- 1Instituto Universitario para el Desarrollo Social Sostenible (INDESS), Universidad de Cádiz, Cádiz, Spain
- 2Department of Psychology, Universidad de Cádiz, Cádiz, Spain
- 3Universidad Nacional de Educación a Distancia (UNED), Algeciras Centre, Cádiz, Spain
- 4Department of Psychobiology, Universidad de Murcia, Murcia, Spain
- 5Department of Psychology and Anthropology, University of Extremadura, Cáceres, Spain
- 6Instituto de Investigación e Innovación en Ciencias Biomédicas de la Provincia de Cádiz (INiBICA), Universidad de Cádiz, Cádiz, Spain
Mindfulness is both a non-judgmental and present-centered awareness, which has been applied to reduce negative emotions. On the other hand, Trait Emotional Intelligence (TEI) is the way of how good people perceive their emotional intelligence abilities (perceiving, expressing, understanding, and regulating emotions), which are involved in people’s social functioning. This empirical study was designed to analyze whether dispositional mindfulness (DM) and TEI have a potential combined role for children and adolescent’s emotional states. In a sample of primary school students (N = 318), age ranged from 8 to 16 years old (M = 11.25, SD = 2.20), participants filled a TEI measure (ESCQ, Emotional skills and competence questionnaire) and two measures of DM (CAMM, Child and Adolescent Mindfulness Measure and AFQ-Y, Avoidance and Fusion Questionnaire for Youth). Measures selected included: PANAS (Positive affect and negative affect schedule), White Bear Suppression Inventory (a thought suppression inventory), and STAIC (State-Trait Anxiety for Children). Findings pointed out that TEI measures (labeling and expression, understanding, and managing emotions) were positively and significantly related to positive emotional states (especially, positive affect and balance) and negatively with a lower association with state anxiety. However, DM measures were both negatively and strongly associated with negative emotional states (thought suppression, negative affect, and anxiety). Conclusions indicate that a combined effect of both TEI skills and DM based interventions would be more complete than each one separately for better social functioning of children and teenagers.
Introduction
The mental and emotional health of both primary and secondary students is a growing concern. There is a relationship between the low-level adaptive-emotional states and serious outcomes regarding both academic (Jayalakshmi and Magdalin, 2015; Frajo-Apor et al., 2016) and social adaptation to school (Mestre et al., 2006).
When a person reaches adolescence, social-emotional development begins to have an important impact with several relevant outcomes in their lives. For example, this may have an effect on having an adequate social identity (Van Tilburg and Igou, 2011), good social functioning with peers (Lopes et al., 2012), better possibilities of school adaptation (Nathanson et al., 2016), and better mental health and well-being (Afzal et al., 2016). Therefore, everything that favors an adjustment in the adolescents’ affective sphere is of interest to be included in their training processes (Gross and John, 2003). According to the accumulated empirical evidence, two factors seem to have positive impacts on the emotional states at the beginning of adolescence: emotional intelligence (f. i., Mavroveli et al., 2008; Laborde et al., 2014; Perera, 2016) and dispositional mindfulness (f. i., Cullen, 2011; Hinterman et al., 2012; MacBeth and Gumley, 2012).
In the case of EI, two ways of conceptualizing it seem to coexist. On one hand, Ability Emotional Intelligence (AEI), which considers EI as a set of cognitive abilities (perceiving, using, understanding, and managing) for making decisions based on hot information processing — it refers to all information that has a vital meaning for people (Mayer et al., 2016) for adequate personal and social functioning (Peña-Sarrionandia et al., 2015). However, some authors have considered not including “the emotional using” branch in the EI framework because they believe it should be considered as part of the other three branches (Mestre et al., 2016). On the other hand, Trait Emotional Intelligence (TEI) has been defined as a set of emotional self-perceptions placed at the lower standards of personality hierarchy (Petrides et al., 2016). There are also two different approaches to measure EI. While AEI advocates the exclusive use of performance instruments (Brackett and Salovey, 2006) and/or emotional-situation judgment tests (MacCann and Roberts, 2008), like any other type of intelligence, the TEI just uses self-reported instruments, like the TEIQue (Trait Emotional Intelligence Questionnaire, Laborde et al., 2016).
However, when non-adult samples are used to measure emotional intelligent behaviors, investigations have shown stronger relationships with both negative (see Windingstad et al., 2011) and positive (see Mavroveli et al., 2008) emotional states with TEI measures than with AEI ones. Nonetheless, we should admit that the AEI framework has shown advantages (Fiori, 2009), but the theoretical AEI framework might be better explained using the Cattell-Horn-Carroll mental abilities model and emotional appraisal theory (Roberts et al., 2016) since measures of AEI only have assessed a part of the emotional intelligent behavior, the emotional conscious part (Fiori, 2009; Fiori and Antonakis, 2011). Hence, AEI measures still lack information about how extent emotions, AEI measures, and intelligence are related (Roberts et al., 2006; Maul, 2012). Especially for under-17-year-old samples, it would a possibility to build a TEI instrument according to the AEI theoretical foundations (Billings et al., 2014; Davis et al., 2015). Therefore, we used a self-report of AEI (Faria et al., 2006) that encompasses TEI principles to assess emotional intelligent behavior (Azghandi et al., 2007) to study its relationships with both positive and negative emotional outcomes.
Regarding Mindfulness tradition and theories among adolescents, this concept used to be defined as a quality of consciousness (Brown et al., 2009), which implies drawing attention to the experiences occurring in the present moment and developing a non-judgmental accepting awareness of moment-by-moment experience (Kabat-Zinn, 2003). However, dispositional mindfulness (DM) has been defined as a trait in which individuals differ in how they accept and live with commitment (Goodall et al., 2012). Hence, DM might be a predisposition or trait for living in a mindfulness way (Petrides et al., 2017; Turanzas et al., 2018).
A systematic review by Tomlinson et al. (2017) reported how DM was related to the psychological health of people. The authors reviewed non-interventional and quantitative DM’s articles in non-clinical samples. According to their review, DM was negatively related to non-adaptive emotions (such as anxiety or depression symptoms), and positively linked to adaptive cognitive strategies of emotional regulation processes (such as reappraisal and acceptance) and positive emotions (f. i., joyful) (Tomlinson et al., 2017). Similar findings have been reported in samples of adolescents, in which DM was positively related to subjective well-being (Brown et al., 2009), but mostly DM showed negative relationships with some criteria that indicated a certain level of protection, such as lower levels of dysphoric mood and better tolerance to the effects of stress (Ciesla et al., 2012), lower social anxiety (Hambour et al., 2018), and even in gifted adolescents lower levels of depression, anxiety, and negative emotions have been found (Turanzas et al., 2018).
