Affective Polarization Scale (APS)

1. Abstract

The Affective Polarization Scale (APS) is a multidimensional psychometric instrument developed by Brandon McMurtrie, Michael Philipp, Ross Hebden, and Matt Williams (2024) designed to rigorously quantify the psychological and behavioral facets of political sectarianism and outgroup hostility. In contemporary political psychology, affective polarization describes the tendency of citizens identifying with an ingroup (e.g., political party, ideological faction) to express systematic aversion, emotional animosity, social avoidance, and hostility toward members of a political outgroup. While traditional assessments in political science have relied heavily on single-item feeling thermometers or ad-hoc social distance questions that lack structural evaluation, the APS was developed across multiple rigorous psychometric phases to provide a standardized, psychometrically validated scale.

The final scale consists of 15 items distributed evenly across three distinct yet interrelated latent factors: Social Distance (evaluating interpersonal boundary setting and relational avoidance), Aversion (capturing generalized negative trait attribution, perceived moral bankruptcy, and threat perception), and Incivility (measuring schadenfreude, active hostility, mocking, and aggressive political conduct). Items are rated on a standard Likert-type scale ranging from Strongly Disagree to Strongly Agree. The APS demonstrates exceptional psychometric reliability, with internal consistency coefficients (Cronbach’s alpha) ranging from .90 to .94 across individual dimensions and .96 for the composite total score, paralleled by identical McDonald’s omega total (ω_t) values. Structural equation modeling and confirmatory factor analysis support a three-factor solution explaining over 67% to 72% of common variance, with robust convergent validity demonstrated through strong correlations with authoritarianism, political identity strength, and need for cognitive closure. The APS serves as an indispensable tool for political psychologists, sociologists, and behavioral scientists investigating intergroup conflict, democratic erosion, and partisan hostility.

2. Keywords

Affective Polarization, Political Sectarianism, Social Distance, Outgroup Aversion, Political Incivility, Ingroup Favoritism, Partisan Hostility, Intergroup Conflict, Psychometrics, Factor Analysis, Political Psychology

3. Authors

The Affective Polarization Scale was formulated and validated by an interdisciplinary team of behavioral scientists and quantitative psychologists:

• Brandon McMurtrie — School of Psychology, Massey University, New Zealand. Research specialized in social psychology, intergroup dynamics, and ideological divergence.
• Michael Philipp — School of Psychology, Massey University, New Zealand. ORCID: 0000-0001-8203-8018. Specialization in socio-cognitive processes, emotional expression, and political conflict.
• Ross Hebden — School of Psychology, Massey University, New Zealand. ORCID: 0000-0002-0217-7796. Research expertise in quantitative methodology, psychometric measurement, and political attitudes.
• Matt Williams — School of Psychology, Massey University, New Zealand. ORCID: 0000-0002-0571-215X. Focus on statistical modeling, replication science, and social psychological assessment.

4. Purpose

The primary purpose of the Affective Polarization Scale (APS) is to address deep-seated conceptual and methodological limitations in the assessment of partisan hostility. For decades, research in political behavior relied almost exclusively on single-item feeling thermometers (such as those employed in the American National Election Studies), where respondents rate their warmth toward political parties on a 0-to-100 scale. While feeling thermometers capture a broad, visceral sense of valence, they fail to disentangle cognitive stereotyping, personal behavioral avoidance, and active interpersonal animus. Furthermore, they are vulnerable to measurement error, idiosyncratic scale calibration, and floor effects.

The APS was designed to establish a granular, standardized, and theoretically grounded measurement model that quantifies political outgroup animus along three operationally defined axes: structural avoidance (social distance), generalized evaluative derogation (aversion), and malevolent behavioral engagement (incivility). In political science, sociopolitical conflict has increasingly shifted from policy-based disagreements (ideological polarization) to identity-driven mutual antipathy (affective polarization). As citizens view their political opponents not merely as mistaken fellow citizens but as an existential, moral threat, interpersonal social cohesion erodes, democratic norms fracture, and institutional trust collapses.

By providing a psychometrically sound, multi-item battery, the APS serves several vital research and applied functions:

• Empirical Research in Political Psychology: Enables researchers to investigate the psychological antecedents of partisan animus, such as moral conviction, social dominance orientation, and authoritarianism, while mapping downstream democratic consequences such as tolerance for norm-breaking and institutional obstruction.
• Longitudinal and Cross-National Tracking: Provides a standardized metric capable of tracking shifts in democratic health, election-cycle escalation, and political sectarianism across diverse adult populations.
• Intervention Assessment: Acts as an evaluative benchmark for interventions designed to mitigate political animus, including perspective-taking exercises, deliberative polling, cross-partisan dialogue, and bridge-building programs.
• Institutional and Workplace Diagnosis: Facilitates diagnostic screening in professional, academic, and civic organizations seeking to understand how ideological segregation affects teamwork, interpersonal trust, and psychological safety.

