Evaluating emotion regulation ability across negative and positive emotions: psychometric properties of the Perth Emotion Regulation Competency Inventory (PERCI) in American adults and Iranian adults and adolescents

ABSTRACT Objective A critical factor for adaptive psychological functioning is the ability to successfully regulate negative and positive emotions. Various tools and methods have been developed to assess emotion regulation competence. Recently, the Perth Emotion Regulation Competency Inventory (PERCI) was developed to overcome some of the limitations of previous assessment tools including a lack of emotion regulation assessment across both positive and negative emotions. To date, no studies have examined the PERCI’s psychometric properties among adolescents and non-Western general populations. Method To address this gap in the literature, we examined the psychometric properties of the PERCI among Iranian adolescents (n = 557), Iranian adults (n = 926), and American adults (n = 242). Participants also completed Emotion Regulation Questionnaire (ERQ), Toronto Alexithymia Scale-20 (TAS-20), and Depression Anxiety and Stress Scale-21 (DASS-21) for measuring the concurrent validity of the PERCI. Results Confirmatory factor analyses supported the intended eight-factor structure that distinguishes between different emotion regulation components and negative and positive emotions. The eight-factor structure was also found invariant in terms of gender, age, and culture groups. Furthermore, the PERCI demonstrated good internal consistency, test-retest reliability, as well as expected associations with measures of psychopathology, emotion regulation strategy, and alexithymia. Conclusions Our findings indicate that the PERCI has strong psychometric properties among both Middle Eastern and Western samples and can also be utilised with adolescents. KEY POINTS What is already known about this topic: Difficulties in emotion regulation are contributing to the development, maintenance of numerous forms of psychopathology. The assessment of emotion regulation difficulties has been limited as it primarily focusd only on negative emotions. The Perth Emotion Regulation Competency Inventory (PERCI) was recently developed to provide an integrated and valence-sensitive assessment of emotion regulation ability. What this topic adds: The PERCI can be used to measure emotion regulation competency in both adults and adolescents. The intended eight-factor structure of the PERCI that distinguishes between different emotion regulations components and negative and positive emotions was supported. The intended factor structure of the PERCI found invariant in terms of gender, age, and culture groups.

changing the duration, intensity, occurrence, or expression of the emotions in specific contexts.People vary in their ability to regulate their emotions, and it has been shown that difficulties in regulating one's emotions are associated with and predict lower well-being, lesser social functioning, and greater risk for the development and maintenance of psychopathology (Berking et al., 2014;Sheppes et al., 2015;Wirtz et al., 2014;Zeman et al., 2006).

Assessing emotion regulation
The critical implications of emotion regulation ability have made its assessment an important goal in psychological research and clinical practice (Aldao et al., 2010;Gross, 1998).However, until recently, the assessment of emotion regulation was limited by the primary focus of the relevant measures only on the emotion regulation of negative emotions (John & Eng, 2014;Preece et al., 2021).For example, the most commonly used competence measure of emotion regulation i.e., the 36-item Difficulties in Emotion Regulation Scale (DERS; Gratz & Roemer, 2004) only assesses the regulation of negative emotions, and the DERS-Positive, which was recently developed to measure emotion regulation of positive emotions (Weiss et al., 2015), does not assess the ability to regulate the experiential channel of emotion and differs from the DERS in terms of subscales and structure, therefore precluding a meaningful comparison between these measures and provision of an integrated overall index of emotion regulation ability.This is unfortunate, because a comprehensive assessment of emotion regulation ability -capturing one's competency across both negative and positive emotions -is necessary (Preece et al., 2018;Weiss et al., 2015).
Indeed, difficulties in regulating positive emotions have been proposed as one of the main contributing factors to several forms of psychological problems (see Gruber et al., 2020 for a review).For example, the mania or hypomania episodes of bipolar disorder are mainly characterised by an inability to regulate positive emotions (Gruber et al., 2008(Gruber et al., , 2012;;Katz et al., 1991), and enhancing positive emotions has been established as one of the motivational goals for alcohol drinking, which in some people may be driven by an inability of regulating positive emotions, leading to problematic drinking behaviours (Austin et al., 2020;Simons et al., 2017).The potential critical role of ability in regulating positive emotions has been proposed for other disorders such as eating disorders (Engel et al., 2013;Selby et al., 2015), and more broadly, well-being and life satisfaction (see Fredrickson, 2004;Livingstone & Srivastava, 2012).Finally, assessing emotion regulation for both positive and negative emotions is in line with findings revealing the neural activation patterns for regulating negative and positive emotions are different (Kim & Hamann, 2007).