However, there are few and incomplete studies which have included both EI and DM. Most of these studies have used either DM (from EI-experienced authors) or EI as a mediating variable (conversely, from DM-experienced authors). Hence, there is not enough evidence yet to establish moderating and/or mediating factors between DM and EI regarding positive or negative affective criteria. For example, Teal et al. (2018) studied the influence of EI and DM in the well-being of school programs in a sample of 294 male adolescents. Authors hypothesized that EI mediated the relationship between DM and wellbeing (measured using subjective happiness and psychological stress). Findings supported their previous ideas, using multiple mediation models, where different dimensions of EI (measured with SUEIT, Swinburne University Emotional Intelligence Test, Palmer and Stough, 2001) were significantly and positively related to DM. Besides, EI partially mediated the relationship between DM and subjective happiness. However, the authors were not persuasive enough in explaining the reason why they considered DM as a criterion instead of a predictor. Another concern was that the authors did not include female participants so we cannot know to what extent gender roles affected (a potential qualitative moderating factor). Another example, Park and Dhandra (2017a), studied an Indian sample with 319 participants to ascertain whether TEI (using the WLEIS, Shi and Wang, 2007) might moderate the relationship between DM and the impulsive buying tendency. The authors checked this mediator role of TEI and showed that DM was positively related to all components of the TEI measure. Therefore, it is unclear how DM and EI work together, or separately, or under mediating or moderating factors.
Consequently, both previous DM-EI antecedents, mentioned above, pointed to DM as a predictive factor without considering TEI as a predictive variable too, and without enough theoretical explanations of why TEI had to be viewed as mediator. Some interesting reviews about AEI (see Fernandez-Berrocal and Extremera, 2016) or TEI (see Petrides et al., 2016) have highlighted EI as a proven moderator of health outcomes rather than a mediator. However, they have also pointed out that EI’s role as a mediator is still at an early stage.
Following Kazdin (2007), a moderator variable affects the direction and strength between predictors and criteria. However, a mediator variable counts as “a milestone” for the relationship between predictors and criteria. While mediators explain how external variables take on internal psychological significance, moderators highlight when and/or how much the effects will affect a criterion. Hence, how should the DM and/or EI role be explained as a mediator or as a moderator? Some recent studies may have clarified this question.
For example, Miao et al. (2018) conducted a meta-analytic revision of 17 eligible studies to examine in greater depth the potential relationship between EI (no AEI measures were included in the review, just TEI measures) and trait mindfulness (or DM). They concluded that it was not possible to identify all potential moderators in this EI-DM relationship. However, they pointed out that future research should examine “the relationships among EI, mindfulness, and various other outcome variables need further examination and replication” (Miao et al., 2018, p. 106). However, in their review, they state that the DM and the TEI can be both mediators and moderators.
We have also found some more related antecedents such as emotion regulation (ER), as a mediator, where DM was related to some emotional criteria. For example, in a sample of 572 adolescents, it was found that the ER difficulties mediated the relationship between DM and anxious attachment (Pepping et al., 2016). Ciesla et al. (2012) also described a mediating role of ER between DM and psychological health. However, others consider DM has an assisting role with ER (Hambour et al., 2018).
In our opinion, we believe that both DM and EI (including ER, TEI or AEI) require more attention and research on whether some of them have a potential mediating or moderating role in the relationships sought, with interesting criteria for both constructs, such as self-personal (self-cognitive/emotional regulatory processes) and/or social functioning (social anxiety, for example). Especially in heterogeneous samples, like adolescents (without scholar filters yet), it is necessary to explore previously what type of relationships EI, in our case TEI, and DM have with criteria of positive and negative affectivity before considering different models of mediation. The need to study both DM and self-regulatory processes with more attention were already pointed out by Masicampo and Baumeister (2007) since we are still in the initial stages of how DM or TEI are related to adolescents’ affective sphere.
The main purpose of this cross-sectional study, in a sample of Spanish children and adolescents, was to observe the potential significant relations of TEI and DM may have with various criteria of the affective sphere, anxiety trait vs. state, psychological flexibility and the suppression of thought. We also explored the potential mediating effects between TEI and DM with both positive and negative affect of children and adolescents. We hypothesized that while TEI is positively associated with the positive emotional states and negatively with thought suppression, DM will negatively relate to both negative affect and non-adaptive states.
Materials and Methods
Participants and Procedure
The sample comprised 318 Spanish children and adolescents who were selected by quota sampling from various primary and secondary schools in Cadiz (South of Spain). The average age was 11.25 (range = 8–16, SD = 2.20). Subjects were nearly equally divided by gender (49.1% female). Participants completed questionnaires during class time in a single session. Participation was anonymous and voluntary, and data collection followed the ethical guidelines applicable to people under 18. Before completing the questionnaire, participants also presented parental authorization. The ethical recommendations led to 21 participants being excluded from the sample for not providing informed consent from their parents.
Instruments
TEI (Trait Emotional Intelligence)
The Spanish version of the Emotional Skills and Competences Questionnaire (ESCQ, Takšić, 2009) was used to measure emotional competence. This self-report measure was developed using the Mayer and Salovey (1997) model of Emotional Intelligence (EI, perceiving, using, understanding, and managing emotions). Participants had to rate the items on 5-point scales (1-never, 2-seldom, 3- occasionally, 4-usually, 5-always). The short version consists of 45 items combined into three subscales: Perceiving and understanding emotions, which has 15 items (e.g., “When I see how someone feels, I usually know what has happened to him”); Expressing and Labeling emotions scale, 14 items (e.g., “I am able to express my emotions well”), and Managing and Regulating emotions scale, 16 items (e.g., “When I am in a good mood, every problem seems soluble”). The questionnaire was translated into more than ten languages and shows good reliability and constructive validity (Faria et al., 2006). We used an average score (from 1 to 5) for each ESCQ’s scale.
