1 Introduction

Positive psychology research has grown exponentially since its introduction nearly 30 years ago (Seligman and Csikszentmihalyi 2000). Using Google Scholar, the search term ‘positive psychology’ returned 5530 results from 1994–2003, 48,600 from 2004–2013, and 136,000 from 2014–2023 (with 99,500 of these results from 2019–2023). The related positive psychology subfields of positive organizational behavior (Luthans 2002a, b), positive organizational scholarship (Cameron and Dutton 2003), and positive organizational psychology (Donaldson and Ko 2010) quickly followed in popularity. Since its conception by Luthans in 2002, one positive organizationahl behavior construct that has achieved prominence is positive psychological capital, or PsyCap.

PsyCap refers to one’s motivational propensity at work and consists of four related components—hope, self-efficacy, resilience, and optimism (Luthans and Youssef-Morgan 2017). The scope and ongoing intrigue with PsyCap are evidenced through a recent Web of Science search where we identified 937 publications on PsyCap. Research has amassed substantial empirical evidence of PsyCap positively relating to job performance and other desirable workplace outcomes (Avey et al. 2011; Loghman et al. 2023; Nolzen 2018). Specifically, empirical results have consistently found relationships between PsyCap and several critical employee attitudes and behaviors across diverse samples, industries, contexts, and levels of analysis (e.g., Dawkins et al. 2021; Donaldson et al. 2020; Maykrantz et al. 2021; Xia et al. 2022). Over the past two decades, researchers have made tremendous strides in understanding PsyCap and its value as a mainstream construct of interest to research and practice (Loghman et al. 2023). However, as the fields of positive psychology and positive organizational behavior—including PsyCap—have grown, they have received criticism.

These research fields have come under three major criticisms we address (van Zyl et al. 2023). First, the (1) underlying theoretical foundations of PsyCap have been openly and validly questioned (Dawkins et al. 2013; van Zyl et al. 2023). The ‘old wine in new bottles’ criticism asserts that organizational behavior has long studied different positive concepts (e.g., commitment, satisfaction; Roberts 2006), and PsyCap is simply a re-packaging. Hackman (2009) argues that whereas proponents of positive organizational behavior claim this field is brand new, the research and writing in the field are ahistorical. He argues that researchers fail to orient new concepts like PsyCap in what has already been learned from the broader organizational behavior field over many years. Therefore, positive organizational behavior would be more credible if proponents acknowledge and integrate a foundation of historical organizational theory and research (Hackman 2009). This premise is rejected by proponents of positive organizational behavior (Luthans and Avolio 2009), who argue that the intellectual foundations of PsyCap are grounded in what we already know about organizational behavior.

In addition to its ahistorical nature, criticisms of positive psychology and PsyCap have centered on disregarding methodological rigor and cronyism. Concerning (2) the disregard for methodological rigor, these fields have been criticized for being pop psychology based on “quack science” (Ehrenreich 2009; Hackman 2009; Hedges 2009, p. 117). Specifically, critics argue that operationalizing nebulous, socially desirable constructs like happiness is impossible (Ehrenreich 2009; Kristjannson 2010). PsyCap critics have asserted that its existing measurement fails to reflect the theorized higher-order factor structure (Dawkins et al. 2013). Finally, positive psychology and positive organizational behavior have been criticized for (3) cult-like cronyism (i.e., comprising a small, tight-knit group of similar-thinking Western authors supported by overly friendly journal editors). Specifically, critics argue the field’s overemphasis on positivity imposes a neo-liberal ideology that is not culturally generalizable or universally beneficial (Gruber et al. 2011; Judge and Ilies 2004; van Zyl et al. 2023). This myopic positive perspective degrades negativity or neutrality as morally inferior (Fineman 2006). It creates a cult-like mentality (Hedges 2009), as evidenced by only a few scholars acting as the gatekeepers of all research underlying the field (Hackman 2009).

These criticisms have raised numerous fair but difficult questions regarding the underlying intellectual foundations of positive organizational behavior and PsyCap, which are the genesis for this unique bibliometric study. Indeed, these criticisms persist to this day (van Zyl et al. 2023). We seek to answer the following research questions:

  1. 1.

    To what extent is PsyCap research grounded in established, peer-reviewed scientific theory published in reputable journals?

  2. 2.

    To what extent are the intellectual foundations of PsyCap comprised of rigorous methodological and statistical approaches?

  3. 3.

    To what extent were the scholars who informed the intellectual foundation of PsyCap insular versus connected to the broader scientific community?

The purpose of this study is to inform this debate around PsyCap by examining the (1) quality of underlying theoretical frameworks of dominant foundational documents, (2) concerns of originating documents with methodological rigor, and (3) diversity of author networks within the foundation of the field. In addressing these critics regarding PsyCap, we also contribute to the broader debate on the legitimacy of the positive organizational behavior and positive psychology fields. After a brief introduction to the intellectual development of PsyCap, we detail the uniqueness and appropriateness of a bibliometric approach.

1.1 Intellectual development of the PsyCap construct

In developing the PsyCap construct, Luthans explicitly established four inclusion criteria for identifying potential PsyCap components. First, each PsyCap component must possess a robust theoretical foundation. Second, each element of PsyCap was required to be measurable without complex instrumentation (Luthans et al. 2007a, b). Third, Luthans limited PsyCap components to those leaning toward the state-like end of the state-trait continuum (Luthans et al. 2007a, b). PsyCap is defined as more stable than feelings such as moods but more malleable than personality (Luthans and Youssef 2007), so it could be developed through targeted interventions (Luthans et al. 2010; Lupsa et al. 2020). Thus, PsyCap reflects “an individual’s positive psychological state of development” (Luthans et al. 2007b, p. 3). Finally, and in contrast to other positive psychology constructs considered good outcomes in and of themselves, Luthans required that PsyCap components be related to performance. Using these four criteria for evaluating potential constructs for inclusion in PsyCap, Luthans and his colleagues defined PsyCap as a “second-order construct” (Avey et al. 2011, p. 128) composed of hope, self-efficacy, resilience, and optimism (Luthans et al. 2007a, b).

From the education literature, hope refers to one’s expressed capacity to direct energy and find pathways toward achieving a goal (Snyder et al. 1996). Individuals with high levels of hope can recruit more goal-directed energy and generate multiple strategies and contingencies to achieve their desired goals (Peterson and Byron 2008). Self-efficacy, originating from Bandura’s (1997, 2012) work on social cognitive theory, describes an individual’s confidence in their ability to complete a particular task or objective. Self-efficacious individuals tend to “intentionally choose challenging goals” and are “motivated to achieve them” (Luthans and Youssef-Morgan 2017, p. 7). Growing out of the clinical psychology literature, the third component of PsyCap, resilience, refers to an individual’s ability to bounce back from adverse events, uncertain circumstances, and bouts of failure (Bonanno 2005; Masten and Reed 2002). Individuals with high levels of resilience leverage psychological, social, and physiological resources to adapt optimally to negative and stressful situations. Finally, optimism refers to a general belief and expectation that one will achieve positive outcomes through personal effort or external circumstances (Scheier et al. 2001). As a result, individuals with high levels of optimism generate positive expectations for the future, which allow them to recruit the necessary motivation and agency to respond to environmental stimuli, achieve their goals, and overcome challenges when they arise (Seligman 1998).