Perth Emotion Regulation Competency Inventory (PERCI)
In an attempt to improve the comprehensiveness of emotion regulation ability assessment, Preece et al., (2018) developed the PERCI.The PERCI is a 32-item selfreport measure designed to provide an integrated and valence-sensitive assessment of individuals' ability to regulate their emotions for the experiential and behavioural channels of emotion and the ability to decide when it is appropriate to activate emotion regulation goals.It comprises eight subscales, four of which correspond to negative emotions and the other four to positive emotions.A set of subscales assesses the ability to downregulate negative emotions or upregulate positive emotions in terms of the experiential channel of emotions (Negative-Controlling Experience, Positive-Controlling Experience); another set of subscales assesses difficulty in inhibiting main behavioural response tendencies when experiencing negative and positive emotions (Negative-Inhibiting Behaviour, Positive-Inhibiting Behaviour) and the ability to activate the desired behavioural responses when experiencing these emotions (Negative-Activating Behaviour, Positive-Activating Behaviour).Finally, a set of subscales assesses participants' difficulty to determine the appropriate time to regulate their emotions that requires the ability to tolerate emotions in the first place (Negative-Tolerating emotions, Positive-Tolerating Emotions).These subscales can also be combined into relevant composite scores for valence-specific emotion regulation ability and a total scale score from all items as an overall marker of emotion regulation ability (Preece et al., 2018).
The psychometric properties of the PERCI have so far been examined in a few studies, mainly consisting of Australian and American adults (Preece et al., 2018(Preece et al., , 2021)).These studies supported the theoreticallycongruent factor structure of the PERCI, consisting of eight factors corresponding to the eight intended subscales.Moreover, all subscale scores of the PERCI in these studies have displayed good reliability and concurrent validity.For example, significant associations have been found between poor emotion regulation competence (as operationalised by the PERCI) and greater depression, anxiety, and stress symptoms, as well as greater alexithymia levels.To date, only one study has examined the psychometric properties of the PERCI among Iranian adults (Mahdiun et al., 2022).This study used university students and found support for the intended factor structure of the PERCI, and reported good reliability for it, however, the generalisability of their findings is constrained by the sample they recruited.
The results of the few mentioned studies that examined the psychometric properties of the PERCI are promising, but further psychometric studies of the PERCI are needed with more diverse participant groups.For example, to date, the PERCI has been examined only among adults, and no studies examined its utility for adolescents, despite a clear gap in the current research on adolescents' psychopathology and a disproportionately greater focus on the regulation of negative compared to positive emotions in this literature (Young et al., 2019).Moreover, no studies have directly examined the measurement invariance of the PERCI between samples from different cultures.Measurement invariance testing is a critical component of facilitating confident comparisons of a measure scores across different groups, as it determines if a construct is assessed in the same way across these groups (Putnick & Bornstein, 2016).