Dispositional Mindfulness
To assess DM, we used the Child and Adolescent Mindfulness Measure (CAMM; Greco et al., 2011). The CAMM consist of 10 items, responded to on a 5-point Likert scale, ranging from 0 (never true) to 4 (always true). Lower scores would indicate a disposition for having mindful skills in everyday life. This measure is based on the Kentucky Inventory of Mindfulness Skills (KIMS) (Baer et al., 2004), which assesses acting with awareness of the present moment and accepting without judgment. For this study, we used an 8-item CAMM’s Spanish adaptation of Turanzas (2013), which has shown good psychometric properties (Cronbach alpha = 0.82). Turanzas’s CAMM version erased two items (#5 and #10) due to among children produced biased interpretations and misunderstandings. Similar issues have been found in non-English versions (for instance, Italian see Saggino et al., 2017). In this study, we computed this measure as the averaged total score (from 0 to 4). Since items were written in a negative sense, we also recoded the scoring for an easier interpretation. Hence, higher scores indicated higher DM.
Criteria
Cognitive Styles Related to Emotional Functioning
Psychological Inflexibility: Cognitive Fusion and Experiential Avoidance
Psychological inflexibility was measured using the Spanish adaptation of Avoidance and Fusion Questionnaire for Youth (Spanish version of AFQ-Y, Valdivia-Salas et al., 2016). Greco et al. (2008) developed the original instrument to measure psychological inflexibility, comprised of two subscales: cognitive fusion and experiential avoidance, in children and adolescents. According to Hayes et al. (2006), cognitive fusion refers to how verbal processes interfere in the regulation of behavior, while experiential avoidance explains how people react to private of events “even when doing so causes behavioral harm” (p. 7). The AFQ-Y has 17-Likert items ranged from “0” (not at all true) to “4” (very true). Example items include “I must get rid of my worries and fears, so I can have a good life” and “I push away thoughts and feelings that I don’t like.” High scores imply a trend to fuse with own thoughts and feelings. This measure only assesses the negative tendency of cognitive flexibility. Greco et al. (2008) found high Cronbach reliability. For this study average scores were used (from 0 to 4).
Thought Suppression and Intrusion
The White Bear Suppression Inventory (WBSI, Wegner and Zanakos, 1994). Based on previous ideas (Wegner et al., 1987), this instrument comprises 15 items to evaluate chronic thought suppression tendencies. The respondents are requested to indicate their agreement with statements on a 5-point Likert scale ranging from 1 “strongly disagrees” to 5 “strongly agree.” Thus, the total score ranges from 15 to 75, with higher scores indicating greater tendency to suppress unwanted thoughts. It contains statements such as “There are things I prefer not to think about” or “I always try to put problems out of mind.” The WBSI has demonstrated high internal consistency in Spanish (and Portuguese) samples (Ros et al., 2015). This inventory is an indicator of the frequency individuals have intrusive and ruminative thoughts and has been found to correlate positively with depressive symptoms, anxiety, and obsessive-compulsive behavior (Wegner and Zanakos, 1994). For this study, we used average scores (from 1 to 5). According to Schmidt et al. (2009), two subscales would be used (six items each one) - Suppression and Intrusion thoughts.
Emotional and Affective Criteria
Positive and Negative Affect
The Positive and Negative Affect Schedule for Children PANAS-C (Spanish validation is named as “PANASN” by Sandín, 2003). The PANASN was based on the original instrument (Laurent et al., 1999). This is a 30-item measure for children and young adolescents, which assesses Positive affects (PA; e.g., cheerful) and Negative affect (NA; e.g., lonely) using 15 items for each. PANASN also provides a measure of Balance (PA – NA). Participants were asked to describe how they felt during the past few weeks on a 5-point Likert scale ranging from 1 “slightly or seldom” to 3 “much or often.” Spanish PANASC (PANASN) has shown appropriate values of internal consistency, as well as convergent and discriminant validity (Sandín, 2003). For this empirical study, an average score of PANASN was used (from 1 to 3).
Anxiety State-Trait
The State-Trait Anxiety Inventory for Children (STAIC; Spanish version see Spielberger et al., 1982) is a self-report measure which has been widely used to assess state and trait anxiety of children and adolescents. This questionnaire contains two separate, 20-item self-report rating scales for measuring trait and state anxiety. The participant is asked to rate on a 3-point scale the degree to which they are currently experiencing a particular symptom (e.g., I feel 1-not scared, 2-scared, and 3-very scared). Total anxiety scores for the state-anxiety and trait-anxiety scales are obtained by adding up the scores for the 20 items on each scale. Total scores for situational and baseline questions range separately from 20 to 60, with higher scores denoting higher levels of anxiety. Nonetheless, we did not use average scores for STAIC due to their computation.
Data Analysis
To describe features of the sample we conducted a simple analysis to report the sample. To find relevant relations among variables, we conducted Pearson correlations. Probably, the study will have signs of collinearity due to it has several variables as subscales of similar theoretical constructs. In order to find significant relationships, we did regression analyses and mediating and moderating studies using the MACRO plugin in SPSS.
Results
Descriptive data and reliability indices are summarized in Table 1 and correlations between variables are reported in Table 2.
Note that gender was related significantly with positive and negative affect of PANASN, anxiety state of STAI-C, and two subscales of ESCQ (expression and labeling emotions, and emotional managing and regulation). According to this finding, we checked whether there were significant outcomes with these criteria. In light of the observed gender differences and the theoretical considerations outlined in the introduction, we report all subsequent analyses separately by gender only for PANASN and Anxiety state. Apparently, on this occasion gender is a natural/cultural factor rather than a mediator. Hence, we used multiple regression analyses to examine associations between TEI and CAMM with these criteria controlling for just age.
Among boys, and after controlling for age, Expression and labeling emotions remained significantly associated with positive affect [F(5,155) = 14.42, p < 0.01; ß = 0.42, p < 0.001]. However, DM, CAMM (Spanish 8-items version) was associated with negative affect (PANASN) [F(5,155) = 11.92, p < 0.001; ß = −0.47, p < 0.001], but no measures of TEI (ESCQ) were related to negative affect.
