A new study published in Political Psychology suggests that the midpoint of the common left-right political spectrum scale hides a surprising amount of political diversity, potentially mixing genuinely moderate individuals with those holding populist and anti-establishment views. This finding indicates that relying solely on this single measure may obscure important nuances in public opinion, particularly regarding attitudes toward the political system and various social issues.

Previous work had indicated that the midpoint of the left-right self-placement item, a standard measure of political ideology in surveys, is consistently the most frequently chosen option across many democratic nations. This midpoint group has long been recognized as heterogeneous, including individuals who are genuinely centrist, those unfamiliar with the terms “left” and “right,” individuals with low political interest, and those who hold a mix of traditionally left and right-wing stances.

Prior research has also observed “W-shaped” or “M-shaped” relationships when plotting the left-right item against attitudes like skepticism toward government or conspiracy beliefs. These shapes involve “bumps” at the midpoint, where individuals express views similar to those at the extreme ends of the spectrum.

“I, along with most collaborators on this study, had already published a paper reporting a curvilinear relationship between the left-right self-placement item and conspiracy beliefs, such that belief was higher at both extreme ends of the left-right scale, but also the center,” said study author Edward Clarke, a postdoctoral researcher at Philipps-Universität Marburg.

“This seemed to go against conventional wisdom that political centrists/moderates generally hold less extreme attitudes than the far-left and far-right, all the while acknowledging that interpreting what a midpoint response on such scales is difficult. We then decided to explore just how prevalent this ‘midpoint bump’ might be across a range of social and political attitudes, to see if there were commonalities across these attitudes that we could make sense of.”

To conduct their research, the scientists utilized data from two large-scale surveys: the 2019 Australian Election Study (AES) and the 2020 American National Election Studies (ANES). The AES sample consisted of 2,179 participants, with 652 identified as midpoint responders. The ANES sample included 8,280 participants, with 1,818 midpoint responders.

The Australian survey asked participants to place themselves on a scale from 0 (Left) to 10 (Right). The American survey utilized a seven-point scale ranging from “Extremely liberal” to “Extremely conservative.” The researchers also examined responses to questions regarding trust in politicians, attitudes toward immigration, and satisfaction with democracy.

The study employed a two-step analytical approach. First, the team plotted the relationship between left-right self-placement and various political attitudes. They specifically looked for nonlinear patterns in the data. A typical linear relationship would show attitudes becoming progressively more conservative as one moves from left to right. A U-shaped relationship would show the extremes agreeing with each other against the center.

The researchers instead found evidence of W-shaped or M-shaped relationships. This indicates that responses at the midpoint were often distinct from those immediately to their left or right. On several measures, the mean scores of midpoint responders were more extreme than those of center-left or center-right individuals. This phenomenon was particularly visible regarding anti-establishment attitudes.

In the Australian data, midpoint responders showed relatively high support for the death penalty and the belief that immigrants harm the economy. They also expressed significant distrust in the political system. They were more likely to believe that politicians are out of touch and that voting does not make a difference. These “bumps” in the data suggested that the center included people with views typically associated with the political fringes.

The American data showed similar patterns, though somewhat less pronounced. Midpoint responders in the U.S. displayed elevated levels of belief that immigrants harm culture and that the government is run by a few big interests. The researchers confirmed these visual observations using polynomial regression testing. This statistical method identified that a complex, quartic function fit the data better than a straight line for many variables.

The second step of the analysis involved Latent Profile Analysis (LPA). This technique allows researchers to identify unobserved subgroups within a specific population based on patterns of responses. The researchers applied this method exclusively to the participants who had selected the midpoint option. They aimed to see if the “center” was actually composed of distinct types of voters.

In the Australian sample, the analysis identified four distinct profiles among midpoint responders. The largest group, labeled “exclusionary populists,” made up 32 percent of the midpoint. This group reported the lowest trust in the political system and held strong anti-immigrant views. They believed strongly that the people, rather than politicians, should make policy decisions.

