Enhancing students' well-being with a unified approach based on contextual behavioural science: A randomised experimental school-based intervention

A new generation of interventions has begun to move towards principles of acceptance that deal with the context and function of psychological events. The aim of this paper is to analyse the effectiveness of a brief contextual behavioural intervention to improve the psychological well-being of secondary school students. This intervention represents a unified model with key processes based on contextual behavioural science, including Acceptance and Commitment Therapy (ACT) and Functional Analytic Psychotherapy (FAP). We conducted an intervention with 94 students (age range 17 – 19 years), randomly assigned to an experimental group ( n = 50) or control group ( n = 44). Participants took a pretest and post-test of distress, life satisfaction, psychological flexibility and mindfulness. The intervention consisted of three sessions of 1 h each. The results showed significant differences between the groups in distress and significant differences for the interaction (group (cid:1) pre – post) in all the other variables. The intervention had greater benefits for girls than for boys. These results may provide a break-through, thus leading to a process of evidence-based


INTRODUCTION
Students spend much of their time in their classroom, and therefore, schools have the potential to exert a powerful influence on their psychological well-being. Over the last few decades, preventive interventions have been promoted to foster students' well-being. The need of interventions is supported by epidemiological research that has documented excessive levels of psychological issues in young people (Duffy et al., 2019;Global Burden of Disease, 2018;Zuberi et al., 2021). Indeed, the prevalence of psychological distress is increasing among the student population (Center for Collegiate Mental Health, 2016) and is higher among females than males (Nurullah, 2010). There is a strong link between students' distress and their ability to learn (Takahashi et al., 2020;Werner-Seidler et al., 2017). Other authors have concluded that the majority of distress is due to the absence of skills that are required to manage emotions (Durlak et al., 2011;Edwards et al., 2001). Given these circumstances, there is a need to develop strategies for improving skills within the academic arena, which could alleviate the adverse effects of psychological distress on students, as well as its impact on other related variables.
Contextual behavioural science (CBS) is a coherent, multilevel system of philosophical assumptions, scientific values and methodological commitments that drive theory and technology development Zettle et al., 2016). Furthermore, this is the research paradigm underlying both Acceptance and Commitment Therapy (ACT) and Functional Analytic Psychotherapy (FAP). Both therapies are considered to be transdiagnostic models because they understand the human being from a functional standpoint that goes far beyond the usual psychopathological diagnosis. Instead, the 'treat syndromes' principle is a way of targeting an expanded range of processes of change, such as: acceptance, values, and cognition (Hayes, 2019;Hayes et al., 2006Hayes et al., , 2012Timimi, 2014). These approaches belong to the philosophical assumptions of CBS, which assume that human suffering is common to human nature, both in people experiencing clinical conditions or general health problems and in normative populations. Thus, this contextual model addresses the common processes that may be involved in different diagnoses, rather than focusing on the underlying symptoms or disorders of each diagnosis.
On the one hand, ACT focuses on the processes of psychological flexibility that would allow people to adapt to their real circumstances, manage language and live according to their values in the present moment, whereas, FAP provides a context of therapeutic interaction, applying natural contingencies to modify the behaviour through living a meaningful life. For example, in using these principles to obtain perspective about unpleasant thoughts and the commitment to values (academic performance), mindfulness can be included without moving away from the Skinnerian principles of learning (i.e. extinction of rumination, differential reinforcement, contact with the present moment and positive reinforcement) in a psychological way and with educational pedagogy implications.
Combining FAP and ACT integrates the strengths of both, concentrating the core processes of change through language and direct experiences in session. Studies of this FAP-ACT hybrid are common in the literature (Callaghan et al., 2004;Macías & Valero, 2021;Macías et al., 2019), creating a broader and more comprehensive therapy, while remaining theoretically consistent and aligned with the goals of each therapy. This combination is rooted in the behavioural tradition and also in advanced functional analysis, as a procedure for applying these contextual principles to multiple situations. Several authors have advocated the utility of combining both approaches in various clinical conditions (Luciano et al., 2009;Tsai et al., 2009).
