A negativity bias among conservatives offers a parsimonious account of the many social, political, and psychological differences between liberals and conservatives that Hibbing et al. discuss in the target article; but parsimony can oversimplify nuanced phenomena. There is evidence that a negativity bias may underlie the development of a liberal or conservative worldview (sect. 6, para. 10–12; see, e.g., Duckitt & Fisher Reference Duckitt and Fisher2003; Fraley et al. Reference Fraley, Griffin, Belsky and Roisman2012; but see Verhulst et al. Reference Verhulst, Eaves and Hatemi2012); however, we suggest that both liberals and conservatives react to psychological threats in similar ways.

People need strategies to deal with negative and threatening situations, and both conservatives and liberals likely use similar, evolved strategies (Mercier & Sperber Reference Mercier and Sperber2011; Proulx et al. Reference Proulx, Inzlicht and Harmon-Jones2012; Tetlock Reference Tetlock2003). Although a negativity bias may, in part, orient people toward a conservative or liberal worldview and determine whether or not certain stimuli are considered threatening, we suggest that reactions to threats follow a comparable trajectory regardless of ideological orientation. Both liberals and conservatives will dig in their heels to defend their ideological values and beliefs. We will review research from three domains supporting the thesis that, when it comes to responding to negative and ideologically threatening information, liberals and conservatives are more alike than different.

Until recently, researchers and theorists have suggested that conservatives are more likely to be intolerant and prejudiced toward deviant and threatening groups (e.g., Cunningham et al. Reference Cunningham, Nezlek and Banaji2004). This association, however, is largely the product of the groups that researchers typically use as targets – namely, groups that threaten conservative values. When the type of target group includes groups that oppose, violate, or threaten the beliefs and values of liberals, liberals will likewise display prejudice and intolerance toward those groups (Chambers et al. Reference Chambers, Schlenker and Collisson2013; Crawford & Pilanski, in press; Wetherell et al. Reference Wetherell, Brandt and Reyna2013; see also Morgan et al. Reference Morgan, Mullen and Skitka2010).

For example, liberals were equally willing to discriminate against groups that threaten their values (e.g., anti-abortion advocates, religious fundamentalists) as conservatives were to discriminate against groups who threaten their values (e.g., pro-choice advocates, atheists; Wetherel et al. Reference Wetherell, Brandt and Reyna2013). That result has been replicated across different research labs, participant samples, target groups, and measures of intolerance. Once cherished beliefs are threatened, people across the ideological spectrum fight back.

Partisans also similarly defend their ideologies from information that conflicts with their political point of view. The negativity bias hypothesis suggests that conservatives react to threats with greater negativity and motivated information processing than their liberal counterparts. However, for several decades research has shown that liberals and conservatives both show evidence of motivated information processing when confronted with information that contradicts their point of view. For example, both supporters and opponents of the death penalty disparaged research that purportedly contradicted their opinions about the death penalty (Lord et al. Reference Lord, Ross and Lepper1979). That effect has recently been expanded to show biased processing of objectionable political information related to a variety of issues and multiple measures of political ideology (e.g., Crawford Reference Crawford2012; Taber & Lodge Reference Taber and Lodge2006). Some studies even show greater motivated reasoning among liberals and people who are relatively left-wing politically (Crawford et al. Reference Crawford, Jussim, Cain and Cohen2013). In sum, research on motivated reasoning suggests that when confronted with information contrary to their perspective, liberals and conservatives are both adept at avoiding ideologically threatening conclusions, and maintaining the integrity of their beliefs.

Finally, other work has tested how people at both ends of the political spectrum react to more basic threats (e.g., death, lack of control). The negativity bias hypothesis suggests general threats in the environment will make people adopt conservative political positions (see sect. 2, para. 2 and sect. 6, para. 12 of the target article); however, threat-compensation perspectives (e.g., Proulx et al. Reference Proulx, Inzlicht and Harmon-Jones2012) suggest that people will react to threats by affirming their ideological in-group and core ideological values (i.e., liberals affirming liberal values and vice versa). Studies with complete tests of those two competing hypotheses find that both liberals and conservative respond to threats and violated expectations by clinging to their cherished values (e.g., Castano et al. Reference Castano, Leidner, Bonacossa, Nikkah, Perrull, Spencer and Humphrey2011; Greenberg et al. Reference Greenberg, Simon, Pyszczynski, Solomon and Chatel1992; Kosloff et al. Reference Kosloff, Greenberg, Weise and Solomon2010). Proulx and Major (Reference Proulx and Major2013), for example, find that people low on a measure of the Protestant Work Ethic exposed to stimuli that violated their expectations more vigorously, endorse affirmative action policies, whereas people high on the same measure revealed the opposite pattern. Similar results have been obtained with other types of threats. For example, people primed with a lack of control expressed support for their political party (Fritsche et al. Reference Fritsche, Jonas and Frankhanel2008) and threats to freedom and self-sufficiency increased support for meritocracy when meritocratic values were salient and increased support for equality when egalitarian values were salient (Zhu et al. Reference Zhu, Kay and Eibach2013). Together, these results suggest that liberals and conservatives both respond to basic psychological threats with the affirmation of important and salient values.

The above findings offer an important theoretical layer to the negativity bias hypothesis. We agree that liberals and conservatives do differ on a number of dimensions that can be parsimoniously described as a negativity bias (e.g., Brandt & Reyna Reference Brandt and Reyna2010; Jost et al. Reference Jost, Glaser, Kruglanski and Sulloway2003); however, a careful review of the extant research leads to the conclusion that, although a negativity bias may be an underlying cause in the development of political ideologies, it is not manifest in reactions to threatening groups, threatening information, or fundamental psychological and epistemic threats. Instead, when it comes to dealing with negativity and threats, people across the political divide react similarly by defending their attitudes, values, and worldviews with intolerance toward people with differing beliefs, biased processing of attitude-inconsistent information, and the affirmation of core values.

Recent years have seen the rapid accumulation of data on the psychology of political ideology. The field needs a broad, integrative theory to help us connect the multitude of data points related to the foundations of ideology into fundamental patterns. Looking forward, any complete theory of political ideology, its precursors and consequences, needs to account for both the similarities and differences of seemingly divergent political orientations.