Annual Review of Political Science
The Origins and Consequences
of Affective Polarization in the
United States
Shanto Iyengar,1 Yphtach Lelkes,2
Matthew Levendusky,3 Neil Malhotra,4
and Sean J. Westwood5
1
Department of Political Science, Stanford University, Stanford, California 94305, USA
2
Annenberg School for Communication, University of Pennsylvania, Philadelphia,
Pennsylvania 19104, USA
3
Department of Political Science, University of Pennsylvania, Philadelphia,
Pennsylvania 19104, USA
4
Graduate School of Business, Stanford University, Stanford, California 94305, USA
5
Department of Government, Dartmouth College, Hanover, New Hampshire 03755, USA
Annu. Rev. Political Sci. 2019. 22:129–46 Keywords
First published as a Review in Advance on
affective polarization, partisanship, ideology, social identity, American
December 10, 2018
politics
The Annual Review of Political Science is online at
polisci.annualreviews.org Abstract
https://doi.org/10.1146/annurev-polisci-051117-
While previously polarization was primarily seen only in issue-based terms,
073034
a new type of division has emerged in the mass public in recent years: Ordi-
Copyright © 2019 by Annual Reviews.
nary Americans increasingly dislike and distrust those from the other party.
All rights reserved
Democrats and Republicans both say that the other party’s members are
hypocritical, selfish, and closed-minded, and they are unwilling to social-
ize across party lines. This phenomenon of animosity between the parties
is known as affective polarization. We trace its origins to the power of par-
tisanship as a social identity, and explain the factors that intensify partisan
animus. We also explore the consequences of affective polarization, high-
lighting how partisan affect influences attitudes and behaviors well outside
the political sphere. Finally, we discuss strategies that might mitigate parti-
san discord and conclude with suggestions for future work.
129
, INTRODUCTION
America, we are told, is a divided nation. What does this mean? Political elites—particularly mem-
bers of Congress—increasingly disagree on policy issues (McCarty et al. 2006), though there is
still an active debate about whether the same is true of the mass public (Abramowitz & Saunders
2008, Fiorina et al. 2008). But regardless of how divided Americans may be on the issues, a new
type of division has emerged in the mass public in recent years: Ordinary Americans increasingly
dislike and distrust those from the other party.
Democrats and Republicans both say that the other party’s members are hypocritical, selfish,
and closed-minded, and they are unwilling to socialize across party lines, or even to partner with
opponents in a variety of other activities. This phenomenon of animosity between the parties is
known as affective polarization.
We trace the origins of affective polarization to the power of partisanship as a social identity,
and explain the factors that intensify partisan animus. We also explore the consequences of affec-
tive polarization, highlighting how partisan affect influences attitudes and behaviors well outside
the political sphere. Finally, we discuss strategies that might mitigate partisan discord, and con-
clude with some suggestions for future work.
AFFECTIVE POLARIZATION: AN OUTGROWTH OF PARTISAN
SOCIAL IDENTITY
Homo sapiens is a social species; group affiliation is essential to our sense of self. Individuals instinc-
tively think of themselves as representing broad socioeconomic and cultural categories rather than
as distinctive packages of traits (Brewer 1991, Tajfel 1978). Political parties often form along these
lines precisely because group identities are so stable and significant (Lipset & Rokkan 1967).
In the United States, partisanship means identifying with the Democrat group or the Republi-
can group (Green et al. 2002, Huddy et al. 2015). A host of behavioral consequences flow from that
identification. When we identify with a political party, we instinctively divide up the world into an
in group (our own party) and an out group (the opposing party, or out party; see Tajfel & Turner
1979). A vast literature in social psychology demonstrates that any such in-group/out-group dis-
tinction, even one based on the most trivial of shared characteristics, triggers both positive feelings
for the in group and negative evaluations of the out group (see, e.g., Billig & Tajfel 1973). The
more salient the group to the sense of personal identity, the stronger these intergroup divisions
(Gaertner et al. 1993).
