During recent decades, Commitment has been defined and measured in different ways (Gupta, 2017). However, the lack of consensus regarding its definition does not imply the lack of a common body of knowledge that allows us to “distinguish it from other related constructs, such as satisfaction, motivation, implication” (Liou and Nyhan, 1994, p. 100).

Organizational commitment is defined as an emotional, moral and rational phenomenon (Ahmad and Oranye, 2010). Taking into account the different connotations as to the origin of the bond and the main differences among the different contributions, it can be seen in Table 1 that all the authors agree that commitment is a link with the organization that involves either behavior or attitude.

Therefore, it is necessary that the link involves particular behaviors or a positive attitude toward an organization that predisposes the individual to benefit the organization (Meyer and Herscovitch, 2001). Organizational commitment is the extent to which individuals psychologically identify with their work organizations (Idris and Manganaro, 2017). The nature of the links can vary and they include desire, perceived cost and obligation to continue a course of action (Table 1). Although it is useful to consider commitment as spread over a range from the emotional to the instrumental perspective, these approaches reflect different underlying components of commitment and therefore scales of measurement for explaining the construct dimensions will continue to be developed. But, the generally accepted feeling seems to indicate that the consequences of the multidimensional construct links lead us to links of different individuals. These types of links could be set as follows: (1) Affects or an affective link as an affective feeling or emotional link; (2) Fear or a repressive link as a feeling of being trapped; and (3) Normative links as feelings of obligation.

The studies relating to organizational commitment from an empirical point of view and the different interpretations of the links require us to rethink their meanings, especially within the scope of third sector NPOs and particularly, considering that they have volunteer resources. NPOs do not have financial wherewithal to implement human resources policies for promoting involvement and motivation, either for workers or for volunteers (Pearce, 1993; Boezeman and Ellemers, 2008), hence they have to use other tools to attract and retain human resources in the organization. It can be one of the tools that human resources managers utilize in order to analyze employee identification with organizational goals, and loyalty linking employees to their workplace (Zayas-Ortiz et al., 2015). In the next section, taking into account the different contributions made and organizational characteristics, we present the various bonds considered for these organizations.

In general, there is a scientific consensus regarding this conceptual delimitation. But, it diminishes as far as the taxonomy of links is concerned, or the way in which individuals feel tied to the organization. There have been several attempts to classify organizational commitment (Ahmad and Oranye, 2010). After reviewing the different contributions in the body of literature, we raise the idea that the nature of the bond generates different dimensions that, as aforementioned, can be summarized as affections, fears and obligations.

Among the different methods recognized in the field of psychology, our revision of the presented literature indicates that the previous studies usually work with models having different numbers of dimensions (Table 2). To the best of our knowledge, previous studies collected at least six meanings that are viewed as relevant to the level of effort demanded of the individual and his/her own acceptance (attitudinal aspects), and relate this and other factors of individual motivation with a decrease in probability of abandoning the organization. For that reason, exploration of the nature of the relationship and motivations of the individual become the fundamental factors. Next, we present the factors considered and justification for the most relevant factors selected.

In this first interpretation of commitment, we aim to gather the attitudes of an individual that link him/her to the organization, either because he/she appreciates the entity values, or because he/she identifies with them. It has been identified as an antecedent of organization citizenship behavior (Wang et al., 2017). O'Reilly and Chatman (1986) show that this type of attitude arises when workers behave in a certain way, because they want to remain in the organization due to its attractiveness (values and goals), even though its values may not be those that the person would adopt. The individual accepts the influence of values to establish or maintain a satisfactory relationship, hence this dimension emphasizes an aspect of socialization of an instrumental nature. The affection is shown by a feeling of pride that is generated outwards toward the reference group, which finally generates self-esteem owing to the sense of belonging within the organization. Feelings of pride and respect are seen as important motivators in the field of voluntary organizations (Boezeman and Ellemers, 2008). The type of commitment (compared to continuance and normative commitment) that is expected to be most clearly related both to organizational issues would be for example attendance, performance, and organizational citizenship behavior (Hansen and Kjeldsen, 2017) or dimensions of attitudes toward organizational change (Yousef, 2017). The most used and validated measure of organizational commitment in the body of public management literature (Hansen and Kjeldsen, 2017) is affective commitment, and it is especially relevant to volunteering, given the intrinsic motivation, non-monetizable, socio-emotional need of fulfillment and positive work experience ascribed to voluntary contributions to an organization of time, energy and expertise (Ohana and Meyer, 2016).

