The Forum 2018; 16(1): 23â€“45
Shanto Iyengar* and Masha Krupenkin*
Partisanship as Social Identity; Implications
for the Study of Party Polarization
Abstract: Partisanship continues to divide Americans. Using data from the
American National Election Study, as well as implicit attitude tests, we argue that
Americansâ€™ partisan identity has become highly salient. Partisans have become
more negative towards the opposing party on both explicit and implicit measures, and these biases spill over into their everyday decisions. Partisanship has
become one of Americansâ€™ most salient social identities.
The concept of group identity plays a vital role in explaining individualsâ€™ party
choices (Greene 1999; Green, Palmquist, and Schickler 2002; Huddy, Mason, and
AarÃ¸e 2015). It is well established, based on a vast literature in social psychology,
that any form of group affiliation, 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 (Tajfel et al. 1971; Billig and Tajfel 1973). The sense of
group identity is tantamount to group polarization. In the case of societies with
deep cleavages, and where the cleavages are reinforcing (rather than cross-cutting), this sense of â€œus against themâ€ can have destabilizing consequences (see
Lijphart 1969). Dissatisfaction with government performance frequently leads
group members to demand political redress and autonomy, in some cases using
violent forms of protest (Gubler and Selway 2012). Recent manifestations of this
pattern include the unrest in the Russian speaking regions of Ukraine, the sectarian political conflict in Northern Ireland, and independence movements in the
Basque and Catalonian regions of Spain as well as the Tamil districts of Sri Lanka.
Since group-based affect appears to be an ingrained human response, and
individuals typically categorize themselves into multiple groups, an important
question concerns the hierarchy of group affiliations. Which affiliations provide
*Corresponding authors: Shanto Iyengar and Masha Krupenkin, Department of Political
Science, Stanford University, 616 Serra St, Stanford, CA, USA, e-mail: [email protected]
(S. Iyengar); [email protected] (M. Krupenkin)
24â€ƒâ€‚â€‚â€‚â€‰ Shanto Iyengar and Masha Krupenkin
the most meaningful cues? Social identity theorists posited identity salience as
the basis from which to predict the extent of inter-group polarization (see Haslam
et al. 1999; Transue 2007): the more salient the affiliation, the more divergent the
individualâ€™s beliefs about group members. Salience itself can depend on either
dispositional factors, such as the strength of the individualâ€™s loyalty to the group,
or characteristics of the information environment, such as the number of times
the individual is reminded of her group ties. In the case of party affiliation, as we
argue below, there are good reasons to expect identity salience since individuals
acquire their group affiliation at an early stage in the life cycle and because political campaigns â€“ the formal occasions for expressing oneâ€™s partisan identity â€“ are
frequent and lengthy occurrences, at least in the American case.
We argue that partisan affect has become especially salient in American politics. Partisansâ€™ negative feelings towards members of the opposing party on a
variety of measures have continued to rise throughout the 2000s. As we describe
below, the heightened animus influences a wide variety of everyday behaviors,
from dating, to employment decisions, to vaccinating a child. Today, partisanship
may be one of Americansâ€™ most salient group affiliations.
Alternative Definitions of Party Polarization
To the extent partisanship represents a meaningful social identity, partisans
should express not only positive sentiments for their own group, but also negative sentiments toward those affiliated with opposing groups (Tajfel and Turner
1979). This divergence in partisan affect (or affective polarization as it has come
to be known in political science) is sufficiently strong to inculcate a sense of
social distance from political opponents, thus motivating partisans to seek out
and associate with like-minded others. Party affiliation becomes a litmus test for
character and compatibility.
A different definition of party polarization, long favored by political scientists,
is based on ideological rather than affective divergence. In this framework, since
party identification is motivated by policy agendas and positions, the appropriate
metric for calibrating polarization is the distance between partisans in the policy
space. While there is a consensus that American party elites are polarized by this
standard (Stonecash, Brewer, and Mariani 2003; Layman, Carsey, and Horowitz
2006; McCarty, Poole, and Rosenthal 2016), the extent to which the electorate
has followed suit remains unclear. Some scholars argue that the mass public has
polarized on the issues, citing a decline in the number of ideological moderates
(Abramowitz and Saunders 2008; Campbell 2008; Jacobson and Carson 2015),
a near doubling of the average distance between the ideological self-placement
Implications for the Study of Party Polarizationâ€ƒâ€‰â€‚â€‚â€‚ 25
of non-activist Democrats and Republicans between 1972 and 2004 (Abramowitz and Saunders 2008), and the strengthened consistency of votersâ€™ preferences
across issues (Abramowitz 2010). Others, however, contest this description of the
masses, maintaining that the median citizen remains a centrist rather than an
extremist on most issues (Fiorina, Abrams, and Pope 2008; Fiorina 2017).
