Do Birds of a Feather Vote Together, or Is It Peer Influence?

• Published date: 01 March 2018
• DOI: 10.1177/1065912917722417
• Date: 01 March 2018
• Subject Matter: Articles

722417PRQXXX10.1177/1065912917722417Political Research QuarterlyWojcik
research-article2017
Article
Political Research Quarterly
2018, Vol. 71(1) 75 –87
Do Birds of a Feather Vote Together,
© 2017 University of Utah
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or Is It Peer Influence?
https://doi.org/10.1177/1065912917722417
DOI: 10.1177/1065912917722417
journals.sagepub.com/home/prq
Stefan Wojcik1
Abstract
Why and when do legislators vote together on policy? Do legislators decide to vote similarly mainly because of
social influence or similarity? I contribute to the literature by offering a social network theory of voting. It is argued
that close social ties help to establish reputations and to aid the flow of information among peer legislators, leading
to increased influence and increased rates of co-voting among them. I examine the relative effects of information
exchange networks and social exchange networks on rates of co-voting, controlling for similarities among legislators.
The data include legislative votes from 2010 to 2014 in the Brazilian Chamber of Deputies. The results suggest that
social influence stemming from social relationships exert substantial effects on rates of congressional co-voting.
Keywords
political parties, network analysis, Latin America, Brazil
Introduction
I argue that network ties induce co-voting among leg-
islators by establishing reputations and by providing criti-
There is an abundant literature on the effects of institu-
cal information to voting partners. I contribute to the
tions on legislative behavior, but a relatively smaller,
literature by offering a theory of social influence in legis-
though important, literature concerning the relational or
lative voting based on the breadth and depth of social ties,
informal underpinnings of legislative behavior (Bogue
a new data set on co-voting networks for the community,
and Marlaire 1975; Caldeira and Patterson 1987; and an empirical contribution in the form of new findings
Matthews 1959; Pauls, Leibon, and Rockmore 2015;
on legislative networks. In this paper, I focus primarily on
Rogowski and Sinclair 2012; Routt 1938). Political sci-
the role of social influence on legislative co-voting,
ence has made progress in this area, but it remains unclear
which I define as a change in an actor’s legislative voting
to what extent social ties make a substantive difference in
choices as a result of some social pressure by another
voting decisions, especially outside the U.S. context.
actor or group. This paper explores this question using
Social influence strikes at the heart of representation
data from a digital-interactive legislative network survey
in legislatures—if we are to understand the nature of rep-
in the Brazilian Congress.
resentation in legislative systems, then it is important to
understand if and why legislators vote differently because
of social influence. Empirical puzzles linger too, such as
Do Networks Matter for Floor
why rates of co-voting can remain high despite weak
Voting?
institutional mechanisms of enticement or why ideologi-
cally divergent legislators remain personally familiar
Political party scholars have established that when elec-
(Figueiredo and Limongi 2000; Ringe 2010).
toral rules give leaders the tools to reward and punish leg-
This study of political networks provides unique
islators, leaders will whip votes and impose consistent
insights into such issues. Here, I provide evidence sup-
voting patterns (Carey and Shugart 1995; Figueiredo and
porting the view that social networks affect legislative
Limongi 2000; Mainwaring and Scully 1995). For exam-
behavior. The evidence here, drawing on various statisti-
ple, when party leaders can add and remove legislators
cal tests, is suggestive of a link between social influence
from party lists as a form of sanctioning they are more
and co-voting. Nonetheless, inferring social influence
from observational data is very difficult, so here I strive
1University of Colorado Boulder, USA
to provide the reader with a discussion of inferential
Corresponding Author:
threats and the appropriate context for interpreting these
Stefan Wojcik, 2M Street NE, Washington, DC 20002, USA.
findings.
Email: stefan.wojcik@colorado.edu

