Download Discerning the Causes and Effects of Partisan Media Choice in a

Disentanglingthecausesandeffectsofpartisanmediachoiceinapolarized
environment:researchtodateandawayforward
Does media choice cause polarization or does polarization cause media choice? This
paper reviews the literature to date on this question, including research on selective
exposure and persuasion, as well as on credibility, bias and trust. Establishing the
direction of causality has proven empirically challenging, and the extant literature is
decidedly mixed on the questions on whether partisan media can change attitudes, or
merely reinforce them, as well as the extent to which people selectively expose
themselves to news and information that reinforces their preexisting beliefs. Following
this review, we identify shortcomings in the extant literature and propose several new
methods aimed at moving this research program forward toward ultimately disentangling
the relationship between partisan media, individual preferences, persuasion, and political
attitudes and behavior. MatthewA.Baum
HarvardUniversity
JustindeBenedictis-Kessner
MIT
AdamBerinsky
MIT
DeanKnox
MIT
TeppeiYamamoto
MIT
DRAFT-December20,2015
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Introduction
Inrecentyears,pundits,politicians,andordinarycitizenshaveexpressed
growingconcernoverpoliticalpolarizationintheUnitedStates.Ina2013op-ed
article,famedClintonpoliticalguruJamesCarvillewrites,“Ithinkalotofpeoplewill
lookbackatthispointinAmericanpoliticalhistoryandwonderhowthingsgotso
damnscrewedup.”Carville’sexplanation,arguablyreflectingthemostcommon
widespreadconventionalwisdom,isthat:
“…asmuchasanything[it]isthedisturbingfragmentationofthe
media.Today,conservativescangetalltheirinformationfrom
conservativeoutlets,andliberalscangetalltheirinformationfrom
liberaloutfits.Andyoucanspendyourwholelifeneverbeing
challenged,neverhavingtohearorthinkaboutorconfront
viewpointsthataredifferentfromyourown”(Carvill2013).
Theseemingimplicationisthatinaworldoffragmentedmedia,peoples’preexistingpoliticalattitudesdeterminetheirchoicesofnewsoutlets.Ifso,thiswould
representaclearexampleofthepsychologicalphenomenonknownasselective
exposure–thetendencytoseekoutinformationwhichreinforcesexistingviews.
Yet,laterinthesamearticle,Carvilleappearstoreversecourse,arguingthat
partisanmedia“makesbothsidesmoredugin.”Theimplicationhereisthatthe
existenceofapartisanmediacause,oratleastexacerbate,polarization.This
perspectiveplacestheblameatthefeetofthemedia;bypresentingone-sided
versionsofissues,partisanmediaoutletslikeFoxNewsontherightandMSNBCon
theleftdriveAmericansapart.Theseslantednewssourcespersuadeindividualsthat
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theparticularone-sidedversionofissuestheyconsumeconsistsoftheunvarnished
truth.Suchaprocessofpersuasionrepresentsaquitedifferentmechanismthan
selectiveexposure.
Thesetwoperspectivesontherelationshipbetweenthemediaandthepublic
standatoddswithoneanother.Dolike-mindedindividualsseekoutpartisannews
sourcesthatsupporttheirpre-existingbeliefs–resultinginatendencytowarda
particularperspectiveamongconsumersofideologicallynarrowpartisanmedia
outletsbyvirtueofself-selection?Orisitthecasethatconsumersofpartisannews
altertheirviewstoreflectthosepresentedinpartisanoutlets,resultinginincreased
polarizationbetweenconsumersofliberalandconservativenews?Intheformer
instance,mediachoicereflectspolarization;inthelatter,mediachoicecausesit.We
arethuslefttoask:ispublicpolarizationacauseoraconsequenceoftheriseofthe
partisanmedia.AsCarville’stwo-sidedtreatmentsuggests,theprocessesof
selectiveexposureandpersuasionareoftenconflated.
Empiricallydistinguishingbetweenthesetwocausalpathwaysischallenging.
Peoplearenotoriouslypooratestimatingtheirownpastbehavior(Prior2009)or
predictingtheirfuturebehavior(Clauson1968).Inthispaper,webegintomove
forwardindisentanglingthetwocausalprocesses.First,wereviewpasteffortsto
disentangletherelationshipbetweenpartisanmediaandpolarizationanddiscuss
theshortcomingsofthatresearch.Second,weproposeasetofnewmethodsto
answerthiscriticalquestion.Inthispaper,wefocusononepieceofthepuzzle,
consideringhowtheeffectsofpartisanmediavarybasedonthepreferencesofthe
viewersofthosestories.Indoingso,wealsoconsidertherelatedquestionofhow
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accuratelyrespondents’statedpreferencespredicttheiractualchoicesin
experimentaltreatmentsdesignedtoteaseoutthecausesandeffectsofpartisan
mediaconsumption.
PolarizationasCauseorEffectofPersuasion?
Awidespreadconcerninsocialscienceresearch,thathasimportant
implicationsforthestudyofmediaeffects,istheproblemofselection.Whenever
socialscientistsobserveatreatmenteffect–thatisadifferencebetweenactors
exposedtodifferentstimuli--intherealworldwhenitisnotpossibletocontrol
whogetsthetreatment,thequestionarisesastowhethertheeffectresultsfromthe
treatmentitself,orfrompre-existingdifferencesintheactorsexposedtodifferent
treatments.Inthiscase,studiesdesignedtodeterminetheeffectsofpartisanmedia
onpolarizationareillequippedtodeterminewhethersomeoralloftheobserved
differencesinattitudesamongindividualsexposedtodifferentpartisaninformation
stemfromdifferencesintheinformationorintheindividualschoosingtoexpose
themselvestoparticularpartisaninformationstreams.