Evidence-based applications of these contextual therapies have yielded positive results in a wide range of clinical conditions, using both ACT (A-Tjak et al., 2015;Hayes, 2019;Hayes et al., 2006) and FAP Mangabeira et al., 2012), with a combination of these approaches (Macías & Valero, 2021;Macías et al., 2019). Furthermore, it is possible to include mindfulness because this is an effective way of capturing the attention of students. Mindfulness has become a trend around the world, which is partly influenced by admired celebrities practicing mindfulness. Moreover, in academic contexts, the FAP-ACT hybrid has been useful in improving student life satisfaction and school achievement (Cattivelli et al., 2014;Dray et al., 2017;Keogh et al., 2006). This methodology also improves the effectiveness of the intervention, by expanding the goal of the therapy to include clinically relevant behaviours, using the therapeutic relationship as a mechanism of change and functional generalisation, by extending the improvements that are induced in the classroom to other areas of students' lives to provide long-term maintenance.
More specifically, FAP offers the context to promote change by modifying natural contingencies (i.e. increase positive reinforcement) through an intense therapeutic relationship that is based on behavioural principles (i.e. operant and classical conditioning), and ACT allows students to work with perspective-taking and value-based methods in a simple way (Dixon et al., 2020). This combination has been shown to be innovative in the school setting because it allows for unifying the strengths of both models (Callaghan et al., 2004) and producing changes in relatively short periods of time about two or more sessions (Bryan et al., 2012). We incorporated our previous research, together with some other meta-analyses on the use of contextual therapies in adolescents (Gillard et al., 2018;Macías & Valero, 2021;Swain et al., 2015).
To extend the findings that have been obtained with the combination of the two models to other environments, this study aimed to confirm its effectiveness with a brief contextual intervention designed to improve the psychological well-being of secondary school students. Specifically, we expected that the benefits of contextual therapies would also extend to students, thus decreasing stress and increasing satisfaction and psychological flexibility. The programme provides the necessary skills and also acts as a resource or coping philosophy to 'vaccinate' students against dysfunctional behavioural repertoires that can potentially promote difficulties in their psychological well-being.
To the best of our knowledge, this study represents the first attempt to extend this programme, to achieve positive outcomes in an academic setting using a brief and group-based format. The aim of this model is to integrate CBS principles in a simple way taking into account the understanding and intervention adherence of adolescents, through different videos and demonstrations in the classroom. Promoting the well-being of students could increase their ability to cope with the high rates of distress and the challenges they face during this critical period of their development.

METHOD Participants
The participants belonged to three state-funded secondary schools, located in Malaga, southern Spain, all of whom voluntarily agreed to participate in this programme, with the aim of improving the psychological well-being of students. The secondary school head teacher requested the implementation of our training skills to reduce the levels of psychological distress in students, and the parents' council approved the presented programme. All of the participants of the three secondary schools were in the academic year that precedes entry into University, all had similar socio-economic status, the age range was 17-19 years, and all attended all of the sessions, thus showing the maximum rate of adherence to the intervention programme. The total number of participants (94 students: 48 females and 46 males) was entered into a quasirandom assignment to control and experimental groups, according to the alphabetical order of their surnames. From the class list, one student belonged to the control group, and the next student belonged to the experimental group, and this recurring pattern of selection was applied to the whole class. In the experimental group, there were 50 participants (28 females and 22 males), and in the control group, there were 44 participants (20 females and 24 males). The inclusion criteria for the study were that the participants performed at least two of the three sessions and that their participation was voluntary, because anyone could benefit from an effective intervention. The retention rate was 100 per cent, because the intervention was performed during secondary school hours; hence, no data or participants were lost in the analysis of the data.