Although, non-profit employees often feel they are underpaid (Light, 2003; Kim and Lee, 2007; Handy et al., 2008), they may be willing to sacrifice some money (from wage, income) in order to serve a cause or specific social mission (Ohana and Meyer, 2016). In this way, the organization's affective commitment is important in a context of scarce financial resources and can help to resolve the dilemma faced by non-profit managers of how to keep employees committed without offering them the highest possible salary (Ohana and Meyer, 2016).

Secondly, and still referring to this dimension, other studies show an individual's identification with the value system of the organization. In this case, the identification reflects a behavior that is supported by internal values and goals which are also connected with those adopted by the organization. In this case, the concept involves more than mere loyalty. It implies an active relationship with the organization in reaching its goals, as a way to serve one's own interests. In this regard, we will adopt the meaning of Affective from the model of Meyer and Allen (1984, 1991), the significance of the definition given by Mowday et al. (1979), the Internalization dimension of O'Reilly and Chatman (1986), and the meaning compiled under Moral Commitment from Jaros et al. (1993).

The reason why we question the breakdown into these two subdimensions is due to the diversity of interpretations of the emotional aspect of the term. This difference can be seen in the model developed by Jaros et al. (1993) under the itemization of the affective dimension and the meaning given to the moral dimension, or in the O'Reilly and Chatman model (1986) as comprised in the dimensions of identification and internalization.

Affective commitment has been linked to measured involvement in organizational activities, a strong willingness to contribute to achieving organizational goals and a strong desire to remain with the organization (Walumbwa et al., 2010; Idris and Manganaro, 2017). It is found to be strongly related to important organizational outcomes such as attendance, turnover, performance, and organizational citizenship behavior, as well as individual outcomes such as stress and work family conflict (Meyer et al., 2002; Stazyk et al., 2011; Chordiya et al., 2017).

The second attitudinal dimension explains the relationship between an individual and the organization as a sense that his/her withdrawal would imply the loss of some acquired conditions or rights, or that he/she has no other labor alternative (Tekingündüz et al., 2017). According to the definition by Becker (1960), organizational commitment is associated with the assessment made by an individual of the costs involved in the abandonment of the organization where he/she works and/or the costs of renouncing a situation or status resulting from his/her efforts. Commitment is thus defined as a willingness to deploy a determined consistent line of behavior as a result of the accumulation of investments that could be lost if that line of action was abandoned (González and Antón, 1995). Consequently, in the light of commitment related to the investments made, all actions performed by an individual after becoming part of an organization will lead to attempting to justify his/her continuance (Becker, 1960; Salancik, 1977).

Along with the prior aspects, the explanation based on the continuity/fear argument, another key factor stands out: the lack of alternatives. McGee and Ford (1987) pioneered the study of commitment bi-dimensionality based on Becker's theory. These authors suggested the existence of two interpretable factors: the perceived sacrifice associated with neglect and the lack of alternatives.

The results obtained that split Continuous commitment into two dimensions are supported by studies that use discriminatory factor analysis, such as studies by Allen and Meyer (1996), Hackett et al. (1994), Iverson and Buttigieg (1999), Meyer et al. (2002), Meyer et al. (1990), and Somers (1993). Although there are other results that indicate uni-dimensionality such as those results obtained by Dunham et al. (1994), Kou et al. (1997), and Powell and Meyer (2004).

Moreover, works in the field of voluntary organizations demonstrate empirically that normative commitment does not imply a significant relationship for this type of person-organization relationships (Liao-Troth, 2001; Stephens et al., 2004; Dawley et al., 2005).