Inrecentyears,manyscholars(e.g.,Levendusky,2013;Arceneauxand
Johnson,2013;Prior,2007)haveexploredthepoliticalconsequencesofincreased
mediachoiceinthe21stcentury.Todate,theresultsfrominvestigationsintothe
questionofwhetherattitudesdriveinformationseeking,oraredrivenbyit,is
decidedlymixed.ThereisnoquestionthatAmericansareincreasinglyableto
consumeunbalancednews.ThetypicalU.S.householdnowreceivesabout190
televisionchannels,morethanatenfoldincreasesince1980andupnearly50%since
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2008.Thisdoesnotincludecountlessofferingsonradio,inprint,and,ofcourse,on
theInternet.Thatsaid,sincemostAmericanscontinuetopredominantlyrelyon
televisionfortheirnews(Pew2014),weprimarilyfocusourdiscussionontelevision.
Thisexplosionofmediaoutletshasvastlyincreasedthechoicesavailableto
consumersandallowedforthedevelopmentofideological“niche”news
programming(Hamilton,2005).Partisanmediaarewidelyaccessible(Baumand
Groeling2010,Groeling2013)andoftenpresentnewsthatismorebeneficialtoone
partythantheother(BaumandGroeling2008,2010).Forinstance,thepublic
routinelyassociatesFoxNewsandMSNBCasbeingheavilybiasedtowardthe
RepublicanandDemocraticparties,respectively(Ladd2012).Butdopartisan
mediacontributeto,orsimplyreflect,polarizationamongconsumers?Most
researchtodatehaslargelyfailedtoaddress,letaloneresolve,thisquestion.
Therearearguablythreedistinctstrandsofthisresearcharea.Thefirst
focusesonthepossibilitythatmediafragmentationenhancespoliticalpolarization
bytheprocessofpersuasiononthepartofthepartisanmedia.Thesecondtreats
polarizationasprimarily,oratleastsignificantly,asacauseoffragmentation
throughindividuals’decisionstoselectivelyexposethemselvestopartisanmedia.
Thethirdstrandcombineselementsofbothofthefirsttwo,focusingonpotential
effectsonperceptionsregardingthereliabilityandtrustworthinessofthemediain
general,andbeliefsaboutmediabiasinparticular.Indoingso,itconsidersresulting
downstreameffectsonpoliticalattitudesandbehavior.1Wediscusseachstrandof
1Researchonmediatrustmightarguablybemoreaccuratelycharacterizedas
eitheramediatorofpersuasionandselection,orevenaneffectthereof.However,
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research,beforeturningtoadiscussionofthepromiseandlimitationsofexisting
researchonthesetopicsandproposingacorrectiveforonesuchlimitation.
SelectiveExposure
Researchdatingbacktothe1940shastheorizedaboutthepotentialroleof
selectiveexposureinexplainingpoliticalattitudes.Thisresearch,–perhapsmost
famouslyLazarsfeld,Berelson,andGaudet’s(1948)studyofthe1940presidential
electionandCampbelletal.’s(1960)theoryofminimalism--foundevidenceofsuch
selectiveexposuretopartisaninformationinmediaconsumptionpatterns.
Sincethe1960s,theliteraturehasgrownexponentially.Manyresearchers
(Stroud2011;Arceneauxetal.2012;GainesandKuklinski2011;IyengarandHahn
2009)haveshownthatDemocratsandRepublicans–especiallythestrongest(Kim
2009;Iyengaretal.2008),andmostpoliticallyengaged(BennettandIyengar2008)
partisans–prefertoconsumenewsthatsupportstheirpre-existingbeliefswhile
avoidingnewsthatchallengesthosebeliefs.Totheextentthatindividualsareselfconsciouslyselectingintoideologicallyfriendlymediaenvironments,itappearsthat
partisanorideologicalpreferencesdrivemediachoice.
Someadditionalresearch,however,hasidentifiedpotentiallimitstoselfselection.Forinstance,MessingandWestwood(2012)findthatendorsementsfrom
otherpeopleinaperson’ssocialnetworkcancounteracttheselectivityofpartisans
intoideologicallyconsonantnews.GentzkowandShapiro(2010),inturn,findthat
ideologicallyextremepeopleareactuallymore,ratherthanless,likelythantheir
sincethisconcepthasbeenmuchmorewidelyappliedbyscholars,forpurposesof
thisreviewwetreatitasananalyticallydistinctcategory.
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moremoderatecounterpartstoencounterideologicallyopposingnewssitesonthe
internet.Ofcourse,televisionandtheInternetdifferinnumerousrespects,
complicatingeffortstogeneralizeacrossthesemedia.
Despitethislatterevidencethatselectiveexposureislessthanubiquitous,a
greatdealofevidencesuggeststhatitisarealphenomenon;onewithpotential
consequencesforthepracticeofpoliticsbecauseitcanleadtoincreasinglyinsulated
partisaninformationsilosamongthepublic.Ifindividualsareonlyexposedtoone
sideoftheargument,compromiseandmoderationofviewsbecomeslessfrequentas
individualsarelesslikelytoencounterinformationchallengingtheirpre-existing
attitudes.Thispossibilityhaspromptednumerousscholarsandpoliticalobserversto
worryabout“mechannels”(Sunstein2001),“thedailyme”(Negroponte1995)–
bothalludingtoself-imposedideologicalstovepipescreatedbyindividuals--and
“filterbubbles”(Pariser2012),wherebynewsproviderscontributetothestovepipe
byobservingusers’newschoicesandthenfilteringtheirofferingstothatindividual
tomatchhisorherrevealedpreferences.Each of these closely related concepts focuses
on the potential dangers associated with individuals’ insulating themselves, or being
insulated by news providers, from opposing viewpoints in their media consumption.
Persuasion
Thesecondschoolofthoughtarguesthatpolarizationresultsfromthe
influenceofmediaexposureonpoliticalattitudes;thatis,throughtheprocessof
persuasion..Thisviewrepresentsafairlyrecentturnintheliterature.Asnoted
above,earlyresearchbysociologists(e.g.,Lazarsfeld,etal.1948,Berelson,
LazarsfeldandMcPhee1954))andsocialpsychologists(Campbelletal.1960)
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advancedtheselectiveexposurehypothesisandconcludedthatpeople’sattitudes
werelargelyimmunetopoliticalpersuasionviathemedia.Severaldecadeslater,the
tideofevidencebegantoturn.Revisionistscholarscounteredthatwhilemedia
exposuremaynotnecessarilychangepeople’sminds,themediacouldstillinfluence
expressedattitudesandbehaviorbychangingwhatpeoplethinkabout,orhowthey
thinkaboutit,throughpriming,framing,andagendasetting(e.g.,Iyengarand
Kinder1987,Druckman2001,ChongandDruckman2007).