Abundant reviews of the PsyCap literature—meta-analyses, narrative reviews, and one initial bibliometric study—have provided valuable insights regarding the veracity of the construct. Regarding meta-analyses, Avey et al. (2011) performed the first meta-analysis by aggregating findings from 51 published and file drawer empirical studies based on over 12,000 employees. Results indicated that PsyCap significantly and positively correlated with desirable work outcomes, including satisfaction, commitment, and performance, and significantly and negatively related to undesirable work outcomes, such as counterproductive work behaviors, stress, and turnover intentions. Bolstering these early findings and illustrating the growth and continued relevance of PsyCap, the most recent meta-analysis by Loghman et al. (2023) based on 244 studies and over 96,000 participants found that several types of leadership are significant antecedents of employee PsyCap, PsyCap positively relates to work engagement, and PsyCap negatively relates to burnout. Additional variables such as country sample origin, cultural characteristics, and study design moderated many of these relationships. Finally, Lupșa et al.’s (2020) meta-analysis of 3911 research participants from 41 PsyCap interventions demonstrated that the overall effect of PsyCap interventions was significant for each component of PsyCap and that these PsyCap interventions, on average, had a significant impact on well-being and performance. These meta-analyses clearly show compelling relationships between PsyCap and critical organizational outcomes and the construct’s ongoing utility and popularity to the present day.

Narrative reviews have also provided specific insights on PsyCap throughout the construct’s history. Dawkins et al. (2013) reviewed the PsyCap construct thoroughly and critically, particularly its theoretical components, validity, and measurement-related limitations. The review and synthesis by Newman et al. (2014) offered a detailed account of the existing body of research on PsyCap. They specifically outlined the various multi-level applications, mediating mechanisms, and moderating influences associated with PsyCap and its outcomes. Luthans and Youssef-Morgan (2017) reviewed different aspects of the field, such as the theoretical mechanisms of PsyCap, relations with other variables, levels of analysis, how PsyCap spreads between people, and practical implications for PsyCap. Most recently, Nolzen (2018) conducted a comprehensive literature review of 139 peer-reviewed journal articles on PsyCap to identify gaps and provide a detailed agenda for future research. Although meta-analyses and narrative reviews each contribute additional unique insights, a bibliometric review adds a unique perspective to understanding the field of PsyCap and is the appropriate technique for addressing the aforementioned research questions.

1.2 The uniqueness and appropriateness of a bibliometric study

Although bibliometric methods have existed for decades (Kessler 1963; Small 1973), technological advancements in data-related resources and analytical software have improved their ease of use (Jacso 2005). In support of this approach, organizational behavior scholars’ use of bibliometric methods is growing, with top journals recently publishing bibliometrics studies on leadership (Batistič et al. 2017), leader development (Vogel et al. 2021), work engagement (Wood et al. 2016), and positive organizational psychology (Martín-del-Río et al. 2021). Bibliometric methods examine the interrelationships and patterns of documentFootnote 1 meta-data (e.g., citations, sources, authors). Referred to as science mapping (Cobo et al. 2011), bibliometric methods allow the visual depiction of the network based on the strength or closeness of relationships between each pair of documents. Clusters, or sub-groupings, are defined by pattern similarity and represented by different colors in the network. Different bibliometric methods (e.g., historiography, bibliographic coupling, document co-citation) offer unique insights (see Zupic and Čater 2015 for an overview of bibliometric methods).

In contrast to meta-analyses and narrative reviews, bibliometric methods provide a more objective, quantitative, and inclusive approach to examining a field of study. Meta-analytic reviews are limited to the quality and quantity of extant empirical research focusing on specific independent variable-dependent variable relationships. Therefore, meta-analyses fail to address the aforementioned criticisms regarding the underlying intellectual foundations of PsyCap. Authors of narrative reviews restrict the number of articles reviewed to a manageable number based on their subjectively determined perceived importance. Thus, narrative reviews are limited in scope, influenced by author biases (Zupic and Čater 2015), and focus on primary PsyCap research. As a result, prior meta-analyses and narrative reviews fail to fully and objectively address the underlying intellectual foundations that informed the field of PsyCap (i.e., secondary—or cited—documents).

Rather than relying on an author’s subjective whim or bias regarding what documents to include in a review, bibliometric studies objectively determine the documents selected for inclusion based on citation metrics (i.e., an objective measure of influence). This process typically involves analyzing a subset of documents that meet or exceed a minimum citation threshold. Second, bibliometric analyses allow researchers to quantitatively analyze citations and other document meta-data to visualize and describe patterns of relationships within a body of literature (Zupic and Čater 2015). A visual network is depicted based on quantitative indices that relate documents (e.g., co-citation strength). Finally, bibliometric software can handle thousands of documents, permitting a greater scope of analyses than other common types of review papers. Even when a subset of documents is included in visual depictions, the analysis draws from an inclusive data set.

One previous bibliometric study on PsyCap has been published, demonstrating the potential of this approach to the PsyCap field. Goswami and Goswami (2023) conducted a citation analysis, bibliographic coupling, co-citation analysis, and content analysis. Aligned with their chosen bibliometric methods, the authors aimed to understand current trends in the PsyCap field. In contrast, the current study explicitly responds to critiques by examining the underlying foundations of PsyCap by leveraging co-citation analyses. We perform one overlapping analysis—document co-citation. However, the small sample (N = 61) underlying Goswami and Goswami’s (2023) document co-citation was similarly limited in scope to past narrative reviews and is significantly less than the current study. Finally, in contrast to the current study, they omitted source and author co-citation analyses.

Although extant studies and reviews have significantly added to the understanding of PsyCap, none have systematically and directly responded to the barrage of aforementioned criticisms questioning the underlying intellectual foundations of the field. In the current study, we employ three forms of co-citation analysis (i.e., document, source, and author) and content analysis to objectively and rigorously investigate multiple criticisms of the field. Roughly 73% of bibliometric studies in organizational research have included some form of a co-citation analysis, making it the most common bibliometric method (Zupic and Čater 2015). Co-citation analysis provides a novel, data-driven approach to examining a field of study. It is the most robust bibliometric technique for objectively and thoroughly investigating the underlying intellectual foundation of a given field, eclipsing what is possible through traditional review approaches (Zupic and Čater 2015).

We carefully selected co-citation analysis because of its alignment with our three research questions, allowing us to examine the underlying foundations of the field of PsyCap (i.e., secondary documents). Co-citation analysis examines the frequency with which two “units” (e.g., documents, sources, authors) are cited together (Zupic and Čater 2015, p. 3). Document co-citation examines the frequency with which documents are cited together, source co-citation examines the frequency with which sources are cited together, and author co-citation examines the frequency with which authors are cited together. By identifying patterns of co-citation of each type of information and extrapolating these patterns into visual network maps, these analyses generate insights regarding the most central documents, sources, and authors that informed the development of PsyCap research and how each of those documents, sources, and authors relate to each other. By examining patterns of relationships among secondary document meta-data, co-citation analyses allow a deeper and more nuanced understanding of PsyCap’s underlying intellectual foundations than previous research (e.g., Goswami and Goswami 2023). Thus, this paper provides an objective perspective into the critical, ongoing debate regarding the credibility of PsyCap and the broader field of positive organizational behavior.

