Introduction

Lazarus and Folkman (1984)[2]conceptualize psychological stress as an emotional response to one’s appraisal of an imbalance between a stressor and one’s perceived ability to cope with it. Perceived pressure, unrealistic expectations, unfavorable comparisons to others and fear of failure contribute to appraisal processes that fuel psychological stress for adolescents [3]. Thus, understanding mechanisms that impact the appraisal process is a critical step in mitigating negative adolescent emotional experiences. Mindfulness-based school interventions (e.g., yoga) have recently exploded in order to enhance adolescent emotional well-being [4]. Although the emerging evidence is promising we have much to learn about the processes explaining how mindfulness serves this purpose during adolescence [4-6].

In yoga practice, the experience of mindfulness is cultivated. Mindfulness is defined as present-focused attention with characteristics of non judgment and openness to one’s experience [7,8]. The processes underlying the effects of mindfulness on stress are not fully elucidated [9], particularly with adolescent samples. Mindfulness research with adults demonstrates that mindfulness is associated with neurocognitive self-regulation processes of executive functions, attention, and memory [10]. Teper, Segal, & Inzlicht (2013) [11] proposed a model suggesting that mindfulness activates self-regulation processes through the present-moment awareness and non-judgmental acceptance of emotional experiences, thus providing cues which stimulate executive functions in order to modulate emotional well-being. Thus, mindfulness may reduce a negative stress response by way of executive functions moderating the appraisal process, to apply [2] perspective. This model theoretically links mindfulness with emotional experiences, such as stress, by way of executive functioning, a neuropsychological construct representing skills involved in forming, maintaining, and shifting mental sets used in goal-directed behavior [12].

Short, Mazmanian, Oinonen, and Mushquash(2016)explored a model to evaluate whether the relationship between trait mindfulness and emotional well-being was mediated by executive functioning and self-regulation using a two phase study in young adults. In phase one, self-reported dispositional mindfulness and neurocognitive performance were assessed. Four weeks later, in phase two, self-reported executive functioning, self-regulation, and emotional well-being were assessed. Results supported a model where self-reported trait mindfulness at time one directly predicted time two assessed self-reported executive functioning and self-regulation, and indirectly predicted emotional well-being. In addition to trait mindfulness, there is evidence that state or situational mindfulness has independent associations with emotional well-being [13-15]. However, there is no research examining trait and state mindfulness side by side as potential mechanisms for explaining stress in adolescents.

Self-compassion is another core mechanism that may help explain adolescent emotional well-being. Self-compassion involves a compassionate stance towards one’s self in times of failure or suffering through self-kindness, a sense of common humanity, and mindfulness [16] and has received initial support for adolescents’ adaptive regulation of cognitions and emotions [17]. Although there is some conceptual overlap with mindfulness, self-compassion explains unique variance in emotional well-being beyond mindfulness in adults [18,19]. Though self-compassion strategies have been included as part of mindfulness programming in schools [2,6]we only have limited evidence linking aspects of self-compassion with adolescent stress  [17,21,22]. Given the similar functions underlying mindfulness and self-compassion, executive functioning may also serve to mediate the association between self-compassion and emotional responses.

The purpose of this study was to extend the model supported by [1] to an adolescent sample and to include both trait and state mindfulness as well as self-compassion to predict stress by way of executive functioning. We tested our proposed model (see Figure 1) with a pilot study employing a 12-week yoga curriculum. This model was relevant to test in the yoga context given that no mean changes were observed in trait level mindfulness, self-compassion, or stress¹. Based on [1] we hypothesized that trait mindfulness and self-compassionate time one would negatively predict problems with executive functioning directly and stress indirectly at time two. Based on [13-15]we hypothesized that students’ average levels of state mindfulness experienced during the yoga classes across the 12 weeks would negatively predict stress directly.