For this third and final dimension of reference, there is less research and empirical contributions in the body of literature than for those previously mentioned dimension, despite its importance in explaining Organizational Commitment. One of the main problems found in the definition of this dimension is the lack of consensus as to its meaning, although the work goes on to consider that the policy linkages reflect a sense of obligation (Meyer and Herscovitch, 2001). As such, a committed person will feel compelled to stay connected with the organization (normative linking). One of the factors that has contributed to the lack of clarity with respect to the affective dimension relates to the high levels of correlation with this dimension, as obtained in previous studies. The person has normative commitment while showing loyalty to their organization and they present suitable behavior and conduct with motivation for doing good for the organization (Tekingündüz et al., 2017). This dimension is still unknown and probably the most controversial dimension (Jaros, 2017) bearing in mind the implications included in previous works (Juaneda-Ayensa and González-Menorca, 2007; González and Guillén, 2008; Grant et al., 2008; Meyer and Parfyonova, 2010), we break this dimension into two types of link: Moral Obligation and Gratitude.

The need for internal consistency presented in the cognitive dissonance theory of Festinger (1957) is reflected in the concept of Moral Obligation. It describes the tendency of individuals to reconcile internal inconsistencies. Because of this desire for internal consistency, attitudes and beliefs of an individual may not only be determinants of their behavior, but a result of it. This approach assumes that attitudes are relatively private, malleable, and not always clearly identifiable. In comparison, behaviors are more public, and once acted out, irrevocable (although the consequences are not). Thus, attitudes, which are easily modifiable elements, will be molded around the least malleable factor, or behaviors, the mechanism by which the individual strives to maintain consistency between them (Oliver, 1990). This would mean that an action taken modifies an attitude if there is any inconsistency between them. According to this theory, people who are committed to participate/collaborate on a project should continue with it in order to avoid contradicting his/her line of action that was already begun. If they were to decide to interrupt it, it would be a contradiction and therefore internally inconsistent.

The second meaning of this dimension is Gratitude, defined as a sense of obligation due to the feeling of having received more than what has been given. In this case, social exchange theory is of significant importance. According to Blau (1964), relationships between two parties, when one of them provides benefits to the other, the imbalance in the relationship confers an obligation on the second party. The person feels there is an imbalance regarding benefit, and this fosters a sense of debt to the organization, i.e., strengthens the feeling of obligation to the organization and attempts to balance it, believing this behavior to be appropriate to contribute to balance in the exchange.

We believe it is important to look at this dimension in depth in the context of NPOs. In an attempt to enhance the theory of normative commitment, González and Guillén (2008) consider that the normative dimension should be grouped with rational judgments regarding the moral sphere of the individual, and include whatever has to do with moral judgments (fairness) and moral practice (responsibility), which to some extent is what we intend to compile under the dimensions of Gratitude and Moral Obligation. On the other hand, we consider that in the NPO, this moral connotation is relevant and it is particularly influenced by NPO characteristics, including the role of demands and political pressure aimed at ensuring a level of rights for a group or society in general and the role these activities play in transforming individuals. From this point of view, linking to one of these organizations is a public demonstration of certain convictions, and activities performed under the auspices of the entity support identification of the individual with the organization's ideology. In the event that there is incomplete identification between the value and belief systems of the organization and the individual, the size of the organization, and the difficulty to model this value system will indoctrinate individuals as a tool of socialization. The result will be a link with the organization as a consistent behavior based on public demonstration of an ideological system. However, we must include ideological or ethical issues in this section [the significance of the normative commitment of the Allen and Meyer (1990) scale] in which the relationship is reflected and manifested in the permanence within the organization that are generated from the value system of the individual who becomes “tied” to the acquired commitments.

When gratitude is felt toward the organization, the more relevant argument is based on the fact that most of these organizations provide services that are not provided by the public or private sector, and the organizations offer solutions to problems for people in situations of some complexity, helping them feel connected to the organization as a show of gratitude for the support received.