5. Psychological Construct

Affective polarization is operationalized within the APS as a multidimensional psychological syndrome defined by pronounced emotional aversion, cognitive delegitimization, behavioral withdrawal, and hostile celebration directed toward members of a political outgroup. The construct transcends mere disagreement over fiscal or social policies; it manifests as a moralized intergroup bias where the outgroup is dehumanized, excluded from one’s moral community, and actively targeted for social sanction. The APS deconstructs this overarching construct into three psychometrically validated sub-dimensions:

Social Distance

The Social Distance dimension builds upon foundational sociological and psychological frameworks of relational segregation, originally conceptualized by Emory Bogardus. In the context of political sectarianism, social distance reflects an individual’s conscious aversion to forming personal, intimate, or geographic ties with members of the political outgroup. Items within this subscale assess boundary-setting behaviors, such as reluctance to have an outgroup member move next door, distress at the prospect of a close family member or friend marrying an outgroup affiliate, and intentional avoidance of cross-partisan friendships and social interactions. Social distance demonstrates that political identity has permeated private life, transforming political affiliation into an exclusionary criterion for basic human interaction.

Aversion

The Aversion dimension captures the evaluative, stereotypic, and threat-oriented cognitive appraisal of political opponents. It reflects the extent to which an individual views the outgroup as fundamentally malevolent, dishonest, and socially noxious. Rather than viewing the opposition as expressing differing values, high-aversion individuals ascribe deep moral deficits to outgroup members, categorizing them as inherently “immoral,” “hypocritical,” “mean,” “unfriendly,” and “dangerous.” This moral delegitimization activates strong psychological disgust and defensive hostility, providing the cognitive justification needed to treat the outgroup as an illegitimate political actor.

Incivility

The Incivility dimension captures the active, behavioral, and emotional hostility directed toward the outgroup, extending beyond passive dislike to proactive aggression and malicious joy. This subscale measures schadenfreude (experiencing pleasure when adverse events befall outgroup members), satisfaction when outgroup members are publicly humiliated or “look bad,” a proactive desire to provoke outgroup anger, approval of social mocking, and the desire to see political adversaries forcefully “put in their place.” Incivility represents the most socially volatile component of affective polarization, strongly predicting aggressive online trolling, toxic political rhetoric, and the endorsement of anti-democratic actions.

6. Theoretical Framework

The conceptual architecture of the Affective Polarization Scale is anchored in the convergence of several major theories of intergroup relations and social cognition:

Social Identity Theory and Self-Categorization

Originating from the seminal work of Henri Tajfel and John Turner, Social Identity Theory (SIT) posits that an individual’s self-concept is substantially derived from perceived membership in social categories. When political party or ideological alignment transitions from a collection of policy preferences into a core social identity, intergroup competition inevitably triggers ingroup favoritism and outgroup derogation. Under Self-Categorization Theory, depersonalization occurs: the self and others are no longer perceived as unique individuals, but as interchangeable exemplars of their political archetype. This accentuates perceived intergroup differences while minimizing intragroup variation, establishing the psychological foundation for the generalized negative trait attributions captured in the APS Aversion subscale.

Socio-Functional Threat Theory and Moral Foundations

Intergroup antipathy is strongly amplified when the outgroup is perceived as an existential or moral threat. According to Integrated Threat Theory (Stephan & Stephan), groups react with hostility when they perceive realistic threats (threats to political power, economic well-being, or physical security) and symbolic threats (threats to values, worldviews, and moral systems). Political adversaries are increasingly categorized as moral violators whose actions threaten the stability of the state. When politics becomes moralized, political compromise is perceived as moral capitulation. This perception justifies interpersonal avoidance (Social Distance) and retaliatory hostility (Incivility), as individuals seek to insulate their social networks from moral contagion.

Sectarianism and Affective Partisanship

Recent theorizing by Finkel et al. (2020) synthesizes these dynamics into the framework of political sectarianism, characterized by three central psychological pillars: othering (viewing outgroups as fundamentally distinct), aversion (evaluating outgroups as morally bankrupt and malevolent), and moralization (viewing political struggles as zero-sum conflicts between good and evil). The APS directly operationalizes these three components, translating theoretical constructs of sectarian animus into empirically verifiable indicators of social withdrawal, trait delegitimization, and aggressive incivility.

7. Validity

The Affective Polarization Scale was subjected to thorough psychometric validation procedures across three empirical studies conducted by McMurtrie et al. (2024), establishing strong content, construct, convergent, and discriminant validity.