2 Methods

As stated, to examine the underlying intellectual foundations of the PsyCap field, we conducted document, source, and author co-citation analyses, which leverage secondary documents as the target of analysis.

2.1 Identifying primary and secondary documents

The first step in any bibliometric method is to define the field of study and identify documents for inclusion. Co-citation leverages two types of documents—primary and secondary. Primary documents refer to any document on the field of study (i.e., PsyCap). They are primary because they explicitly contribute to that field’s knowledge and, thus, have been targeted by the prior meta-analyses and literature reviews on PsyCap. We conducted a comprehensive search on Web of Science to identify all PsyCap primary documents. Web of Science is preferred for co-citation analysis because it offers broad coverage of research within the Social Sciences and provides multiple types of meta-data in formats compatible with bibliometric software (Zupic and Čater 2015). Meta-data leveraged in this study include each primary document’s reference list with information on secondary documents, sources, and authors. To account for differences in terminology used by authors studying PsyCap, we searched multiple variations of the construct’s name (i.e., “PsyCap” or “PsycCap” or “PsychCap” or “Psychological Capital” or “Positive Psychological Capital”). Web of Science returned documents that contained any of the above terms in the title, abstract, or keywords. This search yielded 937 unique primary documents.Footnote 2

The second type of document—secondary documents—is the target of this study. Secondary documents are those referenced by primary documents. Thus, secondary documents represent knowledge the field drew upon to inform the intellectual development of the field (Zupic and Čater 2015). The 937 primary documents on PsyCap referenced a total of 28,428 secondary documents. These 28,428 secondary documents represent the entire intellectual foundation of the PsyCap field. Those secondary documents contain meta-data analyzed in co-citation analyses to examine that foundation: the secondary documents themselves, the sources (i.e., journals) where the secondary documents were published, and the authors of the secondary documents.

2.2 Co-citation analyses

As mentioned, we utilize three types of co-citation analysis to examine PsyCap’s intellectual foundations and answer the three research questions: document co-citation, source co-citation, and author co-citation. First, document co-citation identifies the most influential pieces of work underlying the development of a given field and unearths patterns or themes within that work. Document co-citation examines the interrelationships among these cited, or secondary, documents. When two secondary documents are cited together within a primary document, they are considered co-cited (Small 1973). For example, suppose a primary document on PsyCap by Luthans and colleagues (Luthans et al. 2007a, b) cites Bandura (1997) on self-efficacy and Podsakoff et al. (2003) on common method variance. In that case, the latter two secondary documents (i.e., Bandura and Podsakoff et al.) are co-cited by the Luthans et al. (2007a, b) primary document. The assumption underlying document co-citation is that frequently co-cited secondary documents have content in common that links them together (Zupic and Čater 2015).

Document co-citation examines the frequency of co-citations among all possible pairings of secondary documents and yields a numerical co-citation strength score for each secondary document. Using the full counting method, each time a pair of secondary documents co-occur in the reference list of a primary document, they receive 1 point toward their co-citation strength (Perianes-Rodriguez et al. 2016). Documents with higher co-citation scores are more prevalent within the intellectual foundation of a given body of work. In addition to generating co-citation strength scores for secondary documents, the analysis creates a visual network displaying clusters or subgroups of secondary documents with a relatively high degree of similarity based on co-citation patterns (Waltman et al. 2010).

Source co-citation and author co-citation operate similarly to document co-citation. However, they analyze different types of secondary document meta-data. Specifically, source co-citation examines co-citations among pairings of sources (e.g., journals, book titles) among secondary documents. Thus, source co-citation illuminates top publication outlets within the intellectual foundations of a field and generates a network of top sources among secondary documents. On the other hand, author co-citation examines the frequency of co-citations among all possible pairings of authors among secondary documents. Therefore, author co-citation illuminates top authors in the intellectual foundations of a field and generates a network of top secondary document authors. Together, these two types of co-citation analyses augment the document co-citation in answering research questions about sources and authorship that inform the PsyCap field.

2.3 Interpreting co-citation visualizations

We conducted each co-citation analysis by importing the data from Web of Science into the software tool VOSviewer (van Eck and Waltman 2014). VOSviewer provides network maps composed of nodes, links, and clusters that define the network. Nodes (i.e., circles) represent secondary documents, sources, or authors that vary in size based on their overall co-citation link strength. The larger the node, the more times the secondary document, source, or author was co-cited by the 937 primary documents on PsyCap. Links (i.e., curved lines between nodes) indicate that a given pair of documents, sources, or authors have been co-cited (i.e., appeared together in the same reference lists of primary documents). In VOSviewer, we customized the number of co-citations required to visually depict a line (i.e., 40 for secondary documents, 400 for sources, and 100 for authors). This setting is adjusted to visualize the primary connections among pairs of nodes and clusters. If the setting is set too low, the map will be overrun with lines, obfuscating important links between documents and clusters. Conversely, if the setting is too high, all lines disappear. Therefore, the link setting is adjusted to make the most prominent connections among documents and clusters visually apparent. For example, any two secondary documents connected by a curved line were cited together at least 40 times among the 937 primary documents. The absence of a line does not mean the documents were not co-cited together at all; instead, they were co-cited together 39 times or less. Finally, VOSviewer also assigns clusters using different colors to group the secondary documents, sources, or authors with similar co-citation patterns. Secondary documents, sources, or authors visualized with the same node color are co-cited similarly by primary documents. For example, if there are 20 secondary documents of the same color, then those 20 documents share a similar pattern of being cited by primary documents. Still, that pattern was simultaneously unique from other secondary documents in a different colored cluster.

2.4 Content coding

To supplement the breadth covered in the co-citation maps, we coded the content of 100 secondary documents used in the document co-citation analysis to provide richer insights into answering our research questions regarding the intellectual foundations underlying PsyCap. We selected those 100 secondary documents cited the most by the population of 937 primary documents because they are the most influential to the field of PsyCap. Three Ph.D.-level organizational psychologists and two doctoral students were trained in the coding scheme. Specifically, each coder recorded each document’s publication type (e.g., journal, book, book chapter), journal name, year of publication, type of paper (e.g., theoretical, review, correlational, experimental), and underlying theories (e.g., Conservation of Resources Theory, Broaden-and-Build Theory). Coders integrated different spellings or terminology of any content type (e.g., theories) into the same term or phrase so as to report accurate frequencies. Two coders independently reviewed each secondary document, yielding the following percent agreement: 100% for the publication type, year of publication, and name of the journal; 96% for the type of paper; and 93% for underlying theories included in the document. In cases of a coding discrepancy, a third coder independently reviewed the document and made a final decision in discussion with the original coders.Footnote 3

3 Results

Responding to criticisms of PsyCap origins, our research questions emphasize the foundations underlying the PsyCap field (i.e., secondary documents). Of the 28,242 secondary documents cited by the 937 primary documents focusing on PsyCap, some are more foundational to the PsyCap field than others. Specifically, secondary documents cited most frequently by our sample of primary documents inform the PsyCap field more than those cited only a few times. Thus, we set a minimum citation threshold for secondary documents of at least 15 citations, which yielded a visually manageable co-citation network map of 262 most influential (i.e., frequently cited) secondary documents (see Fig. 1).

