As the heat of the presidential contest rises, we become more sensitive to the animosities between party activists: Obama is a European socialist; Romney is a greedy exploiter. It seems that Americans have become increasingly and more bitterly divided in their politics. Yet, researchers over the last decade or so have found that this impression of growing polarization is false in one way, though true in another.

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On the issues, even most of the divisive ones such as abortion or the “safety net,” Americans have not, it seems, become more divided. Positions have stayed pretty constant or, at least, not gotten more vitriolic. But Americans have become more divided and more vitriolic on party politics. Republican and Democrat partisans have lined up on opposite sides of issues more consistently, ideologically, and vehemently than was true for a few generations. (See this earlier post.) (Update: See this 2014 post and subsequent ones on The Monkey Cage blog for a summary of what political scientists know about polarization. See this 2014 Pew report on trends in polarization.)
A newly published study (abstract, paper gated) by Stanford political scientist Shanto Iyengar and two colleagues in Public Opinion Quarterly further clarifies this dynamic. The take-away message may be that the increase in political partisanship is perhaps better described as blood sports than as deep ideology.
Not My Daughter, You Won’t!
Iyengar and his co-authors, Gaurav Sood and Yphtach Lelkes, focus on Americans’ feelings about the parties. They draw on many surveys, but the key one is the American National Election Survey, an academic poll that has been conducted for decades. The ANES asks respondents to rate how “warm” or “cold” they feel toward various groups on a scale from a hot 100 down to a chilly zero. From the late 1970s through the late 2000s, Americans rated their own political party pretty consistently, at about an average of 70 on the scale. However, Americans rated the other party increasingly cooly, from about a 47 average four decades ago down to about a 35 average these days. This trend portrays a growing animosity toward the other side. Notably, the gulf in party temperatures is now wider than that between whites and blacks and that between Catholics and Protestants.
A pair of surveys asked Americans a more concrete question: in 1960, whether they would be “displeased” if their child married someone outside their political party, and, in 2010, would be “upset” if their child married someone of the other party. In 1960, about 5 percent of Americans expressed a negative reaction to party intermarriage; in 2010, about 40 percent did (Republicans about 50 percent, Democrats about 30 percent).
A note of caution: This party animosity is not historically new, just new to last several decades. At least partisans today are not brawling with and killing one another, as was true in the 19th century. But something seems to have changed since the less polarized era of the mid-20th century.
Explanations
Iyengar and colleagues agree with earlier researchers who have found that Americans have not polarized around ideology or policy. The ANES asked the warm/cold question about liberals and conservatives, and the temperature gap between “my” ideological group and “that” ideological group has stayed about the same since the 1970s – liberals express about a 20-point warmth gap and conservatives about a 30-point gap.
In any case, political scientists have long established that most Americans cannot reliably identify which specific policies each party supports, that people adopt party loyalties quite early in life, and that most stick to those loyalties whatever happens. (Look, I expected my kids to bleed Giants orange and detest Dodger blue from birth to eternity. So far, so good.) Americans’ party polarization cannot be that much about the issues.
The authors point instead to the intensification of media attacks in the last few decades. They find that the warmth gap was highest among Americans in battleground states and Americans exposed to the largest number of negative political ads. Another study, by John Geer, describes how negative ads have increased — and increased, he finds, because the media increasingly turned them into news stories, multiplying their exposure and turning up the heat.
Studies such as the one by Iyengar and colleagues are sharpening our understanding of what this political polarization is about. Increasingly, for most Americans it looks to be less about substantive issues and more about team (or gang) loyalty.
(Cross-posted on The Berkeley Blog on September 26, 2012.)
UPDATE, October 20, 2016:
In the midst of the bitter Hillary Clinton v. Donald Trump election contest, the Pew survey organization highlighted key attitudes that separate Trump and Clinton supporters. None is more stark than this: The poll asked respondents whether “life for people like you today is worse than it was 50 years ago.” Clinton supporters: 19% said yes; Trump supporters: 81% said yes. (This was the greatest gap except for the question specifically about about Trump’s pledge to build a wall with Mexico.) One can see this 62-point difference as evidence about what motivates people to support Trump v. Clinton: dissatisfaction versus satisfaction with the last half-century. One can alternatively see it as evidence of how Trump v. Clinton supporters line up their worldviews to fit with their political commitments and the stances of their candidates. In either case: polarization!
UPDATE, July 24, 2018
Klar, Krupnikov, and Ryan published an article in 2018 that seeks to qualify the “you can’t marry my daughter” finding. “What seems like negative affect toward the other party is, in fact, negative affect toward partisans from either side of the aisle and political discussion in general. Relying on two national experiments, we demonstrate that although some Americans are politically polarized, more simply want to avoid talking about politics. In fact, many people do not want their child to marry someone from their own party if that hypothetical in-law were to discuss politics frequently.” “… Polarization is a dominant trait only among the one-third of respondents who identify as strong partisans… The majority of individuals are not ‘affectively’ polarized”; rather, many are averse to partisan politics.” “… These results do not imply that affective polarization has not increased… Rather, scholars are underestimating how much people dislike their own party.”
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