1. Methods

      1.1 Participants and Procedures

Participants (N = 20) were primarily Caucasian (85.0%) and female (90%) and in 10^ththrough 12^th grades (M_age = 16.45, SD = 1.0). Twenty-three students participated in the yoga curriculum² (Author Citation a, under review) as part of their Physical Education (PE) class (one student joined late and was not included; another student had developmental difficulties and one student did not complete the final assessments). Each week of the 12-week curriculum was led by a certified yoga instructor (200-hour Anusara Yoga Teacher Training certification program) and focused on a theme (e.g., self-compassion; overcoming obstacles) that was integrated into two yoga sessions that week (1 50-minute and 1 80-minute). Each yoga practice included an introduction and centering exercise, practice moving through and holding different asanas (i.e., poses) and a closing and meditation exercise. Students in this class typically elect this class to fulfill their PE requirement, do not participation in school sports, may have low interest in traditional physical education, and are mostly female. The majority (90%) of participants reported beginning to begin intermediate yoga experience. Participants completed the measures of trait mindfulness and self-compassion the week before beginning a 12-week yoga program (time one) in their physical education class. State mindfulness was assessed immediately following one yoga class per week. At the end of twelve weeks, participants completed the measures of executive functioning and stress (time two).

      1.2 Measures

Trait mindfulness was assessed using [23] 20-item Philadelphia Mindfulness Scale. Two subscales capture trait awareness (e.g., “I am aware of what thoughts are passing through my mind”) and acceptance (e.g., “There are things I try not to think about”). Responses fall on a 5-point Likert scale of never to very often, with higher scores on each scale reflecting higher levels of mindful awareness or acceptance. This measure has supporting evidence of internal consistency reliability and validity [23]. Alpha reliability was low for both trait mindfulness scales. Several items³had low inter-item correlations. With these items removed, reliability improved for the awareness scale (α = .71) and the acceptance scale (α = .69).

Self-compassion was assessed using [24] Self-Compassion Scale. The 26-item scale assesses three positive (self-kindness, common humanity, mindfulness) and three negative (self-judgement, isolation, over-identification) dimensions underlying self-compassion. Participants respond to how often they experience a particular response to pain and suffering (e.g., “I see my failings as part of the human condition” - common humanity; “When I’m feeling down I tend to obsess and fixate on everything that is wrong” - over-identification) using a 5-point scale ranging from almost never to almost always. A total average score was calculated where higher scores reflect higher self-compassion. Conceptual and psychometric properties of the scale are supported, including for adolescents [16,25].

Stress was assessed using the Perceived Stress Scale [26]. The PSS items tap into the perceived level of stress experienced in the last week (modified from last month to provide a more proximal indicator of perceived stress; similar modifications are not expected to decrease validity) (e.g., “In the last week, how often have you felt difficulties were piling up so high that you could not overcome them”). The PSS contains 14 items and is scored on a 5-point scale with response options ranging from never to very often. The PSS has supporting evidence for psychometric properties [26] and use in adolescent samples [21].

Executive functioning was assessed with the self-report form of the Delis Rating of Executive Functions [27], a rating scale of reported behavioral problems for 11-18-year-olds. There are 36 items asking the individual to rate the frequency of behaviors in the last 6 months on a 4-point scale ranging from seldom or never to daily. These items are used to calculate six scores or indices of executive function. Threescore represent dysfunction relative to 1) behavior (“I say things I wish I hadn’t”), 2) emotion (“I try to control my anger but I just can’t”), and 3) cognition (“I have a difficult time putting my thoughts down in writing”). There are also three clinically derived scores representing dysfunction of 1) attention &working memory (“I get confused when I have two or more things to do at the same time”), 2) activity level impulse control (“I just can’t help doing things that I’m told not to do”), and 3) compliance &anger management (“I get really upset when people interfere with what I’m doing”). The six indices are presented as T scores, age and gender adjusted, with values of 50 representing the norm sample average. Evidence supports reliability, content, construct, and concurrent validity [27].Internal consistency reliability information was not available for scores obtained through the DREF online interface.

State mindfulness experienced during the yoga classes was assessed immediately following class each week using the State Mindfulness Scale for Physical Activity [28]. The SMS-PA has six items each capturing mindfulness of mental (e.g., “I was aware of different emotions that arose in me”) and physical objects (e.g., “I felt present in my body”) during a specific experience. Responses to how much each item was experienced fall on a 5-point scale ranging from not at all to very much. All 12 items were averaged with higher scores representing higher mindfulness during the yoga class. Weekly scores were averaged across the twelve weeks to represent average state mindfulness experienced in the yoga class. Initial evidence supports the internal consistency reliability, factorial, and construct validity using adult samples [28]and with youth samples as young as 10 years-old (Author Citation b, under review). Alpha reliability was good across assessments (α_range= .76 - .97) and when averaged across time points (α_average = .90).

