Political violence stems from both the extreme left and right, but not in equal measure. More ideologically motivated killings have been perpetrated by the far-right in the United States than by far-left movements over the last four decades,1 and attacks by members of the far-right have increased precipitously in the last few years.2 A similarly asymmetric and accelerating association between violence and the political right has been observed in countries throughout the world.3 A Darwinian approach to the threat psychologies distinguishing left from right political orientation can help make sense of the link between violence and extreme conservatism.

Broadly speaking, when environments are dangerous, vigilance against threats and adherence to tried-and-true behaviors are adaptive strategies. Conversely, when environments are safe, threat-vigilance and adherence to the tried-and-true can lead to wasteful expenditures of effort on defense, and failures to adopt beneficial innovations. Given that environmental danger varies, and that individuals vary in the degree to which they are equipped to confront or endure threats, natural selection favors genetic variation within populations in reactivity to indications of threat. This distribution in relative threat-reactivity appears to manifest in some of the values and intuitions informing one’s political orientation, and may partially explain the abiding distinction between conservatives, who prioritize the preservation of cultural traditions and the welfare of the in-group as safeguards against a world perceived as fraught with enemies, and progressives, who view change and between-group cooperation as beneficial opportunities in a world perceived as relatively safe.4 Consistent with this functional perspective, convergent evidence indicates that conservatives process threat-related cues with greater salience and reactivity than do progressives.5 Notwithstanding recent evidence that political orientation does not reliably track skin conductance responses to threatening pictures,6 conservatives have been found more distracted by threatening imagery,7-9 more emotionally reactive to threatening images,6 and more likely to perceive ambiguous facial expressions as indicating malevolent intent relative to progressives.10

Such varied expressions of threat-reactivity may be understood as heightened negativity bias, a pattern observed across many species.11,12 Insofar as threats are more imminent than benefits of comparable magnitude, and can preclude the opportunity to reap benefits (e.g., due to injury or death), failing to detect and respond to potential threats carries greater fitness costs than failing to detect and respond to potential benefits. Natural selection, therefore, favors the evolution of psychological mechanisms that assign greater weight to potential threats than to potential benefits or other sorts of information. In our species, information regarding potential threats has been found more attention-grabbing, memorable, and evocative than information about potential benefits,13 and people tend to believe false claims to a greater degree when framed as threats than as benefits.14

The tendency to believe spurious claims about threats makes adaptive sense. As in other forms of negativity bias, failing to believe true threat claims is often costlier than mistakenly believing false threat claims, due to the lopsided difference between the costs of suffering harm versus unnecessary precaution.14 Conservatives appear more prone to negativity bias with regard to credulity toward false threat claims, even when the threats in question are apolitical in nature, with no such difference observed regarding claims about potential benefits.15,4 The overall findings indicate that the link between political orientation and threat-credulity is not explicable by demographic variables, differences in reasoning abilities, or gullibility regarding non-threat topics.15 Rather, conservatives appear to believe false claims about threats due to an underlying threat-reactivity which manifests in an array of perceptual, affective, cognitive, and behavioral tendencies which were likely advantageous in perilous ancestral environments.

Political orientation seems to be heritable as well as contingent on environmental influences. A cross-cultural analysis of over 12,000 adult twin pairs found evidence that genetic factors contribute 10-59% of the variance in political ideology in samples spanning four decades and five societies.16 In addition, early exposure to unsafe environments increases threat-reactivity throughout the lifespan,17,18 potentially inclining individuals toward conservatism. Within-group exchanges of information (i.e., “information bubbles”) may solidify such endogenous propensities and strengthen investment in one’s left or right political coalition.

If, as the large and growing body of evidence outlined above suggests, conservatives truly are more threat-reactive and more credulous of alleged threats, then a polarized media environment in which conservatives are inundated with disinformation about outgroup threats may set the stage for far-right extremism to flourish. Indeed, levels of conservatism track the intensity of belief in conspiracy theories.4 The functional model of conservatism sketched here predicts that information regarding ostensibly threatening out-groups should garner greater attention, emotional salience, memory, and credulity among conservative audiences, potentially engendering a positive feedback loop wherein individuals feel motivated to seek further information regarding putative threats—and to confront them aggressively.