Among girls, and after controlling for age, however, Age, DM, and TEI were related to positive affect of PANASN affect [F(5,149) = 25.69, p < 0.001]. Emotional managing and regulation (ß = 0.55, p < 0.001) and dispositional mindfulness (ß = 0.21, p < 0.01) remained significantly and positively associated with positive affect. However, age (ß = −0.16, p = 0.012) was negatively related to positive affect. Regarding negative affect, only dispositional mindfulness was significant [F(5,1149) = 8.88, p < 0.001; ß = −0.48, p < 0.001]. As with boys, and controlling for age, anxiety state remained negatively significant [F(5,149) = 9.26, p < 0.001] with dispositional mindfulness (ß = −0.45, p = 0.002) and emotional managing and regulation (ß = −0.33, p < 0.001). Reported multiple regression analyses that control for age were just significant among girls in negative affect, which may be explained because age is confused with academic achievement in this sample, given that students who repeat a grade tend to be older. However, we repeated the main analyses controlling simultaneously for age with the rest of the criteria and did not find essentially identical results.
Regarding AFQ-Y, cognitive inflexibility, we did not run further analyses beyond correlations due to the fact that it is well known the strong relationship existing between dispositional mindfulness and cognitive inflexibility (see Tay and Kuykendall, 2016). Our study found moderate and negative relationships (we recall that we recode CAMM items for a better interpretation) between DM and fusion cognitive (r = −0.58, p < 0.01) and experiential avoidance (r = −0.57, p < 0.01). However, TEI measures did not show significant relationships for these criteria.
All measures from White Bear Suppression Inventory (WBSI) were negatively and significantly (p < 0.001) related to DM (rtotal = −0.59, rsuppression = 0.51, and rintrusion = 0.55). However, just total scores of WBSI had significant correlations with age and emotional managing and regulation. Nonetheless, only DM was significant after multiple regression [F(3,313) = 55.78, ß = 0.57, p < 0.001].
Regarding Anxiety trait, while among boys just DM remained significant [F(4,156) = 63.93, p < 0.001, ß = 0.68, p < 0.001], girls obtained also Emotional managing and regulation (MR) [F(4,150) = 31.11, p < 0.001, ßMR = 0.24, p < 0.05, ßDM = −0.65, p < 0.001].
Finally, Anxiety state was significant with emotional regulation (MR) and dispositional mindfulness (DM) for both boys [F(4,155) = 9.09, p < 0.001, ßMR = −0.43, p < 0.01, ßDM = 0.41, p < 0.001] and girls [F(4,150) = 11.65, p < 0.001, ßMR = −0.33, p < 0.01, ßDM = −0.45, p < 0.001]. This is the only moderation relationship among CAMM, TEI, and a criterion (anxiety state) that was significant. Below, Figure 1 shows the moderation effect when CAMM (DM) is predicting anxiety estate, moderated by TEI (ESCQ total score).
Discussion and Conclusion
Our main purpose was to study potential significant relations that both TEI and the DM may have with diverse criteria of the affective sphere, anxiety (trait and state), psychological inflexibility, and suppression and intrusion of thoughts. As it was noted earlier, we expected that TEI were more related to positive affect rather than with negative affect and suppression and intrusion of thoughts. But we also hypothesized a better prediction of DM (negatively) among negative emotional and cognitive criteria than TEI.
Regarding EI, our TEI measure is theoretically based on AEI theory (Mayer et al., 2016) and it was cross-culturally validated by Faria et al. (2006) and, besides, ESCQ has been reported to have good psychometric properties (Takšić et al., 2009). However, it should be considered as a TEI measure rather than an AEI one because TEI is measured using self-report tests and has been described as an “emotion-related dispositional trait which forms part of the personality domain” (Narula and Rugman, 2014, p. 1). Hence, ESCQ should have also common variance with the scales derived from similar constructs (convergent validity) of personality trait (see Faria et al., 2006). Furthermore, TEI factor has been reported as a distinct oblique within the Big Five space (Pérez-González and Sánchez-Ruiz, 2014).
With these caveats in mind, our TEI findings should be interpreted as tentative. Nevertheless, it is interesting how once again gender presented a key role in understanding how participants perceived themselves differently their emotional skills, especially children and adolescents (Windingstad et al., 2011). Among boys, we found that expressing and labeling emotions were positively and significantly related to positive affect. However, among girls, positive affect was combined, related to emotional managing and regulating and DM. We have already pointed how Teal et al. (2018) studied the influence of EI and DM in the well-being school programs in a sample of 294-male adolescents, where DM and TEI were linked to explain happiness. Despite using a different measure of TEI and positive criterion than these authors, we did not find this mediating relationship among boys, but we did among girls.
Male and female adolescents may use their emotional skills differently to develop a better perception of their positive affect. Although ESCQ is a self-reported measure, as TEI instruments are, it is also based on an AEI framework. In this same direction, others studies using AEI performance measures in male-and-female adolescents have pointed out how girls prefer to use emotional regulation abilities to improve their social functioning and positive states while male adolescents prefer to use them to achieve goals (Mestre et al., 2006; Lopes et al., 2012; Billings et al., 2014; Hawn et al., 2015; Fernandez-Berrocal and Extremera, 2016).
In our study, female participants that scored higher in DM also scored higher in the positive affect of PANASN. Some meta-analyses have reported a mediating effect of TEI in DM (Tomlinson et al., 2017; Miao et al., 2018), although gender was not considered as a factor of positive mental health. Regarding the possibility of female adolescents having better dispositional mindfulness for both social and self-functioning, further research including both factors (EI and DM) is needed. This is especially important if samples are heterogeneous (without academic filters), and more studies are necessary to examine gender as a mediator. In earlier stages of development, boys and girls have shown differences both in TEI studies (O’Connor and Little, 2003; Tett et al., 2005; Billings et al., 2014; Mikolajczak et al., 2014) and AEI measures (Allen et al., 2014; Fernandez-Berrocal and Extremera, 2016; Lopes et al., 2012; Mestre et al., 2006, 2017). These consistent outcomes involve an integrated intervention for developing positive outcomes among adolescents considering these gender differences. For example, Turanzas et al. (2018) have reported a combined treatment of DM and EI for gifted children based on second-generation of mindfulness-based on interventions (Van Gordon et al., 2015), where gifted children received mindful sessions and EI sessions with promising findings.