The present study
To address these gaps, the current study was designed to examine the psychometric properties of the Persian version of the PERCI among Iranian adults and adolescents and to test its measurement invariance between the Iranian sample and an American adult sample.We tested PERCI's factor structure, measurement invariance (across different cultures, gender, and age groups), internal consistency, test-rest reliability, and concurrent validity.For the concurrent validity, relationships were examined between emotion regulation ability and emotion regulation strategy use, alexithymia, depression, anxiety, and stress symptoms.Because models of emotion regulation implicate greater emotion regulation difficulties as a critical factor in the development and maintenance of affective disorders (Cisler et al., 2010;Joormann & Siemer, 2014), we expected a positive association between greater PERCI scores and higher levels of depression, anxiety, and stress symptoms.Similarly, we expected that greater PERCI scores would be associated with higher alexithymia scores, as it has been shown that difficulties in identifying and describing emotions might compromise emotion regulation ability (Edwards & Wupperman, 2017;Swart et al., 2009).Regarding the emotion regulation strategies associated with emotion regulation ability, we expected high PERCI scores would be associated with more use of suppression which is usually linked to poorer mental health and maladaptive outcomes, and less use of reappraisal which is usually linked to good mental health and adaptive outcomes (Aldao et al., 2010;Cutuli, 2014;Gross & John, 2003).

Participants and procedure
Ethics approval for this project was granted by the University of Western Australia Human Research Ethics Committee and Babol University of Medical Sciences in Iran.All participants provided informed consent for their data to be used.For the Iranian adolescent sample, parents provided the consent form for their adolescents to participate in the study.Data were recruited using online platforms between January to August 2021.Three samples of participants were recruited.

Iran adolescent sample
The adolescent sample comprised 672 participants from three elementary schools in two cities (Gilan and Tehran) in Iran who completed the online survey administered via the Porsline platform.Participants with incorrect responses to an attention check question (which asked them to select a specific scale response) and those who completed the questionnaires too quickly (i.e., less than 2 seconds for each item; Becerra et al., 2020) were excluded.The final sample consisted of 557 adolescents (295 female, 262 male).The adolescent participants mean age was 14.94 (SD = 1.29), with the range of 12-17 years old.In terms of education, 337 of adolescents were elementary school students and 220 were doing high school.Adolescent participants were given bonus course credits for completing the survey.

Iran adult sample
The Iranian adult sample consisted of 1040 participants from the general population.They completed the online survey administered via the Porsline platform.One hundred forty participants were excluded during quality screening because they failed attention checks or completed questionnaires too quickly, indicative inattentive responding (i.e., same criteria as indicated above for adolescent sample).The final sample consisted of 926 participants (574 female, 352 male).These participants mean age was 32.52 (SD = 9.65), with the range of 18-65 years old.The majority of Iranian adults were married (n = 514), followed by single participants (n = 393).Eighteen participants were divorced, and one lost their spouse.The distribution of highest educational attainment was 173 postgraduate degree, 311 Bachelor's degree, 386 college degree, 54 elementary school and 2 primary school.In terms of ethnicity, 482 participants identified themselves as Fars, 223 as Turk, 89 as Kurd, 65 as Gilak/Mazani, 52 as Lur, 10 as Arab, and 5 as Balooch.Iranian adult participants were given access to five monetary prize draws for their participation.

United States adult sample
The American sample completed the questionnaires in an online survey using Amazon Mechanical Turk (MTurk; Litman et al., 2017).Two hundred and sixtyeight participants completed the questionnaires.After excluding participants with inattentive or too quick responses (i.e., failed attention check, or completed too quickly), the final sample consisted of 242 participants (97 female, 144 male, 1 participant identified their gender as other).These participants mean age was 40.69 (SD = 11.91), with the range of 20-73 years old.The distribution of highest educational attainment was 25 postgraduate degree, 98 Bachelor's degree, 26 associate degree, 41 college degree, 91 high-school qualification, and two elementary school.In terms of ethnicity, the majority of American participants identified as White (n = 199), followed by African American (n = 20), Asian American (n = 16), Native American (n = 5) and two who identified as other.American participants' marital status was not recorded.They were compensated US$3 for participation.

