The Psychometric Properties of the Farsi (Persian) Version of the Structure of Temperament Questionnaire (STQ-77)

This psychometric report summarises the investigation of the properties of the Farsi (Persian) version of the Structure of Temperament Questionnaire-Compact, designed to test adults aged 18 to 90. The Structure of Temperament Questionnaire-Compact (STQ-77) is a 77-item questionnaire based on the paradigm of activity-specific differentiation between the temperament components. In contrast to other temperament models, including the earlier versions of the STQ, the STQ-77 is structured in line with the neurochemical model Functional Ensemble of Temperament (FET). The FET summarises the contributions of neurotransmitters, hormones and opioid systems to regulating consistent behavioural patterns (temperament traits in healthy individuals, including animals and symptoms of psychiatric disorders in psychopathology). The links of the STQ-77 structure to the neurochemical biomarkers of the FET provide content validity to its scales. Using the samples of 116 Iranian participants (M/F = 43/73), this study examined the psychometric properties of the Farsi version of the STQ-77 (STQ-77Fa), including the scales’ reliability, sex differences in the norms and its factorial structure. The results showed high-reliability indices for the STQ-77Fa scales. Factor analysis using eigenvalues less than one showed that the STQ-77Fa has activity-specific factor structure similar to that found in the English, Russian and Portuguese adult versions of the STQ-77. Both four- and six-factor solutions showed the factors of Physical Aspects, Social-verbal Aspects, Mental efforts and Emotionality. However, the Emotionality-related scales were entangled with the Social scale in the four-factor but not in the six-factor solutions. Moreover, the six-factor solution separated orientation-related traits (Empathy, Sensation seeking, Probabilistic processing), confirming the FET’s separation of this group from endurance-like and integration-like behavioural aspects. The analysis of sex differences in STQ-77Fa scores showed a pattern that is consistent with sex differences literature: significantly higher Motor-physical endurance, Sensation seeking and dispositional Satisfaction in males, in comparison to females. Overall, these results suggest high reliability and consistent factor structure of the STQ-77Fa, supporting the activity-specific approach in temperament.

Introduction

This psychometric report summarizes the investigation of the properties of the Farsi (Persian) version of the Structure of Temperament Questionnaire-Compact designed to test adults aged 18 to 90. Temperament traits are considerably more stable than other individual attributes such as personality (Rusalov, 2018; Strelau, 1998). If personality refers to individual differences influenced by sociocultural factors (including culturally developed components of identity and values), temperament relates to universal dynamical features of behaviour. The origin of the concept of temperament refers to (neuro)chemically-based individual differences in behavioural regulation, which are present both in pre-cultural individuals (animals, infants) and adult humans (Trofimova, 2016, 2021, 2022).

The Structure of Temperament Questionnaire-Compact (STQ-77) is a 77-item questionnaire based on the paradigm of activity-specific differentiation between the temperament components. In contrast to other temperament models, including the earlier versions of the STQ, the STQ-77 was initially developed from neurophysiological studies on adults and only then was adapted to children of several age groups. The STQ-77 is a 12-component questionnaire that assesses 12 temperament (biologically-based) traits. Unlike any other temperament test, the STQ-77 is based on the neurochemical framework Functional Ensemble of Temperament (FET). The FET summarizes the functionality of neurotransmitters, hormones and opioid receptor systems, grouping temperament components according to 12 universal functional aspects of behaviour (Trofimova, 2021, 2022; Trofimova & Gaykalova, 2021; Trofimova & Robbins, 2016). The 3 x 4 grouping of the FET and STQ-77 components corresponds to Luria’s theory of the three major brain regulatory systems (orientation, integration and energetic maintenance). Moreover, the STQ-77/ FET follow the neuroscience-based activity-specific approach in psychological assessment (Rusalov, 1989, 2018; Rusalov & Trofimova, 2007) that differentiates between temperament traits related to physical, social and mental (probabilistic) aspects of behaviour. As a result, the STQ-77 is the only test that screens for temperament traits related to physical aspects of behaviour (Physical Endurance and Physical Tempo) in both adults and children. All twelve aspects of behavioural regulation highlighted in this framework appeared to be regulated by well-identified neuroanatomic and neurochemical biomarkers (Trofimova, 2021; Trofimova & Gaykalova, 2021).