Fig. 1
figure 1

Document co-citation map of 262 secondary documents. Note The minimum number of citations is 15, the co-citation minimum threshold is 20, and the minimum link strength is 40

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This high-level view of secondary documents shows that the field comprises multiple unique but well-integrated clusters. That is, although there are numerous distinct clusters (indicated by node color), the clusters are densely connected and moderately overlapping. This observation suggests that the foundations of the field are cohesive and connected rather than fragmented into distinct, siloed research streams. The red cluster represents the theoretical core of the field of PsyCap, containing the underlying theoretical and empirical work on the four components of hope, self-efficacy, resilience, and optimism that inform PsyCap. The field’s foundations expand from there into the multiple distinct yet interrelated sub-streams of research.

To dive deeper into the three research questions, we look closely at document co-citation, source co-citation, and author co-citation, all supplemented with in-depth content analysis. We organize results based on the three research questions investigating the (1) quality of underlying theoretical frameworks to assess the degree of theoretical grounding of PsyCap research, (2) reliance on well-founded methodological and statistical practices among empirical research studies, and (3) diversity of author networks to address the question of insularity versus breadth across the academy.

3.1 PsyCap’s theoretical foundations

To what extent is PsyCap research grounded in established, peer-reviewed scientific theory published in reputable journals? To answer this question, we conducted (a) document co-citation cluster analysis, (b) content analysis of theories, (c) sources co-citation, and (d) content analysis of sources.

First, we generated a document co-citation map of 100 secondary documents to provide a more detailed examination of this question. Following the practices of other bibliometric authors (Vogel et al. 2021), we selected the 100 secondary documents that were most influential to the foundations of PsyCap (i.e., a minimum of 15 citations) and most interconnected with other secondary documents (i.e., 40 link strength). Zooming in on these top 100 secondary documents allows us to closely examine the co-citation clusters and conduct content analysis. As can be seen in Fig. 2, there are unique themes in each of the four clusters. And the themes were somewhat related across each of the clusters. This observation is evident by the visually high degree of interconnectedness between clusters. This finding suggests the intellectual roots of PsyCap are well integrated. A closer examination of each cluster, however, indicates that there are also meaningful differences between clusters. Two of the four distinct clusters emerging in this map address the issue of underlying theoretical frameworks.

Fig. 2
figure 2

Document co-citation map of top 100 secondary documents. Co-citation minimum strength threshold is 40

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3.1.1 Document co-citation Cluster 1 (red): theoretical foundations of PsyCap

Cluster 1 (red), the largest of the four clusters with 39 documents, speaks directly to the question of theoretical grounding underlying PsyCap research. Specifically, one of the main distinguishing characteristics of this cluster is that it consists of a high number of seminal theoretical and other highly cited non-empirical works on the four sub-factors of PsyCap. Most of the 39 documents in this cluster are non-empirical works (i.e., theoretical, review, prescriptive, or a mixture of these three). More specifically, this cluster includes early papers on self-efficacy by Bandura (1986, 1997) and Stajkovic (Stajkovic 2006; Stajkovic and Luthans 1998a, b), resilience by Masten (2001), Masten and Reed (2002) and Wagnild and Young (1993), hope by Snyder (2000, 2002), Snyder et al. (1991, 1996, 2002), and optimism by Seligman (1998). Other notable documents in this cluster were Peterson (2000) and Fredrickson (2001), both highly influential scholars in positive psychology during PsyCap’s origins. This cluster also includes eight foundational articles on PsyCap by Luthans (i.e., Luthans 2002a, b; Luthans and Youssef 2004, 2007; Luthans et al. 2005; Luthans et al. 2006a, b; Luthans et al. 2006a, b; Luthans and Avolio 2009). Finally, as can be observed in the map, documents in this cluster are also highly connected to influential documents in other clusters, suggesting this core body of theoretical work has remained foundational in informing the PsyCap field.

3.1.2 Document co-citation cluster 2 (blue): leadership

Further addressing the theoretical grounding of PsyCap foundations, the blue cluster 2 (n = 19) is dominated by several different types of papers focused on leadership. Indeed, research often examines the relationship between leadership behaviors and follower PsyCap (Loghman et al. 2023). The secondary documents in this cluster seem to represent the theoretical foundation of such work. This cluster covers major leadership theories, including authentic leadership (e.g., Avolio et al. 2004; Avolio and Gardner 2005; Walumbwa et al. 2008) and transformational leadership (Gooty et al. 2009). Other secondary documents of note in this cluster are Avey’s (2014) article on antecedents of PsyCap (of which leadership is positioned as a critical antecedent) and Blau’s (1964) book summarizing social exchange theory, one commonly used theory to examine relationships between leader behavior and follower outcomes. There is a healthy mix of method types in this section, including theoretical (e.g., Avolio and Gardner 2005), empirical (e.g., Rego et al. 2012), and even methodological (e.g., Hayes 2013). This cluster’s existence and composition suggest that leadership scholarship heavily informed PsyCap research.

3.1.3 Content analysis: theory

Next, to understand in richer detail what theories comprise the foundation of PsyCap research, we coded all theories utilized in each of the top 100 secondary documents. Of the top 100 secondary documents on PsyCap, authors relied on other theories with more traditional roots in organizational behavior. Hobfoll’s psychological resource theory (2002) was discussed in 20 secondary documents, the conservation of resources theory (Hobfoll 1989) was discussed in 14 documents, and the job-demands resources model (Bakker and Demerouti 2007) was discussed in seven documents. In general, these resource-based theories assert all individuals possess varying degrees of psychological resources that enable them to survive, operate, adapt, and even flourish in variant environments. In addition, these resources interrelate. For example, a person low in self-efficacy would be less likely to have high self-esteem and, therefore, be higher in stress and lower in well-being. Individuals leverage these resources (e.g., a salesperson leveraging extraversion) to operate in their environment and, when optimal, achieve well-being. Contextual events can drain (e.g., being terminated from a place of work) or enhance (e.g., being promoted) these resources; thus, resources are not universally stable. Resource theories were leveraged in PsyCap research as authors argued that hope, self-efficacy, resilience, and optimism were resources encapsulated in a broader root form of individual positive psychological resources (i.e., PsyCap). Thus, PsyCap has been argued to be a vital psychological resource (Luthans and Youssef 2007).

Of the top 100 secondary documents, 22 also explicitly referenced Fredrickson’s (2001) broaden-and-build theory of positive emotions, a theory squarely situated in positive psychology. This theory suggests that positive emotions broaden an individual’s awareness, open them to exploratory thoughts and actions, and, over time, build new skills and psychological resources. PsyCap researchers primarily used the broaden-and-build theory to explain the synergistic process of the four PsyCap resources (e.g., Luthans et al. 2006a, b). Although aspects of Fredrickson and Losada’s (2005, 2013) work in positive psychology, such as the positivity ratio, have faced significant criticism (Brown et al. 2013; Friedman and Brown 2018), the broaden-and-build framework has been a prominent theory guiding PsyCap research (Luthans and Youssef-Morgan 2017).

As observed in Cluster 1 (red), the third group of traditional organizational behavior theories underlying PsyCap research is aligned to its four dimensions. The self-efficacy component of PsyCap explains why Bandura’s (1991) social cognitive theory was frequently relied upon, with 16 secondary documents on this theory. Similarly, the PsyCap dimension of hope explains why hope theory (Snyder 1995) dominated discussion in 14 secondary documents. Finally, mainstream organizational behavior theories, including social exchange and self-determination theories, were discussed in 8 and 6 secondary documents, respectively. Except for the broaden-and-build theory, the theoretical frameworks frequently cited by PsyCap researchers are established and well-reputed organizational behavior theories.