Design
A pretest-post-test design was employed with a control group and random assignment of two conditions: one experimental group with ACT plus functional analytic strategies and the other to the control group. All of the participants completed the questionnaires before and after the intervention, and the control group was evaluated at a similar time as when the intervention took place. The sample was equally distributed across the three schools where the study was conducted. Within each class, the participants were randomly split between the control group and an experimental group. Pretests were given at the same time, and then, the post-tests were applied after the intervention.

Instruments
For quantitative analysis, several questionnaires were used to evaluate the elements of general well-being (distress, life satisfaction, psychological flexibility and mindfulness) that were the targets of the protocol (Table 1). The mindfulness variable was added, because this has been shown to correlate with self-regulatory behaviour, positive emotions and physical and psychological well-being (Smith et al., 2019) and it was the gateway to introducing and adding complex processes of change. The following questionnaires were used: General Health Questionnaire-12 (GHQ-12; Goldberg, 1978). This scale is a 12-item selfreport questionnaire that measures psychological distress. Items are graded using a 4-point scale from better than usual to much less than usual. A Likert-type scale was used (0, 1, 2, 3). The higher scores on this questionnaire indicate higher levels of psychological distress. A cut-off point of 12 is considered to be the limit for presenting a risk of distress (Hardy et al., 2003). The Cronbach's alpha coefficient on this scale for the current study was .76.
Satisfaction with Life Scale (SWLS; Diener, 2009). This scale is a five-item questionnaire that is designed to measure satisfaction with life. Participants indicate the extent to which they agree or disagree with each item, using a 7-point scale ranging from 1 (strongly disagree) to 7 (strongly agree). Higher scores on this questionnaire are taken to indicate greater life satisfaction. The Cronbach's alpha coefficient of this scale for the current study was .83.
Acceptance and Action Questionnaire II (AAQ-II; Bond et al., 2011). This scale is a sevenitem Likert-type self-report questionnaire that was created to measure psychological flexibility. This scale provides a total score and assesses experiential avoidance and psychological acceptance, which are key aspects of ACT. This instrument contains seven items rated from 1 (never) to 7 (always). Higher scores indicate lower levels of psychological flexibility. The Cronbach's alpha coefficient for the current study was .88. Programme based on contextual behavioural science (CBS) with the main activities 1. Programme benefits to promote intervention adherence and motivate students (EO). Building empathy, awareness, courage, love and behaviourism (ACL model of FAP). 2. Self-disclosures, shaping and modelling towards target behaviours. 3. Emphasis on the therapeutic alliance, emotional validation and positive reinforcement. Confidential and safe atmosphere within the group: groupal activity. 4. Language as the source of human suffering. Unpleasant thoughts versus values. 5. Functional group analysis (Table 2) and 'Text messages on your mobile phone'. 13. Perspective taking (hierarchical deictic relations and distinction). Homer Simpson and Autopilot.
Acceptance and observing exercise: 5 min of present moment and attention to breathing. Video: 'Celebrities and mindfulness'. 14. Relapse prevention. Metaphor: 'The rider', 'Japanese Bamboo', 'The mud' and 'Sticky notes'. 15. Home practice assignments seeking functional generalisation and functional interpretation. Acting with barriers (thoughts and feelings) towards values. Awareness in daily life and physicalisation.
Note: EO (establishing operation): Increases the current effectiveness of certain stimuli, objects or events as reinforcement. This table presents the main activities used to promote the changes. They include role plays, videos, metaphors, home assignments and examples. It is not a protocol or a recipe, they are only processes that allow changes to be produced and their flexibility allows to adjust it to each context for better outcomes.
Five Facets Mindfulness Questionnaire (FFMQ; Baer et al., 2006). This scale is the most widely used internationally to measure mindfulness and consists of 39 elements to assess five facets of mindfulness (observing, describing, acting with awareness, nonreactivity and nonjudging). The items are rated from 1 (never or very rarely true) to 5 (very often or always true). The scores on this questionnaire show a negative association with depression, anxiety and stress. The Cronbach's alpha coefficients for the current study were .70 (nonreactivity), .82 (observing), .77 (acting with awareness), .76 (describing), and .71 (nonjudging).