In addition, this type of link may have a particular impact on NPOs and as suggested by Meyer and Allen (1997), commitment characterized by a sense of obligation might be a better predictor of employment outcomes in collective contexts where social ties and regulatory obligations are most relevant.

Then, we propose a concept as a three-dimensional model which, depending on the different connotations attributed by the authors, can have each of its dimensions broken down into two sub-dimensions (Figure 2).

Affective commitment has been linked to increased involvement in organizational activities, involvement in organizational activities, a strong willingness to contribute to achieving organizational goals and a strong desire to remain with the organization (Walumbwa et al., 2010; Idris and Manganaro, 2017). Continuance and normative dimensions of commitment have been critiqued for their inconsistencies with affective commitment (Chordiya et al., 2017). Normative commitment is usually strongly linked to affective commitment (Guerrero and Herrbach, 2009) and is linked to individuals' sense of obligation to stay in the organization (Wang et al., 2017).

The information was obtained from 14 non-profit organizations that operate in various fields of activity, but all of them are characterized as direct services. The areas of activity are services for children, mental disability, and the promotion of employment, physical disability, and a volunteer organization. The samples were obtained by the directors of the entities. The directors distributed the questionnaires and they committed themselves to respecting the anonymity of those respondents wishing to undertake the completion of the questionnaires.

The final sample consists of 235 questionnaires, of which 156 (66.38%) pertain to workers and 79 (33.61%) pertain to volunteers. The average seniority in the organization is 4.51 years with a standard deviation of 4.67 and a maximum of 26 years and a minimum of 6 months. Sixteen percent of the sample consisted of people who stayed less than a year in the organization, 46.6% were there for a period of 1–5 years, 27.7% for 5–10 years, and only 9.7% spent over 10 years in the organization. As for the level of education, the largest proportion of the sample comprised people with a mid-level university education (34.7%) followed by graduate degrees (25.4%), and only 10.9% have a level of basic studies.

One of the main drawbacks in the organizational commitment study is the use of different measurement scales, and the problems inherent to cultural questions, and the linguistic adaptation of questionnaires to specific contexts. In this sense this work analyzes the meaning of the construct identifying different structures and comparing among them. From the comparative analysis of structural models, we can highlight several aspects.

First, in relation to the interpretation of the composition of the latent variable Organizational Commitment, it consists mainly of contributions from the individual's emotional bonds with respect to the organization, followed by normative and yet, the Continuity dimension values are not enough to ensure that this type of relationship creates a relevant link with respect to the entity. Therefore, we cannot accept the existence of the Continuity dimension as reflected in other studies (Meyer et al., 1990, 2002; Somers, 1993; Dunham et al., 1994; Hackett et al., 1994; Iverson and Buttigieg, 1999; Powell and Meyer, 2004), but it confirms, to the best of our knowledge, the results obtained in previous research relating to the scope of voluntary activities (Liao-Troth, 2001; Stephens et al., 2004; Dawley et al., 2005).

According to previous studies (i.e., Meyer and Allen, 1984, 1991; O'Reilly and Chatman, 1986; Jaros et al., 1993; Boezeman and Ellemers, 2008) the breakdown of the Affective dimension is confirmed and we obtain empirical evidence of the difference between the links generated by feelings of Identification and those generated by feelings of Pride of ownership.

The Commitment configuration to reflect upon is related to the breakdowns made in the normative dimension. This dimension is an important motivational force that has been overlooked and underutilized (McCormick and Donohue, 2016; Meyer and Parfyonova, 2010) and as McCormick and Donohue (2016) point out, they have been the object of conceptual reconfiguration over time (Wayne et al., 2009). In recent years, it has become a moral obligation (Meyer and Parfyonova, 2010). The second theoretical implication is that feelings promoted by the need for internal consistency and meeting responsibilities acquired (Moral Obligation dimension), based on cognitive dissonance theory of Festinger (1957), are stronger links with respect to the entity than those that may be generated by feelings of gratitude toward the organization, feelings that are reflected in the Gratitude dimension and based on the social exchange theory of Blau (1964), which does not show a sufficient level of variance and hence reliability.