Another point of view and two questions also arise from our research: Does emotional intelligence predict the criteria of positive psychology better than dispositional mindfulness? Is DM a better predictor of outcome related to clinical psychology (anxiety, stress, negative emotions) than EI? Further research is needed to clarify this question but some antecedents from both EI models suggest a tentative-affirmative answer for the first question. From AEI research with children and adolescents, EI is related to a healthier psychological functioning (Rivers et al., 2012), a better resilience linked to emotional regulation ability (Mestre et al., 2017), a good understanding of complex emotional written (Barchard et al., 2013), a promoting adaptation (Davis et al., 2015), and more adaptive and positive emotional strategies (Peña-Sarrionandia et al., 2015). From TEI research with children and adolescents, individual differences in TEI appear to be a good predictor for social functioning: across the life span (Petrides et al., 2016), better academic performance (Petrides, 2016), social acceptation (Windingstad et al., 2011), and for personal functioning (Waugh et al., 2008; Laborde and Allen, 2016). However, with negative social functioning criteria (f.i., social misconduct), the findings have been indicated with the label “shreds of evidence are not as strong as we would like,” especially with AEI (Mavroveli et al., 2008; Fiori and Antonakis, 2011; Kong, 2014; Laborde and Allen, 2016). So, EI may be a stronger predictor for positive than negative adaptive criteria.
Regarding the second question, whether DM is a better predictor or not of outcomes related to clinic psychology (anxiety, stress, negative emotions) than EI. While our TEI measure was more related to positive outcomes, higher scores of DM were more related to lower scores of both negative emotional and cognitive criteria. Our findings matched with various studies about DM and positive and negative criteria [for children-and-adolescent studies (see Zhang and Wu, 2014; Roemer et al., 2015; Park and Dhandra, 2017b; Tomlinson et al., 2017)]. And female participants showed a combination of DM and EI effects for some criteria.
Due to some limitations (measures, sample sizes, and sample without EI and/or DM interventions among others), our findings should be interpreted tentatively. Further research may clarify if it is worth combining DM and EI designs in interventions with children and adolescents can combine DM and EI designs. If EI increases positive emotions and DM can slow-down negative emotions, then instructors could achieve wider outcomes in their interventions.
Compliance With Ethical Standards
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. We also followed the Spanish Law regarding Data Protection. According to article 13.1 of the Spanish Organic Law of Data Protection, the “data of persons over 14 years of age may be processed with their consent, except in those cases in which the Law requires the assistance of the holders of parental authority or guardianship. In the case of minors under 14 years of age, the consent of the parents or guardians will be required.”
Informed Consent
Children and adolescents from this research participated voluntarily and they had to sign an informed consent according to the Spanish Organic Law of Data Protection. Written informed consent was obtained from the parents/legal guardians of all participants.
According to the Research and Ethical Committee of INDESS (Institute for University Research on Social and Sustainable Development, University of Cadiz, Spain), we had to follow following ethical recommendations: (a) all participants had to bring an informed consent from their parents, especially minors under 14 years old; (b) we had to inform and receive permission from AMPA —“Asociación de Padres y Madres del Centro Escolar” (every Spanish school has its own parents association), and (c) the study had to be approved by the Cadiz Education Office of the Andalusian Government. Accordingly, the study was approved by the AMPA and, the Cadiz Education Office of the Andalusian Government, and Ethics and Research Committee of INDESS.
Ethics Statement
This study was carried out following the recommendations of the Scientific Integrity and Ethics at CSIC guidelines (Spanish Higher Council for Scientific Research). We also proceeded to gather the written informed consent from all participants, which was written under the Declaration of Helsinki. The protocol was also approved by the Ethical Research Committee of INDESS (University Institute of Research on Sustainable and Social Development, Universidad de Cádiz, Spain).
Author Contributions
JM and VL-R designed the research and wrote and revised the whole process of the manuscript. JT, MG-G, and JG led the research and conducted the investigation. JC and JM made the statistical analyses. GT revised and contributed to the writing and revision of the manuscript.
Funding
This research has been funded by the Regional Research Project EMOROBOTIC: “Emotional Management through Robot Programming in Primary School” (Junta de Extremadura IB16090) and by Consolidation of Research Groups (Junta de Extremadura GR18091/18.hj.11). This research has been partially also granted by INDESS (University Research Institute for Sustainable Social Development, Universidad de Cádiz).
Conflict of Interest
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.
References
Afzal, A., Atta, M., and Malik, N. I. (2016). Role of positive psychological capital in prediction of emotions and subjective wellbeing among adolescents. J. Indian Acad. Appl. Psychol. 42, 72–81.
Allen, V. D., Weissman, A., Hellwig, S., MacCann, C., and Roberts, R. D. (2014). Development of the situational test of emotional understanding - brief (STEU-B) using item response theory. Pers. Individ. Differ. 65, 3–7. doi: 10.1016/j.paid.2014.01.051
Azghandi, A. A., Memar, F. F., Taghavi, S. H., and Abolhassani, A. (2007). The validity and reliability of petrides and furnham’s trait emotional intelligence questionnaire. J. Iran. Psychol. 3, 157–168.
Baer, R. A., Smith, G. T., and Allen, K. B. (2004). Assessment of mindfulness by self-report: the Kentucky inventory of mindfulness skills. Assessment 11, 191–206. doi: 10.1177/1073191104268029
Barchard, K. A., Hensley, S., Anderson, E. D., and Walker, H. E. (2013). Measuring the ability to perceive the emotional connotations of written language. J. Pers. Assess. 95, 332–342. doi: 10.1080/00223891.2012.736906
Billings, C. E. W., Downey, L. A., Lomas, J. E., Lloyd, J., and Stough, C. (2014). Emotional Intelligence and scholastic achievement in pre-adolescent children. Pers. Individ. Differ. 65, 14–18. doi: 10.1016/j.paid.2014.01.017
Brackett, M. A., and Salovey, P. (2006). Measuring emotional intelligence with the Mayer-Salovey-Caruso Emotional Intelligence Test (MSCEIT). Psicothema 18, 34–41.
Brown, K. W., Kasser, T., Ryan, R. M., Alex Linley, P., and Orzech, K. (2009). When what one has is enough: mindfulness, financial desire discrepancy, and subjective well-being. J. Res. Pers. 43, 727–736. doi: 10.1016/j.jrp.2009.07.002
Ciesla, J. A., Reilly, L. C., Dickson, K. S., Emanuel, A. S., and Updegraff, J. A. (2012). Dispositional mindfulness moderates the effects of stress among adolescents: rumination as a mediator. J. Clin. Child Adolesc. Psychol. 41, 760–770. doi: 10.1080/15374416.2012.698724
Cullen, M. (2011). Mindfulness-Based interventions: an emerging phenomenon. Mindfulness 2, 186–193. doi: 10.1007/s12671-011-0058-1
Davis, W. L., Leslie, P. J., College, A. T., and Carolina, S. (2015). A comparison of emotional intelligence levels between students in experiential and didactic college programs. Int. J. of Emot. Educat. 7, 63–65.
