Introduction

Persistent concerns about the quality of public services in Indonesia underscore the urgency of strengthening civil servant competencies beyond procedural compliance (1, 2). Although organizational inefficiencies and unclear service systems have been widely reported, these issues also reveal a deeper gap in the interpersonal capabilities of public officers, particularly their ability to communicate assertively in complex citizen interactions (3, 4). Assertiveness, defined as the capacity to express one’s thoughts and needs confidently while respecting others’ rights, is fundamental for maintaining professionalism in public service (5, 6). However, assertive communication is not solely a learned skill; it is also shaped by underlying personality traits.

Among the Big Five personality dimensions, extraversion, characterized by sociability, confidence, and a proactive orientation toward social engagement, has been consistently linked to assertive behavior (7, 8). Yet, existing studies show inconsistent results, with some identifying a strong association and others reporting negligible or context-dependent effects (9, 10). These discrepancies suggest that the relationship between extraversion and assertiveness may vary across occupational and cultural settings, particularly in professions requiring both authority and empathy. The Civil Service Police Unit (Satpol PP) represents a unique case for examining this relationship (11, 12). Tasked with enforcing regional regulations and maintaining public order, Satpol PP officers often navigate emotionally charged interactions where excessive passivity or aggression can escalate conflict (13). For millennial officers, those born between 1981 and 1996, balancing assertiveness with social sensitivity poses additional challenges, given generational tendencies toward individualism and digital communication styles (14, 15).

Grounded in Eysenck’s personality theory, this study investigates the relationship between extraversion and assertive behavior among millennial Satpol PP officers in Probolinggo City. By situating personality and behavior dynamics within a high-contact public service context, the research contributes to refining theoretical understanding of extraversion’s behavioral implications and offers practical insights for personnel training and public service improvement.

Methodology

Study Setting and Participant Profile

The study was conducted at the headquarters of the Civil Service Police Unit (Satpol PP) of Probolinggo City, East Java, Indonesia. Satpol PP is a municipal government agency mandated to enforce regional regulations, maintain public order, and safeguard community welfare. All active-duty Satpol PP officers born between 1981 and 1996 were invited to participate. A total of 184 officers completed the questionnaires, representing the full target population of millennial-generation personnel.

Based on the Eysenck Personality Questionnaire–Revised Short Form (EPQR-S) scoring, 130 participants (70.83%) were classified as having extraverted personality traits, while 54 (29.17%) were identified as non-extraverted. Consistent with the study’s theoretical focus on the variability of assertive behavior within the extraverted trait group, only the 130 extraverted officers were included in the main correlation analysis. The remaining 54 introverted participants were retained for descriptive reporting but excluded from inferential analyses. This analytical decision was made to explore behavioral dynamics specifically within individuals who exhibit dominant extraversion characteristics.

The study involved 184 active Satpol-PP personnel identified as part of the millennial generation (born 1981–1996), aged between 28 and 43 years. The sample included both permanent and non-permanent Satpol-PP personnel. Personality traits were measured using the EPQR-S scale, from which 130 individuals (70.83%) were classified as extraverted. These 130 participants formed the analytical sample for the correlation analysis between extraversion and assertive behavior.

Study Design and Rationale

A quantitative, cross-sectional, correlational design was employed to examine the relationship between extraversion and assertive behavior among millennial Satpol PP officers. This design allows for estimation of the strength and direction of association between psychological constructs as they naturally occur, without variable manipulation.

Instruments and Measures

Extraversion personality traits were assessed using the EPQR-S, adapted for use in Indonesian samples following established cross-cultural adaptation procedures: forward translation by two bilingual experts, synthesis, back-translation, expert-panel review, and pilot testing with 30 civil servants to ensure semantic and conceptual equivalence.

Assertive behavior was measure by the Assertiveness Inventory by Alberti and Emmons was translated and culturally adapted using the same procedure. The scale consists of 20 items rated on a 5-point Likert scale (1 = Strongly Disagree to 5 = Strongly Agree), covering equality in interpersonal relations, emotional expressiveness, autonomous action, self-defense of rights, and respect for others’ rights.

Internal consistency reliability in this study was acceptable (EPQR-S α = 0.81; Assertiveness Inventory α = 0.87). Construct validity was examined using exploratory factor analysis with oblique rotation, revealing factor patterns consistent with theoretical expectations.

Procedure

Data were collected over two weeks in July 2024 at the Satpol PP headquarters. Questionnaires were administered in a designated private room during work h to reduce environmental bias. A trained research assistant supervised each session, provided standardized instructions, and answered procedural questions. Average completion time was 20 min. Questionnaires with more than 10% missing responses were excluded; isolated missing values were handled using mean substitution after confirming randomness of missingness.

Data Analysis

All analyses were performed using IBM SPSS Statistics version 26. Descriptive statistics (mean, standard deviation, skewness, kurtosis) were computed for all variables. Normality was tested using the Shapiro–Wilk test and inspection of Q–Q plots; linearity and homoscedasticity were checked via scatterplots and residual analyses. Assumptions for parametric testing were met; therefore, the Pearson Product-Moment Correlation was used to evaluate the association between extraversion and assertive behavior. Spearman’s rho was additionally computed as a sensitivity analysis, yielding comparable results. Statistical significance was set at p < .05 (two-tailed). Effect sizes were interpreted following Cohen (1988), where r = .10 is small, r = .30 medium, and r = .50 large. The observed correlation of r = .389 (p < 0.001; 95% CI [.26, .51]) was therefore categorized as moderate in strength.