The instrumental account of party affiliation is an appealing theory, especially
to scholars who study representation. It provides a clear mechanism for electoral
accountability; representatives whose policy decisions stray from the preferences
of their constituents will be penalized at the next election (Page and Jones 1979;
Fiorina 2017). But in the US, empirical evidence for the â€œreward-punishmentâ€
theory has always been scant (Achen and Bartels 2017). One of the earliest challenges came from the scholars who developed the concept of party identification
(Campbell et al. 1960). They discovered that relatively few people reasoned about
politics in ideological terms, and concluded that partisan identity was primarily
affective. Parallel work, based on more unstructured, depth interviews revealed
that ordinary citizens had considerable difficulty â€œconnecting the dotsâ€ when
thinking about their interests in relation to the actions of government (Lane 1962).
Citizensâ€™ political naivetÃ© is one reason for doubting the utility of the instrumental theory of partisanship. Another is the body of work on the origins and
underpinnings of partisan identity over the course of the life cycle (Converse 1969;
Green, Palmquist, and Schickler 2002; Jennings, Stoker, and Bowers 2009). Political socialization researchers discovered that children acquired a sense of party
identification surprisingly early in life (e.g. Tedin 1974; Alford et al. 2011), without
any â€œflickering awarenessâ€ (Jennings and Niemi 1974, p. 265) of party differences
on the issues. Moreover, as people moved through the life cycle, with corresponding changes in economic circumstances and interests, their sense of partisanship
proved relatively stable despite considerable change in their stances on the issues
(Sears 1971; Niemi and Jennings 1991; Jennings, Stoker, and Bowers 2009).
Finally, the strength of the affective relative to ideological bond between
voters and parties is further substantiated by research showing that affect-based
or motivated reasoning trumps reasoning based on hard evidence. Despite extensive documentation to the contrary, a significant proportion of Republicans (over
40 percent) continue to believe that former President Obama is a Muslim (New
York Times). More recently, large majorities of Republicans ignore the consensus judgment within the intelligence community â€“ widely reported by the news
media â€“ and deny that the Russians interfered in the 2016 election. Partisansâ€™
tendency to discount or reject uncongenial information is well-established (Lord,
Ross, and Lepper 1979; Kunda 1987). Seminal work by Lodge and others has
documented the pervasive use of confirmatory bias and motivated skepticism in
information processing; both heuristics allow partisans to protect their sense of
26â€ƒâ€‚â€‚â€‚â€‰ Shanto Iyengar and Masha Krupenkin
identity from short-term threats (Taber and Lodge 2006; Lodge and Taber 2013).
Increased access to partisan news sources has only furthered partisansâ€™ ability to
take refuge in supportive â€œecho chambersâ€ (Sunstein 2017).
In short, as summarized above, there is ample evidence indicating that the psychological underpinnings of party identification in the US are more affective than
ideological in nature. The more meaningful definition of party polarization, therefore, is the degree to which partisans consider their opponents a stigmatized out
group. In this paper, using national survey data, we provide evidence on the extent
of affective polarization in the US. We then discuss the new role of party affiliation
as a meaningful cue for non-political attitudes and behaviors. In closing, we speculate over the factors that have given rise to heightened affective polarization.
Partisan Negativity Continues to Rise
The 2016 election maintained the trend of rising partisan negativity in the American electorate. From the 1980s onward, partisans have grown increasingly more
hostile toward the opposing party. Figure 1 shows partisansâ€™ mean ANES feeling
thermometer ratings for both their own and the opposing party between 1978
In this analysis we limit our attention to respondents in the personal
interview survey mode. While both Democrats and Republicans have maintained strong and generally stable positive feelings for their preferred party (with
average feeling thermometer ratings hovering around 70 for the entire period),
both sets of partisans have grown dramatically more negative toward each
Figure 1:â€‚In Party and Out Party Feeling Thermometers.
1â€‚Independent leaners are treated as partisans in all analyses.
Implications for the Study of Party Polarizationâ€ƒâ€‰â€‚â€‚â€‚ 27
other. The out party feeling thermometer ratings in 2016 (30.5) and 2012 (31.9)
are noticeably lower than those recorded in 1988 (45.54). Interestingly, the 2016
campaign â€“ arguably the most divisive in recent history â€“ resulted not only in
increased hostility for the out party, but at least in the case of the Republicans,
also in less enthusiasm for the in party. The mean Republican party thermometer
rating among Republicans fell to the lowest level in the entire series.
Despite the drop in Republicansâ€™ ratings of their party, the in-group evaluations remained relatively stable between 2012 and 2016, at least in comparison to
evaluations of the out group. Partisans became considerably more hostile toward
the opposing party in 2012 and 2016 than even in 2008. Figure 2 shows the distribution of out party thermometer ratings between 2004 and 2016. In both 2004 and
2008 (as well as all prior years), the thermometer rating had a mode of 50, indicating that many partisans felt indifference rather than animus toward their opponents. In 2012, however, the most frequent rating of the out party was zero. This
trend persisted into 2016, when the most common responses were 30, 15, and zero.
