical perspectives and how employee perceptions of HRM are examined When it comes to employee perceptions of HRM examined as an antecedent, mediator, or outcome in relation to the various theoretical perspectives used to explain employee perceptions of HRM, findings show that the SHRM process framework is the most frequently used framework to explain employee perceptions of HRM as a predictor and mediator, as well as an outcome variable (see Table 3). Next, social exchange theory is used in six studies to explain employee perceptions of HRM as a predictor and mediator in the relationship between manager-rated HRM and employee and organizational outcomes. From a communication perspective, five studies used HRM system strength, one study used HR attribution theory, and five studies used social information processing theory, to explain in studies where employee perceptions of HRM are examined as a predictor and mediator in the relationship between manager-rated HRM and employee and organizational outcomes. From an occupational health perspective, the job demands-resources model and job demand-control theory are used to explain employee perceptions of HR practices in studies where HRM is investigated as a predictor or mediator.
Integrating the conceptualizations and how employee perceptions of HRM are examined Next, we explore how employee perceptions of HRM are conceptualized in relation to whether studies examined employee perceptions of HRM as an antecedent, mediator, or outcome in their study. As can be seen in Table 4, the highest number of studies (16) included a mixture of a descriptive and evaluative conceptualization in their research, when investigating employee perceptions of HRM as an antecedent variable. Next, the evaluative conceptualization is used the most when employee perceptions of HRM are investigated as a predictor variable. It is interesting to note that a clear conceptualization of employee perceptions of HRM has not been examined as an outcome variable. In addition, when it comes to the descriptive conceptualization, no study included this conceptualization as a mediator in the relationship between manager-rated HRM and employee or organizational outcomes. A descriptive conceptualization of employee perceptions of HRM has only been used when this construct is studied as a predictor variable.
Integrating theoretical perspectives and conceptualizations of employee perceptions of HRM A variety of theoretical perspectives have been used to explain employee perceptions of HR practices. Regarding the studies using a descriptive Note. One study included employee perceptions of HRM as an antecedent, mediator, and outcome variable .
conceptualization, four studies relied on the SHRM process model. One study used the social exchange theory to explain employee perceptions of the presence or availability of HR practices. Three studies draw from an occupational health perspective and use the job demands-resources model (Demerouti et al., 2001). No study has used the communication perspective to explain a descriptive type of conceptualization.
In terms of evaluative conceptualizations, seven studies draw from the SHRM process model to explain a certain type of evaluative conceptualization. In addition, studies that draw from a communication perspective used the HRM system strength theory or HRM attribution theory to investigate an evaluative conceptualization, such as employees' satisfaction with HR practices, their mental evaluations of HR practices, and the relevance or meaningfulness of HR practices. Furthermore, the occupational health perspective is used by one study to investigate an evaluative conceptualization, drawing from job demand-control theory. Finally, one other perspective, HR differentiation, is used to explain an evaluative conceptualization.
Looking at Table 5, the results show that in 25 out of the 45 studies, a mixture of a descriptive and evaluative conceptualization of employee perceptions of HRM is used. The theoretical perspective that most often uses a mixture of different types of employee perceptions is the SHRM process framework (Nishii & Wright, 2008). In addition, from an exchange perspective, in five studies, social exchange theory is used to describe employee perceptions of HRM using a descriptive and evaluative conceptualization. Furthermore, seven studies draw from a communication perspective to describe how the social context affects how employees perceive HR practices, in which a mixture of descriptive and evaluative conceptualizations have been used. One other theory, the theory of reasoned action, has been used to describe a mixture of conceptualizations. Finally, it is interesting to note that studies using an occupational health perspective do not employ a combination of perceptions. For example, studies using the JD-R model tend to use items that are more conceptually clear. Note. One study included employee perceptions of HRM as an antecedent, mediator, and outcome variable .