Morerecently,evidenceforpersuasionhasbeguntoemerge.Forinstance,in
hisseminalstudyofpublicopinionZaller(1992)arguedthatthelackofevidencefor
persuasionresultedfromresearcherslookinginthewrongplaces.Zallerfoundthat
mediaexposurehaslimitedeffectontheattitudesoftheleast-andmost-politically
awareindividuals,albeitfordifferentreasons.Theleastpoliticallyaware
individualstendednottoreceivepoliticalmessagesfromthemedia,whilethemost
highlyawareindividualspossessedsufficientconsiderationsregardingmostissues
thattheywereabletosuccessfullycounter-argueanydissonantmessagestowhich
theywereexposed.Thisleftthemoderatelypoliticallyawaremostamenableto
persuasion:theypayenoughattentiontobeexposedtopoliticalmessagesbutlack
sufficient“ammunition”(intheformofconsiderationsaboutissues)tobeatback
informationtheyencounteredthatchallengedtheirpre-existingbeliefs.Notably,
however,anyresultingpolarizationeffectsfromtheprocessthatZaller’sRAS
(receive-accept-sample)modeldescribesdonotdependonthepartisanorientation
oftheoutletpresentingtheinformation.Partisansarecapableoffilteringoutpro-
andcounter-attitudinalinformationcontainedwithinagivennewsitemthatmay,in
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thenet,beideologicallybalanced.Zaller’smodelissimilarinmanyrespectstothe
theoryofmotivatedreasoning,wherebyindividualsare“motivated”toacceptproattitudinal,orconsonantinformation,whilerejectingcounter-attitudinal,or
dissonantinformation.Theformerissimplyeasiertoprocess,requiringless
cognitiveeffort,thanthelatter.
BuildingonZaller’swork,otherscholarshavesearchedforevidenceof
persuasioneffectsfrompartisanmedia.Forinstance,Levendusky(2013)findsthat
newsattributedtoright-leaningFoxNewsismorelikelythannewsattributedto
left-leaningMSNBCtopersuadeconservatives(forcomparablefindings,seealso
e.g.,Feldman2011b,Bullock2011,JeritandBarabas2012).Thatsaid,some
evidencehasemergedsuggestingthatAmericansarenotyetentirelyensconcedin
impenetrableinformationsilos.Forinstance,Dilliplane(2013)reportsevidence
thatinformationfromcounter-attitudinalmediamaypersuadeevenstrong
partisansandthehighlypoliticallyaware.Alongtheselines,Feldman(2011a)finds
thatbothpro-andcounter-attitudinalvisualmediacaninfluencepolitical
ideologues.However,theevidenceonwhenpartisanmediaarepersuasiveismixed.
Additionalresearchappearstosuggestthatpartisanmediacanproduce
tangiblepersuasioneffects.Forinstance,withrespecttoclimatechange,countless
pundits,particularlyontheleft,haveblamedFoxNewsforthewidespreadbelief,
primarilythoughbynomeansexclusivelyamongRepublicans,thateitherclimate
changeisnotreal,orifitisrealthathumansarenotcontributingtoit(Meyer2012).
Hmielowksi,Feldman,Myers,andLeiserowitz(2013:13),inturn,concludeinpartthat
“themoreAmericansuseconservativemedia,thelesscertaintheyarethatglobal
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warmingishappening.”Theclearimplicationoftheirfindingsisthatpartisanmedia
havewidened,ifnotcreatedinthefirstinstance,thedivideonclimatechangebetween
DemocratsandRepublicans,primarilybydissuadingRepublicansofitsvalidity.
MediaTrustandPoliticalAttitudesandBehavior.
Thisthirdpredominantstrandofpolarizationresearchisarguablyan
extensionofthepriortwo,ratherthanaseparateenterprise.Thatsaid,because
scholarshaveinvestigatedthecausesandeffectsoftrustinnumerousdomains
beyondpersuasionandselectiveexposure,wetreatithereasaseparatecategory
(thoughwealsopointouthowtrustmediatesthepriortworesearchstrandswe
havediscussed).
So,inthepresentcontext,wefocusourattentiononscholarlyeffortsto
delineatetheeffectsofmediachoiceonpolarizationofattitudestowardsthemedia.
Asnotedabove,confidenceintraditional(TV,newspaper)andnew(Internet)media
outletsreachedall-timelowsin2014.Indeed,accordingtoGallup,between1976
and2014,thepercentageofAmericansexpressing“greatdeal”or“afairamount”of
trustinthemediaoverallfellfrom72to44percent.Aconsequenceofthisdistrust
wereonfulldislpayinthe2016Republicanprimarydebates–particularlythe
October28,2016CNBCdebate--wherecandidatesfromTedCruztoMarcoRubioto
BenCarsonandDonaldTrumpearnedamongtheirstrongestliveaudienceand
(fellowpartisan)voterapprobationwithaccusationsofmediabiasagainst
themselvesandtheirparty.Indeed,attacksonthemediaasbiasedandunreliable
emergedasamongthemostreliableapplauselinesamongRepublicanand
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Independentvotersinthe2016primarycampaign.
Thatsaid,objectivelyestablishingthepresenceorabsenceofpartisanbiasin
newscontenthasprovendifficult.Self-describedmediawatchdoggroupssuchas
theMediaResearchCenter(MRC),theCenterforMediaandPublicAffairs(CMPA),
andFairnessandAccuracyInReporting(FAIR)claimtoobjectivelyanalyzemedia
content,yettheyroutinelydisagreeontheincidence,severity,anddirectionofbias
inthemedia.Scholarlyattemptstoassessmediabiasaresimilarlyinconclusive(e.g.,
Efron,1971;Patterson,1993;Sutter,2001).Amongtheprincipaldifficultiesin
establishingthepresenceorabsenceofmediabiasisestablishingacleardefinition
ofwhatexactlyconstitutesbias.Severalrecentstudies(Groseclose2011,Groseclose
&Milyo,2005;Gentzkow&Shapiro,2006,Baum&Groeling2008,Hamilton2003)
havesoughttoempiricallymeasuremainstreamnewsmediacontentagainst
variousstandards,buthavecometoverydifferentconclusions.