Crucially, the pattern of heightened reactivity and credulity toward potential threats characteristic of the conservative mind is not associated with fearfulness or timidity, but with confidence in the ability to triumph through force. Cues of threat often exacerbate intergroup antipathy,19,20 and conservatives display not only a lower threshold for identifying out-group members as threats,10,21 but also greater confidence in achieving victory through warfare,21 in a pattern observed in the United States, the United Kingdom, and Spain, and which should theoretically replicate in other societies.22,23 By contrast, the same data portray progressives as less inclined to categorize out-group members as threats, less confident in attaining victory through force, and more inclined to seek negotiation and accommodation. As such, far-right extremists commit acts of political violence moreso than their far-left counterparts in an exaggerated pattern consonant with the differences observed among individuals who fall within the normal spectrum of political attitudes.

To be clear, the overwhelming majority of conservatives do not appear unusually prone to violence, and violence is perpetrated at times by the far left. The present commentary should not be mistaken as an argument that acts of violence are necessarily related to conservative political ideologies, as extremism is motivated by many and complex factors. Our intention here is not to caricature individuals on the basis of their political values, but to summarize emerging evidence that natural selection shaped threat-processing mechanisms that psychologically distinguish left from right, generating somewhat distinct phenotypes evolved to function best within safe versus dangerous environments, respectively. These baseline differences in conservatives’ threat-reactivity, credulity and aggression appear alarmingly susceptible to exaggeration when subjected to the malign influence of propagandist media.