Participants filled out paper questionnaires, and the data were then manually entered into a database for analysis by two of the researchers.

Procedure
Three secondary schools were invited to take part in the study, to promote health in the academic environment, and they all accepted, with approval being obtained from the principal of each establishment. Approval for the study was also obtained from the corresponding Parents' Association. All parents were informed of the purpose of the study and the procedures, and no parents withheld their permission. Prior to any data collection, participants signed informed consent forms, which included a statement of the study objectives and confidentiality procedures. This study was approved by the Experimental Ethics Committee (47-2018-H), and all procedures were carried out in accordance with the Declaration of Helsinki.
The intervention was implemented in the same daily participation classroom, during a free 1-h time slot within their academic schedule. Each group session lasted about 60 min. The participants in each secondary school received the intervention across three group sessions (16, 17 and 17 students for each centre, respectively). The therapist was the same for all three groups and has 6 years of therapeutic experience under close supervision of experts in contextual psychotherapies.
All participants in the experimental group attended all three group sessions. The first two sessions took place on consecutive weeks, and the final session was held after an interval of 2 weeks. This latency period was used to practice the skills that were learned in the first two sessions. The intervention lasted 4 weeks, and post-test measures were completed just after the last session.
The programme was implemented using an adaptation of the '2 + 1' format (Barkham & Shapiro, 1990). This brief group intervention was based on strategies that were developed within the ACT framework by Wilson and Luciano (2002), including a short version of ACT, that was originally designed in the primary care field (Glover et al., 2016;Strosahl et al., 2012), and FAP (Tsai et al., 2009). All of these strategies were integrated to produce rapid changes (Macías et al., 2019). The intervention also presented the adoption of a stepped-care perspective: Quick interventions will not resolve the concerns for all students; however, the students could develop value-based intervention actions and acquire skills and resources with a focus towards additional care, if necessary. This brief ACT value-based intervention is an abridged version that distils the core methods (Table 1). In addition, we included mindfulness applications to introduce acceptance resources for coping with internal events. Readers are encouraged to consult the applications of the protocol at the workplace (Macías & Valero, 2021;Macías et al., 2019).
The philosophy of the intervention was to treat each session as if it were the last, inducing radical changes and promoting functional generalisation to other contexts ( Table 1). The mindfulness variables were disguised by including more complex processes based on Relational Frame Theory (Hayes et al., 2001), such as fostering hierarchical frames, which may produce changes in how participants relate with their thoughts and sensations to promote discomfort acceptance and reduce the control of internal experiences; responding to processes of extinction; and differential reinforcement with perspective-taking exercises (i.e. to reduce overthinking). Mindfulness is an attractive way of introducing adolescents to the benefits of more in-depth practices. Other examples of modelling or mentoring (i.e. as per celebrities who practise mindfulness) were also used, such as adapting language to the background of adolescents with functional equivalences/examples, as they could memorise in a better way (i.e. using videogames, series and films metaphors). The central processes were avoidance results (creative hopelessness), acceptance of private experiences, promoting mindfulness, awareness, commitment to a meaningful life that is normally connected with the presence of unwanted private events and functional analysis (Table 2). During the initial session, we presented the benefits of the programme and what it promotes. We worked with the experiential avoidance and control as a problem (i.e. the unworkable results of emotion/thought suppression); we designed a functional group analysis session in the classroom with the students ( Table 2) that incorporated the most common private events and the ways of coping with these events: clarification of values and commitment, creative hopelessness (i.e. consequences of struggle) and, finally, the self as context (i.e. acting with barriers). The second session focused on briefly summarising the previous session, which included exercises in defusion, promoting attention and awareness and the willingness to deal with unpleasantness (i.e. thoughts, sensations, feelings and emotions). for example, 'I'm not good enough', 'I am a looser', 'I am going to fail' (Table 2) and perspective taking through the participation in hierarchical frameworks with the deictic-self perspective (see Törneke et al., 2015). FAP was integrated into all exercises, in which the therapist promotes an intense and genuine therapeutic relationship Muñoz-Martínez & Follette, 2019), with all students carrying out personal self-revelation, with the purpose of being a mentor or model who is able to cope with difficulties in life, while considering the experiences which emerged during lectures, and shaping clinically relevant behaviours (i.e. problem behaviours) for others in a more flexible way. Problem behaviour was provoked in situ (i.e. imagination/role play during the intervention), target behaviour was reinforced and functional generalisation and functional interpretation were promoted: How can you extend these changes into your everyday life? For example, When laziness appears within me, and I immediately play video games, am I closer to the university or further away from it? The objective of the final session was to promote commitment to a life based on values (such as studying for a degree, having more satisfactory social relationships and improving partner and family relationships). We worked on relapse prevention and the acceptance of discomfort. All group sessions included homework assignments that were related to the content of each session, along with exercises and metaphors, to produce functional generalisation in the students' daily lives.