Content Validity

The instrument development process began with an initial pool of 35 candidate items derived from social distance literature, trait rating inventories, and assessments of schadenfreude and political incivility. An expert panel of political and social psychologists evaluated the items for clarity, relevance, and construct coverage. Item-level Content Validity Index (I-CVI) assessments resulted in the elimination of ambiguous or redundant statements, pruning the pool to 27 items. The retained items demonstrated an average I-CVI of 0.67, which is recognized as fair to robust for broad social-psychological constructs (Polit et al., 2007). Further empirical testing and psychometric refinement narrowed the scale to the 15 most representative, high-loading items (5 items per dimension).

Construct and Convergent Validity

Convergent validity was evaluated by correlating the APS composite and subscale scores with validated benchmarks in political and personality psychology:

• Feeling Thermometers: APS scores correlated strongly and inversely with traditional outgroup feeling thermometers (standardized r typically exceeding -.60), demonstrating that the scale accurately captures outgroup antipathy while explaining unique variance in behavioral avoidance.
• Political Identity Strength: Ingroup identification strength exhibited substantial positive correlations with APS total scores (r values ranging from .35 to .52), supporting the Social Identity Theory prediction that intense ingroup loyalty fuels outgroup derogation.
• Right-Wing Authoritarianism (RWA) and Social Dominance: Total and subscale scores correlated significantly with RWA (r ≈ .30 to .45), reflecting ideological rigidity, submissive deference to ingroup authority, and aggressive sanctioning of non-conformists.
• Need for Cognitive Closure (NFCC): Statistically significant correlations emerged between the APS and Need for Closure (r ≈ .25 to .38), confirming that individuals who crave cognitive certainty and disambiguation are more prone to outgroup stereotyping and interpersonal avoidance.

Discriminant Validity

Discriminant validity was established through confirmatory factor modeling, demonstrating that a three-factor latent structure fit the data significantly better than a single-factor unidimensional model. Additionally, average variance extracted (AVE) estimates for each subscale exceeded the squared correlations between latent factors, confirming that Social Distance, Aversion, and Incivility represent distinct components of political animus rather than indistinguishable manifestations of a single general factor.

8. Reliability

The Affective Polarization Scale exhibits outstanding internal consistency across multiple independent samples of adult respondents in the United States. Psychometric evaluation reported by McMurtrie et al. (2024) indicates uniform reliability across all three subscales as well as the global composite measure:

• Total Composite Scale: Cronbach’s alpha (α) was documented at .96, indicating near-optimal internal consistency for a 15-item inventory without excessive item redundancy.
• Social Distance Subscale: Cronbach’s alpha ranged between .90 and .93 across validation samples.
• Aversion Subscale: Cronbach’s alpha demonstrated high stability, ranging from .91 to .94.
• Incivility Subscale: Cronbach’s alpha ranged between .90 and .92.
• McDonald’s Omega (ω_t): To account for potential violations of tau-equivalence, composite reliability was evaluated using McDonald’s total omega. The ω_t coefficients matched or stayed within 0.002 of their corresponding Cronbach’s alpha values across all dimensions (Total ω_t = .96; Subscales ω_t = .90 to .94), providing conclusive evidence of internal structural integrity.

Item-total correlations across all 15 items consistently exceeded .65, with inter-item correlations within each respective factor remaining comfortably between .55 and .78. These metrics indicate that the scale is resilient against measurement error and psychometrically reliable for both experimental and observational research designs.

9. Factor Analysis

The structural validity of the APS was rigorously evaluated using both Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA) across independent split samples of American adults.

Exploratory Factor Analysis (EFA)

Initial exploratory factor analysis of the refined 27-item pool utilizing maximum likelihood extraction with oblimin (oblique) rotation supported a three-factor solution based on parallel analysis, scree plots, and eigenvalues exceeding 1.0. The three latent dimensions collectively explained 67.1% of the total common variance. When the five highest-loading, non-cross-loading items were selected for each of the three theoretical domains (yielding the final 15-item scale), the cumulative explained variance rose to 72.0%.

Confirmatory Factor Analysis (CFA)

Confirmatory factor modeling conducted on an independent validation sample confirmed the superiority of the hypothesized three-factor oblique model over alternative structural formulations (including a unidimensional model and a two-factor model collapsing Aversion and Incivility). Standardized factor loadings across all 15 items were high, ranging from .76 to .92, with all loadings reaching statistical significance (p < .001).

Model Fit Index	Observed Value	Acceptable Cutoff / Criteria	Evaluation
Standardized Root Mean Square Residual (SRMR)	0.03	≤ 0.08 indicates good fit	Excellent
Root Mean Square Error of Approximation (RMSEA)	0.10	≤ 0.08 acceptable; ≤ 0.10 marginal/fair	Acceptable in multi-factor social scales
Cumulative Variance Explained	72.0%	> 50.0% is satisfactory	Strong construct capture

Although the RMSEA point estimate approached the upper boundary of acceptability, the combination of an exceptionally low SRMR (0.03), robust factor loadings, and high explained variance demonstrates that the three-factor model provides a structurally sound and parsimonious representation of affective polarization.