Perth Emotion Regulation Competency Inventory (PERCI)
The PERCI is a 32-item measure of emotion regulation ability across both positive and negative emotions (Preece et al., 2018).Participants rate items on a 7-point Likert scale (1 = strongly disagree to 7= strongly agree), with higher scores indicating more emotion regulation difficulties or poorer emotion regulation ability.In addition to a total score, PERCI provides eight subscale scores and five composite scores from different dimensions of emotion regulation ability (for a list of these scores, see Table 1).We followed a standard translation and back-translation procedure for the introduction of the Farsi version of the PERCI ( Wild et al., 2005).Specifically, the English version of PERCI was translated into Persian by a native Persian speaker psychologist (the first author) and back translated into English by an independent translator.The back-translated version was checked by the developers of the original PERCI and a few minor corrections were applied.PERCI is freely available for use, and a copy of the final Persian and English versions of it with scoring instructions is provided in the supplementary materials.

Emotion Regulation Questionnaire (ERQ)
The ERQ is a 10-item questionnaire that measures the typical use of two emotion regulation strategies i.e., reappraisal (6 items, e.g., "I control my emotions by changing the way I think about the situation I'm in") and suppression (4 items, e.g., "I keep my emotions to myself"; Gross & John, 2003).Items are rated on a 7-point Likert scale (1= strongly disagree to 7= strongly agree), and higher scores of each subscale indicate higher usage of their corresponding strategy.
The ERQ has shown good validity and reliability in different studies (Melka et al., 2011;Preece et al., 2020).The Persian version of the ERQ has also shown good psychometric properties (Hasani, 2016;Khatibi et al., 2021).The adolescents sample completed the modified version of the ERQ for children and adolescents (ERQ-CA; Gullone & Taffe, 2012).The modifications for the ERQ-CA include simplification of the item wording and reduction of the response scale from seven to five points (1= strongly disagree to 5= strongly agree; Gullone & Taffe, 2012).The Persian version of the ERQ-CA has shown good validity and internal consistency among Persian adolescents (Lotfi et al., 2019).

Toronto Alexithymia Scale (TAS-20)
The TAS-20 is a self-report questionnaire measure that assesses alexithymia (Bagby et al., 1994).It consists of 20 items and provides scores for three subscales: difficulty identifying feelings (DIF; 7 items, e.g., I have feelings that I can't quite identify), difficulty describing feelings (DDF; 5 items, e.g., I find it hard to describe how I feel about people), externally oriented thinking (EOT; 8 items, e.g., I prefer talking to people about their daily activities rather than their feelings), and a total score.Participants respond using a five-point Likert scale (from 1 = strongly disagree to 5 = strongly agree).
Higher scores indicate greater alexithymia.Various studies have shown adequate psychometric properties of the TAS-20 (Taylor et al., 2003).The TAS-20 has demonstrated good validity and reliability in the Farsi-speaking population, although, the EOT subscale has shown low internal consistency (Besharat, 2008;Khosravani et al., 2019).

Depression Anxiety and Stress Scale-21 (DASS-21)
The DASS-21 is a 21-item self-report measure of depression, anxiety, and stress symptoms over the past week (Lovibond & Lovibond, 1995).Participants were asked to answer the items using a 0 (did not apply to me at all) to 3 (apply to me very much) scale.Three separate subscale scores can be derived as markers for depression (7 items, e.g., I felt that I had nothing to look forward to), anxiety (7 items, e.g., I was aware of dryness of my mouth), and stress (7 items, e.g., I found it difficult to relax), and all items can also be summed into a total scale score as an overall marker of psychological distress.Both English and Persian versions of the DASS-21 showed acceptable construct and convergent validity as well as internal consistency (Antony et al., 1998;Habibi et al., 2017;Kami et al., 2019).

