At Least Bias Is Bipartisan: A Meta-Analytic Comparison of Partisan Bias in Liberals and Conservatives

Abstract

Both liberals and conservatives accuse their political opponents of partisan bias, but is there empirical evidence that one side of the political aisle is indeed more biased than the other? To address this question, we meta-analyzed the results of 51 experimental studies, involving over 18,000 participants, that examined one form of partisan bias-the tendency to evaluate otherwise identical information more favorably when it supports one's political beliefs or allegiances than when it challenges those beliefs or allegiances. Two hypotheses based on previous literature were tested: an asymmetry hypothesis (predicting greater partisan bias in conservatives than in liberals) and a symmetry hypothesis (predicting equal levels of partisan bias in liberals and conservatives). Mean overall partisan bias was robust ( r = .245), and there was strong support for the symmetry hypothesis: Liberals ( r = .235) and conservatives ( r = .255) showed no difference in mean levels of bias across studies. Moderator analyses reveal this pattern to be consistent across a number of different methodological variations and political topics. Implications of the current findings for the ongoing ideological symmetry debate and the role of partisan bias in scientific discourse and political conflict are discussed.

Ideological measurement in social and political psychology

“…This primary data was consistent with prior findings that suggest political liberals and conservatives engage in stereotypical thinking by exaggerating the moral differences between their respective groups (Graham, Nosek, & Haidt, 2012). Baron and Jost (2019) have criticized and questioned Ditto et al's (2019) conclusions, stating that the studies included in this meta-analysis explicitly used highly polarizing topics that were unlikely to give rise of asymmetric findings. Instead, Baron and Jost (2019) suggest that more work be done examining the endorsement of beliefs that would demonstrate the 13 aforementioned underlying cognitive differences between conservatives and liberals (see Jost, 2017a).…”

“…In recent years, there has been a growing interest in the extent to which self-identifying liberals and conservatives possess a range of convergent or divergent personality characteristics, and express themselves in (dis)similar ways. This work is referred to as research into ideological (a)symmetries, with partisan differences labelled as asymmetries, and similarities labelled as symmetries (Ditto at al., 2019;Jost, 2017a). In this section, an overview of some of the highlights of this research is presented, and a critical explanation of the range of findings within the existing literature is outlined.…”

“…In perhaps the largest and widest-ranging published meta-analysis of cross-spectrum partisan bias against outgroups (e.g., evaluations political outgroup actors and ideological opinions), Ditto et al (2019) used data from 51 studies (N > 18,000) to calculate average bias scored for both liberals and conservatives. They found the meta-analyzed effect sizes for the two groups (rs = .24 and .26, respectively) were not statistically different from one another, supporting the ideological symmetry hypothesis with regard to partisan bias.…”

“…They found the meta-analyzed effect sizes for the two groups (rs = .24 and .26, respectively) were not statistically different from one another, supporting the ideological symmetry hypothesis with regard to partisan bias. Indeed, in their own analysis of primary data using almost 1,000 partisans surveyed on YourMorals.com, Ditto et al (2019) found that perceptions of ideological bias were themselves ideologically biased, with liberals perceiving increased bias among conservatives (comparative to among liberals), and conservatives demonstrating the opposite trend. This primary data was consistent with prior findings that suggest political liberals and conservatives engage in stereotypical thinking by exaggerating the moral differences between their respective groups (Graham, Nosek, & Haidt, 2012).…”

“…When seeking to understand the behavioral implications of ideological positions, the motivated defense of one's worldviews and policy positions is seemingly expressed in a symmetric way at the situational level. Recent examples relate to the cross-spectrum denial of ideologically-inconsistent scientific findings, different levels of self-reported warmth in relation to ideological similar or dissimilar groups, and the motivated avoidance of counterideological information (Brandt, 2017;Ditto et al, 2019;Frimer et al, 2017;Nisbet et al, 2015;Stern & Crawford, 2020;Washburn & Skitka, 2017). As such, political and ideological differences in policy preference may be rooted in core individual differences at the temperamental level (as operationalized in the work of personality psychologists), whereas symmetries may be rooted in the expression and defense of one's worldview at the situational level (as operationalized in emerging research in social psychological science).…”