Irrespectiveofthe“truth,”fromanormativeperspective,mediatrustis
criticalbecausepeoplewhodistrustthemediamayconcludeitcannotreportinan
unbiasedmannerandsodismissitscontentasunreliablealtogether.Moreover,
ordinarycitizensmayalsobegintoseebiasinwhatisactuallyobjectiveand
balancedpoliticalreporting.Numerousstudieshavefoundevidenceofthisso-called
hostilemediaphenomenon(Valloneetal.1985,Giner-SorollaandChaiken1994,
Peffleyetal.2001,GuntherandSchmitt2004,MorehouseMendez2004,Baumand
Gussin2008),wherebytypicalindividualstendtoviewthemediaasbiasedagainst
theirownviews.Asaresult,citizensmayincreasinglybecomesuspiciousofand
antagonistictowardthenewsmediamoregenerally(Arceneauxetal.,2012;Ladd,
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2012).Ladd(2012),infact,findsempiricalevidencethatrisingpublicdistrustinthe
mediahasreducedpublicwillingnesstoacceptinformationfromthemediaas
reliable.Instead,partisanpredispositionsincreasinglydrivepublicbeliefsand
votingbehavior.
Thatsaid,agrowingbodyofresearchshowsthatpeoplereactdifferentlyto
identicalcontentdependingonwhetherornottheyconsiderthesourcetrustworthy
andcredible(BaumandGussin,2008;Druckman,Fein,andLeeper,2012;
Levendusky2013,BaumandGroeling2010).Inparticular,partisanreputation
interactswithperceptionsofcredibilitytomediatethepersuasivenessof
informationappearingonpartisanoutlets.Alongtheselines,BaumandGroeling
(2009)conductedanexperimentinwhichtheyexposedparticipantstoanews
reportaboutacongressionalhearingonnationalsecurityinwhichoneortheother
partypraisedorcriticizedtheBushAdministration’spolicies.Theymodifiedthe
reporttoappearalternatelyasappearingonCNNorFoxNews.Theyfoundthat
participantswhosawcriticismoftheRepublicanpresident’spoliciesonFox,
downgradedtheirassessmentsofthepresident’sperformanceonnationalsecurity.
ThesamewasnottrueofthosewhosawtheidenticalcriticismonCNN,The
oppositepatternemergedforpraiseofthepresident’spolicies.Theauthorsargue
thatthispatternisaresultofcalculationsamongthepublic.Foraconservative
outlet(Fox)tocriticizeaRepublicanpresidentiscostlyrhetoric(thatis,contraryto
Fox’sperceivedinterests),whileforthemoreliberalCNNsuchcriticismisperceived
ascheaptalk.Conversely,respondentsperceivedpraiseofaRepublicanonCNNas
costly,whilethesamepraisetheyviewedthesamepraiseappearingonFoxas
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cheaptalk.Thisimpliesthatexposuretopartisanmediacaninfluenceattitudes,
albeitdependingonwhetherviewersperceivethecoverageinquestionascostlyor
cheaptalk.
Additionalresearchshowsthatwhenindividualsencountercounterattitudinalinformation,itcanproduceabacklash,resultinginevenmorepolarized
opinions(Zaller1992)andgreaterhostilitytowardthemedia(Arceneaux,Johnson,
andMurphy2012).Theselectionofindividualsintoconsumingmediathat
reinforcestheiropinionscouldthusdrivegroupsfurtherapartbothintheir
attitudestowardissuesandpeoplewhodisagreewiththem.Indeed,some
additionalevidencesuggeststhatstrongideologueswhoselectintopartisannews
sourcesbecomemoreideologicallyextreme(Bullock2011,Feldman2011,Jerritand
Barabas,2012),implyingthatexposuretopartisaninformationstreamscan,via
persuasion,increasepolarization,evenamongalready-somewhat-polarized
partisans.Theselatterfindings,alongwiththoseofBaumandGroeling(2010)and
researchonthehostilemediaphenomenon,combinetosuggestanindirectpathway
topolarization.Thatis,thesefindingsraisethepossibilitythatbothselective
exposureandpersuasionmaycontributetopolarizationdirectly,throughtheir
independenteffectsonmediaconsumers,andalsoindirectly,throughtheeffectof
initialtrustandperceivedbiasontheselectionandacceptanceofmediacontent.
Conroy-KrutzandMoehler(2014),inturn,showthatpeoplewillbemore
easilypersuadedbyopposingmediawhenpoliticalcleavagesarelessclearinless
polarizedmediaenvironments(thatis,non-overtly-partisannewsoutlets).
Furthermore,individualswhoarewillingtowatchcounter-attitudinalmediaare
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alsolikelytobepersuadedbyit(Levendusky2013).Thereasonmaybethat
relativelyopen-mindedindividualsaremorelikelytobeinclinedtoexpose
themselvestocounter-attitudinalmedia.Ifso,thispatternwouldbedrivenmoreby
selectionthanpersuasion.Ingeneral,whenindividualsperceiveoppositionalmedia
ascredible,theymayalsofinditpersuasiveregardlessofitsperspective
(Levendusky2013b,BaumandGroeling2008).Thisresearchsuggeststhatevenin
aneraofmediaconsumptionincreasinglycharacterizedbypartisanself-selection,
andevenamongstrongpartisans,theremaystillexistthepotentialformoderation
ofextremeideologicalviews.