      1.3 Data Analysis

Data screening for missing values and normality was conducted and descriptive statistics were calculated. Hypothesized mediational models were tested with path models using Mplus 7. Time onescores of mindfulness (i.e., trait acceptance, and awareness) and self-compassion were entered into the model directly predicting executive functioning at time two and indirectly predicting stressat time two through executive functioning as per [1]. Average state mindfulness during the yoga classes across the 12 weeks was also entered as a direct predictor of stress at the end of the 12 weeks (see Figure 1). Six separate models were run to test each of the six indices of executive functioning. To obtain 95% confidence intervals, we conducted bootstrapping specifying 5000 samples to reduce standardized error bias and for type I error correction [29].Completely standardized path coefficients were reported along with absolute and incremental model fit indices [30]. Given the exploratory nature of our study and small sample size, we report exact p values, confidence intervals and effect sizes for broad interpretation as reliance on significance levels is limiting. Confidence intervals that do not cross 0.00 were interpreted as reliable. Effect sizes were interpreted as minimal (.04), moderate (.25), and strong (.64) [31].

Results and Discussion

There was negligible missing data (.02%) and Little’s MCAR test was non-significant (χ²= 40.34 (47), p = .74), therefore Expectation Maximization imputation was used on all constructs except executive functioning indices (.01% missing but not imputed per [27] and state mindfulness (usedall available weekly state scores to create average state scores, average of 8.6 of 11 scores available).Data screening showed variables to be approximately normal. See (Table 1)for descriptive statistics.

Notes:^Trait mindfulness subscales, BF = Behavior Functioning, EMF = Emotional Functioning, CF = Cognitive Functioning, AWM = Attention & Working Memory, AIC = Activity Level & Impulse Control, CAM = Compliance & Anger Management. * p < .05 **p < .01.

The trait mindfulness subscales (acceptance, awareness)did not significantly predict any of the indices of executive functioning. It is unclear if this was due to marginal reliability of these scales which have limited use with adolescent samples and/or low power. The Philadelphia Mindfulness Scale was used in this study as it conceptually aligned with the suggested mechanisms for the effectiveness of mindfulness through scales of both acceptance and awareness [11]. However, validation with adolescent samples is needed. Research with adults has sometimes demonstrated the stronger role of self-compassion relative to mindfulness when predicting emotional well-being [18,19], which could explain this finding. Further research is necessary to test the hypothesized model with trait mindfulness, executive functioning and stress in larger, more representative adolescent samples and across different yoga experiences.

We proceeded to test the six mediation models with only self-compassion and state mindfulness. All models provided good fit and explained 17% to 46%of the variance in stress (see Table 2). Self-compassion significantly predicted behavioral functioning and activity level impulse control, with a significant indirect effect to stress through activity level impulse control. This finding provides preliminary support for the hypothesized role of executive functioning in explaining the relationship between self-compassion and stress. Results are consistent with [1] who also supported a model with self-reported dysfunction in executive functioning mediating the association of trait level psychological resilience (i.e., mindfulness) and negative emotional well-being (i.e., negative affect). Emerging empirical evidence linking self-compassion with the emotional well-being of adolescents [17,21] coupled with the moderate effect sizes in our results indicate that self-compassion as a resilience factor in adolescents is worthy of more rigorous exploration.

Notes: AWM = Attention & Working Memory, AIC = Activity Level & Impulse Control, CAM = Compliance & Anger Management.

Impulse control has been linked with managing emotional responses with short-term emotional relief over longer-term goal directed emotional well-being [32]. Self-compassion may reduce problems with impulse control and associated behavior regulation problems by allowing one to experience suffering in a gentle way and reducing the need to avoid negative emotional experiences through behavioral responses, such as speaking before thinking. Even with limited power, we were able to detect these associations, with minimal to moderate effect sizes (R² = .18, .19) supporting our conceptualization of how self-compassion can impact psychological and behavioral manifestations of well-being.