Factorial validity
Confirmatory factor analyses (CFA; maximum likelihood estimation with robust standard errors with the Satorra-Bentler scaled χ2 statistic and robust standard errors) were conducted using the lavaan package (Rosseel, 2012) for R version 4.0.2.We examined the eight-factor model that has been found to be the best fitting model of the PERCI (Preece et al., 2018(Preece et al., , 2021)), with eight factors that represent the intended eight valence-specific subscales (see Figure 1).In addition, to test if considering different valence domains and subscale categories represented by the eight-factor model improves the fit of the data with the latent structure of emotion regulation ability, we tested some simpler models as comparative baselines (Preece et al., 2021).These simpler models were a one-factor model comprised of a general factor; a two-factor model that distinguished items based on negative and positive valence, but did not distinguish between the different subscale components of emotion regulation; and a non-valence four-factor model that distinguished items based on their subscale components, but did not distinguish between positive and negative valences.Model goodness-of-fit was judged based on four fit indices: the comparative fit index (CFI), Tucker Lewis index (TLI), root mean square error of approximation (RMSEA), and standardised root mean residual (SRMR).CFI and TLI values ≥.90 were judged acceptable and ≥.95 excellent.RMSEA and SRMR values ≤.08 were judged acceptable and ≤.06 excellent (Bentler & Bonett, 1980;Browne & Cudeck, 1992;Marsh et al., 2004).The models also were directly compared using the Akaike Information Criterion (AIC), which penalises for model complexity, and lower values indicate a better fitting model (Byrne, 2016).Factor loadings ≥.40 were considered meaningful loadings (Stevens, 1992).

Measurement invariance
To examine the measurement invariance of the PERCI across gender, age, and culture, the best fitting factor model was first tested separately for each group in the entire three samples.Then the basic configural invariance model (equal form) was tested followed by progressively more restrictive measurement invariance tests: metric invariance test (equal factor loadings), and scalar invariance test (equal intercepts).Models were compared in terms of the CFI and RMSEA.Full invariance was indicated when absolute differences in CFI (ΔCFI), and RMSEA (ΔRMSEA) were less than .01,and .015,respectively (Chen, 2007;Cheung & Rensvold, 2002).

Internal consistency, temporal stability, and relationships with other constructs
Cronbach s alpha (α) and McDonald's Omega (ω) reliability coefficients were calculated for all PERCI subscale and composite scores.Values ≥.70 were judged acceptable, ≥ .80good, and ≥.90 excellent (Groth-Marnat, 2009).For temporal stability, 79 of the adolescents completed PERCI again with a 2.5 weeks interval.The Intra-Class Correlation (ICC) was selected to measure test-retest reliability as it is a more precise method compared to Pearson correlation (Portney & Watkins, 2009;Shrout & Fleiss, 1979).ICC estimates were calculated using package "irr" for R version 4.0.2 based on a two-way mixed effect model with absolute agreement.This is the ICC form recommended for measuring test-retest reliability when the same subjects score themselves on two or more occasions (for a guide on ICC model selection see Koo & Li, 2016).For ICC, values between .between-group factors of participant groups (Iranian adolescents vs. Iranian adults vs.American adults) and gender (male vs. female), and dependent variable of PERCI subscales.

Descriptive statistics and reliability coefficients
Descriptive statistics and reliability coefficients for all questionnaires including PERCI subscale and its composite scores are displayed in Table 1.All PERCI subscales and composite scores showed acceptable to excellent alpha reliabilities, with the exception of the Negative-tolerating emotions subscale for Iranian adults (α = .66,ω = .67)and adolescents (α = .62,ω = .63).The ICC values for PERCI subscales, composite scores, and the total scale among the adolescent sample indicated moderate to good test-retest reliability (ICC values =.54 to .88,all ps < .001).Paired sample t-tests for PERCI scores between two assessments were non-significant for all subscales (all ps > .08;see supplementary materials).

Factor structure
Fit indices for all CFA models for the three samples are displayed in Table 2.The intended eight-factor model was the best fitting model in the three samples and indicated a good fit to the data.All items loaded well on their intended subscale factor (i.e., >.40; see Table 3), and all factors were significantly positively correlated except the negative-tolerating emotions factor in the Iranian adults and adolescents samples that were not correlated with subscales for positive emotion regulation (see supplementary material).The eight-factor model was substantially better fitting than the one-, two-, and four-factor models, thus confirming the statistical value of distinguishing between the different valence categories and subscale components.