The participants in the control group only completed the questionnaires, in the first and last session; also, they had about an hour to ask questions about the tests, but usually, they did not have any doubts.

Data analysis
Our aim was to evaluate the effectiveness of this brief programme in the student population, so we hypothesised that psychological well-being variables (i.e. distress, life satisfaction, psychological flexibility and mindfulness) would improve after its implementation, as had occurred in other arenas (Macías & Valero, 2021;Macías et al., 2019). First, we made a one-factor ANOVA with all the variables in the preview measurement, to test the equality of both groups from the outset. Later, we conducted a series of ANOVA with repeated measures for two factors in all the variables. The pre-post scores were the within-subjects factor, and the group (experimental or control) was the intersubjects. Also, we made the same ANOVA with repeated measures considering the sex as intersubject factor, to find out if there was any difference between the sexes. The data were tested for normality using the Shapiro-Wilk test and for sphericity using the Mauchly test. The data analyses were conducted using SPSS 22.0 for Mac.

RESULTS
The initial comparison between the control and experimental groups showed no significant differences, indicating that the scores on the different questionnaires were similar at the start of the study with both groups.
The results of the ANOVA with repeated measures (2 groups Â 2 measurements) are displayed in Table 3. In relation to distress of GHQ, significant effects were found for group and for the interaction (group Â pre-post), with a high effect size (η 2 = .885). The experimental group showed lower scores on the post-test than the control group (M = 8.64 vs. M = 15.75) which could indicate a decrease in distress. The difference between the experimental and control groups was À10.22 points for girls, whereas this was À5.2 points for boys. Therefore, distress was less severe for girls when compared with boys. Figure 1 shows this difference about distress in GHQ-12, and it seems to indicate that females benefits more from the intervention.
Regarding life satisfaction with the SWLS, no significant effects of group were found, but the interaction group Â pre-post was significant, with large and medium effect size (η 2 = .948). The experimental group showed higher scores on the post-test than the control group (M = 25.52 vs. M = 22.11). The difference between the experimental and control groups was  5.88 points for girls, whereas this was 1.76 points for boys. Therefore, life satisfaction was higher for girls than for boys.
Also, psychological flexibility measured with AAQ-2 showed similar results, with no significant principal effects for groups, but significant for interaction with pre-post, and a high effect size (η 2 = .863). Similar results were found for the total scores of mindfulness (FFMQ), and they were significant for the interaction groups Â pre-post factors, The analysis of the different scales of FFMQ repeated the same results with significance for the interaction, a large effect size and higher scores in the experimental group (M = 125.76 vs. M = 118.23). Specific data for each variable in the different groups and pre-post measurements can be found in Table 3.