LimitationsandPromiseofExistingResearch
Todate,whenattemptingtoisolatethecausalstoryunderlyingthese
hypothesizedeffectsofmediafragmentation,scholarshavestruggledtoresolvethe
underlyingselectionproblem.Inotherwords,wheneversocialscientistsobservea
differenceintherealworldbetweenindividualsexposedtodifferenttreatments,
thequestionarisesastowhethertheeffectresultsfromthetreatment,orfrompreexistingdifferencesintheindividualsexposedtodifferenttreatments.Inthiscase,
evencontrolledexperimentsdesignedtodeterminetheeffectsofpartisanmediaon
polarizationareillequippedtodeterminewhethersomeoralloftherealworld
observeddifferencesinattitudesamongindividualsexposedtodifferent
informationstemfromdifferencesintheinformationorintheindividualschoosing
toexposethemselvestoparticularinformationstreams.Mappingfromthe
laboratorytotherealworldintroducessomedifficultinferentialproblems.
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Typicalexperimentsbeginbyassessingparticipants’politicalpartisanship
andideology.Researchersthenpresentparticipantswithoneoftwosetsof
treatments:(a)multiplenewsitemsfromwhichtochoose,or(b)asinglerandomly
assignednewsitem,withparticipantssubsequentlyaskedtheiropinionsononeor
moreissuesoverwhichpartisansusuallydisagree.Theformerdesignallows
investigatorstodeterminetheextenttowhichparticipantschooseinformation
sourcescompatiblewiththeirpreexistingbeliefs,aswellastomeasuredifferences
inattitudesbetweenparticipantsexposedtodifferentinformationsources.The
latterdesignallowsforinvestigationofpersuasioneffectsforthesinglesource,but
doesnotaccountfortheself-selectionthattakesplaceintherealworld.
Forinstance,Feldman(2011a)exposedparticipantstooneofthreenews
clipsrelatedtohealthcarereformfromleft-leaning(CountdownwithKeith
Olbermann),right-leaning(GlennBeck),andcentrist(NewsHourwithJimLehrer)
outlets.Shethenassessedattitudechangeamongparticipants,dependingontheir
partisanorientation.Thisstudyiswellsuitedtomeasuretheattitudinaleffectsof
exposuretoaparticularinformationstream.Yetbecauseitcannotaccountforthe
heterogeneityintroducedbyself-selectionintomediasources,itdoesnotaddress
thepossibilitythattheobservedtreatmenteffectsmaybeover-statedbyvirtueof
forcingparticipantstowatchaparticularnewsitem,irrespectiveoftheir
preferences.Numerousstudies(e.g.,Levendusky2013;Taniguchi2011;Feldman
2011b;JeritandBarabas2012;BaumandGroeling2009;SlothuusanddeVreese
2010haveemployedsimilardesignstoinvestigatevariationsonasimilartheme:
thesestudiesalltakeupthequestionofhowmucheffectdoesexposureto
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informationhaveonindividuals’attitudes,conditioningontheirpartisanship,
ideology,orpoliticalawareness.
Studiesthataccountforself-selectionthroughtheseconddesignarerelatively
rare.OnerecentexampleisEllithorpeetal.(2013),whostudytheeffectsofdifferent
mediaenvironmentsonnewsconsumptionandattitudes,findingthatthechoice
environmentplaysanimportantroleinmediatingtheeffectsofmediaconsumption
onpoliticalattitudes.NatalieStroud(Stroud,2011),inturn,invitedexperimental
subjectstoparticipateinalaboratorystudy.Inthewaitingroom,whilethey
nominallywaitedtobeginthestudy,shepresentedthemwithavarietyofnewsand
entertainmentmagazinesthatweresimplyplacedonatablenearwheretheywere
sitting.Sheobservedtheirmagazinechoicesandtheamountoftimetheyspentwith
eachmagazinetoestimatetheamountofselectiveexposurebehavior.
KevinArceneauxandhiscolleagues(ArceneauxandJohnson,2013;
Arceneauxetal.,2012)offeravariationonthisthemethatrepresentsanimportant,
yetincomplete,stepforward.Inbothstudies,Arceneauxandhiscolleaguesconduct
aseriesofexperimentsaimedinpartataddressingtheselectionproblemin
polarizationandpersuasionresearch.Inonesetofstudies,themethodology
approximatestheforcedexposuredesignthatexperimentersstudyingmotivated
reasoningandpersuasiontypicallyutilize.Asdescribedabove,theexperimenters
presentaliberal,conservative,orentertainmentnewsstorytoarespondent,and
thenobservetheeffectsofthattreatmentonsubsequentattitudes(seeStudy1in
Figure1,below).Arceneauxandhiscolleaguesgoonestepfurther,however,by
conductingparallelexperimentsinwhichtheyallowedparticipantstochoosefrom
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amenuofoptions–asistypicalforexperimentsinvestigatingselectiveexposure--
includingbothpartisannewsfromtheleftandrightandseveralentertainment
programs(seeStudy2inFigure1,below).
Bycomparingtheobservedattitudinaleffectsacrossstudies,Arceneauxand
hiscolleaguessoughttoestimatetheextenttowhichobservedtreatmenteffects
resultedfromeitherselectiveexposure(attitudesdrivingexposure)orpersuasion
(exposuredrivingattitudes).Theirprimaryconclusionisthatpartisanattitudes
drivemediaexposuremuchmorethanexposuredrivesattitudes.
TheWayForward
SortingOutCauseandEffect
WhileArceneauxandhiscolleagueshavetakenasignificantstepforward,
theirapproachcannotfullyresolvethedirectionofcausalityproblem,asitdoesnot
allowrandomassignmentacrosschoiceselectionconditions.Nordoesitcorrectfor
theeffectsofbiasedestimatesofsubjects’truemediapreferencesandresulting
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over-orunder-estimatesofthetruelikelihoodofexposure.Consequently,wehave
nowayofknowingwhetherrespondentswhowatched,say,FoxNewsbecausethey
choseitwerecomparabletotheircounterpartswhowereassignedtowatchFox
News.