Another Australian group, labeled “establishment centrists,” comprised 11 percent of the midpoint. These individuals were the opposite of the populists. They were politically engaged and expressed high trust in the democratic system.

A third group, representing 29 percent, appeared “cross-pressured.” These voters held a mix of left-wing views on income equality and right-wing views on immigration. A final group, labeled ‘skeptical centrists’ (27 percent), held middling views on issues but scored lower than establishment centrists on the belief that voting makes a difference.

The American data revealed three profiles among the moderates. The majority, about 71 percent, fit the description of genuine centrists who held moderate views between the left and right. However, two smaller groups displayed clear populist traits. A “valence populist” group, representing 10 percent of the midpoint, expressed high skepticism of government and believed in widespread corruption.

A second U.S. group, labeled “exclusionary populists,” made up 19 percent of the midpoint. This group combined anti-establishment sentiment with concerns that immigrants harm American culture. When looking at voting intentions for the 2020 election, the valence populists were notable for their dissatisfaction. A significant portion intended to vote for a third-party candidate or Donald Trump, rather than Joe Biden.

The researchers then tested whether these specific groups were responsible for the statistical “bumps” observed earlier. They created new plots of the data while sequentially removing each latent profile. When the populist profiles were removed from the analysis, the relationships between ideology and attitudes largely smoothed out.

This suggests that the “extreme center” is driven by these specific subgroups. In the Australian data, removing the exclusionary populist profile significantly reduced the non-linearity for items regarding political trust. In the U.S. data, the large number of genuine centrists tended to dilute the effect of the populists. However, the populist profiles still exerted enough influence to create visible irregularities in the data trends.

This study provides evidence that the single left-right self-placement item can conceal significant political diversity within its midpoint, including populist beliefs that are often associated with the political extremes. This suggests that survey measures of political orientation may be providing a distorted view of what “between left and right” signifies to many individuals.

“The main thing to take away is that while around one-third of people may identify their politics as centrist or moderate when asked, this can mean quite different things for different people,” Clarke told PsyPost. “In fact, it can mean completely opposite things.”

“Those that are ideologically centrist or moderate in the traditional sense hold generally positive attitudes toward the existing political system. Members of another midpoint response group are skeptical of the political system and hold anti-establishment or populist attitudes, which are attitudes that are generally at odds with those of the more ideological centrists.”

A limitation of this research is its focus on two Anglophone nations, Australia and the United States. Future research should consider conducting similar analyses in a broader range of countries, particularly where the left-right scale might have different meanings. Additionally, the labels assigned to the latent profiles are interpretations based on the data and theoretical perspectives, and thus should be considered with some caution.

“An important caveat relates to the labelling of the midpoint profiles,” Clarke explained. “Although informed by the data and theoretical perspectives, the labels are our interpretations of the pattern of results and therefore should be taken cautiously. To add more empirical weight to our claims, it would be great to run a similar analysis on midpoint respondents using a reliable and valid populism scale, for instance.”

Looking forward, “we would like to conduct similar analyses using reliable and valid measures of populist and anti-establishment attitudes, to provide a better test of the claim that some populists indeed self-place on the midpoint of the left-right item. Another important extension would be to conduct more cross-national work, as our study was limited to Australian and U.S. datasets.”

Despite these limitations, the research clearly indicates that the midpoint of the left-right scale contains distinct political profiles, with varying levels of political engagement and attitudes toward the establishment.

“Although this is not a new idea, I think that psychologists and political and social scientists need to reflect on how we design our measures of political orientation and ideology, because we are potentially receiving a distorted image of what ‘between left and right’ means to people,” Clarke said.

The study, “Extremism at the center: Uncovering political diversity among midpoint responders on the left–right self-placement item,” was authored by Edward J. R. Clarke, Frank Eckerle, John R. Kerr, Stephen R. Hill, Mathew Ling, Mathew D. Marques, and Matt N. Williams.