Stressors linked to the work context are considered by the International Labor Organization (ILO, 2016) and the World Health Organization (WHO, 2020) as a new epidemic. A study by the European Agency for Safety and Health at Work states that 25 % of workers experience stress related to the development of their duties during all or almost all their working time, and a similar percentage states that work has a negative effect on their health (Eurofound & European Agency for Safety and Health at Work, 2014).

Considering the important economic consequences and the negative effect of stressors on the physical and emotional health of employees, different authors have proposed this construct as one of the main study focuses of Work and Organizational Psychology (García, 2020; Wang et al., 2020). The context of public universities is no stranger to this reality. Different authors have observed that stress is one of the most frequent problems in universities, negatively affecting the different groups that work there (Díaz-Corchuelo, 2015; Elema et al., 2021; Han et al., 2020; Lee et al., 2022; Mark & Smith 2018; Puertas-Molero et al., 2018; Stang-Rabrig et al., 2022; Williams et al., 2017; Xu et al., 2023)

Employees of higher education institutions have suffered important changes that increase their sources of stress (Martínez-Díaz et al., 2021; Urbina-Garcia, 2020). The global emergence of the socio-health crisis associated with COVID-19 meant a radical change in the context of universities. These centers responded to the pandemic by promoting the use of ICT in administration and management procedures, as well as teleworking to minimize social contacts. This has led to the implementation of new ways of developing job functions, causing a reduction in the employee's levels of autonomy and an increase in their role ambiguity (Hegney et al., 2021; Kinman & Johnson, 2019; Kinman, 2014; Kuvaas & Buch, 2020).

On many occasions, when the effects of the pandemic in public universities have been studied, attention has been focused mainly on the groups of students and teaching and research staff (Husky et al., 2020; Odriozola-González, 2020), without paying attention to the effects of these changes on the technical staff of management, administration and services. These professionals are in charge of the technical, economic and administrative management of the University, as well as support, advice and assistance in the development of the functions of the rest of the members of the institution (Organic Law 6/2001, of December 21^st, of universities). Therefore, it is essential to know the effect of these changes on these key professionals when optimizing the results of the services provided in these educational organizations (Poalses & Bezuidenhout, 2018).

Role ambiguity describes situations where the employee perceives a lack of clear information about their functions (Rizzo et al., 1970; Schmidt et al., 2014). The concept of role ambiguity has gone through different stages and controversies in its definition (De Clercq, 2019). It is currently accepted that role ambiguity is the dimension of role stress that refers to the uncertainty experienced by employees, about the key requirements of their job and how they are expected to behave (Keshavarz & Mohammadi, 2011; Martínez-Díaz et al., 2020). Employees in situations of role ambiguity will feel hindered by considering that there are significant information deficiencies, so they will adopt non-creative behaviors, establishing routine behavior patterns as a stress coping mechanism (Maden-Eyiusta, 2019). Therefore, most research associates this variable with negative outcomes such as emotional exhaustion (Singh et al., 2012), depression (Schmidt et al., 2014) or reduced work performance (Zhou et al., 2016). However, at certain levels of perceived ambiguity, these same workers could significantly increase their effort and creativity in search of reversing that situation for their own benefit (De Clercq, 2019). Already Kahn et al. (1964) in an influential study stated that situations of ambiguity can challenge employees and increase their ability to meet performance requirements, although it is still unclear how this change occurs in employees' emotional reaction to ambiguity occurs.

A large group of studies focus their attention on role ambiguity within higher education institutions, as one of the main stress factors in groups linked to these institutions (Cladellas-Pros et al., 2018; Nava & Zavala, 2017; Yousefi & Abdullah, 2019). These studies associate ambiguity to low levels of satisfaction, motivation, and productivity, as well as higher staff turnover (Gormley, 2005; Surdez et al., 2017). However, these investigations have been developed on samples of students, teachers and research staff (Malone, 2002; Schulz, 2013; Surdez et al., 2017), not addressing the study of the group of management, administration, and services technical staff.