Discussion
The aim of this paper was to systematically investigate studies using employee perceptions of HR practices. Below we discuss our findings and offer recommendations related to 1) how employee perceptions of HRM can serve as an antecedent, mediator and outcome and what needs to be explored further, 2) what can be done to integrate different perspectives to understand the employee perspective on HRM better, and 3) how research could improve the conceptualization and operationalization of employee perceptions of HRM in the future. On this basis, we broaden the discussion and consider recommendations related to the integration of the three elements. A first major finding related to how employee perceptions of HRM have been examined, concerns the fact that employee perceptions of HRM are mostly investigated as an antecedent in the studies included in our review. A restricted number of studies examined antecedents of employee perceptions of HRM, and only a small number of studies investigated employee perceptions of HRM as outcome variable in their study. These studies focused primarily on the implementation of HRM by line-managers as an antecedent of employee perceptions of HRM. Alternative antecedents of employee perceptions of HRM have received little attention to date. One of the few exceptions are the studies of Bos-Nehles and Meijerink (2018) and Vermeeren (2014), where employee perceptions of LMX and transformational leadership, respectively, were examined as antecedents of employee perceptions of HRM. However, the SHRM process model argued that the background of the employee, employees' previous experience with HR practices, and their personality, also influence how they experience HR practices (Nishii & Wright, 2008). In addition, recent research has shown that manager and coworkers' HR perceptions and demographic dissimilarities affect employee perceptions of HR practices (Jiang et al., 2017). Including such alternative antecedents could help to advance our knowledge on predictors of employee perceptions of HRM, and in particular how different factors together explain how employees perceive HR practices. The following recommendation is therefore provided: Recommendation 1: Predictors of employee perceptions of HR practices are largely unknown and only a small number of studies investigated employee perceptions of HRM as an outcome variable. Future research could examine other antecedents of employee perceptions of HRM (apart from manager-rated implemented HRM), such as the background of employee, their experiences with HR practices, their personality, and the work environment (Nishii & Wright, 2008).
In line with the original thoughts of the SHRM process model (Nishii & Wright, 2008), we see that the majority of studies investigate employee perceptions of HRM as a mediating mechanism in the relationship between manager-rated HRM and motivational employee outcomes and/ or organizational outcomes (e.g. Ang et al., 2013;Den Hartog et al., 2013). Based on these findings, we conclude that much is still unknown about how employee perceptions of HRM serve a mediating mechanism in relation to other predictors (see also recommendation 1), and outcomes other than motivational outcomes (e.g. satisfaction, commitment, and engagement) such as employee health well-being. This type of wellbeing has shown to be predicted by employee perceptions of HRM (Kilroy et al., 2016;Topcic et al., 2016), but is less often investigated compared to other well-being types such as organizational commitment and job satisfaction (Marescaux et al., 2013). We therefore provide the following recommendation: Recommendation 2: Given that employee perceptions of HRM are relatively more often investigated as a mediating mechanism in the relationship between manager-rated HRM and motivational employee outcomes, we recommend future studies to investigate employee perceptions of HRM as mediating mechanism in relationships other than manager-rated HRM and motivational outcomes. In particular, employee health-related well-being (such as job stress and burnout) which is currently a relatively underexplored area, but has shown to be a valuable factor in relation to employee perceptions of HRM (Kilroy et al., 2016;Topcic et al., 2016), could be explored.
The second major point to note relates to the theoretical frameworks that have been used to explain the employee perspective on HRM in the existing studies. The results of our review show that the SHRM process framework (Nishii & Wright, 2008) is mostly used to inform the employee perspective on HRM. As noted, however, this approach is more like a general framework that focuses on the different levels in which variation can exist between, for example, (line) managers and employee perceptions of HRM (Nishii & Wright, 2008) and how these levels can be connected across time, working towards organizational performance. Therefore, studies that use this perspective as a "theoretical" basis tend to run the risk of a rather sloppy conceptualization of employee perceptions of HRM and how such perceptions are connected to other study elements. Relatedly, the theoretical explanation of employee perceptions of HRM is largely only briefly and in broad sense described in such studies. Indeed, most of these studies lack theoretical substance when it comes to the explanation of employee perceptions of HRM. We therefore provide the following recommendation: Recommendation 3: Given the wide range of theoretical perspectives used to explain this construct, as well as the different roles that employee perceptions of HRM have in conceptual models, no single overall theory can account for all relationships that are of interest. However, the theoretical argumentation and underpinning for explaining the employee perspective on HRM can be strengthened and deserves more attention in future research. Therefore, in order to explain the particular construct of employee perceptions of HR practices used in an empirical paper, we recommend studies to use a clear theoretical perspective to provide a detailed explanation of the particular conceptualization. We recommend studies to "be cautious" when using the SHRM process model. Using this framework is not an excuse for specifying in greater detail how the researched links might work and why from a theoretical perspective.