Stronger hostility for the out party is a recent, but rapidly escalating trend
that began at the turn of the century. Figure 3 shows that while the percentage
of partisans who rated the out party between 1 and 49 on the thermometer has
increased steadily since the 1980s, the share of partisans expressing intense negativity for the out party (ratings of 0) remained quite small until 2000. Post-2000,
the size of this group has increased dramatically â€“ from 8 percent in 2000 to 17
percent in 2016. Thus, the first two decades of the 21st Century represent an acute
era of polarization, in which partisansâ€™ mild dislike for their opponents has been
transformed into a deeper form of animus.
The trend of intensified polarization is not limited to any single indicator of
partisan affect. When we look at trait ratings of the presidential candidates (see
Figure 2:â€‚Out Party Feeling Thermometers, 2004â€“2016.
28â€ƒâ€‚â€‚â€‚â€‰ Shanto Iyengar and Masha Krupenkin
Figure 4), there is a steady decline in the applicability of positive traits to the
opposing candidate since 1988 and a corresponding increase in positivity toward
the in-party candidate. The same pattern applies to the affect battery (also shown
Figure 4:â€‚Candidate Traits and Affects Over Time.
Figure 3:â€‚Changes in Out Party Thermometers.
Implications for the Study of Party Polarizationâ€ƒâ€‰â€‚â€‚â€‚ 29
in Figure 4). Since 1980, increasing numbers of partisans experience more negative than positive emotions when thinking about the opposing candidate, a trend
that accelerates following 2000. Conversely, the in-party candidate increasingly
elicits more positive than negative emotions. Thus, unlike the case of the feeling
thermometers, heightened polarization over time in these trait and affect measures reflects both increased in-group favoritism and out-group hostility.
As a robustness test, we consider the extent to which financial incentives
temper the expression of partisan affect. Some scholars have argued that negative evaluations of the out party may represent â€œtop of the headâ€ cheer leading
for the home team, an expressive response that is not thoughtful or well considered (Bullock et al. 2015). In the particular case of answers to political knowledge
questions that reflect well or poorly on the performance of the respondentâ€™s preferred party (e.g. the state of unemployment, or the size of the federal deficit),
there is evidence that partisansâ€™ engage in wishful thinking, i.e. they underestimate the unemployment rate when their party is in power (see Bartels 2002;
Gerber and Huber 2010; Lavine, Johnston, and Steenbergen 2012). However,
when survey respondents are given a token financial incentive to answer correctly, partisans become less likely to provide misinformed responses (that favor
their party) by a factor of more than fifty percent (Bullock et al. 2015; for similar
evidence, see Prior and Lupia 2008; Prior, Sood, and Khanna 2015). As Bullock
and his co-authors summarize their results (2015, p. 559): â€œSurvey respondents
may not think seriously about correct answers under ordinary survey conditions,
but incentives may reduce partisan gaps by causing respondents to think more
carefully about correct answersâ€¦. In either case, the takeaway is the same: conventional survey measures overstate partisan differences.â€
Do ANES survey respondents become less expressive and less prone to
provide polarized evaluations when given a larger financial incentive to participate in the survey? For evidence bearing on this question, we return to the 2016
ANES which includes an experiment that assigned respondents into $10 and $20
prepaid incentive conditions. Since treatment is randomized, we can estimate
the causal effects of the amount received on the standard indicators of affective
polarization. Table 1 shows the results.
Table 1:â€‚ANES 2016 Payment Effects.
p-Value of Difference
Feel Therm 43.76 43.09 ns
Affect 9.10 8.71 ns
Trait 9.50 9.25 ns
30â€ƒâ€‚â€‚â€‚â€‰ Shanto Iyengar and Masha Krupenkin
The results given in Table 1 show no noticeable moderation of attitudes in
the $20 condition. The differences between the in and out party evaluations are
reduced when the incentive to take the survey is increased, but the magnitude of
the â€œcash effectâ€ is trivial.2
This pattern suggests that partisansâ€™ negative evaluations of the opposition are not merely symptoms of instinctive partisan cheer
leading, but represent respondentsâ€™ genuine beliefs. It is also worth noting that
while the distinction between cheer leading and sincerity may be of interest to
survey researchers, it is likely of no consequence to elected officials who interpret their supportersâ€™ harsh evaluations of the opposition as a signal to go on the
attack when running for reelection.
The ANES data establish not only that partisans increasingly dislike their
opponents, but also that the party cleavage is the most affect-laden in contemporary American society. Expressions of negative affect toward the out group
are not nearly as pronounced when groups are defined on the basis of ethnicity, gender, religion, or other salient cleavages (Iyengar, Sood, and Lelkes 2012;
Muste 2014). In the ANES, feeling thermometer ratings of Muslims, atheists,
gays and other marginalized groups are not nearly as negative as ratings of the
opposing party (see Figure 5 for illustrative data from the 2016 ANES). The historical trend of increased negativity directed at partisan opponents may therefore
be a product of the gradual diffusion of norms that temper evaluations of social
Figure 5:â€‚Feeling Thermometer Ratings of Different Groups (2016 ANES).