  1. Miller, E. (2017). Ideological motivations of terrorism in the United States, 1970-2016. Retrieved from the National Consortium for the Study of Terrorism and Responses to Terrorism: https://www.start.umd.edu/pubs/START_IdeologicalMotivationsOfTerrorismInUS_Nov2017.pdf
  2. Jones, S.G. (2018). The rise of far-right extremism in the United States. Retrieved from the Center for Strategic and International Studies: https://www.csis.org/analysis/rise-far-right-extremism-united-states
  3. Koehler, D. (2019). Violence and terrorism from the far-right: Policy options to counter an elusive threat. Retrieved from the International Centre for Counter-Terrorism-The Hague: https://icct.nl/wp-content/uploads/2019/02/Koehler-Violence-and-Terrorism-from-the-Far-Right-February-2019.pdf
  4. Samore, T., Fessler D.M.T., Holbrook, C., & Sparks, A.M. (2018) Electoral fortunes reverse, mindsets do not: Political orientation, credulity, and conspiracism following the 2016 U.S. elections. PLoS ONE, 13(12): e0208653. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0208653
  5. Hibbing, J.R., Smith, K.B., & Alford, J.R. (2014). Differences in negativity bias underlie variations in political ideology. Behavioral and Brain Sciences, 37, 297–350. https://motyl.people.uic.edu/NegativityBiasCommentary.pdf
  6. Osmundsen, M., Hendry, D., Laustsen, L., Smith, K., & Petersen, M. (2019, June 21). The Psychophysiology of Political Ideology: Replications, Reanalysis and Recommendations. https://doi.org/10.31234/osf.io/49hfg
  7. Cararro, L., Castelli, L., & Macchiella, C. (2011). The automatic conservative: Ideology-based attentional asymmetries in the processing of valenced information. PLoS One, 6, https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0026456
  8. Dodd, M. D., Balzer, A., Jacobs, C. M., Gruszczynski, M. W., Smith, K. B. & Hibbing, J. R. (2012) The political left rolls with the good; the political right confronts the bad. Philosophical Transactions of the Royal Society of London, Biological Sciences. 367(1589), 640–49.
  9. McLean, S.P., Garza, J.P., Wiebe, S.A., Dodd, M.D., Smith, K.B., Hibbing, J.R., & Espy, K.A. (2014). Applying the Flanker task to political psychology: A research note. Political Psychology, 35, 831–840. https://www.jstor.org/stable/43783824
  10. Vigil, J.M. (2010). Political leanings vary with facial expression processing and psychosocial functioning. Group Processes and Intergroup Relations, 13, 547–558. https://doi.org/10.1177/1368430209356930
  11. Rozin, P., Royzman, E.B. (2001) “Negativity Bias, Negativity Dominance, and Contagion,” Personality and Social Psychology Review, 5(4), 296–320. https://www.wisebrain.org/media/Papers/NegativityBias.pdf
  12. Garcia, J., Hankins, W.G., & Rusiniak, K.W. (1974) “Behavioral Regulation of the Milieu Interne in Man and Rat,” Science, 185(4154), 824–831. https://science.sciencemag.org/content/185/4154/824.long
  13. Ito, T.A., Larsen, J.T., Smith, N.K., & Cacioppo, J.T. (1998) “Negative Information Weighs More Heavily on the Brain: The Negativity Bias in Evaluative Categorizations,” Journal of Personality and Social Psychology, 75(4), 887–900. http://dx.doi.org/10.1037/0022-3514.75.4.887
  14. Fessler, D.M.T., Pisor, A.C., & Navarrete, C.D. (2014). “Negatively-biased Credulity and the Cultural Evolution of Beliefs,” PLoS ONE, 9(4), e95167. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0095167
  15. Fessler, D.M.T., Pisor, A.C., & Holbrook, C. (2017). “Political Orientation Predicts Credulity Regarding Putative Hazards,” Psychological Science, 28(5), 651–660. https://journals.sagepub.com/doi/full/10.1177/0956797617692108?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%3dpubmed
  16. Hatemi, P.K., Funk, C.L., Medland, S.E., Maes, H.M., Silberg, J.L., … Martin, N.G. (2009). “Genetic and Environmental Rransmission of Political Attitudes Over a Life Time,” Journal of Politics, 71, 1141–1156. https://www.procon.org/sourcefiles/genetic-and-environmental-transmission-of-political-attitudes-over-a-life-time.pdf
  17. Loman, M.M., & Gunnar, M.R. (2010). “Early Experience and the Development of Stress Reactivity and Regulation in Children,” Neuroscience & Biobehavioral Reviews, 34(6), 867-876. https://doi.org/10.1016/j.neubiorev.2009.05.007
  18. VanTieghem, M.R., & Tottenham, N. (2017). “Neurobiological Programming of Early Life Stress: Functional Development of Amygdala-Prefrontal Circuitry and Vulnerability for Stress-Related Psychopatholog,” In E. Vermetten, D. Baker & V. Risbrough (Eds.), Behavioral Neurobiology of PTSD (pp. 117-136). Cham, Switzerland: Springer.
  19. Holbrook, C. (2016). “Branches of a Twisting Tree: Domain-specific Threat Psychologies Derive from Shared Mechanisms,” Current Opinion in Psychology, 7, 81-86. https://www.sciencedirect.com/science/article/pii/S2352250X15002006
  20. Jonas, E., McGregor, I., Klackl, J., Agroskin, D., Fritsche, I., Holbrook, C., Nash, K., Proulx, T., & Quirin, M. (2014). “Threat and Defense: From Anxiety to Approach,” In J. M. Olson & M. P. Zanna (Eds.), Advances in Experimental Social Psychology (pp. 219 - 286). San Diego, CA: Academic Press.
  21. Jost, J.T., & Amodio, D.M. (2012). “Political Ideology as Motivated Social Cognition: Behavioral and Neuroscientific Evidence,” Motivation and Emotion, 36, 55–64. http://dx.doi.org/10.1007/s11031-011-9260-7
  22. Holbrook, C., López-Rodríguez, L., Fessler, D.M.T., Vázquez, A., & Gómez. A. (2017). “Gulliver’s Politics: Conservatives Envision Potential Enemies as Readily Vanquished and Physically Small,” Social Psychological and Personality Science, 8, 670-678. https://doi.org/10.1177/1948550616679238
  23. Holbrook, C., López-Rodríguez, L., Gómez, Á. (2018). “Battle of Wits: Militaristic Conservatism and Warfare Cues Enhance the Perceived Intellect of Allies Versus Adversaries,” Social Psychological and Personality Science, 8, 670-678. https://doi.org/10.1177/1948550617746219

Header image: "Gun rights advocates lobby," Jan. 20, 2020 by VCU Capital News Service via Flickr