The STQ-77 is a derivative of the earlier version of the STQ, which structure was derived from electrophysiological studies of adult temperament (Rusalov, 1989, 2018; Rusalov & Trofimova, 2007). Evidence for the construct, concurrent and discriminatory validity of the English, Russian, Chinese, Portuguese, and Polish versions of the STQ was demonstrated during the past 32 years through significant correlations with internationally known scales, such as the Eysenck Personality Questionnaire (Rusalov, 1989; Trofimova & Araki, 2022), the Beck Anxiety Inventory (Trofimova & Sulis, 2016a, 2018); the Five Factor Inventory of personality (Araki & Trofimova, 2021; Trofimova, 2010b; Trofimova & Araki, 2024); the Pavlovian Temperamental Survey (Strelau, Angleitner, & Newberry, 1999; Trofimova, 2009; Trofimova & Araki, 2022); the I7 Impulsiveness Questionnaire (I-7) (Trofimova & Sulis, 2011); Zuckerman’s Sensation Seeking Scale (Araki & Trofimova, 2021; Trofimova, 2010b; Trofimova & Araki, 2024); the Hamilton Depression Inventory (I. Trofimova, 2010; Trofimova & Sulis, 2016b, 2018); Personality Assessment Inventory (Trofimova & Christiansen, 2016); empathy and polymathy measures (Trofimova & Araki, 2024), documented school grades (Trofimova, Zvereva, Zvereva, & Sergienko, 2025), estimated high school grades (Trofimova & Araki, 2025; Trofimova et al., 2025), speed of reading and writing (Trofimova, 2009; Trofimova & Sulis, 2011), time of performance on the verbal classification tasks (Trofimova & Sulis, 2011), symptoms of Generalized Anxiety (Trofimova & Sulis, 2016a), Major Depression (Trofimova & Sulis, 2016b, 2018)), psychotic symptoms (Trofimova & Christiansen, 2016; Zvereva, Zvereva, &Pyatnitskaya, 2021), EEG studies (Rusalov & Trofimova, 2007), comorbid anxiety and depression (Trofimova & Sulis, 2018) and a serotonin depletion experiment (Kanen, Robbins, & Trofimova, 2022).

Translational studies of the STQ started in the late 1980s-mid-1990s when Russian STQ was adapted to English (Bishop & Hertenstein, 2004; Bishop, Jacks, & Tandy, 1993; Brebner & Stough, 1993; Digman & Shmelyov, 1996; Dumenci, 1995, 1996; Rusalov, 1989; Stough, Brebner, & Cooper, 1991; Strelau et al., 1999). Over the years, its Compact STQ-77 English version was translated to 24 languages and was psychometrically investigated in 12 languages (see (Araki & Trofimova, 2021; Rusalov & Trofimova, 2007, 2011; Trofimova & Araki, 2022, 2024). Several versions for children of five age groups were also developed for the Extended (150 items) STQ (Rusalov, 2004; Rusalov & Trofimova, 2007), and Compact (77 items) STQ-77 (Rusalov & Trofimova, 2007; Trofimova et al., 2025; Zvereva et al., 2021).

The primary objective of our study was to examine the psychometric properties of the scales in the pilot Farsi (Persian) version of the adult STQ-77 (ATQ-77Fa), including scale variation, descriptive statistics, reliability indices, sex differences in norms, and the factorial structure of this version. Our hypothesis suggests that the STQ-77Fa has sufficient internal consistency and factor structures similar to the original and other language versions of the STQ-77.