2â€‚Since the ANES experiment targeted households (addresses) rather than individual household
members, there is the possibility that the effects of the treatment have been diluted in Table 1
since the respondent may not have received the cash. We attempted to more precisely specify the
recipient of the payment by limiting the analysis to respondents from households with two or
fewer members. The results of this analysis did not alter the pattern reported in Table 1.
Implications for the Study of Party Polarizationâ€ƒâ€‰â€‚â€‚â€‚ 31
groups, but that are non-applicable to groups defined on the basis of political
ideology. Racism has become taboo, but it is perfectly acceptable to impute
undesirable traits and behaviors to political opponents. By this account, survey
data will inevitably highlight the party divide relative to other social cleavages.
Implicit Partisan Polarization
Since political party affiliation is an â€œunprotectedâ€ identity in the sense that it is
considered appropriate to view oneâ€™s opponents unfavorably, a more stringent
test of affective polarization is to define affect at the level of an implicit or subconscious attitude. Experiments on the most fundamental aspects of the human
mind, such as the ability to perceive (e.g. vision) and remember (memory) have
shown not only that the human brain can operate outside conscious awareness,
but also that such unintended thought and feeling may even be the dominant
mode of operation (Bargh 1999). Evidence from behavior and direct measures of
the brain suggest it may be useful to think about two separate systems that have
evolved to support the unconscious and conscious aspects of thought. Greenwald
and Banaji (1995), among others, have argued that the analysis of group attitudes and stereotypes could gain from an analysis of relatively more automatic
versus reflective forms of thought and labeled the new system of interest as one
that tapped implicit social cognition as distinct from explicit social cognition.
Psychologists now believe that the mindâ€™s architecture precludes introspective
access for the most part and have developed measures of implicit preferences
and beliefs (see Banaji and Heiphetz 2010, for a review) that exist independently
of consciousness. The assumption is that although explicit attitudes do in fact
reflect genuine conscious preferences (which, in the case of race, have changed
profoundly over the course of the past 60 years), they shed no light on less conscious and therefore inaccessible preferences that may nevertheless influence
behavior. In the area of race, there is now an extensive literature on implicit attitudes, their relationship to explicit attitudes, and their prediction of behaviors
(see Wittenbrink, Judd, and Park 1997; McConnell and Leibold 2001).
Interest in implicit attitudes has led to the development of measurement
methods that bypass the standard posing of questions altogether and that instead
rely on the speed of responses that associate concepts (such as Democrat and
Republican) and valenced attributes (such as good and bad). Based on the idea
that groups automatically associated with these attributes will be responded to
faster and with fewer errors, these measures focus on the error rates and time
taken to respond to associations of, for instance, In Groupâ€‰+â€‰Good and Out
32â€ƒâ€‚â€‚â€‚â€‰ Shanto Iyengar and Masha Krupenkin
Groupâ€‰+â€‰Bad and the opposite conceptâ€‰+â€‰attribute pairs such as Out Groupâ€‰+â€‰Good
and In Groupâ€‰+â€‰Bad. There are several such methods for observing implicit group
prejudice, the most well-known of which is the Implicit Association Test or IAT
(Greenwald, McGhee, and Schwartz 1998). Since these implicit measures are not
subject to cognitive processing, they provide a more spontaneous measure of
feelings toward out groups, feelings that are not masked by the intrusion of social
norms. Unobtrusive measures of group prejudice such as the IAT are much harder
to manipulate than explicit self-reports, producing more valid results (Asendorpf,
Banse, and MÃ¼cke 2002; Boysen, Vogel, and Madon 2006).
Political scientists have recently incorporated implicit measures of partisan
affect to assess the extent of party polarization (Iyengar and Westwood 2015;
Theodoridis 2017). Iyengar and Westwood adapted the IAT procedure to associations of â€œDemocratsâ€ and â€œRepublicansâ€ with the standard set of positively
valenced (Wonderful, Best, Superb, Excellent) and negatively valenced (Terrible, Awful, Worst, Horrible) attributes. Following Greenwald, Nosek, and Banaji
(2003), Iyengar and Westwood used the â€œD-scoreâ€ to interpret the BIAT results.
The score, which can range from âˆ’2 to 2, is calculated by subtracting the mean
response times for the round pairing Democrats with positive attributes from
the mean response times for the round pairing Republicans with the same positive terms (for full details on the computation of the D-score, see Greenwald,
Nosek, and Banaji 2003). This difference in response latency is then divided by
the pooled standard deviation over both rounds of the procedure. Positive scores
indicate that participants respond faster to Republican-good than to Democrat
good pairings. Since people respond faster to group attribute pairs for which
they have acquired ingrained or automatic associations, this pattern would indicate greater positive affect for Republicans, whereas the inverse pattern would
reflect greater positive affect for Democrats. The obtained D-scores in this study
broken out by Democratic, Republican, and non-partisan identifiers are presented in Figure 6.