One of the theories that makes it possible to deepen the study of the influence that role ambiguity presents on employee response is the theory of Job Demands and Resources (JD-R) (Bakker & Demerouti, 2017). In the pioneering studies on this theory, job demands are perceived as those circumstances that interfere with or inhibit a person's ability to achieve their goals (Cavanaugh et al., 2000; Demerouti & Bakker, 2011). The negative influence of these, maintained over time, can cause health deterioration and weaken employee engagement, thus making it difficult for organizations to achieve their objectives and reducing employee well-being (Bakker & Demerouti 2013). However, recent studies (De Clercq, 2019; McMahan & Evans, 2018) are betting on the fact that job demands need not carry only a negative connotation. Bakker and Demerouti (2017), the precursors of this theory, after a recent review, present the demands from a double perspective, dividing them into hindering demands and challenging demands.

Recently, the multiplicative impact of job demands and job resources on employee well-being has been pointed out in the JD-R Theory. One of the propositions of this theory indicates that job demands can amplify the impact of job resources on work engagement, so that, in environments with high or challenging job demands, job resources become more importance on work engagement, buffering the negative effect of job demands. Specifically, employees who experience work engagement are intrinsically motivated to stay engaged, which leads them to proactively optimize their jobs. Over time, this proactive behavior generates personal and work resources to cope with job demands, which in turn promotes work engagement (Bakker et al., 2023).

When analyzing the effect of demands on the employee, the element to which most attention is directed is engagement. The importance of studying this construct lies in its sensitivity to stressors at work (Curran & Prottas, 2017). In this negative influence, the dimension of engagement that has shown the greatest sensitivity to role ambiguity is intellectual engagement (Abu-Hamour, 2018). This variable has increased its relevance in scientific publications in recent decades, especially due to its link to the achievement of competitive advantages and success (Crawford et al., 2010; Harter et al., 2002; Saks & Gruman, 2014). The first conceptualization of intellectual engagement is that proposed by Soane et al. (2012). According to these authors, engagement is operationalized based on the satisfaction of employees' needs. In this approach, the authors differentiate between three relevant aspects to study within engagement: intellectual dimension, social dimension, and affective dimension. Thus, intellectual engagement can be considered as the level of mental absorption in the work and the worker's willingness to contribute their abilities to improve it. More recently, authors such as Khalid et al. (2015) define intellectual engagement as the effort made by employees to contribute their knowledge and intellectual capacity to better perform work tasks.

An explanation for the sensitivity of intellectual engagement towards the increase in role ambiguity is found in the Conservation of Resources theory (Hobfoll, 1989). From this approach it can be predicted that high levels of ambiguity associated with job functions will begin to affect mainly intellectual engagement. In this way, public employees would show an initial pattern of disengagement of their intellectual contribution in response to job ambiguity, directing their effort to minimize the net loss of resources. In line with this idea, the first hypothesis of this paper states that:

Hypothesis 1: Workers subjected to work contexts with increasing levels of role ambiguity initially show a reduction in their level of intellectual engagement with the organization.

Despite the primacy of works that have addressed the study of role ambiguity as an hindrance (De Clercq, 2019), recent studies linked to the JD-R model have proposed the possibility that, when job demands arise, workers could change their way of responding to this situation in a significant way (Eatough et al., 2011; Gilboa et al., 2008; Tadić et al., 2015). These studies suggest that employees can react positively to situations of ambiguity when they perceive that facing them can lead to positive consequences.

Very few studies have addressed the possible positive influence of role ambiguity on employee engagement, and more specifically on their intellectual contribution (Sun et al., 2019). Solberg & Wong (2016) have found results along these lines, and conclude that, in certain situations with high levels of job demands, increases in employee engagement levels can be generated, depending on the perception that they have of the conditions in which high demands appear. In this line, the results found by Antwi et al. (2019) and Martín-Martín et al. (2022) are of interest, where it is concluded that positive and negative responses to a demand can occur at the same time in a work context, with a curvilinear relationship appearing between these variables depending on the degree to which the stressor is perceived by the employee. Based on this, the

Hypothesis 2: The relationship between role ambiguity and intellectual commitment will not be linear, but curvilinear, generating at a certain point a change in tendency.

Therefore, this paper aims to open a new line of debate on the possible curvilinear effect, from negative to positive of role ambiguity as a job demand on the intellectual contribution of employees, based on the distinction between hindrance demands and challenge demands made by Bakker and Demerouti (2017) from the JD-R model.