Faria, L., Santos, N. L., Takšić, V., Räty, H., Molander, B., Holmström, S., et al. (2006). Crosscultural validation of the emotional skills and competence questionnaire (ESCQ). Psicologia 20, 95–127.
Fernandez-Berrocal, P., and Extremera, N. (2016). Ability emotional intelligence, depression, and well-being. Emot. Rev. 8, 311–315. doi: 10.1177/1754073916650494
Fiori, M. (2009). A new look at emotional intelligence: a dual-process framework. Pers. Soc. Psychol. Rev. 13, 21–44. doi: 10.1177/1088868308326909
Fiori, M., and Antonakis, J. (2011). The ability model of emotional intelligence: Searching for valid measures. Pers. Individ. Dif. 50, 329–334. doi: 10.1016/j.paid.2010.10.010
Frajo-Apor, B., Pardeller, S., Kemmler, G., and Hofer, A. (2016). Emotional Intelligence and resilience in mental health professionals caring for patients with serious mental illness. Psychol. Health Med. 21, 755–761. doi: 10.1080/13548506.2015.1120325
Goodall, K., Trejnowska, A., and Darling, S. (2012). The relationship between dispositional mindfulness, attachment security and emotion regulation. Pers. Individ. Differ. 52, 622–626. doi: 10.1016/j.paid.2011.12.008
Greco, L. A., Baer, R. A., and Smith, G. T. (2011). Assessing mindfulness in children and adolescents: development and validation of the Child and Adolescent Mindfulness Measure (CAMM). Psychol. Assess. 23, 606–614. doi: 10.1037/a0022819
Greco, L., Lambert, W., and Baer, R. (2008). Psychological inflexibility in childhood and adolescence: development and evaluation of the avoidance and fusion questionnaire for youth. Psychol. Assess. 20, 93–102. doi: 10.1037/1040-3590.20.2.93
Gross, J. J., and John, O. P. (2003). Individual differences in two emotion regulation processes: implications for affect, relationships, and well-being. J. Pers. Soc. Psychol. 85, 348–362. doi: 10.1037/0022-3514.85.2.348
Hambour, V. K., Zimmer-Gembeck, M. J., Clear, S., Rowe, S., and Avdagic, E. (2018). Emotion regulation and mindfulness in adolescents: conceptual and empirical connection and associations with social anxiety symptoms. Pers. Individ. Dif. 134, 7–12. doi: 10.1016/j.paid.2018.05.037
Hawn, S. E., Overstreet, C., Stewart, K. E., and Amstadter, A. B. (2015). Recent advances in the genetics of emotion regulation: a review. Curr. Opin. Psychol. 3, 108–116. doi: 10.1016/j.copsyc.2014.12.014
Hayes, S. C., Luoma, J. B., Bond, F. W., Masuda, A., and Lillis, J. (2006). Acceptance and commitment therapy: model, processes and outcomes. Behav. Res. Ther. 44, 1–25. doi: 10.1016/j.brat.2005.06.006
Hinterman, C., Burns, L., Hopwood, D., and Rogers, W. (2012). Mindfulness: seeking a more perfect approach to coping with life’s challenges. Mindfulness 3, 275–281. doi: 10.1007/s12671-012-0091-8
Jayalakshmi, V., and Magdalin, S. (2015). Emotional Intelligence, Resilience and Mental Health of women college students. J. Psychosocl. Res. 10, 401–408.
Kabat-Zinn, J. (2003). Mindfulness-based interventions in context: past, present, and future. Clin. Psychol. Sci. Pract. 10, 144–156. doi: 10.1093/clipsy/bpg016
Kazdin, A. E. (2007). Mediators and mechanisms of change in psychotherapy research. Annu. Rev. Clin. Psychol. 3, 1–27. doi: 10.1146/annurev.clinpsy.3.022806.091432
Kong, D. T. (2014). Mayer–Salovey–Caruso Emotional Intelligence Test (MSCEIT/MEIS) and overall, verbal, and nonverbal intelligence: meta-analytic evidence and critical contingencies. Pers. Individ. Differ. 66, 171–175. doi: 10.1016/j.paid.2014.03.028
Laborde, S., Allen, M. S., and Guillén, F. (2016). Construct and concurrent validity of the short- and long-form versions of the trait emotional intelligence questionnaire. Pers. Individ. Differ. 101, 232–235. doi: 10.1016/j.paid.2016.06.009
Laborde, S., and Allen, M. S. (2016). Comment: measurement and the interpretation of trait EI research. Emot. Rev. 8, 342–343. doi: 10.1177/1754073916650498
Laborde, S., Lautenbach, F., Allen, M. S., Herbert, C., and Achtzehn, S. (2014). The role of trait emotional intelligence in emotion regulation and performance under pressure. Pers. Individ. Dif. 57, 43–47. doi: 10.1016/j.paid.2013.09.013
Laurent, J., Catanzaro, S. J., Joiner, T. E., Rudolph, K. D., Potter, K. I., Lambert, S., et al. (1999). A measure of positive and negative affect for children: scale development and preliminary validation. Psychol. Assess. 11, 326–338. doi: 10.1037/1040-3590.11.3.326
Lopes, P. N., Mestre, J. M., Guil, R., Kremenitzer, J. P., and Salovey, P. (2012). The role of knowledge and skills for managing emotions in adaptation to school social behavior and misconduct in the classroom. Am. Educ. Res. J. 49, 710–742. doi: 10.3102/0002831212443077
MacBeth, A., and Gumley, A. (2012). Exploring compassion: a meta-analysis of the association between self-compassion and psychopathology. Clin. Psychol. Rev. 32, 545–552. doi: 10.1016/j.cpr.2012.06.003
MacCann, C., and Roberts, R. D. (2008). New paradigms for assessing emotional intelligence: theory and data. Emotion 8, 540–551. doi: 10.1037/a0012746
Masicampo, E. J., and Baumeister, R. F. (2007). Relating mindfulness and self-regulatory processes. Psychol. Inq. 18, 255–258. doi: 10.1080/10478400701598363
Maul, A. (2012). Examining the structure of emotional intelligence at the item level: new perspectives, new conclusions. Cogn. Emot. 26, 503–520. doi: 10.1080/02699931.2011.588690
Mavroveli, S., Petrides, K. V., Shove, C., and Whitehead, A. (2008). Investigation of the construct of trait emotional intelligence in children. Eur. Child Adolesc. Psychiatry 17, 516–526. doi: 10.1007/s00787-008-0696-6
Mayer, J. D., and Salovey, P. (1997). “What is emotional intelligence?,” in Emotional Development and Emotional Intelligence: Educational Implications, eds P. Salovey and D. J. Sluyter, (New York, NY: Harper Collins), 3–34.