As expected, Democratsâ€™ and Republicansâ€™ scores diverged significantly, indicating that they more rapidly associated their party than the opposing party with
positive attributes. A more fine-grained analysis of the differences between weak
and strong partisans (for details, see Iyengar and Westwood 2015), showed a mix
of expected and unexpected results. While strong Republicans exhibited the most
bias in favor of their side, it was the weak Democrats who showed the greatest inparty favoritism. Overall, the results from this study show that the survey measures of party affect summarized earlier should not be dismissed as mere â€œcheap
talk.â€ When cognitive processing is suppressed, as in the IAT procedure, the divergence in sentiment for the in and out party persists. Moreover, as Iyengar and
Westwood go on to demonstrate, the level of implicit group polarization based on
Implications for the Study of Party Polarizationâ€ƒâ€‰â€‚â€‚â€‚ 33
party affiliation exceeds implicit polarization based on the most salient of social
cleavages, namely, race. â€œFrom our perspective, the difference in the magnitude
of the partisan and racial divides in implicit affect is especially telling. Racial
identity is acquired at birth, and racial attitudes are deeply ingrained (see Baron
and Banaji 2006). For partisanship to approach (and surpass) race, the underlying animosity must be more substantial than previously thought. The data show
that negative associations of opposing partisans are faster (more automatic) than
negative associations of African Americans.â€ (p. 696).
Strikingly, the pattern of stronger polarization based on partisanship vis-a-vis
salient social cleavages applies to divided and unified societies alike. In a crossnational study that included the cases of the Basque region of Spain and Belgium
â€“ both deeply fractured societies â€“ the researchers found that the impact of party
affiliation on inter-personal trust exceeded the effects of linguistic or ethnic identity (see Westwood et al. 2015). â€œPartyismâ€ dominates other forms of out group
In summary, there is a wealth of evidence at the level of attitudes â€“ both
explicit and implicit â€“ demonstrating that Americans have become polarized on
the basis of their partisan identity and associated feelings for their compatriots
and opponents. The ANES time series suggests that the electorate has been highly
polarized post-2000 and the evidence from implicit tests of partisan bias demonstrate that the survey data reflect genuine divergence of sentiment rather than
impression management or other forms of insincere survey response.
Figure 6:â€‚D-Score by Party.
34â€ƒâ€‚â€‚â€‚â€‰ Shanto Iyengar and Masha Krupenkin
Behavioral Evidence of Affective Polarization
The pattern of results based on attitudinal data is unequivocal, partisans increasingly harbor hostility toward their opponents and the divergence in affect is not
symptomatic of superficial thinking on the part of survey respondents. Nonetheless, it is fair to raise questions over the meaningfulness of survey data given the
notorious weak connections between attitudes and behaviors. In this next section,
we summarize the evidence on affective polarization as manifested in real-world
behavior. Attitudes and behaviors both point to heightened polarization.
The most startling evidence of affective polarization comes from research
that documents the applicability of party cues to entirely nonpolitical settings. To
the extent their out-group animus is genuine, partisans should take individualsâ€™
political affiliation into account when considering their trustworthiness. They
should also be unwilling to enter into friendships or other meaningful relationships with political opponents. In effect, affective polarization implies that partisan identity has strengthened to the point where partisanship should act not only
as a marker of political views, but also as an indicator of character and personal
Using available sources of â€œbig dataâ€ including national voter files, researchers have documented that the party cue does in fact influence the decision to
enter into inter-personal relations. The level of spousal partisan agreement has
increased significantly over the period marked by heightened polarization. In a
longitudinal analysis spanning 1965â€“2015, Iyengar, Konitzer, and Tedin (2018a)
find that spousal agreement moved from 73 to 82 percent, while disagreement
fell from 13 to 6 percent. Since the 1965 sample of spouses had been married for
decades, the baseline level of agreement is likely inflated by post-marriage convergence, i.e. one spouse moving in the direction of the other. When the researchers limit the focus to younger couples, they find a more impressive shift; among
recently married couples in 1973, spousal partisan agreement registered at 54.3%.
For the comparable group of recently married couples in the 2014 national voter
file, spousal partisan agreement reached 73.9%. This is an increase of 36 percent
in partisan agreement among couples who have had little opportunity to persuade
each other. Increased spousal partisan homogeneity among couples who have
been together for a relatively short period suggests a substantial strengthening of
the selection mechanism underlying spousal agreement. To the extent individuals
take politics into account when selecting a mate, there should be only small differences in spousal political agreement between couples who have been together
for 5 or 50 years. In fact, in the analysis reported by Iyengar, Konitzer, and Tedin
(2018a), the difference in partisan agreement between couples married for less
than 6 years and couples married for more than two decades is only 10 percentage
Implications for the Study of Party Polarizationâ€ƒâ€‰â€‚â€‚â€‚ 35
points (72 vs. 82 percent). Further corroborating the selection explanation, these
authors also show only weak effects of age on spousal agreement.