The average experience of state mindfulness during the 12 weeks of yoga classes predicted stress in all models except for behavioral functioning and activity level impulse control, demonstrating a robust negative association with stress even with executive functioning included in the model. Both trait, or dispositional levels of psychological variables, such as self-compassion, and state level experiences may be important to consider when examining the effects of yoga interventions and is supported by work with adults demonstrating the independent effects of state and trait mindfulness [13]. Thus, yoga interventions that foster state mindfulness and self-compassion may reduce stress responses, regardless of students’ dispositional tendencies in mindfulness. Even in cases where students’ dispositional tendencies do not change, as was the case in this study, these state-level experiences may effect change in well-being. These results reflect recent systematic reviews of the mindfulness literature which suggest that more than half of mindfulness interventions do not demonstrate significant self-reported mindfulness change [33]and that assessment of mindfulness practice is a significant predictor of emotional well-being [15,34]. Further work using more rigorous experimental research designs could shed more light on the relative importance of changes in dispositions versus state experiences during contemplative-based school interventions. Further, although we aligned our model with the procedures of [1], true mediation should be tested with executive functioning assessed prior to stress [35].

Conclusions

This study explored the association between trait mindfulness and self-compassion with executive functioning and stress in adolescents participating in a yoga curriculum at school. By including self-compassion in this study, we extended [1] findings to a construct that is both conceptually and empirically distinct from mindfulness [36]. This study provides promising evidence supporting further examination of the role of state mindfulness and self-compassion in reducing adolescent stress, areas of study with minimal empirical research evidence, but high popularity and enthusiasm for implementation [4]. Our results should be considered as preliminary and viewed within limitations of sample and design. Future studies can build from this preliminary evidence by examining larger, more diverse samples with the use of more rigorous experimental research designs to detail the unique effects of trait mindfulness, self-compassion, and state mindfulness in adolescent emotion regulation processes.

Footnotes

¹Contact the corresponding author for details about null findings regarding mean change in these variables.

² Contact the corresponding author for details about the yoga curriculum. Because the yoga curriculum employed a regular educational practice, this study was determined to be exempt from Institutional Approval. Parents were informed of the curriculum and the study procedures. All parents provided permission and students provided assent to participate.

³Awareness items removed included “When talking with other people, I am aware of their facial and body expressions”; “When I shower, I am aware of how the water is running over my body”. Acceptance items removed included “There are aspects of myself I don’t want to think about”; “I tell myself that I shouldn’t feel sad”.

Figure 1: Hypothesized Model.