Table 1 shows the means, standard deviations, and bivariate correlations between the variables. We observed a significant negative correlation between perceptions of role ambiguity and intellectual engagement (-0.31**). The relationships between role ambiguity with age and intellectual engagement with age were not significant. These results suggest that increased role ambiguity for the worker, in terms of perceptions of ambiguity, was associated with a lower intellectual engagement.

Table 1 Table 1 Descriptive data and correlations Note.

**p > 0.001, n/s: not significant

The results of the hierarchical regressions are presented in Table 2. The results indicated that linear perceived benefit terms predicted a reduction of the values of intellectual engagement in employees (β: -0.33, p < 0.05). In contrast, the linear overprinting (role ambiguity squared) was also significant, but with a change of sign to show a positive influence (β: 0.27, p < 0.05). This shows variation in intellectual engagement, beyond the predictive capacity of the linear term and the control variables (ΔR2: 0.06, p < 0.001). Therefore, our findings supported a curvilinear relationship between perceptions of role ambiguity and intellectual engagement. Because the contribution of the squared terms was significant, the maximization hypothesis was rejected.

Table 2 Table 2 Regression analysis Note.

β Standardized Coefficient.

The positives β in the final step show non-linear relationships, represented by U-shapes (see Figure 1). This figure confirmed the asymmetric curvilinear shape in relationships. The highest intellectual engagement is observed around the low role ambiguity zone. Intellectual engagement scores are reduced when perceptions approach mid-levels of perceptions of role ambiguity. Finally, intellectual engagement improves slightly when perceptions approach the area of role ambiguity.

Figure 1. Figure 1. Curvilinear relationship between role ambiguity and intellectual engagement.

The present research study contributes to deepening the knowledge of the different roles that labor demands can take in the organizational context of a public administration, and how these can vary, affecting the consequences they have for employees and the organization itself. Specifically, the results demonstrate the influence of the perception of role ambiguity in the technical staff of management, administration and services of a Spanish university on their evaluations of intellectual engagement towards their organization. The results confirm an asymmetric curvilinear relationship, in which the evaluations of intellectual engagement are reduced in these employees when they perceive increasing situations of role ambiguity. This negative influence on the level of intellectual engagement changes and becomes positive when faced with medium or even high perceptions of role ambiguity, increasing the employee's intellectual engagement when their perceptions of role ambiguity rise to the highest values ​​of the scale. These results lead us to confirm the two hypotheses previously stated in this study. The first hypothesis stated that workers subjected to work contexts with increasing levels of demands, such as role ambiguity, will initially experience a reduction in their level of intellectual engagement with the organization. In the second hypothesis, it is proposed that the relationship between role ambiguity and intellectual engagement will not be linear, but curvilinear, generating at a certain point, a change in trend. The findings of non-linear relationships between role ambiguity and intellectual engagement in management, administration and services employees of a Spanish public university, identify the double role of role ambiguity. Depending on the employee's level of perception of this demand, it can act as a hindrance demand or as a challenging demand regarding their emotional state.

The results shown in this study despite supporting in its first hypothesis the research generated around the negative influence of demands in higher education institutions in line with other previous results (Díaz-Corchuelo, 2015; Elema et al., 2021; Han et al., 2020; Lee et al., 2022; Mark & Smith, 2018; Puertas-Molero et al., 2018; Stang-Rabrig, et al., 2022; Williams et al., 2017;Xu et al., 2023), also confirm that job demands do not have to entail only negative consequences (De Clercq, 2019; McMahan & Evans, 2018). The data reinforce the idea of ​​Martín-Martín et al. (2022) and Solberg & Wong (2016), who conclude that, in certain situations with high levels of job demands, the employee response will be to increase engagement levels.

In the specific case of role ambiguity object of this study, this is a construct that is traditionally identified as a hindering demand (Cladellas-Pros et al., 2018; Maden-Eyiusta, 2019; Nava & Zavala, 2017; Yousefi & Abdullah, 2019). Very few works that have addressed the possible positive influence of role ambiguity (Martínez-Díaz et al., 2021), and especially in the administration and services staff of a public university. The results of this research are in line with those authors who point out that role ambiguity has a negative effect on the engagement of public administration employees, but we clarify that this negative effect will be mainly in the initial periods of perception of role ambiguity, when the worker increases this perception. For all these reasons, this paper opens a new line of debate on the possible positive effect of this job demand on the intellectual contribution of employees, although this occurs at the highest levels of perceived ambiguity.