As we have indicated above, spousal agreement post-marriage is attributable to any number of explanations, only one of which is the use of politics as
a selection criteria. On inferential grounds, therefore, evidence that derives
from married couples is not the most compelling. A more fertile source of data
concerns the pre-marital dating phase when individuals can reveal their interpersonal preferences. Huber and Malhotra (2017) leverage data from an online
dating website where they have access to both the datersâ€™ personal profiles as
well as their messaging behavior. They find that partisan matching increases
the likelihood of a dyad exchanging messages by 10 percent. To put that difference in perspective, the comparable difference for couples matched on
socio-economic status (using education as the indicator) is 11 percent. Thus,
partisanship appears to be just as relevant as social standing in the process of
selecting a romantic partner. The authors replicate this result in the context of
a survey experiment where they demonstrate that after exposure to a dating
profile that includes the target individualâ€™s political ideology, ideological
agreement significantly enhances the participantâ€™s interest in dating the target
If partisanship has become a relevant factor for entering into meaningful personal relationships, does it also enter into less emotion-laden exchanges such
as casual friendships? A recent national survey by the Pew Research Center suggests that Americans are not prone to associate with opposing partisans. Almost
two-thirds of Democrats (64 percent) and a clear majority of Republicans (55
percent) report that they have â€œjust a fewâ€ or zero close friends who identify with
the opposing party. Similar results appear in the experiment on dating choices
(Huber and Malhotra 2017); the researchers find that ideological disagreement
not only reduces interest in pursuing a romantic relationship, but also in initiating friendship with the target individual.
Another personally salient arena into which the partisan cue has intruded
is decision making on matters of health care. Krupenkin (2018) shows that partisans are less likely to vaccinate their children when the opposing party holds the
presidency, suggesting that partisanship influences Americansâ€™ trust in government agencies. In 2003, when George W. Bush was president, Democrats were
more wary of the smallpox vaccineâ€™s safety than Republicans. However, in 2009
and 2015, during the Obama administration, Republicans were less convinced
that the H1N1 and MMR vaccines were safe. These partisan differences in vaccination were significantly mediated by respondentsâ€™ levels of government trust,
suggesting that partisan vaccination gaps are the result of mistrust of government
agencies among individuals identifying with the party out of power. Krupenkin
36â€ƒâ€‚â€‚â€‚â€‰ Shanto Iyengar and Masha Krupenkin
further demonstrates that actual rates of vaccination reflect partisan differences;
between 2001 and 2008, the granting of personal belief exemptions to childhood
vaccinations grew most quickly in Democratic school districts, while after 2008,
the growth was concentrated in more Republican school districts.
Partisan biases also appear in the behavior of medical practitioners. Hersh
and Goldenberg (2016) find that Republican and Democratic physicians advise
patients differently on health issues with clear political ramifications (e.g. abortion), but behave uniformly on apolitical health topics. Finally, on the question of
willingness to enroll in subsidized health insurance, Lerman, Sadin, and Trachtman (2017) shows that Republicans were substantially less willing than Democrats to enroll in health insurance exchanges set up by the Affordable Care Act.
Party Cues and Economic Behavior
Thus far, we have summarized evidence showing that partisanship spills over
into social interactions and health-related choices. But can partisanship also
impact consumer choice such as the decision to purchase a product? There are at
least two possible mechanisms by which party cues influence consumer behavior. The first, directly tied to polarization, leads consumers to boycott or avoid
products and brands they associate with the opposition party. In the aftermath of
the high school massacre in Florida, many companies announced that they were
ending long-standing benefits provided to members of the National Rifle Association. These companies assumed that tacit endorsements of controversial political
groups can lead to consumer backlash. As outlined below, there is some evidence
to suggest that in the current era, consumers do favor companies, products or
brands they associate with their own party.
The second possibility is that partisanship impacts consumer behavior
through economic expectations and consumer confidence. In the aftermath of
an election, supporters of the victorious party may feel euphoric about the state
of the economy, now that their party controls government, and this sense of generalized optimism may motivate purchasing behavior. McConnell et al. (2018)
conducted a field experiment in which they offered individuals the opportunity
to buy a heavily discounted gift card. They assigned some prospective buyers to
conditions featuring a subtle partisan signal to the effect that the seller is either a
co-partisan or opposing partisan. Although they detected no evidence of discrimination against the out-party seller, buyers offered nearly twice the price for the
card from the co-partisan seller. Panagopoulos et al. (2016), on the other hand,
found that approximately 20 percent of individuals were unwilling to accept a
Implications for the Study of Party Polarizationâ€ƒâ€‰â€‚â€‚â€‚ 37
gift card from a company described as having made financial contributions to the
In addition to product markets, partisanship may distort labor markets.
Using an audit study, Gift and Gift (2015) conducted a field experiment where they
mailed resumes providing information about a job candidateâ€™s partisanship in a
heavily Democratic and heavily Republican area. In the predominantly Democratic county, applicants with a Democratic affiliation were 2.4 percentage points
more likely to receive a callback than applicants with a Republican connection.