3.1.4 Sources co-citation analysis

To further examine the critique that positive psychology concepts are born out of pop psychology, we performed a source co-citation to identify the primary outlets of publications (e.g., journal articles, books) on which PsyCap authors built the field. The source co-citation utilized the sources of secondary documents as the unit of analysis. The sources are the journals that primary PsyCap researchers drew from in building the knowledge domain of PsyCap. The source co-citation identified 9712 unique secondary sources of secondary PsyCap documents. However, some of these sources are more influential than others because they are used more frequently, whereas those sources rarely used are considered less influential to the field of PsyCap. We deemed the 130 sources with at least 50 citations the most influential sources underlying the PsyCap field and visualized these top sources in the co-citation map (see Fig. 3). In this map, the larger the node, the more often that particular publication source (e.g., journal outlet) was co-cited by PsyCap researchers. Additionally, we set the minimum line threshold so that a link appears between any pairs of sources if they are co-cited at least 400 times.

Fig. 3
figure 3

Source co-citation map of top 130 sources with at least 50 citations in secondary documents. Co-citation minimum strength threshold is 400

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Notably, many top-tier academic journals are central to this map, including the Journal of Applied Psychology, Journal of Organizational Behavior, The Leadership Quarterly, Personnel Psychology, Journal of Management, Academy of Management Journal, Journal of Occupational and Organizational Psychology, Psychological Bulletin, Journal of Personality and Social Psychology, International Journal of Human Resource Management, Journal of Occupational Health Psychology, and Journal of Vocational Behavior. The central location of these journals within the map illustrates that they played a prominent role in contributing to the field’s foundations. This map also contains numerous methodological journals, including Organizational Research Methods, Psychological Methods, Behavioral Research Methods, and Multivariate Behavioral Research. Finally, the map includes top practice-based outlets such as Harvard Business Review.

To assess the overall quality of academic journals within this source co-citation analysis, we gathered the 2- and 5-year impact factor for each included academic journal outlet. Of the top 130 sources, there were 109 unique academic journals. Their average 2-year impact factor was 6.67 (SD = 4.43), and their average 5-year impact factor was 5.66 (SD = 3.75) (see Fig. 4 for a visual of the distribution of 5-year impact factor scores).

Fig. 4
figure 4

Frequency distribution of 5-year impact factor scores of the top 109 academic journals

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3.1.5 Content analysis: sources

The content analysis of the top 100 secondary documents similarly supports the breadth and quality of sources that comprise the foundations of the field. Contrary to the criticism of the field, we found that 80 of the top 100 secondary documents were peer-reviewed journal articles, with only 20 being books or book chapters. Among the most frequently included journal outlets, nine were published in Journal of Organizational Behavior, seven in Journal of Leadership and Organizational Studies, six in American Psychologist, five in Journal of Management, five in Journal of Applied Psychology, four in Leadership Quarterly, and three each in Personnel Psychology, Journal of Personality and Social Psychology, and Psychological Bulletin.

3.2 PsyCap’s methodological and empirical foundations

To what extent are the intellectual foundations of PsyCap comprised of rigorous methodological and statistical approaches? To address this second major critique of PsyCap foundations, we found that the other two clusters in the document co-citation were specifically methods-focused (see Fig. 2). Following these cluster descriptions, we supplement the scientific mapping with content analysis of methods issues in the top 100 secondary documents.

3.2.1 Document co-citation cluster 3 (green): PsyCap’s statistical approaches and early empirical work

A distinguishing feature of the document co-citation cluster 3’s 33 documents is its relatively high amounts of methodological documents, addressing the methodological rigor underlying PsyCap. The methodological documents include well-known articles such as Podsakoff et al. (2003) paper on common method bias, Baron and Kenny’s (1986) article on moderation and mediation analyses, three widely cited papers on structural equation modeling practices (Fornell and Larcker 1981; Anderson and Gerbing 1988; Hu and Bentler 1999), Preacher and Hayes’ (2008) paper on testing for indirect effects, Hair et al. (2010) book on multivariate analysis, and Aiken et al. (1991) book on multiple regression. Although these analytical approaches are pertinent to the broader field of organizational behavior, they also appear to be prominently informative for PsyCap researchers. As these are among the top 100 secondary documents, it suggests that PsyCap research has regularly referred to and relied upon these methodological practices.

3.2.2 Document co-citation cluster 4 (yellow): experimental foundations of PsyCap

The fourth document co-citation cluster (yellow) includes nine secondary documents and further relates to methodological rigor. Of particular note is that this cluster contains multiple early PsyCap experimental studies. Such research is often referenced as empirical support for PsyCap’s state-like nature (e.g., Luthans et al. 2008, 2010), which has since come under debate (Dawkins et al. 2013) despite a meta-analysis finding support for the positive impact of experimental manipulations of PsyCap (Lupșa et al. 2020). There are also a few articles on the relationship between PsyCap and well-being and how these concepts are essential for employee performance and success (Avey et al. 2010; Luthans et al. 2013; Lyubomirsky et al. 2005). Although this is the smallest cluster, this early body of work investigating PsyCap’s malleability has been an important driver of its continued study in interventions and experimental research, which are highly needed in organizational behavior (Eden 2017).

3.2.3 Content analysis: methods

To further investigate methods used in secondary documents to examine the ‘quack science’ critique, we performed a content analysis on method-related data within the top 100 secondary documents. In other words, do PsyCap papers cite secondary documents that use less or more rigorous research methods? If the ‘quack science’ critique is accurate, we would expect the secondary document pool to include primarily non-empirical articles and to see research designs lacking rigor in empirical ones.

Content analysis results suggest about half of the top 100 documents were empirical articles (48%) employing various research designs, including experimental, longitudinal, psychometric, and meta-analysis. Specifically, of the top 100 documents, 27 of them were correlational, 15 were theoretical, 14 were a mixture of multiple non-empirical types (e.g., review and prescriptive), 11 were review papers, nine were methodological (e.g., Aiken et al. 1991), nine were scale development, four were meta-analyses, four were experimental studies, four were a mixture of multiple empirical types (e.g., correlational and experimental), and three documents were prescriptive (i.e., articles that provide practice-based recommendations such as Coutu’s 2002 article in Harvard Business Review). Together, these results suggest that the methodological approaches of the intellectual roots of PsyCap research have a balance of theoretical and empirical research. However, the empirical research cited by PsyCap researchers appears to utilize less rigorous empirical methods (e.g., correlational methods) than more rigorous methods (e.g., experimental).

3.3 PsyCap’s breadth of source of inquiry

Lastly, to what extent were the scholars who informed the intellectual foundation of PsyCap insular versus connected to the broader scientific community? To examine this question, we performed an author co-citation analysis supplemented with a content analysis of the top 100 secondary documents.

3.3.1 Author co-citation analysis

To investigate author breadth, we performed an author co-citation on the sample of secondary documents from the Web of Science. For author co-citation, the unit of analysis is the authors of secondary documents. These authors are the key conversants to which PsyCap researchers have attributed their knowledge by citing them. There were 18,247 unique authors among the 28,428 secondary documents. Some of these authors were more influential to the foundations of PsyCap than others because they were cited repeatedly, whereas others were relied upon only a few times. So, to focus on the most influential authors, we generated a visualization of the 108 authors with 40 or more citations on secondary documents. In this author network map, the larger the node, the more often that particular author was co-cited by PsyCap researchers. We also customized the map so that a link appears between any pair of authors co-cited at least 100 times (Fig. 5).