Partisanship is a particularly salient and powerful identifier for two main reasons. First, it is
acquired at a young age and rarely changes over the life cycle, notwithstanding significant shifts
in personal circumstances (Sears 1975). Second, political campaigns—the formal occasions for
expressing one’s partisan identity—recur frequently and last for many months (or even years) in
the contemporary United States. Indeed, some even argue that modern governance is effectively
always about the next campaign (Lee 2016), meaning that individuals constantly receive partisan
cues from elites. It is no surprise, therefore, that ordinary Americans see the political world through
a partisan prism.
From a social identity perspective, affective polarization is a natural offshoot of this sense of
partisan group identity: “the tendency of people identifying as Republicans or Democrats to view
opposing partisans negatively and copartisans positively” (Iyengar & Westwood 2015, p. 691).
However, changes in the contemporary political and media environment have exacerbated the
divide in recent years, as we explain below.
130 Iyengar et al.
, Our conceptualization of polarization as rooted in affect and identity stands in contrast to a
long tradition in political science of studying polarization as the difference between the policy
positions of Democrats and Republicans (Fiorina et al. 2005). Indeed, there is ongoing schol-
arly disagreement over the extent of such ideological polarization. Some scholars argue that the
mass public has polarized on the issues, citing a decline in the number of ideological moderates
and a near doubling of the average distance between the ideological self-placement of nonactivist
Democrats and Republicans between 1972 and 2004 (Abramowitz & Saunders 2008). Others dis-
pute this description of the masses, maintaining that the median citizen remains a centrist rather
than an extremist on most issues (Fiorina et al. 2008).
We do not take a position on this ongoing debate. Rather, we argue that affective polarization is
largely distinct from the ideological divide, and that extremity in issue opinions is not a necessary
condition for affective polarization (Iyengar et al. 2012, Mason 2015). Indeed, in some settings,
affective polarization can increase while ideological divisions shrink (Levendusky & Malhotra
2016a). While there are important connections between affective and ideological polarization
(Abramowitz & Webster 2016), to which we return below, they are theoretically and empirically
distinct concepts. In this article, we focus exclusively on the affective dimension of polarization.
HOW DO WE MEASURE AFFECTIVE POLARIZATION?
Scholars have used three main classes of techniques to measure affective polarization: survey self-
reports of partisan affect, implicit or subconscious tests of partisan bias, and behavioral measures
of interpersonal trust and group favoritism or discrimination based on partisan cues.
Survey Self-Reports
Survey self-reports are the most basic and widely used measure of affective polarization in the
literature. While scholars have relied on several different survey items, the most central is the
“feeling thermometer” question from the American National Election Study (ANES) time se-
ries. The feeling thermometer was originally created as a “neutrally worded means of eliciting
responses to a wide variety of candidates” (Weisberg & Rusk 1970, p. 1168) but has become the
primary vehicle for measuring affect toward a wide range of groups in the electorate. Typically,
respondents are asked to rate Democrats and Republicans (or the Democratic and Republican
Parties) on a 101-point scale ranging from cold (0) to warm (100). Affective polarization is then
computed as the difference between the score given to the party of the respondent and the score
given to the opposing party, which we also refer to as the out party. In the ANES time series (see
Figure 1), this measure shows a significant increase in affective polarization since 1980, rising
from 22.64 degrees in 1978 to 40.87 degrees in 2016 (Iyengar et al. 2012). It is particularly note-
worthy that (a) the change is not that people like their own party more over time; rather, there
is an increase in out-party animus, especially in recent years, and (b) affective polarization actu-
ally decreased between 2012 and 2016. Other over-time measures of partisan affect show similar
patterns (e.g., Pew Research Center 2017).