The corresponding bias in favor of co-partisans was 5.6 percentage points in the
Republican area. On the other side of the labor market, McConnell et al. (2018)
examine how partisan cues impact employee behavior. The researchers hired
workers to complete an online editing task and subtly conveyed the partisan
leanings of the employer. Unlike Gift and Gift (2015), they find that partisan bias
takes the form of in-group favoritism rather than out-group prejudice. The only
significant results obtained in comparisons between the co-partisan condition
and the no information control group. People accepted lower wages (by a factor
of 6 percent) from a co-partisan employer.
Partisans also evaluate economic conditions differently depending on the
party of the president. When the president is an out-partisan, partisans are more
likely to say that the economy is doing poorly, while the opposite is true when
the president is a co-partisan. As we have already noted, some scholars (Bullock
et al. 2015; Prior, Sood, and Khanna 2015) have suggested that such misperceptions are cheap talk. However, Krupenkin, Hill, and Rothschild (2018) find that
partisans do modify their purchasing behavior when party control of the presidency switches. While partisans may engage in wishful thinking when answering survey questions, their purchasing behavior is more likely to represent firm
beliefs. If partisans genuinely believe that economic conditions are faltering
under an out-party president, they should avoid making risky financial decisions, such as buying a car, house, or investing in the stock market. Using Bing
referencing automobile, house, and stock purchases as indicators of
consumer interest, the authors find that Democrats were significantly less likely
to utilize these search terms after Trump was elected, while Republicans showed
no change. The authors replicated the browsing behavior results through an analysis of DMV registration data, which showed that car registration rates increased
among residents of predominantly Republican zip codes after Trump was elected.
3â€‚Search data is a good predictor of purchasing behavior across a wide variety of both durable
and consumer goods (Kholodilin, Podstawski, and Siliverstovs 2010; Choi and Varian 2012; Wu
and Brynjolfsson 2015).
38â€ƒâ€‚â€‚â€‚â€‰ Shanto Iyengar and Masha Krupenkin
These results suggest that partisan bias in perceptions of the economy carry over
into the realm of consumer activity, especially for supporters of the losing party.
The work on marriage, dating, health-related and consumer behavior is representative of a broader literature documenting the applicability of partisan cues
to non-political settings (for a review of this literature, see Iyengar et al. 2018b).
Other instances of partisan bias include evaluations of high school studentsâ€™
academic credentials (Iyengar and Westwood 2015) and assessments of physical
attractiveness (Nicholson et al. 2016), Overall, it appears that the party cue is now
all-encompassing and just as likely to influence nonpolitical as political choices.
The intensification of partisan sentiment over the past three decades cries out for
explanation. Polarization is likely the consequence of a wide variety of factors,
including changes in the media environment, increased social homophily, and
partisan sorting. In addition to independently inducing negative sentiment, each
of these factors reinforce the others, further contributing to the rise of affective
While the period in question encompasses multiple societal changes in the
US â€“ greater ethnic and religious diversity, a declining manufacturing sector,
and heightened income inequality, for example â€“ it was also a time of seismic
changes in the media environment. Twenty four hour cable news channels
emerged as competitors to network news. The availability of cable television
in the 1970s provided partisans their first real opportunity to obtain news from
like-minded sources (Fox News first for Republicans, and MSNBC later for Democrats). The development of the Internet provided a much wider range of media
choices, which greatly facilitated partisansâ€™ ability to obtain political information
and commentary consistent with their leanings. In a break with the dominant
paradigm of non-partisan journalism, a growing number of outlets, motivated
in part by the commercial success of the Fox News network, offered reporting in
varying guises of partisan commentary. The political blogosphere, with hundreds
of players providing news and analysis â€“ often vitriolic â€“ developed rapidly as a
partisan platform, with very little cross-party exposure (Adamic and Glance 2005;
Lawrence, Sides, and Farrell 2010). The creation of vast online social networks
permitted extensive recirculation of news reports, even to those not particularly
motivated to seek out news.
While there are good reasons to believe that the new media environment has
contributed to the growth in partisan animus, by facilitating access to partisan
Implications for the Study of Party Polarizationâ€ƒâ€‰â€‚â€‚â€‚ 39
news and commentary, it is possible that enhanced consumer choice also sets in
motion processes that weaken polarization. As media platforms have multiplied,
consumers gain access not only to more news providers, but also entertainment
providers. The availability of entertainment programming on demand enables
some to drop out of the political arena entirely (Prior 2007). Thus, the net impact
of the increased empowerment of consumers is unclear.
In fact, despite the myriad changes in the media environment, the evidence to
date demonstrating that news consumption exacerbates polarization is less than
unequivocal. While experimental studies of online browsing behavior confirm
the tendency of partisans to self-select into distinct audiences (see Iyengar and
Hahn 2009), more generalizable real-world studies find few traces of audience
segregation. In their pioneering analysis of Americansâ€™ web browsing behavior
(conducted in 2008), Gentzkow and Shapiro (2011) found that online audiences
were only slightly more segregated than audiences for network or cable news.