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76
Political Research Quarterly 71(1)
capable of enforcing party unity. Party leaders are less
view, leadership imposes discipline from the top–down.
capable of enforcing unity when, as in Brazil, ballots
However, research should pay equal attention to the social
allow voters to cast votes for individuals. Similarly, unity
network ties that help to build trust, provide information,
is challenged when legislators compete with other mem-
and align the expectations of members from the bottom–up.
bers of their party for votes (Carey and Shugart 1995).
High rates of unity among legislators is a consequence of
Regional electoral districts (also a Brazilian feature) tend
sharing strong ties or overlapping ties, and may either
to generate locally focused campaigns and diminish the
enhance or erode existing institutional forces like
allure of incentives coming from national level bosses
partisanship.
(Samuels 2000).
In the political networks field, the literature has shown
Despite the many insights that have been gleaned from
that networks act as systems of social exchange—social
examining formal rules, scholars frequently ignore infor-
communication, deliberation, and discussion, but schol-
mal social rules in legislative settings (Carey and Siavelis
ars know less about whether they establish patterns of
2006). There are many exceptions, with a growing and
legislative behavior. The literature on political networks
committed group of scholars taking up this question,
and legislatures has analyzed how congress is connected
more often than not in the American subfield (Bogue and
(Fowler 2006), how cosponsorship relations affect bill
Marlaire 1975; Caldeira and Patterson 1987; Matthews
success (Kirkland 2011), how networks define political
1959; Pauls, Leibon, and Rockmore 2015; Rogowski and
parties outside the legislature (Koger, Masket, and Noel
Sinclair 2012; Routt 1938). Much of this work demon-
2010), how observing behavior of opposing groups
strates the hidden power of interpersonal influence in
affects voting behavior (Ringe, Victor, and Gross 2013),
policymaking. Formal rules are sometimes insufficient to
and how physical proximity affects voting patterns
establish discipline in legislative settings in the first
(Masket 2008; Rogowski and Sinclair 2012). Yet, there
place, and it is in these settings that informal institutions
has been little work to incorporate the ideas of social
reveal themselves as important determinants of party
proximity into a theory about credibility and influence.
cohesion (Ringe 2010). Informal rules and interactions
Opportunities for monitoring render overlapping net-
(“social sanctioning”) may be as strong or stronger than
works powerful tools for building expectations of appro-
formal rules in generating patterns of unified voting, as
priate behaviors among members in the networks (Ostrom
legislators make agreements to support one another’s leg-
1990; Putnam 1992). As behaviors of individuals are
islation and are unwilling to defect after such agreements
observed over time, their track records are recorded in the
are made.
minds of the people with whom they interact, and expec-
Broadly, the current literature demonstrates that co-
tations of future behavior are created. Violating expecta-
voting occurs at the intersection of preferences, informa-
tions engenders considerable costs. Those with whom
tion, and rules.1 By and large, but with numerous
one is socially connected may no longer be amenable to
exceptions, scholarship in this area tends to operate under
cooperation, and actors at two or three degrees of separa-
the assumption that legislators make decisions based on
tion may be even less willing to cooperate, that is, peers
individualistic preferences (but see citations above),
may be unwilling to maintain network ties once they have
rules, and/or pressure from their parties. However, reality
determined that an actor is unreliable. Positive reputa-
is more complex and more social than existing studies
tions can be established in many ways, but relevant here
would lead us to believe. The contours of intimate inter-
is the transmission of credible information about con-
personal social relations affect the workings of legislative
nected peers through network linkages.
processes, and tend to be correlated with ideology and
Networks not only provide insight into the credibility
party membership. They do so by embedding legislative
of information but also transmit legislatively relevant
decision making within them through processes of social
content. We know that coordination occurs at the inter-
influence. As such social relations are correlated with
section of preferences and information about other actors’
preferences and party affiliation, by theorizing a social
expected behavior (Aldrich 1995; Downs 1957; Duverger
model of voting, we can cast new light on all three factors
1954). We know that individuals are more likely to trade
at once.
off their sincere preferences for proximate ones if they
Discipline, cohesion, and agenda control all help to
can be more certain their proximate preferences are...