Threat-Related Attentional Bias in Anxious and Nonanxious Individuals

24 Pages·2006·0.52 MB·English

PsychologicalBulletin Copyright2007bytheAmericanPsychologicalAssociation
2007,Vol.133,No.1,1–24 0033-2909/07/$12.00 DOI:10.1037/0033-2909.133.1.1
Threat-Related Attentional Bias in Anxious and Nonanxious Individuals:
A Meta-Analytic Study
Yair Bar-Haim, Dominique Lamy, and Marian J. Bakermans-Kranenburg and
Lee Pergamin Marinus H. van IJzendoorn
TelAvivUniversity LeidenUniversity
Thismeta-analysisof172studies(N(cid:1)2,263anxious,N(cid:1)1,768nonanxious)examinedtheboundary
conditionsofthreat-relatedattentionalbiasesinanxiety.Overall,theresultsshowthatthebiasisreliably
demonstratedwithdifferentexperimentalparadigmsandunderavarietyofexperimentalconditions,but
thatitisonlyaneffectsizeofd(cid:1)0.45.Althoughprocessesrequiringconsciousperceptionofthreat
contributetothebias,asignificantbiasisalsoobservedwithstimulioutsideawareness.Thebiasisof
comparablemagnitudeacrossdifferenttypesofanxiouspopulations(individualswithdifferentclinical
disorders, high-anxious nonclinical individuals, anxious children and adults) and is not observed in
nonanxiousindividuals.Empiricalandclinicalimplicationsaswellasfuturedirectionsforresearchare
discussed.
Keywords:attentionalbias,selectiveattention,anxiety,threat
A normative function of the mechanisms underlying fear is to phobias (McNally, 1999), or in children (Ehrenreich & Gross,
facilitate detection of danger in the environment and to help the 2002). Other reviews have focused on specific issues within the
organism respond effectively to threatening situations. Biases in field,suchasprocessingbiasesinanxietyversusdepression(Dal-
processingthreat-relatedinformationhavebeenassignedaprom- gleish&Watts,1990;Mineka&Gilboa,1998),nonverbalinfor-
inent role in the etiology and maintenance of anxiety disorders mationprocessinginanxiety(Mogg&Bradley,2003),orprocess-
(A. T. Beck, 1976; Eysenck, 1992; Mathews, 1990; Mathews & ing biases in anxiety as measured specifically by the emotional
MacLeod, 2002; Williams, Watts, MacLeod, & Mathews, 1988). Stroopparadigm(MacLeod,1991;Williams,Mathews,&MacLeod,
Specifically, several authors have suggested that the attentional 1996).Otherworkhasrevolvedontheliteraturerelevanttotesting
systemofanxiousindividualsmaybedistinctivelysensitivetoand aspecificmodelofthreatprocessinginanxiety,suchasMoggand
biasedinfavorofthreat-relatedstimuliintheenvironment.Over Bradley’s (1999b) cognitive-motivational model, Fox’s (2004)
the last 2 decades, this notion has fostered intensive research on review on maintenance versus capture of attention in anxiety-
attentional biases in anxiety using different experimental tasks relatedbiases,orMansell’s(2000)top-downmodelofprocessing
both in clinical populations displaying a variety of anxiety disor- biases in anxiety. The field lacks, however, an updated encom-
dersandinnonclinicalindividualsreportinghighlevelsofanxiety. passing and systematic review. In addition, there has not been a
Although several narrative reviews have been published on singlequantitativereviewoftheconsiderableamountofavailable
topicsrelatedtoprocessingbiasesinanxiety,theyweretypically dataassessingtheoveralleffectsizeandtheinfluenceofthemajor
selective in nature. Some reviews have focused on processing moderators related to threat processing in anxiety. For in-depth
biasesinselectedpopulations,suchasinindividualsexperiencing discussions of the advantages inherent in meta-analysis versus
posttraumaticstressdisorder(PTSD;Buckley,Blanchard,&Neill, narrativereviews,seeCooperandHedges(1994)andCooperand
2000), social phobia (Clark & McManus, 2002; Heinrichs & Lindsay (1998). Therefore, the objective of the present meta-
Hofman, 2001; Musa & Lepine, 2000), obsessive–compulsive analysis was to assess the magnitude and boundary conditions of
disorder(OCD;Summerfeldt&Endler,1998),generalizedanxiety threat-related biases in anxiety by organizing the extant database
disorder (GAD; Mogg & Bradley, 2005), or panic disorder and according to variables identified as potential modulators of the
phenomenon.