They concluded that â€œInternet news consumers with homogeneous news diets
are rare. These findings may mitigate concernsâ€¦. that the Internet will increase
ideological polarization and threaten democracyâ€ (p. 1831). More recent work,
however, also using large-scale tracking of online browsing behavior, suggests
that news audiences are becoming more segregated. A 2013 study showed that
although most people relied on ideologically diverse online sources such as
web aggregators (Flaxman, Goel, and Rao 2016), audience segregation tended
to increase among individuals who used search engines to locate news stories
and among social media users who encountered links in their news feed. Both
these pathways to news exposure feature personalized algorithms, making it
more likely that individuals encounter information consistent with their political
loyalties. In the case of Facebook, now a major source of news, most individuals
are embedded in politically homogeneous networks, increasing the likelihood of
exposure to polarizing messages.
To the extent partisans do gravitate to like-minded news providers, the
diffusion of high-speed Internet has facilitated this behavior. In those parts of
the country where broadband is more available, traffic to partisan news sites is
greater (Lelkes, Sood, and Iyengar 2017). Moreover, Lelkes et al. go on to show
that broadband diffusion has strengthened partisan affect. Moving from a county
with the fewest number of broadband providers to a county with the highest
number increased affective polarization by roughly 0.07 (an effect roughly half as
large as the effect of partisansâ€™ political interest).
A different potential cause of strengthened polarization is social homophily. We have described studies documenting strengthened processes of socialization by which families come to agree on their partisan loyalties. Family
agreement creates an inter-personal echo chamber that facilitates polarization.
40â€ƒâ€‚â€‚â€‚â€‰ Shanto Iyengar and Masha Krupenkin
When family members identify with the same party, they also express more
extreme positions on the issues and harbor hostile views toward their opponents. In the case of a 2015 national survey of married couples, respondents
evaluated the presidential candidates Hillary Clinton and Donald Trump (using
the ANES 100 point feeling thermometer). Among spouses who agreed on their
party identification, the average difference between the in-party and out-party
candidate evaluation was 59 points (70 vs. 11 degrees on the thermometer).
Among the few pairs consisting of spouses with divergent loyalties (DemocratRepublican pairings), this margin of difference fell by more than 30 degrees.
Partisan agreement within the family strengthens polarization (see Iyengar,
Konitzer, and Tedin 2018a).
Given the importance of family socialization to the development of partisan
attitudes, it appears that the rate at which any given society will undergo polarization is conditional on the extent to which partisans grow up in homogeneous
environments. Recent simulations by Klofstad, McDermott, and Hatemi (2013)
suggest that spousal agreement rapidly induces ideological polarization, reaching a stable equilibrium by the 11th generation, but with most of the increased
polarization occurring as early as the fifth generation (Klofstad, McDermott,
and Hatemi 2013, pp. 530â€“531). We would similarly expect generations to move
increasingly apart on their feelings toward the opposing party to the extent family
members share these sentiments.
Yet another explanation for the increased level of inter-party animus in the
American context, one favored by scholars of ideological polarization, is the phenomenon of â€œsortingâ€ or the increased confluence of votersâ€™ partisan, ideological,
and policy preferences (see Levendusky 2010; Mason 2015; Fiorina 2017). Over
the same period marked by heightened partisan affect, a number of social and
economic cleavages including ethnicity, urban-rural residence, gender, and religion have all come into alignment with the party divide. This process is thought
to have contributed to polarization by reinforcing individualsâ€™ partisan identities.
However, in one of the few efforts to estimate the impact of sorting on partisan
affect, Lelkes (2018) finds that changes over time in affective polarization have
occurred at the same rate among voters who are more or less ideologically sorted.
In closing, affective polarization has any number of consequences, most deleterious, on the body politic. Partisansâ€™ disdain for their opponents sends a clear
signal to elected officials that compromise and realpolitik will not be respected.
Gridlock and inaction have become normal legislative occurrences. Policies
are enacted only when one party imposes its will on the other, with the result
that minority parties view enacted policies as illegitimate. It is no accident that
Republicans have made repeal of the Affordable Care Act their overriding political priority.
Implications for the Study of Party Polarizationâ€ƒâ€‰â€‚â€‚â€‚ 41
At the level of electoral politics, heightened polarization has made it almost
impossible for partisans to abandon their partyâ€™s candidates, no matter their
limitations. In contrast, the Access Hollywood tape would surely have ended the
candidacy of any presidential candidate in any election cycle from the 1980s or
1990s. Yet in Alabama, in 2017, evidence of inappropriate relations with under-age
women hardly caused concern among Republican voters, a mere seven percent of
whom defected. In the present era, one has to wonder how severe the shortfall
from conventional norms must be before electoral support evaporates. Partisans
have become so committed to their candidates that the standard finding of public
opinion research in the pre-polarization era â€“ voter ignorance of current events
â€“ has had to be updated. Today, we observe a more insidious form of ignorance in
the form of partisansâ€™ willingness to believe in misleading appeals and â€œalternative facts.â€ At some point, this breakdown in common knowledge can only lead
to a political crisis.
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