Method

2.1. Samples

The Farsi-speaking sample consisted of 116 adult volunteer participants (M/F = 43/73, aged 18-59, Mean age = 32.3 years, SD = 8.98). The participants were residents of Zahedan City, Iran. This study was approved by the Ethics Committee of the Institutional Review Board of the Zahedan University of Medical Sciences, Iran.

2.1. Measures

All participants completed the STQ-77Fa and a brief demographic form.

Compact Structure of Temperament Questionnaire for Early School children (STQ-77Fa) (Rusalov, 2004; Rusalov & Trofimova, 2007) has 77 statements, assigned to 12 temperamental scales (6 items each) and the validity scale (5 items) listed in the Attachment 1. The STQ-77 uses the Likert scale format: “strongly disagree (1),” “disagree (2),” “agree (3),” “strongly agree (4)” and organizes the 12 temperament scales into four sub-groups:

The Endurance group involves three scales referring to the ability of an individual to sustain prolonged activities: Physical Endurance, (ERM), Social Endurance (ERS) or Mental (Intellectual) Endurance (ERI).

The Speed of Integration group involves three scales referring to the speed of composition of actions: Physical Tempo (TMM), the speed of speech and reading and of other verbal activities, Social Tempo (TMS), and the Plasticity scale (PL). The plasticity scale assesses the ability to adapt quickly to changes in situations, to change the program of action, and to shift between different tasks.

The Behavioural Orientation group involves three scales referring to the sensitivity of an individual to three different types of behavioural reinforcers: basic physical sensations and pleasures, as well as their tendency for sensation-seeking and risk-taking behaviour (Sensation Seeking, SS); orientation of actions in response to another person’s emotional state (Empathy, EMP); and the ability of an individual for adequate understanding and expectations of probabilities and causal relationships between events, the efficient extraction and processing of new knowledge (Probabilistic processing, PRO).

The Emotionality group involves three scales referring to a tendency to be optimistic, confident (sometimes overly optimistic) regarding one’s own performance, and unaffected by other people’s warnings and criticism (dispositional Satisfaction, SF); the emotional reactivity, a poor ability to control immediate impulses for actions (Impulsivity, IMP), and a tendency for expectations of negative outcomes and low tolerance of uncertainty (Neuroticism, NEU). Finally, the Validity scale assesses the social desirability bias in the answers, with results within the range of 15-20 on this scale being considered invalid as this indicates a positive impression bias in the responses.

The Farsi version of the STQ-77 (STQ-77FA) is presented in Attachment 1. This version was used in neurochemical investigation to the role of oxytocin in clinical and healthy samples in Iran, confirming the predictions of the FET neurochemical framework (Khalili, et al, 2025).

2.3. Statistical procedures

Statistical processing included the calculations of the descriptive scale statistics (means, SD, confidence intervals), item-total correlations and reliability coefficients (Cronbach’s alphas).

We also performed factor analysis with the aim of assessing how well the measured variables represent the theoretical latent dimensions. Factor analysis of scale scores using principal components with the varimax-normalized rotation first used the eigenvalues no less than one. Since the scales were expected to interact, a similar analysis was then performed for the solutions with the eigenvalues no less than 0.9, 0.8, 0.7, 0.6 and 0.5 to find the optimal solutions with the maximal eigenvalue and percentage of explained total variance.

Sex differences were assessed using the nonparametric T-test for independent samples.

Results

Table 1 shows the descriptive statistics for the scales of both versions of the STQ-77Fa as well as the Cronbach alphas obtained for each scale.

Table 1. Means, Standard Deviations (SD) and standardized Chronbach Alpha for the STQ-77Fa scales

The range of each item in the scales was 1 to 4, and the range on the temperament scales was 6 to 24 (except the ERS scale, which had the range 6 to 23).

Item-total correlations showed grouping of the highest correlations around the scales that these items belong. Several items related to the Neuroticism scale had to be slightly edited for more precise expressions, and the final text of the STQ-77Fa items is given in the Attachment 1. As seen, all values of reliability coefficient (standardized Chronbach alpha) were in the high range for the scales of this test.