Fig. 5
figure 5

Author co-citation map of top 108 authors with at least 40 citations in secondary documents. Co-citation minimum strength threshold is 100

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The visual illustrates that Luthans and some of his close colleagues from the University of Nebraska-Lincoln (UNL) are the most co-cited PsyCap scholars among secondary document authors. However, this network also contains many scholars contributing to the underlying foundations of PsyCap research with four unique clusters of authors. Cluster 1 (red) comprised authors primarily involved in the early research on the four components of PsyCap. These include Bandura and Stajkovic (self-efficacy), Snyder (hope), Masten (resilience), and Seligman (optimism). Cluster 1 also contained multiple early positive psychology scholars, including Cameron, Lyubomirsky, C. Peterson, and S. Peterson. Cluster 2 (green) had prominent authors, such as Bakker, Hobfoll, Salanova, and Schaufeli, focusing on occupational health, job resources, and work engagement. Cluster 3 (blue) had a large contingent of leadership scholars, including Avolio, Bass, Gooty, Norman, Sweetman, and Walumbwa. Lastly, cluster 4 (yellow) contained a wider variety of scholar types, including those focused on methodology, job happiness, satisfaction, stress, and well-being, including Cohen, Culbertson, Diener, Hu, Kline, Lazarus, and Maslach. Luthans and Avey were also in this cluster, and they are positioned in the center of the co-authorship map and thus equidistant to authors in other clusters.

To determine the prominence of Luthans and UNL affiliates more precisely, we examined how many UNL-affiliated authors were present among the top 108 included authors and precisely how many UNL-affiliated authors were in each cluster’s top five most cited authors. Whereas a higher proportion of UNL-affiliated scholars would imply that the field as a whole or a particular cluster is more insular, a lower proportion of UNL-affiliated scholars would mean that the field or a specific cluster possesses greater inclusion of scholars with more diverse perspectives. For this analysis, we defined UNL-affiliated scholars if they were one of the following: a UNL professor, UNL student, UNL graduate, co-author with Luthans, co-author with a UNL graduate, co-author with someone who has published with Luthans or a UNL affiliate, or family relative of Luthans. This definition was intended to capture those who had a relatively direct connection with Luthans’ original work on PsyCap at UNL. Of the 108 authors, 14 were affiliated with UNL, and 94 were not. In cluster 1, Youssef-Morgan was the only author in the top five most cited authors affiliated with UNL. In cluster 2, none of the top five were affiliated with UNL. In cluster 3, two of the top five were affiliated with UNL (Walumbwa and Avolio). Lastly, in cluster 4, two of the top five were affiliated with UNL (Luthans and Avey). This data suggests that Luthans and UNL-affiliated scholars have prominence as some of the top scholars but that the broader field’s intellectual foundations comprise many more non-affiliated scholars than scholars affiliated with UNL.

3.3.2 Content analysis: authors

Through content analysis of the top documents in the document co-citation, we further examine the prevalence of dominant authors co-cited frequently by PsyCap research and, as a result, significantly contributed to the development of the PsyCap field. Among our sample of the top 100 secondary documents, there were 132 unique authors. Regarding UNL affiliation, we found that 33 authors were affiliated with UNL, and 99 were not affiliated with UNL. PsyCap originator, Luthans, is by far the most significant contributor. He is an author of 37 of the top 100 secondary documents. The subsequent most published authors are Avey and Avolio (each with 17 authorships) and Youssef-Morgan (8 authorships). These authors are alumni and previous faculty from UNL, where Luthans initiated research on PsyCap. Other notable authors of secondary documents are Bakker (8), Peterson (7), Snyder (7), and Schaufeli (6). These top authors correspond to some of the abovementioned theories included in these documents as well as early and currently active PsyCap scholars. From the diversity perspective, only a few top conversants are outside the United States, and only one is a woman (Youssef-Morgan). Beyond the top conversants just described, the top secondary documents contained more than 100 additional authors that built the scholarly foundation of PsyCap. Thus, we observed a dominant core of authors, many of whom had some affiliation with UNL. But more broadly, the network of authors that PsyCap researchers cite is also comprised of many scholars heralding from different universities and schools of thought.

4 Discussion

Critique and reflection are central to the process of advancing scientific knowledge. True to scientific form and since the inception of PsyCap, critics of the field of positive psychology (e.g., Ehrenreich 2009; Hedges 2009), positive organizational behavior (e.g., Hackman 2009), and PsyCap (e.g., Dawkins et al. 2013) have called into question these fields’ legitimacy (see van Zyl et al. 2023 for a recent, comprehensive discussion). Healthy debate, such as the back-and-forth between Hackman (2009) and Luthans and Avolio (2009), is valuable, yet only through examining the evidence can we progress toward a resolution. Thus, the purpose of this paper was to leverage the bibliometric methodology of co-citation analysis to evaluate the intellectual foundation and structure of the body of research underlying PsyCap. Specifically, we sought to answer three questions: (1) To what extent is PsyCap research grounded in established, peer-reviewed scientific theory published in reputable journals? (2) To what extent do the intellectual foundations of PsyCap comprise rigorous methodological and statistical approaches? (3) To what extent were the scholars who informed the intellectual foundation of PsyCap insular versus connected to the broader scientific community?

Unlike previous reviews, co-citation analysis is uniquely suited to inform this debate. Traditional literature reviews have a limited scope, such as a period of time or covering a specific journal or set of journals, and rely on an author’s subjective lens to determine what documents are essential to emphasize or even include. Meta-analytic reviews are also limited to aggregation of only primary, quantitative research. However, co-citation analysis allows us to access the entirety of significant works, authors, and sources frequently cited and co-cited by primary PsyCap researchers, increasing objectivity, quantitative rigor, and scope of inquiry. These methodological advantages help address previous limitations of summative works and answer the research questions at hand. Our bibliometric procedures identified and investigated initially gathered samples of 28,428 unique secondary documents, 9714 sources of secondary documents, and 18,247 authors of secondary documents, with final maps and in-depth content analyses performed on the most influential subsets of each, which were selected based on explicated and logical criteria. This breadth eclipses traditional review techniques with a much larger and more inclusive data set. We added depth by closely examining the objectively selected (based on citation indices) top 100 secondary documents through cluster and content analysis. Although this study does not exhaustively address all the ongoing criticisms facing the broader positive psychology field (van Zyl et al. 2023), we thoroughly vet a substantial portion of the most relevant critiques facing PsyCap research. We examined the intellectual structure and content of the most frequently cited secondary documents, sources, and authors. Thus, we directly scrutinized the core foundation of the PsyCap field.