Finally, in this study we have aimed at adapting organizational commitment to a specific field, and one which is as peculiar as voluntary organizations. The main theoretical contribution is, regarding NPOs, the most significant links to people who work in an NPO are those that are related to affective ties. In conclusion, this theoretical implication is aligned with motivational theory on intrinsic/extrinsic motivational factors and contribute to demonstrate how intrinsic motivations are more relevant than extrinsic motivations.

Research on commitment in NPOs underlines the role that management and human resources practices can play in fostering employee commitment (Cunningham, 2001; Alatrista and Arrowsmith, 2004). To undertake such research it is essential to identify the factors that promote the commitment and retention of NPO employees (McCormick and Donohue, 2016).

The first managerial implication is the individual's emotional bonds to the organization, defined as affective commitment, which are of great importance to NPOs. Employees and volunteers of NPOs are highly sensitive to the organization's mission and values and they strongly identify with the organization's social mission. NPO internal consumers need these affective bonds to feel committed to the organization and to bring the best to the organization (Ohana and Meyer, 2016) and these bonds influence motivation (Somers, 2010; Cohen, 2011). In considering individual links, this commitment is key to attitudes and behaviors, including higher performance, organizational citizenship behavior, as well as lower levels of turnover and absenteeism (Cunningham, 2001; Meyer et al., 2002; Ridder and McCandless, 2010). Strong employee engagement with values, missions, and goals is therefore essential to organizational success and organizational survival (Ridder and McCandless, 2010). Incorporated into the stated mission, organizational values provide guidance and justification for the decisions and behavior of members of the organization (O'Reilly et al., 1991; Lawrence and Lawrence, 2009). In this sense, in accordance with our results, the main implication for managers is that they have to declare publicly and clearly the organization's mission and values, and this declaration is a key factor in addressing the following:

Regarding volunteer engagement, this is the main aspect with which to attract and retain motivated volunteers because those volunteers feel that they identify with the organizational mission and values. Often, volunteers are motivated to join organizations on the basis of the compatibility of their individual beliefs and values with the organizational values that are adopted (Amos and Weathington, 2008; Van Vuuren et al., 2008).

Motivational aspect for employees: Non-profit employees often feel they are underpaid (Light, 2003; Kim and Lee, 2007; Handy et al., 2008) but they may be willing to sacrifice some money in order to serve a cause or specific social mission (Ohana and Meyer, 2016). In this way, in a context of scarce financial resources, our second recommendation is that human resources managers should consider the definition of job position and must establish mechanisms to promote appropriate activities in considering how they contribute to the mission of the organization. This is more effective than other retention systems such as reward systems (continuance commitment).

It is thus crucial to stress those work experiences that contribute to the feeling of belonging, and to develop an organizational culture based on common values and goals rather than on economic rewards, which can be impractical and unusual in most organizations. There is also evidence of links related to feelings of obligation and normative commitment, which have come to be associated with an accountability and a greater control of one's own activity that promotes long-lasting behaviors, although concerning this type of relationship there is little empirical support that backs previous results of our work. Therefore, we consider it important to deepen the knowledge of elements linking people with the organization in the context of NPOs and the relationship among them.

Although this work contributes to a better understanding of the nature of links between individuals and NPOs, it has also some limitations. The main limitation of this research is the size of the sample. In future works, it should be interesting to use larger and representative samples to deepen research into the differences between employees and volunteers. Although, the internal meaning of each dimension is still an open debate, and is necessary to clarify the relation between Affective and Normative dimensions, another future research could aim to analyze the relations of each dimension with other variables (e.g., satisfaction, social performance, organization culture) and their effects on them over time. We hope new works will explore these future research lines because are essential to develop mutually beneficial and satisfactory relationships between organization and person.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The reviewers JL, SG and handling Editor declared their shared affiliation, and the handling Editor states that the process nevertheless met the standards of a fair and objective review.