Measurement invariance
Next, the measurement invariance of the eight-factor model was tested across gender, age, and culture.To examine the measurement invariance across gender, the eight-factor model was tested separately for males (n = 496) and females (n = 671) in the Iranian adult and American adult samples.The two samples were combined to increase the power of the analysis 1 .Equality constraints were imposed on all factor loadings.As shown in Table 4 the ΔCFI and ΔRMSEA (=.001) indicated full metric invariance.Next, equality constraints were imposed on all item intercepts to test scalar invariance, which indicated full scalar invariance.The same procedure was carried out for the measurement invariance of age.To control for potential effects of culture, the age measurement invariance was tested using Iranian adults (n = 926) versus Iranian adolescents (n = 557) samples.The eight-factor structure was also invariant across age categories as the CFI and RMSEA values did not differ substantially (i.e., <.01) for the configural, metric, and scalar models.
Next, the measurement invariance for culture was tested across Iranian adult (n = 926) and American adult (n = 242) participants.There was configural and full metric invariance for culture.However, at the scalar level, the ΔCFI exceeded the .01criterion, indicating noninvariance.Inspection of the modification indices suggested that freeing the constraints for items 2, 14, 15, and 30 would improve the fit of the model.As can be seen in Table 4, after doing so, the ΔCFI (=.009) indicated partial scalar invariance for culture.The intercepts for these four items were higher for Iranians (b = 5.18, 4.38, 2.59, and 3.04 for items 2, 14, 15, and 30, respectively) compared to American participants (b = 3.33, 3.28, 2.14, and 2.58 for items 2, 14, 15, and 30, respectively).

Comparing emotion regulation competency
The ANOVA results with participant groups (Iranian adolescents vs. Iranian adults vs.American adults) and gender (male vs. female) for the composite scores i.e., negative-emotion regulation, positive-emotion regulation, and general-emotion regulation are reported here, and the results for all PERCI subscales could be found in the supplementary material.The main effect of participant groups was significant in all three ANOVA analyses, Fs( 2  .577.645.77424-When I'm feeling good, I can't allow those feelings to be there.
.652 .614.91328-When I'm feeling good, I believe those feelings are unacceptable.
.716 .722.83732-When I'm feeling good, I must try to eliminate those feelings.
.658 .644.898 Maximum likelihood estimation with robust standard errors with the Satorra-Bentler scaled χ2 statistic and robust standard errors was used for the reported confirmatory factor analyses.All loadings were statistically significant, p < .001.

Relationships with other constructs/measures
Correlations between the PERCI and the DASS-21, TAS-20, and the ERQ for all three samples were consistent with our expectations (see Table 5).A table containing all Pearson correlations is provided in the supplementary materials.Poor overall emotion regulation ability, as assessed by the PERCI total score, was significantly associated with higher usage of suppression, less usage of cognitive reappraisal; higher levels of alexithymia; and higher levels of depression, anxiety, and stress.

Discussion
The current study examined the psychometric properties of the PERCI among Iranian and American adults, as well as a sample of Iranian adolescents.Overall, the PERCI performed well in all these samples.In what follows, the main findings are reviewed and discussed in turn.

Factorial structure
With respect to the factorial structure of the PERCI, the predicted eight-factor model (reflecting the intended eight subscale structure) was found to be the best fitting model in all three samples.These findings replicate past work mainly in English-speaking adult samples (Preece et al., 2018(Preece et al., , 2021)), and extend the current literature by demonstrating for the first time the utility of the PERCI among an adolescent sample.The superiority of the eight-factor model over other simpler models supports the significance of distinguishing between the processing of negative and positive emotions and accounting for different regulation components to measure the multidimensional nature of emotion regulation ability construct more comprehensively.