Although the feeling thermometer is the workhorse survey item, scholars have also adopted
alternative measures. Levendusky (2018a) and Levendusky & Malhotra (2016a) use trait ratings
of party supporters to measure affective discord: Are they intelligent, open-minded, and generous,
or hypocritical, selfish, and mean (see also Garrett et al. 2014, Iyengar et al. 2012)? Levendusky
& Malhotra (2016a) also count the number of things people can bring to mind that they like and
dislike about the parties as a quasi-behavioral measure. Other scholars have substituted the extent
www.annualreviews.org • Affective Polarization in the United States 131
The Origins and Consequences
of Affective Polarization in the
United States
Shanto Iyengar,1 Yphtach Lelkes,2
Matthew Levendusky,3 Neil Malhotra,4
and Sean J. Westwood5
1
Department of Political Science, Stanford University, Stanford, California 94305, USA
2
Annenberg School for Communication, University of Pennsylvania, Philadelphia,
Pennsylvania 19104, USA
3
Department of Political Science, University of Pennsylvania, Philadelphia,
Pennsylvania 19104, USA
4
Graduate School of Business, Stanford University, Stanford, California 94305, USA
5
Department of Government, Dartmouth College, Hanover, New Hampshire 03755, USA
Annu. Rev. Political Sci. 2019. 22:129–46 Keywords
First published as a Review in Advance on
affective polarization, partisanship, ideology, social identity, American
December 10, 2018
politics
The Annual Review of Political Science is online at
polisci.annualreviews.org Abstract
https://doi.org/10.1146/annurev-polisci-051117-
While previously polarization was primarily seen only in issue-based terms,
073034
a new type of division has emerged in the mass public in recent years: Ordi-
Copyright © 2019 by Annual Reviews.
nary Americans increasingly dislike and distrust those from the other party.
All rights reserved
Democrats and Republicans both say that the other party’s members are
hypocritical, selfish, and closed-minded, and they are unwilling to social-
ize across party lines. This phenomenon of animosity between the parties
is known as affective polarization. We trace its origins to the power of par-
tisanship as a social identity, and explain the factors that intensify partisan
animus. We also explore the consequences of affective polarization, high-
lighting how partisan affect influences attitudes and behaviors well outside
the political sphere. Finally, we discuss strategies that might mitigate parti-
san discord and conclude with suggestions for future work.
129
, INTRODUCTION
America, we are told, is a divided nation. What does this mean? Political elites—particularly mem-
bers of Congress—increasingly disagree on policy issues (McCarty et al. 2006), though there is
still an active debate about whether the same is true of the mass public (Abramowitz & Saunders
2008, Fiorina et al. 2008). But regardless of how divided Americans may be on the issues, a new
type of division has emerged in the mass public in recent years: Ordinary Americans increasingly
dislike and distrust those from the other party.
Democrats and Republicans both say that the other party’s members are hypocritical, selfish,
and closed-minded, and they are unwilling to socialize across party lines, or even to partner with
opponents in a variety of other activities. This phenomenon of animosity between the parties is
known as affective polarization.
We trace the origins of affective polarization to the power of partisanship as a social identity,
and explain the factors that intensify partisan animus. We also explore the consequences of affec-
tive polarization, highlighting how partisan affect influences attitudes and behaviors well outside
the political sphere. Finally, we discuss strategies that might mitigate partisan discord, and con-
clude with some suggestions for future work.
AFFECTIVE POLARIZATION: AN OUTGROWTH OF PARTISAN
SOCIAL IDENTITY
Homo sapiens is a social species; group affiliation is essential to our sense of self. Individuals instinc-
tively think of themselves as representing broad socioeconomic and cultural categories rather than
as distinctive packages of traits (Brewer 1991, Tajfel 1978). Political parties often form along these
lines precisely because group identities are so stable and significant (Lipset & Rokkan 1967).
In the United States, partisanship means identifying with the Democrat group or the Republi-
can group (Green et al. 2002, Huddy et al. 2015). A host of behavioral consequences flow from that
identification. When we identify with a political party, we instinctively divide up the world into an
in group (our own party) and an out group (the opposing party, or out party; see Tajfel & Turner
1979). A vast literature in social psychology demonstrates that any such in-group/out-group dis-
tinction, even one based on the most trivial of shared characteristics, triggers both positive feelings
for the in group and negative evaluations of the out group (see, e.g., Billig & Tajfel 1973). The
more salient the group to the sense of personal identity, the stronger these intergroup divisions
(Gaertner et al. 1993).