Mayer, J. D., Caruso, D. R., and Salovey, P. (2016). The ability model of emotional intelligence: principles and updates. Emot. Rev. 8, 290–300. doi: 10.1177/1754073916639667
Mestre, J. M., Guil, R., Lopes, P. N., Salovey, P., and Gil-Olarte, P. (2006). Emotional intelligence and social and academic adaptation to school. Psicothema 18(Suppl.), 112–117.
Mestre, J. M., MacCann, C., Guil, R., and Roberts, R. D. (2016). Models of cognitive ability and emotion can better inform contemporary emotional intelligence frameworks. Emot. Rev. 8, 322–330. doi: 10.1177/1754073916650497
Mestre, J. M., Núñez-Lozano, J. M., Gómez-Molinero, R., Zayas, A., and Guil, R. (2017). Emotion regulation ability and resilience in a sample of adolescents from a Suburban Area. Front. Psychol. 8:1980. doi: 10.3389/fpsyg.2017.01980
Miao, C., Humphrey, R. H., and Qian, S. (2018). The relationship between emotional intelligence and trait mindfulness: a meta-analytic review. Pers. Individ. Dif. 135, 101–107. doi: 10.1016/j.paid.2018.06.051
Mikolajczak, M., Brasseur, S., and Fantini-Hauwel, C. (2014). Measuring intrapersonal and interpersonal EQ: the Short Profile of Emotional Competence (S-PEC). Pers. Individ. Dif. 65, 42–46. doi: 10.1016/j.paid.2014.01.023
Narula, R., and Rugman, A. (2014). Introduction to the special issue on competence-creating subsidiaries. Long Range Plann. 47, 1–3. doi: 10.1016/j.lrp.2013.10.005
Nathanson, L., Rivers, S. E., Flynn, L. M., and Brackett, M. A. (2016). Creating Emotionally Intelligent Schools with RULER. Sch. Adm. 73, 19–22. doi: 10.1177/1754073916650495
O’Connor, R. M., and Little, I. S. (2003). Revisiting the predictive validity of emotional intelligence: self-report versus ability-based measures. Pers. Individ. Dif. 35, 1893–1902. doi: 10.1016/S0191-8869(03)00038-2
Palmer, B., and Stough, C. (2001). SUEIT: Swinburne University Emotional Intelligence Test: Interim Technical Manual. Victoria: Swinburne University of Technology.
Park, H. J., and Dhandra, T. K. (2017a). Relation between dispositional mindfulness and impulsive buying tendency: role of trait emotional intelligence. Pers. Individ. Differ. 105, 208–212. doi: 10.1016/j.paid.2016.09.061
Park, H. J., and Dhandra, T. K. (2017b). The effect of trait emotional intelligence on the relationship between dispositional mindfulness and self-esteem. Mindfulness 8, 1206–1211. doi: 10.1007/s12671-017-0693-2
Peña-Sarrionandia, A., Mikolajczak, M., and Gross, J. J. (2015). Integrating emotion regulation and emotional intelligence traditions: a meta-analysis. Front. Psychol. 6:160. doi: 10.3389/fpsyg.2015.00160
Pepping, C. A., Duvenage, M., Cronin, T. J., and Lyons, A. (2016). Adolescent mindfulness and psychopathology: the role of emotion regulation. Pers. Individ. Differ. 99, 302–307. doi: 10.1016/j.paid.2016.04.089
Perera, H. N. (2016). The role of trait emotional intelligence in academic performance: theoretical overview and empirical update. J. Psychol. 150, 229–251. doi: 10.1080/00223980.2015.1079161
Pérez-González, J. C., and Sánchez-Ruiz, M. J. (2014). Trait emotional intelligence anchored within the big five, big two and big one frameworks. Pers. Individ. Dif. 65, 53–58. doi: 10.1016/j.paid.2014.01.021
Petrides, K. V. (2016). Four thoughts on trait emotional intelligence. Emot. Rev. 8:650504. doi: 10.1177/1754073916650504
Petrides, K. V., Gómez, M. G., and Pérez-González, J.-C. (2017). Pathways into psychopathology: modelling the effects of trait emotional intelligence, mindfulness, and irrational beliefs in a clinical sample. Clin. Psychol. Psychother. 24, 1130–1141. doi: 10.1002/cpp.2079
Petrides, K. V., Mikolajczak, M., Mavroveli, S., Sanchez-Ruiz, M. J., Furnham, A., and Pérez-González, J. C. (2016). Developments in Trait Emotional Intelligence. Emot. Rev. 8, 335–341. doi: 10.1177/1754073916650493
Rivers, S. E., Brackett, M. A., Reyes, M. R., Mayer, J. D., Caruso, D. R., and Salovey, P. (2012). Measuring emotional intelligence in early adolescence with the MSCEIT-YV: psychometric properties and relationship with academic performance and psychosocial functioning. J. Psychoeduc. Assess. 30, 344–366. doi: 10.1177/0734282912449443
Roberts, R. D., MacCann, C., Guil, R., and Mestre, J. M. (2016). Reimagining emotional intelligence: a healthy, much needed, and important progression for the field. Emot. Rev. 8, 334–334. doi: 10.1177/1754073916650506
Roberts, R. D., Schulze, R., O’Brien, K., MacCann, C., Reid, J., and Maul, A. (2006). Exploring the validity of the Mayer-Salovey-Caruso Emotional Intelligence Test (MSCEIT) with established emotions measures. Emotion 6, 663–669. doi: 10.1037/1528-3542.6.4.663
Roemer, L., Williston, S., Rollins, L., and Wetter, D. W. (2015). Mindfulness and emotion regulation. Handb. Mindful. Self Regul. 3, 107–120. doi: 10.1007/978-1-4939-22635_9
Ros, A. M. J., Ramos, A. O., and Orts, L. M. P. (2015). Inventario de supresión del pensamiento del “oso blanco” (WBSI): propiedades psicométricas de la versión portuguesa (Portugal). Rev. Psicopatol. Psicol. Clin. 20, 125–134. doi: 10.5944/rppc.vol.20.num.2.2015.15167
Saggino, A., Bartoccini, A., Sergi, M. R., Romanelli, R., Macchia, A., and Tommasi, M. (2017). Assessing mindfulness on samples of italian children and adolescents: the validation of the italian version of the child and adolescent mindfulness measure. Mindfulness 8, 1364–1372. doi: 10.1007/s12671-017-0712-3
Sandín, B. (2003). Escalas Panas de afecto positivo y negativo para niños y adolescentes (PANASN). Rev. Psicopatología Psicol. Clín. 8, 173–182. doi: 10.5944/rppc.vol.8.num.2.2003.3953
Schmidt, R. E., Gay, P., Courvoisier, D., Oise Jermann, F., Ceschi, G., David, M., et al. (2009). Anatomy of the White Bear Suppression Inventory (WBSI): a Review of Previous Findings and a New Approach. J. Pers. Assess. 91, 323–330. doi: 10.1080/00223890902935738
Shi, J., and Wang, L. (2007). Validation of emotional intelligence scale in Chinese university students. Pers. Individ. Differ. 43, 377–387. doi: 10.1016/j.paid.2006.12.012
Spielberger, C., Goursch, R., and Lushene, R. (1982). Cuestionario de Ansiedad Estado - Rasgo, STAI. [Questionnaire State - Trait Anxiety]. Madrid: TEA Ediciones.