4.1 PsyCap’s theoretical foundations

The first research question aimed to determine whether PsyCap is grounded in established scientific theory. We found the entire cluster 1 (red) focused directly on the theoretical foundations of PsyCap. More notably, the theoretical underpinnings appear rooted in well-established theoretical frameworks. Traditional and mainstream organizational behavior theories dominated, including resource theories (e.g., COR), social cognitive theory, social exchange theory, and self-determination theory. Furthermore, the four PsyCap components were grounded in established theory and research from outside organizational behavior. The dimension of self-efficacy based on Bandura’s (1997) work is commonly understood as domain-specific and was previously studied beyond the workplace in domains such as academia and sports. Similarly, hope theory, rooted in Snyder’s (2000) and Snyder et al. (2002) work, dominated education. Optimism from Seligman (1998) and resilience from Masten primarily originated in clinical psychology (Masten 2001; Masten and Reed 2002). Perhaps PsyCap is so well-grounded in prior theory and research because, at its origin, Luthans (2002a, b) explicitly identified PsyCap components based on the criteria that they are theory- and research-based. The most compelling evidence supporting the assertion that PsyCap was grounded in solid theory is likely the acceptance by the scientific community, even with the most rigorous standards. This conclusion is evident by 80% of the 100 most influential secondary documents undergirding the PsyCap field being published in the top, peer-reviewed, mainstream organizational behavior journals (e.g., Journal of Organizational Behavior, Personnel Psychology, Journal of Management).

Although there appear to be coherent theoretical foundations among the origins of PsyCap, results from the document co-citation raise questions on the breadth of theoretical perspectives employed in early PsyCap research. In other words, the clusters in the document co-citation map show what has been published, not what is missing. Thus, it is possible major theoretical foundations were missing and (in hindsight) should have been considered, integrated, or both. When considering if significant extant research was left out of the theory formation process, We posit two areas of consideration: optimism theory and resilience theory. Specifically, the role of both optimism and resilience in theory formation from early PsyCap scholars only considered content theory and not process theory. For example, early PsyCap researchers heavily relied on Masten’s work in child clinical psychology for resilience, likely due to her short, published, and Likert scale. However, at the time, the field also regarded a process (rather than a construct) view of resilience (Bonanno 2005; Egeland et al. 1993), which was not incorporated into early consideration. Second, early PsyCap scholars referenced Seligman’s optimism work (which is a process theory of explanatory style) yet heavily cited Scheier and Carver’s (2001) work of positive expectancy (a content theory), again likely due to their short, published, and Likert scale.

Despite these potentially unconsidered theoretical perspectives, the foundations of PsyCap are not theoretically ahistorical and are not grounded in so-called pop psychology. Instead, it appears that PsyCap research generally originates from among original and reputable academic outlets within the broader field of organizational behavior. In this way, PsyCap stands out as a positive exemplar in the field of positive psychology and positive organizational behavior for how to ground new so-called ‘positive’ constructs in well-established theory.

In doing so, fundamental theories underlying PsyCap’s four components should inform hypotheses and intervention design. For example, Bandura’s (1977) social learning theory established evidence that mastery experiences, vicarious learning, and clarifying and supportive instruction facilitate the development of the self-efficacy component of PsyCap. Similarly, hope theory suggests identifying meaningful goals and establishing contingency plans support hope development by increasing goal-directed energy and pathways (Snyder et al. 1991). Reframing past events using a positive attribution style and recalling successes in the past can help people learn optimism (Seligman 1998). Finally, Masten’s (2001) work on resilience supports the (a) identification and building of assets and (b) identification and reduction of risk factors as boosts for this dimension of PsyCap. Targeting interventions toward these developmental mechanisms in a specific PsyCap domain (work and non-work) is imperative for future research to fully leverage the application and power of PsyCap.

4.2 PsyCap’s methodological and empirical foundations

The second research question focused on whether the intellectual foundations of PsyCap were grounded in rigorous methodological and statistical approaches. A typical developmental sequence for a recognized theory begins with research questions, theoretical inquiry, and theoretical development, often followed years later by instrumentation and empirical investigation. Given the first positive organizational behavior citation was 2002 (Luthans 2002a, b), the first PsyCap published work in 2004 (Luthans and Youssef 2004; Luthans et al. 2004), the first PsyCap empirical work in 2005 (Luthans et al. 2005), and the psychometric work not published until 2007 (Luthans et al. 2007a, b), the high rate of advancement drew reasonable suspicion and critique as to the degree of methodological rigor (e.g., Dawkins et al. 2013).

Examination of the secondary documents through co-citation and content analysis suggests that PsyCap research has shared similar methodological concerns as the broader field of organizational behavior. That is, numerous methodological articles were present in the co-citation map. For instance, cluster 3 (green) in the document co-citation analysis included several methodological and statistical documents. However, they were mostly related to best practices in regression analysis. Specifically, PsyCap research most often involves a form of regression because PsyCap is a continuous variable (Aiken et al. 1991). Scholars frequently use conditional process analysis in SPSS to perform various regression models (Hair et al. 2010; Hayes 2013). The other included regression-related articles in the map delineate best practices on moderation and mediation (Baron and Kenny 1986; Preacher and Hayes 2008), as well as on the ins and outs of performing structural equation modeling (Anderson and Gerbing 1988; Fornell and Larcker 1981; Hu and Bentler 1999). On a related note, we observed that much of the empirical research in PsyCap is cross-sectional and, therefore, vulnerable to issues associated with common method bias (Podsakoff et al. 2003). Cluster 4 (yellow) of the document co-citation did include multiple foundational experimental studies. However, taken together, the methodological studies illustrated that the foundations of PsyCap research are predominantly characterized by regression and other correlation-related approaches.

The content analyses of secondary documents corroborated our observations in the co-citation maps. Specifically, the most common empirical study design among secondary documents was correlational. This finding may explain the prevalence of Podsakoff et al. (2003) among secondary documents, in that the field is subject to limitations associated with correlational research (e.g., common method bias). Although correlational methods are unfortunately typical in organizational behavior research, this finding presents a weakness within the intellectual foundations of PsyCap research. Overall, our analyses identified that the field’s intellectual foundations possess qualities of weakness that pervade the broader realm of organizational behavior. Both positive and traditional organizational behavior can benefit from moving from correlational research designs to more rigorous methods, like field experiments (Eden 2017).

4.2.1 Increasing rigor in future PsyCap research

In examining current research on PsyCap, we find that experimental and longitudinal methods were an early intention for PsyCap research (Avey et al. 2008), yet they remain underutilized. Therefore, the first worthwhile direction for future research is to examine known correlations between PsyCap and other variables using more rigorous methods. For example, a cross-sectional study by Choi and Lee (2014) found PsyCap correlated with perceived performance, turnover intentions, work happiness, and subjective well-being after controlling for the Big 5 personality traits. This study provides insight into the incremental validity of PsyCap. However, the cross-sectional correlational design does not illuminate whether PsyCap causes a change in each outcome and whether PsyCap will still predict each outcome at various times in the future. Examining these and other relationships experimentally and longitudinally would provide the field with greater clarity on the impact and lasting effects of PsyCap. Eden (2017) offers a detailed manual for conducting true field experiments to remedy the limitations of the correlational study, the all-too-common study design among PsyCap research.

Several other unanswered research questions also necessitate more rigorous designs. For example, studies should test the magnitude and longevity of effects on PsyCap. What are some of the strongest predictors of PsyCap in the near term? What predictors lead to a more extended change in PsyCap? More studies should examine the duration of antecedents’ effects on PsyCap and the sustainability of PsyCap’s impact on other outcomes. For example, Reichard et al. (2014; cluster 2) tested and found that a 2-h cross-cultural PsyCap intervention in South Africa positively affected cultural intelligence immediately following the intervention and again a month later. Although this is a positive example of applied intervention research, the study failed to include a comparison group or random assignment and only had a month-long gap in examining PsyCap’s sustainability. Indeed, the recent meta-analysis on PsyCap interventions found that most experimental studies lack an active control group (Lupșa et al. 2020). Thus, true experimental and longitudinal research remains needed to better estimate PsyCap's veracity.