Theories of Cognitive Biases in Anxiety
YairBar-Haim,DominiqueLamy,andLeePergamin,theAdlerCenter
forReasearchinChildDevelopmentandPsychopathology,Departmentof Cognitiveaccountsofanxietydifferwithregardtotherolesthey
Psychology,TelAvivUniversity,TelAviv,Israel;MarianJ.Bakermans- assigntobiasesinattention,interpretation,memory,andjudgment
KranenburgandMarinusH.vanIJzendoorn,CenterforChildandFamily
intheetiologyandmaintenanceofanxiety.Accordingtoschema
Studies,LeidenUniversity,Leiden,theNetherlands.
theories(e.g.,A.T.Beck,1976;A.T.Beck&Clark,1997;A.T.
PreparationofthisarticlewassupportedbyIsraeliScienceFoundation
Beck, Emery, & Greenberg, 1985; Bower, 1981, 1987) cognitive
Grant 989/03. Marinus H. van IJzendoorn was supported by the NWO/
processing is guided by schemas that largely determine how in-
SpinozaprizeoftheNetherlandsOrganizationforScientificResearch.
Correspondence concerning this article should be addressed to Yair formationisattendedto,interpreted,andremembered.Inanxious
Bar-Haim,DepartmentofPsychology,TelAvivUniversity,RamatAviv, individuals,schemasarethoughttobebiasedtowardthreat.Asa
TelAviv69978,Israel.E-mail:[email protected] result,threat-relatedmaterialisfavoredatallstagesofprocessing,
1
2 BAR-HAIMETAL.
includingearlyprocessessuchasattentionandstimulusencoding biasareusedintheliteraturebutdonotnecessarilyconverge.The
andlaterprocessessuchasmemoryandinterpretation. first definition refers to a significant difference in the attentional
Other theories suggest that anxious individuals are prone to allocation of highly anxious individuals with respect to threat-
biasesatspecificstagesofinformationprocessing.Someauthors related stimuli relative to neutral stimuli (a within-subject bias).
haveproposedthattheattentionalsystemofanxiousindividualsis The other definition refers to a significant difference between
abnormally sensitive to threat-related stimuli and that these indi- anxious and nonanxious individuals in the pattern of attentional
viduals tend to direct their attention toward threatening informa- allocationtothreat-relatedandneutralstimuli(abetween-subjects
tionduringearly,automaticstagesofprocessing(Williamsetal., bias).
1988). This idea is consistent with the literature showing that Anxious individuals are sometimes found to attend preferen-
evaluationofstimulusemotionalvalencemaytakeplaceatavery tially to threat-related stimuli relative to neutral stimuli (within-
early stage of processing, automatically, and in the absence of subjectbias)butnotsignificantlymoresothancontrolparticipants
awareness(e.g.,LeDoux,1995,1996;Ohman,1993).Abnormal- (e.g., Kyrios & Iob, 1998). Such findings imply a threat-related
ities in the threat-detection mechanism of anxious individuals biasthatdoesnotspecificallycharacterizeanxiousindividuals(no
would therefore lead them to adopt a hypervigilant mode toward between-subjectsbias).Conversely,asignificantdifferenceinthe
threat. A quite different proposal is that inhibition of detailed attentional allocation pattern of anxious individuals relative to
processingofthreateninginformationisthecoredeficitinanxiety, nonanxious controls (between-subjects bias) is sometimes re-
which is reflected in avoidance of threatening stimuli (Foa & ported, while at the same time, anxious individuals show no
Kozak,1986;Mogg,Bradley,DeBono,&Painter,1997).Accord- significanttendencytoallocatetheirattentiontothreateningrela-
ing to this view, threat-related biases in anxiety are confined to tive to neutral material (no within-subject bias). This pattern of
laterstagesofprocessing. resultsmayarise,forexample,whenanxiousparticipantsshowa
Morerecentmodelshavesuggestedamorecomplexpatternof nonsignificant attentional bias toward threat whereas control par-
biasesthatmayreconciletheseapparentlyconflictingviews.They ticipantsshowabiasawayfromthreat(e.g.,Musa,Lepine,Clark,
haveemphasizedthetimecourseofattentionalallocationinmain- Mansell,&Ehlers,2003;Stewart,Conrod,Gignac,&Pihl,1998).
taininghighlevelsofanxiety(e.g.,Clark&Wells,1995;Eysenck, Yet, in both instances of divergence between the within-subject
1992; Mathews & Mackintosh, 1998; Mogg & Bradley, 1998; and between-subjects definitions of the bias, the finding that is
Williams,Watts,MacLeod,&Mathews,1997). consistent with the idea of anxiety’s being associated with a
Williamsetal.(1997,1988)andothers(seeAmir,Foa,&Coles, threat-related attentional bias has most often been put forward,
1998; Mogg et al., 1997) have proposed that anxious individuals whichcontributestotheimpressionthatthethreat-relatedbiasin
tendtodirecttheirattentiontowardthreatduringearly,automatic anxiousindividualsislargeandrobust.
stagesofprocessing,whereasduringlater,morestrategicstagesof Inaddition,studiesofthethreat-relatedbiasinanxietyusually
processing, they tend to direct their attention away from threat. differalongawidearrayofvariables,withpositivefindingsofan
Automatic allocation of attentional resources to threat-related attentional bias often being found in one of the relevant experi-
stimuli would serve to enhance an individual’s anxious state, yet mental conditions but not in others within the same study. The
subsequent avoidance of such stimuli would prevent more elabo- myriad of variables used in studies of threat-related biases in
rateevaluationprocessesthatcoulddeflatethethreateningvalueof anxiety can be grouped under two broad categories: procedural
thesestimuliandtherebyreduceanxiety. variablesandpopulation-relatedvariables.