Since the scales were expected to interact, factor analysis of scale scores using principal components with the varimax-normalized rotation was performed for the solutions with eigenvalues no less than 1.0, 0.9, 0.8, 0.7, 0.6 and 0.5 to find the solutions with the maximal and optimal percentage of explained total variance. The solution with the eigenvalue no less than 1.0 brought the minimal percentage of explained variance (61%) and three factors. Since this level of explained variance was too low, other solutions were considered.

The four-factor solution explained 69% of variance with the eigenvalue no less than 0.9; the five-factor solution – 77% with the eigenvalue no less than 0.85; the six-factor solutions explained 83% variance with the eigenvalue no less than 0.8, 0.7 and 0.6, and the seven-factor solution explained 88% variance with the eigenvalue no less than 0.5. Tables 2 and 3 showed the solutions with four and six factors since the 7-factor solution used low value for the eigenvalues.Both, 4-factor and 6-factor solutions brought the factor structure that is in line with activity-specific approach, separating the components of temperament to those regulating physical, social and mental (intellectual-informational, probabilistic) aspects as well as emotionality.

Both factorial solutions, however, combined Emotionality traits with either social traits (in 4-factor solution) or mental traits (Mental endurance and Plasticity). Both versions had an independent factor of Empathy. The six-factor solutions, however, separated orientation-related traits (Empathy, Probabilistic Processing, Sensation seeking) as was proposed in the FET and the structure of the STQ-77.

The analysis of sex differences with the nonparametric T-test for independent samples showed statistically significant differences (at p < 0.05) for the scales of Motor-Physical Endurance (ERM), Sensation Seeking (SS) and dispositional Satisfaction (SF) (Tables 4). There were significantly higher scores on these scales in responses of males, in comparison to females.

Table 2. The results of factor analysis of principle components with varimax normalized rotation, with eigenvalue no less than 0.9, for the scales of the STQ-77Fa, N=116: four factors solution explained 69% of total variance. Bold font shows the scales with the highest loading on the factor

Table 3. The results of factor analysis of principle components with varimax normalized rotation, with eigenvalue no less than 0.8, for the scales of the STQ-77Fa, N=116. Six factors solution explained 83% of total variance. Bold font shows the scales with the highest loading on the factor

Table 4. The results of T-test assessing sex differences in the scores of the scales of the STQ-77Fa: N=116. M/F = 43/73. Traits with significant sex differences are selected in bold

Discussion

This study investigated the psychometric properties of the pilot version of the Farsi (Persian) Structure of Temperament Questionnaire-Compact. The results showed sufficiently high reliability indices for the scales of this test. The analysis of item-total correlations showed the expected pattern of associations of the items with the corresponding scales. Two Neuroticism items were slightly edited for more precise expressions.

It is our opinion, that the application of factor analysis to the scores of the scales measuring the interconnected, mutually regulating behavioural aspects has methodological limitations (Sulis, 2018; Trofimova et al., 2022; Trofimova, Robbins, Sulis, & Uher, 2018). These limitations relate to the fact that factor analysis uses matrices of linear correlations and looks for independence in the resulting factors

Meanwhile, all behavioural aspects show nonlinearity and interdependence (Sulis, 2018; Trofimova et al., 2022; Trofimova et al., 2018). However, to meet the expectations of the psychometric community, the factor analysis was performed for this data.

Factor analysis used the principal components method with the varimax-normalized rotation. We expected the factors not to be completely independent, so we investigated the solutions with various minimal sizes of the eigenvalues that would maximize the amount of explained variance.