Results

Descriptive Statistics

Descriptive statistics for extraversion and assertive behavior are summarized in Table 1. The data show that the extraversion scores ranged from 0 to 12, with a mean of 7.67, while assertive behavior scores ranged from 19 to 58, with a mean of 35.45. Both variables demonstrate sufficient variation among participants.

Both variables exhibited adequate variability and approximately normal distributions based on Shapiro–Wilk tests (p = 0.200) and visual inspections of Q–Q plots. This indicates that the data meet the assumptions for parametric testing.

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Correlation Analysis

Participants were categorized into two groups based on their extraversion scores. Respondents with scores ≥ 7 were classified as highly extraverted, while those scoring < 7 were classified as introverted in Table 2.

The majority (70.83%) were categorized as extraverted, indicating a predominance of outgoing personalities among Satpol-PP officers. These 130 extraverted officers formed the analytical subsample for testing the study hypothesis, aligning with the study’s theoretical focus on variability within extraverted traits.

Assertive behavior was categorized based on the mean score (M = 35), with scores ≥ 35 indicating high assertive behavior and scores < 35 indicating low assertive behavior. A total of 119 respondents (64.67%) demonstrated high levels of assertive behavior (see Table 3).

Assumption Testing

Normality testing using the Kolmogorov–Smirnov test indicated that the data were normally distributed (p = 0.200). Linearity testing using ANOVA confirmed a significant linear relationship between extraversion and assertive behavior (p < 0.0001).

Hypothesis Testing

Pearson’s Product–Moment Correlation was conducted among the 130 extraverted participants (see Table 4). The analysis revealed a statistically significant positive relationship between extraversion and assertive behavior (r = 0.389, p < 0.01). According to Cohen’s (1988) conventions, this represents a moderate correlation, explaining approximately 15% of the variance (r² = 0.15) in assertive behavior.

While statistically meaningful, this finding suggests that extraversion alone is not the sole determinant of assertiveness. Other psychological, situational, and organizational variables likely influence the degree to which extraverted tendencies translate into assertive actions.

Discussion

This study examined the relationship between extraversion and assertive behavior among millennial Satpol-PP officers in Probolinggo City. The results demonstrated a statistically significant positive correlation (r = 0.389, p < 0.01), indicating that officers with higher levels of extraversion tend to exhibit more assertive behavior in interpersonal and enforcement contexts. In line with Eysenck’s personality theory, extraverted individuals typically characterized by sociability and outward energy are more likely to express their thoughts and emotions openly (16, 17).

However, the magnitude of correlation was moderate, explaining only about 15% of the variance in assertive behavior. This distinction between statistical and practical significance suggests that while personality traits contribute meaningfully, assertive behavior in the workplace is also strongly influenced by environmental, organizational, and situational factors (18, 19). Within Satpol-PP’s quasi-paramilitary structure, officers must balance assertive communication with obedience to hierarchical norms and procedural discipline (20). Such constraints likely suppress the full behavioral expression of extraversion, leading to moderate rather than strong associations.

The results can also be interpreted through a trait context interaction framework. While Eysenck emphasized biological and dispositional determinants, contemporary personality models such as the Five-Factor Model recognize that traits are expressed differently depending on environmental affordances (21). In structured and high-authority organizations, extraverted individuals may not always translate social confidence into overt assertiveness (22). This finding therefore extends Eysenck’s model by illustrating that organizational context moderates the manifestation of personality-driven behaviors.

In practical terms, these insights suggest that personality-informed training programs could enhance the professional effectiveness of public officers. Developing structured assertiveness and communication training may help officers channel extraversion into constructive, respectful, and confident interaction styles (23). Leadership should also promote a culture that values assertive communication as a component of professionalism rather than defiance (24).

Despite these contributions, several limitations should be acknowledged. Although data were collected from 184 officers, only 130 extraverted participants were analyzed to align with the study’s theoretical focus. This limits generalizability to the broader Satpol-PP population. Additionally, control variables such as age, gender, and tenure were not included, and the reliance on self-report measures may have introduced social desirability bias. The cross-sectional design also precludes causal inference. Future research should incorporate multivariate or longitudinal designs, as well as peer and supervisor assessments, to better capture the dynamic interplay between personality and behavior in public service contexts.

Conclusion

The present study identified a statistically significant moderate positive relationship between extraversion and assertive behavior among millennial Satpol-PP officers in Probolinggo City (r = 0.389, p < 0.01), suggesting that extraversion contributes to—but does not solely determine—assertive tendencies in public service settings. This finding aligns partially with Eysenck’s personality theory, which links extraversion to social expressiveness, yet it also demonstrates that assertive behavior is context-dependent, shaped by organizational hierarchy, role expectations, and cultural norms within the Satpol-PP’s enforcement environment. The reliance on self-reported data and a cross-sectional design limits causal inference and may introduce social desirability bias, warranting cautious interpretation of personality–behavior alignment. Rather than implying a generalizable predictive link, these results emphasize the interaction between personality dispositions and institutional context. Practically, developing assertive communication through targeted training, leadership support, and structured professional development may help officers channel extraversion into effective, respectful public engagement. Future research should employ longitudinal or multivariate approaches incorporating other personality traits, organizational variables, and observational data to better explain how individual and contextual factors jointly shape assertive behavior in government institutions.