As the results of our review show, apart from the SHRM process framework, a number of other theoretical perspectives are used to explain the employee perspective on HRM, and in a more detailed/specific way to argue for any linkages investigated. In particular, an exchange perspective, the communication perspective, and the occupational health psychology perspective are identified to explain employee perceptions of HRM. These theoretical frameworks are more advanced and specific in describing causes and consequences of employee perceptions of HRM, and in explaining particular conceptualizations of employee perceptions of HRM, compared to the SHRM process framework. Following the job demands-resources model, for example, a recent study showed that some implemented HR practices are perceived as demands and others as resources, and that these perceptions are differentially related to employee well-being outcomes (e.g. Conway et al., 2016). This also reflect results and recommendations from previous overview studies in the area of employee perceptions of HRM. In particular, the review of Wang et al. (2020) also argues that theories of HR communication could be enriched as theoretical grounding to understand information processing, sense making and communication from management to their employees. Based on the above, the following is recommended: Recommendation 4: In order to determine the type of theoretical perspective a study wants to use, we recommend studies to utilize the distribution of theories explained in this study (i.e. theoretical perspectives drawing from I) an exchange perspective, II) communication perspective, or III) occupational health psychology perspective), to identify the theoretical perspective that suits the particular research question best.
The third point that stands out in this respect is that other exchange related theoretical perspectives, such as person-environment fit theory and psychological contract theory, have been suggested but not applied yet to explain employee perceptions of HR practices and how these perceptions are linked to motivational outcomes . These theories could help to study the extent to which the needs of the employee fit or match with the HR practices that are offered to employees and how the employees' evaluation of how their work behavior is facilitated or hindered by the HR practices influences their behavior, which is an underexplored area of research. Future research could, for example, examine whether employees who use HR practices and who perceive HR practices as contributing to their performance differ from employees who do not use HR practices but argue that receiving the HR practice would have contributed to their performance (a type of outcome expectancy, discussed in P-E fit theory). These perceptions about the added value of HR practices on an individual level might provide valuable information for organizations, because the aim of (S)HRM is to design and implement HR practices in such a way that HR practices contribute to desired employee attitudes and performance that will ultimately benefit the organization Lepak & Boswell, 2012). We therefore recommend the following: Recommendation 5: Future studies are recommended to examine employee perceptions of HR practices from other exchange related theoretical perspectives such as psychological contract theory and personenvironment fit theory to investigate the fit or match between the offered HR practices and the employees' needs.
On the conceptualization side, results of our review show that employee perceptions of HR practices are investigated using different forms based on a descriptive and evaluative approach (Beijer et al., 2019). However, more than half of the studies in this review included a combination of different conceptualizations in their study, resulting in measures of employee perceptions of HR practices that include a mixture of descriptive and evaluative conceptualizations or different evaluative conceptualizations in one measure. Given this observation, there is a need for more transparency to be created by categorizing the conceptualizations and to be more specific in the type of conceptualization used in research measures (Beijer et al., 2019). We therefore recommend the following: Recommendation 6: In line with the need for more transparency that can be created by categorizing the conceptualizations and to be more specific in the type of conceptualization used in research, separate measures, especially with regard to descriptive and evaluative approaches, to improve the quality of the item content that fits the type of conceptualization, should be used.
In particular, the evaluative category of employee perceptions would appear to be in need of further specification when looking at the different evaluative conceptualizations in Table 2. That is, employee perceptions of the mental evaluation of the implemented HR practices (e.g. the extent to which the employee receives extensive training opportunities) can be seen as something different compared to, for example, the effectiveness of HR practices for individual performance (e.g. the extent to which the employee received the trainings that are necessary to perform the job effectively). More affective types of evaluations might yet be another category (for example evaluations in terms of fairness, justice, or job satisfaction facets).
It might be informative for HR research to study carefully what has been explored from the cognitive psychology perspective on surveys, as most of the research we reviewed in this paper relies heavily on employee surveys (Neisser, 1967;Schwarz & Sudman, 2012 ). Any survey response can be considered a "cognitive task in a social setting". In cognitive psychology, a distinction is often made into cognitive evaluations about the stimulus (in the environment), about mediational process (mental events), or about responses (behavior) (Miller, 1960;Schwarz & Sudman, 2012). For our purpose of conducting HR research using employee surveys, we might want to create measures of HR practices that align well with the fundamental three stages described above (stimulus-mediation-response). One could measure how employees evaluate the stimulus (i.e. HR practices), or what mental events are triggered by the HR practices (including emotional responses) according to employees, and finally how employees think that their behavior is influenced by such HR practices. One alternative would be to measure each of these three options as clear and separate as possible. Alternatively, one could design employee measures to reflect an optimal balance of each of the three types of cognitive evaluations mentioned. Based on these findings, the following recommendations are provided: Recommendation 7: A further distinction in evaluative perceptions of HR practices could be made. Drawing from the cognitive psychology approach to surveying (Schwarz & Sudman, 2012), evaluations about the stimulus itself (i.e. HR practices), the mediational process triggered by the stimulus (i.e. HR practices), and responses/behaviors as related to the stimulus (i.e. HR practices) can be distinguished. A further systematic exploration of the types of evaluative perceptions of HR practices would be desirable in future research and could be used to design measures that are as "clear/separate" as possible or as "balanced" as possible according these three categories of evaluations.