Concurrent validity
With respect to concurrent validity, the expected correlations were found between the PERCI and other measures.Specifically, greater difficulties in emotion regulation for both negative and positive emotions were associated with higher levels of depression, anxiety, and stress.This is in line with previous research arguing that the inability to regulate one's emotions can lead to longer and more severe periods of distress that can, in turn, develop into depression, anxiety, and stress (e.g., Mennin et al., 2009;Wirtz et al., 2014).Moreover, greater levels of emotion regulation difficulties for both emotion valences were associated with higher levels of alexithymia within all three groups.This is in line with the suggested critical role of identifying and describing emotions in one's ability to regulate those emotions (Edwards & Wupperman, 2017;Preece et al., 2022;Swart et al., 2009) and extends previous research showing the association between alexithymia and difficulties in regulating negative emotions by providing evidence that the same association pattern exists between alexithymia and difficulties in regulating positive emotions.With respect to emotion regulation strategy use, greater emotion regulation difficulties for both emotion valences were significantly correlated with greater use of suppression strategy within all three samples, and lower use of reappraisal strategy among American and Iranian adults.For the adolescent group, however, only the difficulty in the regulation of positive emotions was significantly associated with lower use of reappraisal, and no significant association was found between negative emotion regulation difficulty and reappraisal.This points out the potentially important role of positive emotions and their regulation in adolescence psychopathology.Although further studies are needed to address the role of positive emotion regulation in adolescence, recent studies are increasingly showing the critical importance of considering positive emotions relevant to adolescents psychopathology (Fussner et al., 2015;Gilbert, 2012).For example, in line with the present findings, it has been shown that adolescents with stronger maladaptive beliefs about the usefulness of positive emotions reported more depression, anxiety, and stress symptoms.Interestingly, however no significant association was found between adolescents' beliefs about the usefulness of negative emotions and the same psychopathology symptoms (Mazidi et al., under review).Moreover, the significant gender difference showing that in general female participants reported greater ability than men in regulating their positive emotions further highlights the importance of distinguishing negative and positive emotions when assessing emotion regulation competency.However, age seems to be a potentially important factor to consider for genderrelated differences in emotion regulation as female adolescents reported higher emotion regulation ability than male adolescents for both positive and negative emotions.

Psychometrics
In terms of reliability, acceptable to excellent internal consistency was found for almost all subscales and composite scores of the PERCI among the three studied samples, with the only exception of the Negative-tolerating emotions subscale for Iranian adults and adolescents.The internal consistency of this subscale in the only other study that examined the psychometric properties of the PERCI among a sample of Iranian university students was identical to the current study (i.e., Cronbach's α: .66;Mahdiun et al., 2022).The lower reliability of this subscale among Iranian samples might be due to the relatively lower factor loadings of its items (ranging from .467 to .666), which reflects that its items were functioning less well in capturing the variance associated with the relevant construct among Iranian participants.Future research can examine if this pattern is replicated in other non-western samples and what could be some underlying reasons for it.Another novel contribution of our study was examining the test-retest reliability of the PERCI for the first time among adolescents.The PERCI total score and all subscales including negative-tolerating emotions demonstrated acceptable and good testretest reliability.

Measurement invariance
Importantly, the current study also addressed the measurement invariance of the confirmed eight-factor model of the PERCI across gender, age groups, and the two studied cultures.Full metric and scalar invariance were obtained for gender and age, and full metric and partial scalar invariance was present across cultures.As such, this supports that the latent structure of the emotion regulation difficulty construct, as assessed by the PERCI, manifests similarly across these demographic categories (Putnick & Bornstein, 2016).This is important because it shows that this instrument can be confidently employed to measure and compare emotion regulation difficulty levels between individuals who differ in these demographic backgrounds, and paves the way for more robust cultural studies in this field using the PERCI to get a valence-specific emotion regulation difficulty assessment (Cheung & Rensvold, 2002).