Morerecently,we(Benedictis-Kessner,Baum,Berinsky,andYamamoto
2016)attempttoaddressthisdilemmabyintegratingbothchoiceconditionsintoa
singledesign.Inthisstudy,followingapre-test,participantsarerandomlyassigned
toeitheraforcedchoiceorfreechoicetreatmentcondition,wherethetwo
conditionsapproximatetheaforementionedfirstandseconddesigns,respectively,
employedbyArceneauxandhiscolleagues.Participantsinbothconditionswatched
anewsreportongas/oilpricesfromFox(BillO’Reilly)orMSNBC(RachelMaddow),
oranentertainmentsegment(fromJaimeOliver:Jaime’sKitchenorDirtyJobs).This
design–illustratedinFigure2--makesitpossible,toagreaterextentthaninprior
research,todisentangleselectionandpersuasion.
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Ultimately,wefindclearevidenceofbothselectiveexposureandpersuasion
amongrespondentsexposedtobothtreatments.Whilemostrespondents,giventhe
opportunity,dosortintoviewingnewsfromtheirsideoftheideologicalspectrum,
themajorityofpeople–bothpartisansandindependents–expressapreferencefor
entertainmentratherthanpartisannewsshows.Thismajorityalsoappeartobe
persuadable,aswatchingpartisannewsproducedsubstantivechangesintheir
opinions.
ReliabilityofPreferenceClaims
Inthesamestudy(Benedictis-Kessneretal.2016),wealsodevelopan
uncertaintycorrectionproceduretoestimatetheeffectsofrespondentsmisstating
theirtruemediapreferences.Thisallowstheresearcherstoestimatethesampling
errorintheirdata.Theproblemisthat,forwhateverreason,somerespondents’
truepreferencesmaydifferfromtheirstatedpreference.Throughanovel
applicationofapatientpreferencetrial(PPT),describedindetailinaseparate
paper(Knox,Yamamoto,Baum,andBerinsky2015),thisprocedure,illustratedin
Figure3,estimatesminimumandmaximumerrormarginsinrespondents’stated
preferences.2
2ThePPTapproachhasbeenutilizedinpriorsocial(e.g.,GainesandKuklinski,
2011;Arceneaux,JohnsonandMurphy,2012)andmedical(Kingetal.,2005;
HowardandThornicroft,2006)scienceresearch.
19
FIGURE3.DiagramofPPTDesign
Note:blueboxesrepresentrandomassignment;dashedboxindicatesoptionalcomponent.
Themethodologyconsistsoftwoparts.Participantsfirststatetheir
preferences–inthisinstanceovermediaoutlets--inapre-treatmentsurvey(Si).
Followinganoptional“washout”period,theexperimentthenconsistsof
randomizingthemintooneoftwodesignconditions(Di):eitherastandardRCT
design(Di=0)orintoaself-selectioncondition(Di=1),inwhichtheycanchoose
fromamenuofmediaoutlets.Theirstatedpreferencesdonotinfluencetheir
assignedcondition.Theexperimentersthenassesstheoutcomemeasure(Yi).
Thenoveltyofthedesignisthatitallowstheexperimenterstomeasurethe
extenttowhichexantestatedpreferencespredictexpostactualtreatment(media
outlet)choices.Inparticular,weimplementasensitivityanalysistoestimatethe
assumedinformativenessofsubjects’statedpreferencesrelativetotheirrevealed
preferences.Wethenusethisanalysistoassesstheeffectsonthequantityof
interest(inthiscaseattitudesregardingseveralpoliticalissues)asthisparameter
varies.Theendresultisanimprovedestimateoftherelationshipbetweenmedia
consumption(thetreatment)andpoliticalattitudes(theoutcomevariables).Figure
20
4presentsanillustrativeexampleoffindingsfromapilotstudyimplementedvia
AmazonMechanicalTurkandbasedontheaforementioneddesignfromBenedictisKessneretal.(2016)employingthisprocedure.
Figure4comparestheresultsfrompointestimates,assumingnosampling
error(thickbars),withthosefromconfidenceintervalboundsthattakesampling
errorintoaccountviabootstrapping,andemployingtheaforementionedcorrection
procedure(thinbars).Theoutcomevariableinthisinstanceisthepropensityof
participantstoindicatethattheywouldsharethestorysegmenttheywatched(via
emailorsocialmedia).Thisresultcomparesthedifferenceinpropensitytosharea
pro-attitudinalnewsstory(e.g.,aRepublicanwatchingFoxoraDemocratwatching
MSNBC)withthepropensitytoshareanentertainmentstory,amongparticipants
whoexpressedapreferenceforpro-attitudinalnews,counter-attitudinalnewsor
entertainment.Theseresultsshowastrongpositiveincreaseinthepropensityto
sharethestoryamongindividualswhopreferredapro-attitudinalvideoandwere
21
assignedthepro-attitudinalvideo,regardlessofassumptionregardingconfidence
intervals.However,amongindividualswhopreferredacounter-attitudinalvideo
butwereassignedapro-attitudinalvideo,thepointestimatesurprisinglysuggestsa
(marginally)significantlygreaterpropensitytosharethenewsstoryrelativeto
respondentswhopreferredanentertainmentvideo.Thisrelationshipdisappears
withtheerrorcorrectionprocedure.Inshort,oncethepropensityofrespondentsto
incorrectlypredicttheirownbehavioristakenintoaccount,thisseeminglycounterintuitivepatterndoesnotemerge.
Conclusion
Scholarsfromnumerousacademicdisciplines,rangingfromsociologyto
psychologytoeconomicstopoliticalsciencetocommunications,havedevoted
considerableattentionthroughoutthepost-WorldWarIIeratounderstandinghow
consuminginformationviathemediainfluencespublicopinion.Theexplosionof
consumerchoiceoverthepastseveraldecadesandwithittheresurgenceofan
Americanpartisanpress,emergingintandemwithaparallelriseinpartisan
polarizationandpoliticalgridlockinWashingtonD.C.,hasrenewedscholarly
interesttothisresearchagenda.Todate,scholarshavemadeconsiderableprogress
inunderstandingtheroleofpartisanmedia,inparticular,inshapingpolitical
attitudesanddiscourse.Gettingthisstoryrightseemsparticularlyimportantinthe
currentera,wherebuildingcoalitionsacrosspartisanandideologicallinesseems
evermoreelusiveandcitizensincreasinglyquestionthecapacityofourleadersto
overcomepartisanpolarizationinorderaddressthemanyimportantissues
22
confrontingthenation.Togoverneffectively,policymakersneedscholarshipthat
willhelpthemdeterminewhenandhowtheymightbridgethesedivides.Accurately
assessingthemediaconsumptionchoicesofcitizensandanyresultingattitudinal
effectsrepresentsonestepindiscerningapotentialresponsetothisquandary
facingtoday’spoliticiansandpolicymakers.