Looking ahead: An integration of the findings When looking at the integration of the three elements in our review, it becomes clear that due to the different starting points in theoretical perspectives, studies use different conceptualizations and measures, which results in a variety of different ways in how employee perceptions of HRM have been examined. Building on our review findings, we think it is particularly fruitful for the further development of the employee perspective on HRM to distinguish between two lines of research. The first stream of research could focus on applying a more situational view on employee perceptions of HRM. This conceptualization tends to be descriptive in nature, which is mostly used by studies that draw from the occupational health psychology literature. Therefore, these studies could use only one particular conceptualization and use a single theoretical perspective that fit this line of research, such as the occupational health perspective (e.g. Jensen et al., 2013;Kilroy et al., 2016). A second stream of research could use a well-considered combination of different conceptualizations. These studies mostly draw from the exchange or communication perspective, which tend to be less clear in the type of conceptualization and measurement of employee perceptions of HRM. This stream of research is better off taking this well-considered combination of conceptualizations in their study. That is, studies could incorporate a descriptive, mental event, as well as a behavioral component of employee perceptions of HRM in their study, using specific measures. For example with regard to training, it could be asked whether the training I) is offered or used by employees, II) whether employees are satisfied with the training, and III) whether the training helps employees in performing their job. The development of cumulative insights in research on employee perceptions of HRM can be better monitored by following these two lines of research.

Limitations
Although the coding of the item content did not cause any substantial problems, the coding of the theoretical perspective and the type of conceptualizations used, turned out to be challenging to do for some studies. This was because the theoretical framework was not always explicitly mentioned, or because the type of conceptualization that the authors investigated incorporated different types of categorizations compared to what was reflected in the conceptualization by the authors of the study. For example, studies reported to investigate a descriptive type of conceptualization, while a detailed analysis of the items of this scale showed that evaluative conceptualizations were also included. In order to overcome ambiguity in coding, studies that did not incorporate a clear section on the theoretical perspective used, were excluded. On top of this, studies that did not include a full measurement scale or did not refer to an existing validated measure were also excluded. This resulted in a considerable number of studies (57) that were excluded for this review for these two reasons (e.g. Castanheira & Chambel, 2010;Macky & Boxall, 2007).
Second, the systematic literature review conducted for the empirical studies, is based on articles published in 11 refereed international journals in dedicated HRM, applied psychology and management journals. We selected these journals as they are seen as top journals in their field, but we are aware that other relevant studies have been published in other journals and therefore this review is not exhaustive (e.g. Par e & Tremblay, 2007).
A final limitation is that studies had to include an ability, motivation and opportunity enhancing component of HR practices in their study. As there is no fixed set of HR practices that belongs to the categories mentioned, our review includes studies that investigated different types of HR practices, and sometimes also included HR practices that were included as additional HR practices, next to HR practices that fitted our definition. We explicitly did not incorporate single practices literature in this review.

Practical implications
The extent to which the organization's intended HR practices are successfully implemented by (line) managers and how employees perceive these practices, is a question that is of significant interest to HR practitioners. In order to accomplish the goals determined by the HR practices, it is important to identify the factors that affect HR practices and how they impact organizational performance Nishii & Wright, 2008). This study shows that employee perceptions of HR practices are an important predictor of outcomes such as employee motivational outcomes, employee well-being, and organizational performance. Therefore, these perceptions may at least partially account for the success of HR practices that ultimately impact performance . Furthermore, by systematically investigating the construct of employee perceptions of HR practices, this study highlights that managers should pay attention to the different types of HR perceptions during daily conversations with their employees and should distinguish between these different types, as they provide the (HR) manager with different types of valuable information. Furthermore, it would be helpful for (HR) managers to distinguish between employee perceptions of HR practices in terms of how employees evaluate the HR practices in terms of what is offered to them, or what mental events, such as the satisfaction with the HR practices, are triggered by the HR practices (including emotional responses). Finally, how employees think that their behavior is influenced by such HR practices would contribute to the desired attitudes and performance that ultimately benefit the organization. All in all, we believe that both research and practice might benefit from insight into employee perceptions of HR practices and the interpretation of HR practices that we have laid out in this paper.

Disclosure statement
No potential conflict of interest was reported by the author(s).