Takšić, V., Mohoric, T., and Duran, M. (2009). Emotional skills and competence questionnaire (ESCQ) as a self-report measure of emotional intelligence. Psihol. Obz./Horizons Psychol. 18, 7–21.
Tay, L., and Kuykendall, L. (2016). Why self-reports of happiness and sadness may not necessarily contradict bipolarity: a Psychometric Review and Proposal. Emot. Rev. 9:1754073916637656. doi: 10.1177/1754073916637656
Teal, C., Downey, L. A., Lomas, J. E., Ford, T. C., Bunnett, E. R., and Stough, C. (2018). The role of dispositional mindfulness and emotional intelligence in adolescent males. Mindfulness 10, 1–9. doi: 10.1007/s12671-018-0962-8
Tett, R. P., Fox, K. E., and Wang, A. (2005). Development and validation of a self-report measure of emotional intelligence as a multidimensional trait domain. Pers. Soc. Psychol. Bull. 31, 859–888. doi: 10.1177/0146167204272860
Tomlinson, E. R., Yousaf, O., Vittersø, A. D., and Jones, L. (2017). Dispositional mindfulness and psychological health: a systematic review. Mindfulness 9, 23–43. doi: 10.1007/s12671-0170762-6
Turanzas, J. (2013). Adaptación Transcultural de la Escala CAMM (Child and Adolescent Mindfulness Measure) y Estudio Preliminar de Sus Características Psicométricas. Valencia: VIU Valencian International University, doi: 10.1002/jclp
Turanzas, J. A., Cordón, J. R., Choca, J. P., and Mestre, J. M. (2018). Evaluating the APAC (mindfulness for giftedness) program in a Spanish sample of gifted children: a pilot study. Mindfulness 11, 1–13. doi: 10.1007/s12671-018-0985-1
Valdivia-Salas, S., Martin-Albo, J., Zaldívar, P., Lombas, A. S., and Jimenez, T. I. (2016). Spanish validation of the avoidance and fusion questionnaire for Youth (AFQ-Y). Assessment 24, 919–931. doi: 10.1177/1073191116632338
Van Gordon, W., Shonin, E., and Griffiths, M. D. (2015). Towards a second generation of mindfulness-based interventions. Aust. New Zeal. J. Psychiatry 49, 591–592. doi: 10.1177/0004867415577437
Van Tilburg, W. A. P., and Igou, E. R. (2011). On boredom and social identity: a pragmatic meaning-regulation approach. Pers. Soc. Psychol. Bull. 37, 1679–1691. doi: 10.1177/0146167211418530
Waugh, C. E., Wager, D., Fredrickson, B. L., Noll, D. C., and Taylor, S. F. (2008). The neural correlates of trait resilience when anticipating and recovering from threat. Soc. Cogn. Affect. Neurosci. 3, 322–332. doi: 10.1093/scan/nsn024
Wegner, D. M., and Zanakos, S. (1994). Chronic thought suppression. J. Pers. 62, 615–640. doi: 10.1111/j.1467-6494.1994.tb00311.x
Wegner, D. M., Schneider, D. J., Carter, S. R., and White, T. L. (1987). Paradoxical effects of thought suppression. J. Pers. Soc. Psychol. 53, 5–13. doi: 10.1037/0022-3514.53.1.5
Windingstad, S., McCallum, R. S., Mee Bell, S., and Dunn, P. (2011). Measures of emotional intelligence and social acceptability in children: a concurrent validity study. Can. J. Sch. Psychol. 26, 107–126. doi: 10.1177/0829573511406510
Keywords: trait emotional intelligence, ability emotional intelligence, dispositional mindfulness, emotional Intelligence, adolescents
Citation: Mestre JM, Turanzas J, García-Gómez M, Guerra J, Cordon JR, De La Torre GG and Lopez-Ramos VM (2019) Do Trait Emotional Intelligence and Dispositional Mindfulness Have a Complementary Effect on the Children’s and Adolescents’ Emotional States? Front. Psychol. 10:2817. doi: 10.3389/fpsyg.2019.02817
Received: 15 November 2018; Accepted: 29 November 2019;
Published: 20 December 2019.
Edited by:
Stella Mavroveli, Imperial College London, United KingdomReviewed by:
Vladimir Tale Taksic, University of Rijeka, CroatiaWei Xu, Nanjing Normal University, China
Copyright © 2019 Mestre, Turanzas, García-Gómez, Guerra, Cordon, De La Torre and Lopez-Ramos. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Jose M. Mestre, am9zZW1pLm1lc3RyZUB1Y2EuZXM=