It is also unknown how much natural fluctuation in PsyCap tends to occur within individuals over time as a state-like construct. Future research can study the variability of PsyCap over different periods, such as a day, week, month, or year, through repeated-measures designs. Such designs can also examine causal effects through random-intercept cross-lagged panel models (Granger 1969; Usami 2021). In parallel, it is unknown whether individuals tend to have higher PsyCap during certain parts of the day (e.g., do individuals have higher PsyCap in the morning after a cup of coffee than they do at 2 p.m. after lunch?) or if there are consistent daily experiences that are more impactful to daily PsyCap fluctuations such as having adequate sleep, exercise, or positive interpersonal interactions. Using experience sampling methods (Hektner et al. 2007) can allow researchers to answer such questions and provide deeper insight into how PsyCap changes and relates to different variables over time. Pursuing these questions necessitates investigation beyond the dominant cross-sectional methods and leveraging more rigorous longitudinal and experimental designs.

Finally, future research testing at different levels of analysis is needed. Although Luthans et al. (2007a) initially conceptualized PsyCap as an individual-level construct, studying PsyCap across multiple levels of analysis can elucidate details on how PsyCap contagion might occur in positive or negative ways throughout an organization (e.g., Story et al. 2013). Future research should examine how an individual’s PsyCap and the overall PsyCap of a team or organization might influence each other. If a team has low PsyCap and low performance, how might the insertion of a high PsyCap individual into that team impact that team’s PsyCap and subsequent performance? Does the individual affect team-level PsyCap and subsequent outcomes, or does team-level PsyCap have more influence on a given team member’s PsyCap and later individual performance? Studies utilizing cross-level models and social network analysis will deepen our understanding of the scope with which PsyCap is relevant in and beyond organizations.

4.3 PsyCap’s breadth of source of inquiry

The third and final research question was regarding the degree to which the foundational PsyCap authors were insular and cult-like versus expansive and connected to the broader scientific academy. This point was one of Hackman’s (2009) original critiques. It poses a risk to any field because when new paradigms emerge, core researchers and gatekeepers can become biased toward accepting and publishing articles that advance their research program (i.e., cronyism).

Observers may anticipate that an originator of a theory would be heavily represented in primary and secondary documents, such as Bandura (1997) with self-efficacy or Locke et al. (1984) with goal-setting theory. Likewise, analyses of PsyCap founding scholars show a robust connection to its originator, Luthans, and his institution, the University of Nebraska-Lincoln (UNL). Four of the five top publishing authors of secondary documents were either colleagues or doctoral students of Luthans during the early 2000s. Therefore, it can be assumed that there were many commonalities regarding those central authors’ training, objectivist paradigm, and perspective.

However, over time, results also show the broader intellectual foundations of PsyCap are not wholly insular. There were 132 unique authors in the top 100 secondary documents alone. Additionally, although we found a prominent subset of UNL-affiliated scholars in both the author co-citation network and the sample of authors in the top 100 secondary documents, far more scholars were not affiliated with UNL in each analysis. Finally, the sources co-citation revealed sources from various organizational subfields, including positive psychology, social psychology, health and occupational psychology, business, and leadership. The foundational sources were published in well-established, peer-reviewed organizational behavior journals, dampening the likelihood of cronyism among gatekeeping editors. In sum, our findings suggest that the intellectual foundation underlying PsyCap is somewhat insular at its core with Luthans and few affiliates of UNL, but that, more generally, the roots of PsyCap research span numerous researchers and academic journals across diverse fields.

4.3.1 Diversifying inquiry in future PsyCap research

Although Luthans and his colleagues at UNL are historically dominant contributors to PsyCap research, we recognize that a growing number of other scholars, institutions, and countries have pushed PsyCap forward in recent years. As PsyCap researchers go global, we encourage them to test differences in the effects of PsyCap between different populations. Although some studies have examined PsyCap across several populations simultaneously (e.g., countries; Donaldson et al. 2020), and some recent research has investigated whether differences exist in the effects of PsyCap between populations (e.g., Western and Eastern cultures; Babu et al. 2023), little is known on the extent of these implications.

4.4 Limitations and future research

Bibliometric methods are becoming mainstream and preferred for examining or reviewing a field of study. Furthermore, document co-citation is the most frequently published bibliometric method because it can reliably filter the most influential documents underlying a field of study (Zupic and Čater 2015). Thus, it serves as a valuable tool for answering specific research questions regarding the underlying intellectual foundations of the PsyCap field. Despite this, document co-citation is not without limitations. First, this analysis assumes that the more two documents are cited together, the more likely their content is related. Although the inclusion of content analysis supported a richer understanding of secondary document content and interconnectedness, it is essential to note that co-citation patterns can also be influenced by relationships between authors and co-authors rather than their publications’ content.

Another potential limitation of the current study is that the minimum citation threshold of 15 may exclude some (likely newer) secondary documents from the analyses. Although this methodological step reduced the visual network maps to an interpretable number, it gave our research a slight bias towards older secondary documents with more time to acquire citations. Nevertheless, because we remained consistently focused on PsyCap’s underlying foundations (as opposed to making assertions about primary PsyCap research), it is unlikely that this procedural step impacted our subsequent conclusions.

Finally, the current analysis is limited in providing meaningful insights beyond the roots of PsyCap and into other areas, such as identifying current trends in PsyCap research. More specifically, our review does not directly examine the sample of 937 primary documents gathered from our search. To meaningfully understand the current intellectual structure of the field, the degree to which recent research addresses potential limitations from earlier in the field’s history, and to provide recommendations on how to advance PsyCap research, future researchers should utilize bibliographic coupling.

As an underutilized bibliometric method, bibliographic coupling focuses on the primary documents that cite the same secondary documents. In other words, this analysis assumes that the more the reference lists of two primary documents overlap, the stronger their connection (Zupic and Čater 2015). Because this method analyzes relationships between primary documents based on similarities in their citing behavior, it does not require that documents accumulate many citations. Therefore, the coupling strength of a given primary document is not time-dependent like the co-citation strength of a given secondary document from the current study. Notably, emphasizing the citing behavior of primary documents in a bibliographic coupling allows researchers to identify emergent topics and newer developments regarding PsyCap.

5 Conclusion

This study critically examined the underlying intellectual foundations of the field of PsyCap, a dominant ‘positive’ domain of study within organizational behavior. The results of document co-citation, source co-citation, author co-citation, and content analyses suggest that the underlying intellectual foundation of PsyCap contains strengths and limitations. PsyCap research has roots in formal rather than armchair theories and research published in high-quality peer-reviewed academic journals. The underlying foundation includes a variety of research methodologies but is limited by its overreliance on correlational methods for empirical studies, which is also characteristic of the broader field of organizational behavior. And although the core of authors is somewhat insular, numerous scholars from different institutions and disciplines have contributed to its foundations. We provide specific future research avenues for PsyCap authors to build upon its established foundations.