10. Instrument / Measurement Tool

• Instrument Name: Affective Polarization Scale (APS)
• Authors: Brandon McMurtrie, Michael Philipp, Ross Hebden, and Matt Williams
• Publication Year: 2024
• Instrument Type: Self-report questionnaire / psychological inventory
• Number of Items: 15 items
• Target Population: General adult population (18 years and older)
• Subscale Breakdown:
  • Social Distance: 5 items (Items 1 to 5)
  • Aversion: 5 items (Items 6 to 10)
  • Incivility: 5 items (Items 11 to 15)
• Target Group Specification: The scale uses a flexible template design where researchers insert the specific political outgroup into the prompt (e.g., “Democrats,” “Republicans,” “Conservatives,” “Liberals”).
• Response Format: Likert-type response scale ranging from: Strongly Disagree (1), Disagree (2), Somewhat Disagree (3), Neither Agree nor Disagree (4), Somewhat Agree (5), Agree (6), to Strongly Agree (7). Note: A 5-point variant (1 = Strongly Disagree to 5 = Strongly Agree) is also widely implemented.
• Scoring Procedures:
  • All 15 items are scored in a direct, positive direction; there are no reverse-coded items.
  • Subscale Scores: Computed by calculating the arithmetic mean (or sum) of the five items comprising each respective subscale (Social Distance: sum of items 1–5; Aversion: sum of items 6–10; Incivility: sum of items 11–15).
  • Composite APS Score: Computed as the overall arithmetic mean (or total sum) of all 15 items. Higher scores reflect greater levels of affective polarization, outgroup hostility, and partisan animus.
• Administration Method: Self-administered via computer, mobile web survey (Qualtrics, REDCap, Gorilla), or traditional paper-and-pencil format. Completion time is approximately 3 to 5 minutes.

11. Permissions & Fee and Test Year

The Affective Polarization Scale (APS) was published in 2024 in the International Review of Social Psychology. The original research article is published under an open-access model governed by the Creative Commons Attribution 4.0 International License (CC BY 4.0). Under this license, researchers, scholars, and practitioners are permitted to reproduce, distribute, translate, and adapt the scale items and methodology without paying licensing fees or securing explicit prior written permission, provided that full and appropriate academic attribution is given to the original authors (McMurtrie et al., 2024).

Scholars utilizing the APS in empirical research, clinical trials, or cross-cultural investigations are encouraged to cite the foundational 2024 validation paper. Researchers modifying the scale target prompts (e.g., adapting the scale for multi-party democracies or specific regional coalitions) should clearly document their operational adaptations.

12. References

Bogardus, E. S. (1925). Measuring social distance. Journal of Applied Sociology, 9, 299–308.

Finkel, E. J., Bail, C. A., Cikara, M., Ditto, P. H., Iyengar, S., Klar, S., Mason, L., McGrath, M. C., Nyhan, B., Rand, D. G., Reifler, J., Schmitt, C. S., Shariff, A. F., Skitka, L. J., Van Bavel, J. J., Voelkel, J. G., & Druckman, J. N. (2020). Political sectarianism in America. Science, 369(6503), 533–536. https://doi.org/10.1126/science.abe1715

Iyengar, S., Lelkes, Y., Levendusky, M., Malhotra, N., & Westwood, S. J. (2019). The origins and consequences of affective polarization in the United States. Annual Review of Political Science, 22(1), 129–146. https://doi.org/10.1146/annurev-polisci-051117-073034

McMurtrie, B., Philipp, M., Hebden, R., & Williams, M. (2024). Development and validation of the Affective Polarization Scale. International Review of Social Psychology, 37(1), Article 11. https://doi.org/10.5334/irsp.926

Polit, D. F., Beck, C. T., & Owen, S. V. (2007). Is the CVI an acceptable indicator of content validity? Appraisal and recommendations. Research in Nursing & Health, 30(4), 459–467. https://doi.org/10.1002/nur.20199

Stephan, W. G., & Stephan, C. W. (2000). An integrated threat theory of prejudice. In S. Oskamp (Ed.), Reducing prejudice and discrimination (pp. 23–45). Lawrence Erlbaum Associates.

Tajfel, H., & Turner, J. C. (1979). An integrative theory of intergroup conflict. In W. G. Austin & S. Worchel (Eds.), The social psychology of intergroup relations (pp. 33–47). Brooks/Cole.

13. Items of the Scale