The best solutions, in terms of the maximal amount of explained variance, were the four- and six-factor solutions (Table 2 and Table 3), even though the minimum eigenvalues were set to be (correspondingly) 0.9 and 0.8. Six-factor solution not only explained more variance with a reasonable size of the eigenvalues but also showed the activity-specific factor structure that was more similar to the original and other languages-versions of the STQ-77 (Rusalov & Trofimova, 2007). The activity-specific approach, which is also implemented in the neurochemical model FET (Trofimova, 2021, 2022; Trofimova & Robbins, 2016) is seen in the STQ-77 grouping the temperament components of the English, Chinese, Polish, Urdu, Portuguese and Russian versions. This approach differentiates between the physical, verbal and mental aspects of behavioural regulation. The factor structure of the STQ indeed universally shows the factors related to the Physical aspects, Social aspects and Probabilistic aspects, as well as to Emotionality factor (Araki & Trofimova, 2021; Rusalov, 1989, 2018; Rusalov & Trofimova, 2007; Trofimova, 2010a,b). In comparison, the six-factor solution in this sample also revealed the factors of Physical aspects, Social aspects, Probabilistic aspects, and Emotionality. However, the Plasticity and Intellectual Endurance scales also exhibited higher loadings with the Emotionality factor.

Moreover, the orientation-related traits were separated into distinct factors in the six-factor solution (that explained 83% of the variance), forming the factors of Sensation Seeking, Empathy and Probabilistic processing. This is in line with the suggestion of the FET framework to separate orientation-related aspects of behavioural regulation from the endurance-related, integration-related and emotionality-related aspects, as these aspects have different neurochemical biomarkers (Trofimova & Gaykalova, 2021). Such separation aligns with the current literature highlighting the neuroanatomic and neurochemical differences within hypothalamic-pituitary systems regulating physical and social aspects of behavioural orientation (see (Trofimova & Gaykalova, 2021) for review).

The analysis of sex differences in STQ-77Fa scores showed a pattern that is consistent with the literature related to sex differences. Male participants in this study had significantly higher scores on the Motor-physical endurance, Sensation seeking and dispositional Satisfaction scales. It is well known from the sport and athletic industry that, statistically-speaking, males have in average stronger upper body and (especially in youth) higher risk and sensation seeking, in comparison to females, and this is noticeable from very early childhood (Trofimova, 2015). Females are also known to have more frequent episodes of dysphoria (dispositional dis-satisfaction by incoming events before they occure), often linked to pre-menstrual dysphoria syndrome, post-partum depression or other issues related to their hormonal cycles. This can explain the significantly lower scores on the dispositional Satisfaction scale reported by females, in comparison to males. Sex differences in physical endurance and sensation seeking emerge very early in life and are universal across cultures – this is indicative of their biological origin, with a likely evolutionary explanation, as discussed earlier (Trofimova, 2015).

Conclusions

5.Conclusion

In summary, our study investigated the psychometric properties of the pilot Farsi (Persian) version of the STQ-77 (STQ-77Fa). The results showed:

– High reliability and consistent factor structure of the STQ-77Fa;

– The six-factor solution with the factors similar to the activity-specific structure of the other language versions of the STQ-77, namely the factors of Physical Aspects, Social-verbal Aspects, Probabilistic (mental) Aspects and Emotionality.

– Six-factor solution separated orientation-related traits (Empathy, Sensation seeking, Probabilistic processing) confirming the FET’s separation of this group from endurance-like and integration-like behavioural aspects;

– The analysis of sex differences in STQ-77Fa scores showed a pattern that is consistent with the literature related to sex differences: males had significantly higher scores on the Motor-physical endurance, Sensation seeking and dispositional Satisfaction scales.

The limitations of the study include the relatively small size of the sample. More work should be done in investigations of the psychometric properties of the test to overcome their limitations.

Competing interests: No competing interests

Ethics Statement: This study was approved by the Ethics Committee of the Institutional Review Board of the Zahedan University of Medical Sciences, Iran.

CRediT author statement:

Conceptualization: KH

Data curation: KH, MR.

Formal analysis: KH, IT.

Investigation: KH, MR.

Methodology: Development of methods and models KH, IT.

Software: KH, IT.

Validation: KH, IT, MR.

Writing – Original Draft: KH.

Writing – Review & Editing: IT.

Supervision: Oversight and leadership of the research KH, IT.

The authors have read and approved the final version and are responsible for all aspects of the manuscript.

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