However,beforesuchastepcanbesuccessfullytaken,thisresearch
continuestoconfrontimportanthurdles,suchasaddressingtheproblemof
selectionanditsimplicationsforthedirectionofcausality.Inthisreviewwethus
tracedrecenttrendsinscholarlyresearchandproposedseveralpotential
methodologicalimprovementsaimedatachievingbetterestimatesofthecausesand
effectsofmediachoiceinthecontemporaryera.Thenextstepistoimplementthese
methodsforavarietyofoutcomevariablesandonmorerepresentativepopulation
samples.
23
References
Arceneaux,K.andJohnson,M.(2013).ChangingMindsorChangingChannels?
PartisanNewsinanAgeofChoice.UniversityofChicagoPress,Chicago.
Arceneaux,K.,Johnson,M.,andMurphy,C.(2012).Polarizedpolitical
communication,oppositionalmediahostility,andselectiveexposure.Journalof
Politics,74(1),174–186.
Baum,M.andGroelingT.J.(2008).NewMediaandthePolarizationofAmerican
PoliticalDiscourse.PoliticalCommunication25:4:345-65.
Baum,M.andGroeling,T.J.(2010)WarStories:TheCausesandConsequencesof
PublicViewsofWar.Princeton:PrincetonUniversityPress.
Baum,M.andGroeling,T.J.(2009).Shotbythemessenger:partisancuesandpublic
opinionregardingnationalsecurityandwar.PoliticalBehavior,31,157–186.
Baum,M.andGussin,P.2008.“IntheEyeoftheBeholder:HowInformation
ShortcutsShapeIndividualPerceptionsofBiasintheMedia.”QuarterlyJournal
ofPoliticalScience3:1:1-31
Benedictis-Kessner,Justin,MatthewA.Baum,AdamBerinsky,andTeppeiYamamoto.2016.
DisentanglingSelectiveExposureandMediaPersuasion.WorkingPaper.
Berelson,BernardR.,andF.Paul."Lazarsfeld,andWilliamN.McPhee.1954."Voting:
Astudyofopinionformationinapresidentialcampaign(1963).
Bullock,J.(2011).Eliteinfluenceonpublicopinioninaninformedelectorate.
AmericanPoliticalScienceReview,10(3),496–515.
Campbell,Angus,PhilipEConverse,WarrenMillerandDonaldStokes.1960.The
AmericanVoter.Chicago:UniversityofChicagoPress.
24
Carville,James.2013.“Opinion:Disturbingpolarizationinmediaworsenspolitical
partisanship.”TheHill(10/15/13).Availableat:
http://thehill.com/opinion/columnists/james-carville/328731-polarization-inmedia-worsens-partisanship(accessedon10/15/15).
Chong,D.andDruckman,J.N.(2010).Dynamicpublicopinion:Communication
effectsovertime.AmericanPoliticalScienceReview,104(04),663–680.
Chong,Dennis,andJamesN.Druckman."Framingtheory."Annu.Rev.Polit.Sci.10
(2007):103-126.Clausen,AageR.1968.“ResponseValidity:VoteReport.”Public
OpinionQuarterly32(4):588–606.
Conroy-Krutz,Jeffrey,andDevraMoehler.EthnicCuesandBallotDesign.Working
Paper,UniversityofPennsylvania.(January3,2014),2014.
Druckman,JamesN."Onthelimitsofframingeffects:whocanframe?."Journalof
Politics63.4(2001):1041-1066.
Druckman,JamesN.,JordanFein,andThomasJ.Leeper."Asourceofbiasinpublic
opinionstability."AmericanPoliticalScienceReview106.02(2012):430-454.
Ellithorpe,M.E.,Holbert,R.L.,andPalmer-Wackerly,A.L.(2013).Procrastination
andtheshiftingpoliticalmediaenvironment:Anexperimentalstudyofmedia
choiceaffectingademocraticoutcome.CommunicationStudies,64(5),561–578.
Feldman,L.(2011a).Theopinionfactor:Theeffectsofopinionatednewson
informationprocessingandattitudechange.PoliticalCommunication,28(2).
Feldman,L.(2011b).Partisandifferencesinopinionatednewsperceptions:Atestof
thehostilemediaeffect.PoliticalBehavior,33(3),407–432.
Gaines,B.J.andKuklinski,J.H.(2011).Experimentalestimationofheterogeneous
25
treatmenteffectsrelatedtoself-selection.AmericanJournalofPoliticalScience,
55(3),724–736.
Gallup(2014).Americansconfidenceinnewsremainslow.
http://www.gallup.com/poll/171740/americansconfidence-news-mediaremains-low.aspx.
Gentzkow,Matthew,andJesseM.Shapiro.Ideologicalsegregationonlineandoffline.
No.w15916.NationalBureauofEconomicResearch,2010.
Gentzkow,Matthew,andJesseM.Shapiro.Whatdrivesmediaslant?Evidencefrom
USdailynewspapers.No.w12707.NationalBureauofEconomicResearch,2006.
Giner-Sorolla,Roger,andShellyChaiken."Thecausesofhostilemediajudgments."
JournalofExperimentalSocialPsychology30.2(1994):165-180.
Groeling,Tim."Mediabiasbythenumbers:Challengesandopportunitiesinthe
empiricalstudyofpartisannews."PoliticalScience16.1(2013):129.
Groseclose,Tim.Leftturn:HowliberalmediabiasdistortstheAmericanmind.Macmillan,2011.
Groseclose,Tim,andJeffreyMilyo."Ameasureofmediabias."TheQuarterlyJournal
ofEconomics(2005):1191-1237.
Gunther,AlbertC.,andKathleenSchmitt."Mappingboundariesofthehostilemedia
effect."JournalofCommunication54.1(2004):55-70.