Limitations and future directions
A few limitations must be considered when interpreting the findings of the current study.First, the samples recruited in this study were not from clinical populations and the present findings, therefore, may not be generalisable to clinical samples.Second, the PERCI test-retest reliability was not assessed for Iranian and American adult samples, and the study did not recruit American adolescents for more direct comparisons with Iranian adolescents.Third, model fit indices of the intended eight-factor model of the PERCI indicated acceptable model fit for the Iranian adolescent and adult samples, but they did not reach excellent fit thresholds.Therefore, future research could examine ways to optimise model fit for Iranian people.Fourth, the concurrent validity constructs were all measured using self-report questionnaires.The validity of the PERCI could be examined further using behavioural and objective measures of emotion regulation and relevant constructs (Mauss et al., 2005).The above limitations notwithstanding, the current study was the first examination of the PERCI among an adolescent sample.The PERCI may be particularly useful to researchers who study positive emotions and reward sensitivity especially from developmental perspectives.Given that previous assessments of emotion regulation have tended to only consider negative emotions, employing the PERCI by researchers and clinicians may therefore facilitate developing a more comprehensive understanding of emotion regulation processes including the potential differential role of difficulty in regulating positive and negative emotions.For example, future researchers could employ the PERCI to examine if different disorders have distinct profiles of difficulty in regulating negative and positive emotions, as such profiles could help guide case formulations and treatment planning (e.g., Ellard et al., 2010).Moreover, future research could examine the underlying mechanisms of poor emotion regulation competency such as high levels of alexithymia.Such research could be more informative when assessing alexithymia for positive and negative emotions separately to test their interaction with emotion regulation competency of different emotions (see Preece, Becerra, Robinson, & Dandy, 2018).

Conclusions
Overall, our findings replicated the originally proposed factor structure of the PERCI that distinguishes different components of emotion regulation ability for both negative and positive emotions.The current study demonstrated that the PERCI is a tool with strong psychometric properties that can be used to measure emotion regulation competency in both adults and adolescents, and be employed to inform crosscultural emotion regulation research.
50 and .75indicate moderate reliability, values between .75 and .90indicate good reliability, and values greater than .90indicate excellent reliability(Koo & Li, 2016;Portney & Watkins, 2009).Paired sample t-tests were employed to compare PERCI scores between two assessments.The relationships between PERCI scores and DASS-21, TAS-20, and ERQ scores were calculated using Pearson correlations.Finally, to compare three samples scores in emotion regulation competency, 3 × 2 mixed-design ANOVA models were used with

Table 1 .
Descriptive statistics and Cronbach's alpha and McDonald's omega reliability coefficients for the administered measures.
PERCI = Perth Emotion Regulation Competency Inventory, DASS-21 = Depression, Anxiety, Stress Scale-21, ERQ = Emotion Regulation Questionnaire, TAS-20 = Toronto Alexithymia Scale-20, DIF = Difficulty Identifying Feelings, DDF = Difficulty Describing Feelings, EOT = Externally Oriented Thinking.The range of skewness and kurtosis values for the reported variables was −0.62 to 2.09 for Iranian adolescents, −0.80 to 1.45 for Iranian adults, and −1.19 to 6.44 for American adults.A table containing kurtosis and skewness for each variable is reported in the supplementary material.

Table 2 .
Goodness-of-fit index values from confirmatory factor analyses of the PERCI.Maximum likelihood estimation with robust standard errors with the Satorra-Bentler scaled χ2 statistic and robust standard errors was used for the reported confirmatory factor analyses.CFI = comparative fit index, TLI = Tucker Lewis index, RMSEA = root mean square error of approximation, SRMR = standardised root mean square residual, AIC = Akaike information criterion.

Table 3 .
Standardised item factor loadings from confirmatory factor analyses for the eight-factor model.

. Positive-Tolerating Emotions 20
-When I'm feeling good, part of me hates those feelings.

Table 4 .
Measurement invariance for the eight-factor model across gender, age, and culture.Maximum likelihood estimation with robust standard errors with the Satorra-Bentler scaled χ2 statistic and robust standard errors was used for the reported confirmatory factor analyses.CFI = comparative fit index, TLI = Tucker Lewis index, RMSEA = root mean square error of approximation, SRMR = standardised root mean square residual, AIC = Akaike information criterion, ΔCFI = change in comparative fit index, ΔRMSEA = change in root mean square error of approximation.

Table 5 .
Pearson correlations between subscales and composite scores of the PERCI, ERQ,