DISCUSSION
The aim of this study was to analyse the effectiveness of a brief contextual intervention that was designed to improve the psychological well-being of secondary school students. Evidence from previous studies has confirmed the effectiveness of this programme, with the combination of contextual therapies, when used in brief periods in the workplace (Macías et al., 2019;Macías-Mor on & y Valero-Aguayo, 2021a, 2021b. We aimed to provide evidence of its efficacy in other contexts, specifically in the school setting with teenage students, who face rather different challenges from those of working adults. Our hypothesis was that in students, values, functional generalisation, therapeutic relationship, functional analysis (Table 2), closeness or intimacy, as proposed by Kuczynski et al. (2018), are all key processes for producing changes in the dependent variables, and it could underlie other mechanisms of change Hofmann et al., 2021) in that intervention.
In relation to distress, we found that the experimental group showed significantly lower scores on the post-test in comparison with the control group, indicating an improvement in psychological distress. This reduction yielded a mean of 8.47 points on the post-test, which is below the cut-off point of 12, or the limit for presenting a risk of distress (Hardy et al., 2003), while the control group had 16.18 points on the post-test, which is above the cut-off point and is taken to indicate the risk of presenting psychological problems. F I G U R E 1 Average in the GHQ-12 variables (men, M; and female, F), between the experimental group and the control group. The average females benefit more from the intervention. Note: The experimental group decreases scores below the cut-off point of 12 (distress) With regard to the other variables (life satisfaction, psychological flexibility and mindfulness), there were no main effects of groups but of the interaction with measurement time. This could suggest that a longer intervention would be needed to produce higher changes in these scales. Previous research with ACT has shown a delayed longer term pattern of improvement that can be attributed in part, to a focus on greater acceptance and awareness of distress. Thus, the benefits appear to be more consistently observable in the long term (Luoma et al., 2012).
The results also revealed differences between girls and boys. First, girls compared with boys scored lower on distress and higher on life satisfaction. This finding is consistent with the results of previous studies showing that the prevalence of distress may be slightly higher in females than in males (Nurullah, 2010). Second, girls showed a greater improvement in both psychological distress and life satisfaction, indicating that the intervention had a greater benefit for girls than for boys. It is possible that girls are more able to take advantage of the intervention due to a greater capacity for self-reflection than boys during adolescence (Klimstra et al., 2009), and their distress scores were higher before the programme; therefore, they have the capacity to improve more than boys (Flaxman & Bond, 2010). It is also possible, however, that these results are due to a ceiling effect, that is, due to their higher baseline (pretest) scores, boys had a lesser potential for change than girls. Indeed, it has been suggested that low baseline levels of distress can obscure the observed impact of interventions on distress (Macías et al., 2019).
Overall, our results are congruent with those of previous research, indicating that two or more intervention sessions with brief protocols are sufficient to generate changes in people's psychological well-being (Bryan et al., 2012). These findings are also congruent with the results of a meta-analysis regarding the utility of contextual therapies in teenagers (Gillard et al., 2018;Swain et al., 2015). This study sought evidence that a short programme, with a focus on the core processes of contextual therapies, could be useful for students by integrating relevant processes (Hayes & Hofmann, 2017, 2019Hofmann et al., 2021;Ong et al., 2020).
In spite of the positive results reported here, this study has certain limitations that should be considered. First, although we organised a waiting list control group for the intervention, this was finally not implemented due to problems with the secondary school schedule and the coordination of the final exam timetable. Thus, the control group did not receive the intervention, and the participants did not benefit from it due to organisational changes at the secondary school. Furthermore, the total sample can be considered small and would have limitations in its generalisability to other more diverse samples.
Second, the long-term monitoring of these results was not possible because students stopped attending classes to study for the university entrance exam, and thus, they could not be re-recruited. Therefore, it is not possible to draw any firm conclusions about the long-term results of this programme.
Finally, the intervention not only included ACT but also FAP and mindfulness components, and so all of the six key processes of ACTs were not strictly applied (e.g. the self as context, values or commitment to action were only partially worked on). Previous studies that strictly applied ACT processes reported changes in psychological flexibility (Hayes, 2019;Hayes et al., 2006).
We think this short three-session programme constitutes a promising starting point for developing interventions that can produce changes in short periods of time. We might be at a new departure point for creating generations of students with more flexible repertoires.