Hamilton,JamesT.2003.AlltheNewsThat’sFittoSell.Princeton:Princeton
UniversityPress.
Hamilton,J.T.(2005).Themarketandthemedia.InG.OverholserandK.H.
Jamieson,editors,ThePress.OxfordUniversityPress,Oxford.
Hmielowski,J.D.,Feldman,L.,Myers,T.A.,Leiserowitz,A.,andMaibach,E.(2014).
26
Anattackonåscience?mediause,trustinscientists,andperceptionsofglobal
warming.PublicUnderstandingofScience,23(7),866–883.
Howard,LouiseandGrahamThornicroft.2006.“Patientpreferencerandomised
controlledtrialsinmentalhealthresearch.”TheBritishJournalofPsychiatry
188(4):303–304.
Iyengar,S.andHahn,K.S.(2009).Redmedia,bluemedia:evidenceofideological
selectivityinmediause.JournalofCommunication,59,19–39.
Iyengar,S.,Hahn,K.S.,Krosnick,J.A.,andWalker,J.(2008).Selectiveexposureto
campaigncommunication:Theroleofanticipatedagreementandissuepublic
membership.TheJournalofPolitics,70,186–200.
Iyengar,Shanto,andDonaldR.Kinder."Newsthatmatters:agendasettingand
priminginatelevisionage."NewsthatMatters:Agenda-SettingandPrimingina
TelevisionAge(1987).
Jacobson,G.C.(2014).Partisanmediaandelectoralpolarizationin2012:Evidence
fromtheamericannationalelectionstudy.ConferenceonAmericanGridlock.
Jerit,J.andBarabas,J.(2012).Partisanperceptualbiasandtheinformation
environment.TheJournalofPolitics,74(3),672–684.
Kim,Y.M.(2009).Issuepublicsinthenewinformationenvironment:Selectivity,
domainspecificity,andextremity.CommunicationResearch,36,254–284.
Knox,Dean,TeppeiYamamoto,MatthewA.Baum,andAdamBerinsky.2015.Design,
Identification,andSensitivityAnalysisforPatientPreferenceTrials.Paper
originallypreparedforthe2014SocietyforPoliticalMethodologySummer
MeetingandMacMillan-CSAPWorkshopatYaleUniversity(updatedNov2015).
27
King,M.,Nazareth,I.,Lampe,F.,Bower,P.,Chandler,M.,Morou,M.,Sibbald,B.,and
Lai,R.(2005).Impactofparticipantandphysicianinterventionpreferenceson
randomizedtrials:asystematicreview.JourmaloftheAmericanMedical
Association,293(9),1089–1099.
Ladd,J.M.(2012).WhyAmericansHatetheMediaandHowItMatters.Princeton
UniversityPress,Princeton.
Lazarsfeld,PaulFelix,BernardBerelson,andHazelGaudet."Thepeopleschoice:
howthevotermakesuphismindinapresidentialcampaign."(1968).
Levendusky,M.S.(2013).Whydopartisanmediapolarizeviewers?American
JournalofPoliticalScience,57(3),611–623.
Messing,Solomon,andSeanJ.Westwood."Selectiveexposureintheageofsocial
media:Endorsementstrumppartisansourceaffiliationwhenselectingnews
online."CommunicationResearch(2012):0093650212466406.
Meyer,Frederick.2012.StoriesofClimateChange:CompetingNarratives,theMedia,
andU.S.PublicOpinion2001-2010.ShorensteinCenterontheMedia,Press,and
PublicPolicy,DiscussionPaper#D-72(February).
MorehouseMendez,Jeanette."Killingthemessenger:Anexperimentalanalysisof
thehostilemediaeffect."meetingoftheSouthernPoliticalScienceAssociation,
NewOrleans,LA.2004.
Negroponte,Nicholas."BeingDigital-ABook(p)review."Wired.com3(1995).
Pariser,Eli.FilterBubble:WiewirimInternetentmündigtwerden.Hanser,2012.
Peffley,Mark,JasonGlass,andJamesAvery."Publicperceptionsofbiasinthenews
media:Takingacloserlookatthehostilemediaphenomenon."Meetingofthe
28
MidwestPoliticalScienceAssociation,Chicago,IL.2001.
PewResearchCenter.2014.StateoftheNewsMedia2014.Availableat:
http://www.journalism.org/packages/state-of-the-news-media-2014/(Accessed
12/21/15).
Prior,M.(2007).Post-BroadcastDemocracy:HowMediaChoiceIncreasesInequality
inPoliticalInvolvementandPolarizesElections.CambridgeUniversityPress,
Cambridge.
Prior,Markus.2009.“TheImmenselyInflatedNewsAudience:AssessingBiasin
Self-ReportedNewsExposure.”PublicOpinionQuarterly73:1–14.Rosenbaum,P.
R.(2002).ObservationalStudies.Springer-Verlag,NewYork,2ndedition.
Slothuus,R.anddeVreese,C.(2010).Politicalparties,motivatedreasoning,and
issueframingeffects.TheJournalofPolitics,72(3),630–645.
Stroud,N.J.(2011).ThePoliticsofNewsChoice.OxfordUniversityPress,Oxford.
Sunstein,Cass.2001.Republic.com.Princeton:PrincetonUniversityPress.
Taniguchi,M.(2011).Theelectoralconsequencesofcandidateappearancesonsoft
newsprograms.PoliticalCommunication,28(1).
Vallone,RobertP.,LeeRoss,andMarkR.Lepper."Thehostilemediaphenomenon:
biasedperceptionandperceptionsofmediabiasincoverageoftheBeirut
massacre."Journalofpersonalityandsocialpsychology49.3(1985):577.Weprin,
A.(2013).Billclintonturnsmediacriticoncnn.Online,TheBlaze.com.
Yamamoto,T.(2012).Understandingthepast:Statisticalanalysisofcausal
attribution.AmericanJournalofPoliticalScience,56(1),237–256.
Zaller,John.1992.TheNatureandOriginsofMassOpinion.Cambridge:CambridgeUniv.Press.
29