1. Short MM, Mazmanian D, Oinonen K, Mushquash CJ (2016) Executive function and self-regulation mediate dispositional mindfulness and well-being. Personality and Individual Differences 93: 97-103.
2. Lazarus RS and Folkman S (1984)Stress, appraisal, and coping, Springer Publishing Company, New York, NY.
3. Murberg TA and Bru E (2004) School-related stress and psychosomatic symptoms among Norwegian adolescents. School Psychology International 25: 317-332.
4. Zenner C, Herrnleben-Kurz S, Walach H (2014) Mindfulness-based interventions in schools- A systematic review and meta-analysis. Frontiers in Psychology 5: 603.
5. Davidson RJ, Dunne J, Eccles JS, Engle A, Greenberg M, et al. (2012) Contemplative practices and mental training: Prospects for American education. Child Development Perspectives 6: 146-153.
6. Roeser RW and Pinela C (2014) Mindfulness and compassion training in adolescence: A developmental contemplative science perspective. New Directions for Youth Development 142: 9-30.
7. Bishop SR, Lau M, Shapiro S, Carlson L, Anderson ND et al. (2004) Mindfulness: A proposed operational definition. Clinical Psychology: Science and Practice 11: 230-241.
8. Kabat-Zinn J (2005) Coming to our senses: Healing ourselves and the world through mindfulness. Hyperion, New York, NY.
9. Isbel B, Mahar D (2015) Cognitive mechanisms of mindfulness: A test of current models. Consciousness and Cognition 38: 50-59.
10. Chiesa A, Calati R, Serretti A (2011) Does mindfulness training improve cognitive abilities? A systematic review of neuropsychological findings. Clinical Psychology Review 31: 449-464.
11. Teper R, Segal ZV, Inzlicht M (2013) Inside the mindful mind how mindfulness enhances emotion regulation through improvements in executive control. Current Directions in Psychological Science 22: 449-454.
12. Suchy Y (2009) Executive functioning: Overview, assessment, and research issues for non-neuropsychologists. Annals of Behavioral Medicine 37: 106-116.
13. Brown KW and Ryan RM (2003) The benefits of being present: The role of mindfulness in psychological well-being. Journal of Personality and Social Psychology 84: 822-848.
14. Kirken LG, Garland EL, Bluth K, Palsson OLS, Gaylord SA (2015) From a state to a trait: Trajectories of state mindfulness in meditation during intervention predicts changes in trait mindfulness. Personality and Individual Differences 81:41-46.
15. Weinstein N, Brown KW, Ryan RM (2009) A multi-method examination of the effects of mindfulness on stress attribution, coping, and emotional well-being. Journal of Research in Personality 43: 374-385.
16. Neff KD (2016) The Self-Compassion Scale is a valid and theoretically coherent measure of self-compassion. Mindfulness 7: 264-274.
17. Bluth K and Blanthon PW (2015) The influence of self-compassion on emotional well-being among early and older adolescent males and females. Journal of Positive Psychology 10: 219-230.
18. Baer RA, Lykins ELB, Peters JR (2012) Mindfulness and self-compassion as predictors of psychological well-being in long-term mediators and matched nonmediators. The Journal of Positive Psychology 7: 230-238.
19. Van Dam NT, Sheppard SC, Forsyth JP, Earleywine M (2011) Self-compassion is a better predictor than mindfulness of symptom severity and quality of life in mixed anxiety and depression. Journal of Anxiety Disorders 25: 123-130.
20. Meiklejohn J, Phillips C, Freedman ML, GriffinML, Biegel Get al. (2012) Integrating mindfulness training into K-12 education: Fostering the resilience of teachers and students. Mindfulness 3: 291-307.
21. Bluth K, Roberson PNE, Gaylord SA, Faurot KR, Grewen KMet al. (2016) Does self-compassion protect adolescents from stress? Journal of Child and Family Studies 25: 1098-1109.
22. Neff KD and McGeehee P (2010) Self-compassion and psychological resilience among adolescents and young adults. Self and Identity 9: 225-240.
23. Cardaciotto L, Herbert JD, Forman EM, Moitra E, Farrow V (2008) The assessment of present-moment awareness and acceptance: The Philadelphia Mindfulness Scale. Assessment 15:204-223.
24. Neff KD (2003) The Development and Validation of a Scale to Measure Self-Compassion. Self and Identity 2: 223-250.
25. Cunha M, Zavier A, Castilho P (2016) Understanding self-compassion in adolescents: Validation study of the self-compassion scale. Personality and Individual Differences 93: 56-62.
26. Cohen S, Kamarck T, Mermelstein R (1983) A global measure of perceived stress. Journal of Health and Social Behavior 24: 385-396.
27. Delis DC (2012) Delis rating of executive functioning. Pearson,Bloomington, MN.
28. Cox A, Ullrich-French S, French B (2016) Validity evidence for state mindfulness scale scores in a physical activity context. Measurement in Physical Education and Exercise Science 20: 38-49.
29. Hayes AF and Preacher KJ (2014) Statistical mediation analysis with a multicategorical independent variable. British Journal of Mathematical and Statistical Psychology 67: 451- 470.
30. Kline RB (2005) Principles and Practice of Structural Equation Modeling. In:2, The Guilford Press, New York.
31. Ferguson CJ (2009) An effect size primer: A guide for clinicians and researchers. Professional Psychology: Research and Practice40: 532-538.
32. Tice DM, Bratslavsky E, Baumeister RF (2001)Emotional distress regulation takes precedence over impulse control: If You Feel Bad, Do It! Journal of Personality and Social Psychology 80: 53-67.
33. Visted E, Völlestad J, Nielsen MB, Nielsen GH (2015)The impact of group-based mindfulness training on self-reported mindfulness: A systematic review and meta-analysis. Mindfulness 6: 501-522.
34. Kuyken W, Weare K, Ukoumunne O, Vicary R, Motton N et al. (2013) Effectiveness of the Mindfulness in Schools Programme: Non-randomised controlled feasibility study. British Journal of Psychiatry 203: 126-131.
35. MacKinnon DP, Fairchild AJ, Fritz MS (2007) Mediation analysis. Annual Review of Psychology 58: 593-614.
36. Neff KD and Dahm KA (2014) Self-compassion: What it is, what it does, and how it relates to mindfulness. In: M. Robinson, B. Meier, B. Ostafin (Eds.) Mindfulness and Self-Regulation, Springer: 121-140.