Partisanship is a particularly salient and powerful identifier for two main reasons. First, it is
acquired at a young age and rarely changes over the life cycle, notwithstanding significant shifts
in personal circumstances (Sears 1975). Second, political campaigns—the formal occasions for
expressing one’s partisan identity—recur frequently and last for many months (or even years) in
the contemporary United States. Indeed, some even argue that modern governance is effectively
always about the next campaign (Lee 2016), meaning that individuals constantly receive partisan
cues from elites. It is no surprise, therefore, that ordinary Americans see the political world through
a partisan prism.
From a social identity perspective, affective polarization is a natural offshoot of this sense of
partisan group identity: “the tendency of people identifying as Republicans or Democrats to view
opposing partisans negatively and copartisans positively” (Iyengar & Westwood 2015, p. 691).
However, changes in the contemporary political and media environment have exacerbated the
divide in recent years, as we explain below.
130 Iyengar et al.
, Our conceptualization of polarization as rooted in affect and identity stands in contrast to a
long tradition in political science of studying polarization as the difference between the policy
positions of Democrats and Republicans (Fiorina et al. 2005). Indeed, there is ongoing schol-
arly disagreement over the extent of such ideological polarization. Some scholars argue that the
mass public has polarized on the issues, citing a decline in the number of ideological moderates
and a near doubling of the average distance between the ideological self-placement of nonactivist
Democrats and Republicans between 1972 and 2004 (Abramowitz & Saunders 2008). Others dis-
pute this description of the masses, maintaining that the median citizen remains a centrist rather
than an extremist on most issues (Fiorina et al. 2008).
We do not take a position on this ongoing debate. Rather, we argue that affective polarization is
largely distinct from the ideological divide, and that extremity in issue opinions is not a necessary
condition for affective polarization (Iyengar et al. 2012, Mason 2015). Indeed, in some settings,
affective polarization can increase while ideological divisions shrink (Levendusky & Malhotra
2016a). While there are important connections between affective and ideological polarization
(Abramowitz & Webster 2016), to which we return below, they are theoretically and empirically
distinct concepts. In this article, we focus exclusively on the affective dimension of polarization.
HOW DO WE MEASURE AFFECTIVE POLARIZATION?
Scholars have used three main classes of techniques to measure affective polarization: survey self-
reports of partisan affect, implicit or subconscious tests of partisan bias, and behavioral measures
of interpersonal trust and group favoritism or discrimination based on partisan cues.
Survey Self-Reports
Survey self-reports are the most basic and widely used measure of affective polarization in the
literature. While scholars have relied on several different survey items, the most central is the
“feeling thermometer” question from the American National Election Study (ANES) time se-
ries. The feeling thermometer was originally created as a “neutrally worded means of eliciting
responses to a wide variety of candidates” (Weisberg & Rusk 1970, p. 1168) but has become the
primary vehicle for measuring affect toward a wide range of groups in the electorate. Typically,
respondents are asked to rate Democrats and Republicans (or the Democratic and Republican
Parties) on a 101-point scale ranging from cold (0) to warm (100). Affective polarization is then
computed as the difference between the score given to the party of the respondent and the score
given to the opposing party, which we also refer to as the out party. In the ANES time series (see
Figure 1), this measure shows a significant increase in affective polarization since 1980, rising
from 22.64 degrees in 1978 to 40.87 degrees in 2016 (Iyengar et al. 2012). It is particularly note-
worthy that (a) the change is not that people like their own party more over time; rather, there
is an increase in out-party animus, especially in recent years, and (b) affective polarization actu-
ally decreased between 2012 and 2016. Other over-time measures of partisan affect show similar
patterns (e.g., Pew Research Center 2017).
Although the feeling thermometer is the workhorse survey item, scholars have also adopted
alternative measures. Levendusky (2018a) and Levendusky & Malhotra (2016a) use trait ratings
of party supporters to measure affective discord: Are they intelligent, open-minded, and generous,
or hypocritical, selfish, and mean (see also Garrett et al. 2014, Iyengar et al. 2012)? Levendusky
& Malhotra (2016a) also count the number of things people can bring to mind that they like and
dislike about the parties as a quasi-behavioral measure. Other scholars have substituted the extent
www.annualreviews.org • Affective Polarization in the United States 131