Other research groups (e.g., Fox, Russo, Bowles, & Dutton, With regard to procedural variables, the threat-related bias has
2001;Fox,Russo,&Dutton,2002;Yiend&Mathews,2001)have been measured using different paradigms, namely, the emotional
suggestedthatanxietyhaslittleimpactoninitialdetectionofthreat Stroop,dot-probe,emotionalspatialcuing,andvisualsearchpar-
but has a stronger effect in modulating the maintenance of atten- adigms.Althoughthereisstrongevidencethatalltheseparadigms
tion on the source of threat. That is, they have proposed that a reflecttheoperationofattentionalprocesses(e.g.,Driver,2001),it
delay in disengaging from threat stimuli might be the primary isalsogenerallyacceptedthattheydonottapthesameaspectsof
attentional difference between anxious and nonanxious individu- attention (e.g., Shalev & Algom, 2000). In addition, studies have
als. differed in the types of stimuli used, either printed words or
Despitedisagreementsastothespecificcognitivemechanisms pictorialstimuli.Finally,thethreat-relatedbiashasbeenexamined
underlyinganxiety,thereisaconsensusatthetheoreticallevelthat inconditionsthatpreventedconsciousperception(subliminalex-
anxiety is associated with biases in attending to threat-related posure)andinconditionsthatallowedclearawareness(supralim-
information. However, at the empirical level, the wide range of inal exposure). Processes triggered by signs of threat that are
studies concerned with threat-related biases in anxiety offers a perceivedwithorwithoutawarenessmightyielddifferentbehav-
somewhat confusing picture, plagued by contradictory findings ioral outcomes. In addition, with consciously perceived stimuli,
that lack unambiguous explanation. In the next section, we de- attentional effects have been measured at various times after
scribepotentialfactorscontributingtothedivergenceofempirical stimuluspresentation.Giventhedebateconcerningthenotionsof
findingsandtheirinterpretationinthefield. hypervigilance versus avoidance of threat in anxiety, the time
course of attentional allocation to threat-related stimuli is impor-
Operational Considerations in the Study of Attentional tant, because different time frames are likely to yield different
results.
Bias in Anxiety
Withregardtopopulation-relatedvariables,anxiousparticipants
Part of the confusion regarding the empirical findings may be havebeensampledfrompopulationsthatvariedconsiderablyfrom
traceable to the fact that two different operational definitions of onestudytoanother.Somestudieshaveexaminedadults,whereas
ATTENTIONALBIASINANXIETY:META-ANALYSIS 3
othershaveexaminedchildren.Participantseitherwerediagnosed Stroopeffectreferstothedifferenceincolor-namingperformance
with clinical anxiety (clinical population) or only scored high on between congruent (e.g., the word red printed in red) and incon-
questionnairesrelyingonself-reportofeitherstateortraitanxiety gruent(e.g.,thewordredprintedingreen)stimuli.Thepresence
(nonclinical population). Moreover, clinically diagnosed partici- oftheStroopeffectdocumentsthefailuretofocusexclusivelyon
pants differed in the type of anxiety disorder they experienced, the target dimension of color. In the emotional Stroop, the word
namely, GAD, specific phobias, social phobia, OCD, PTSD, and valenceinsteadofitssemanticcongruencewiththeprintedcolor
panic disorder. Whether these participants concomitantly experi- ismanipulated.Forinstance,responselatencytonametheprinted
enceddepressionwasoftenreportedyetseldomcontrolledfor. colorofawordiscomparedwhenthiswordisthreatrelated(e.g.,
Thus, in view of the numerous experiments with diverging “cancer”) relative to when it is neutral (e.g., “plate”). When
results,aquantitativetestoftheoverarchingconclusionstypically pictures instead of words are used, the participant might be re-
drawn as to the existence of a threat-related bias in anxious quired to name the color of a schematic face, with this face
individualsisinorder.Wenowturntoamoredetaileddescription displaying either a neutral or an angry expression. Threat-related
ofthedifferentmoderatorsconsideredinthismeta-analysis. bias is inferred when color naming takes longer with a threat
stimulusrelativetoaneutralstimulus(MacLeod,1991).
TheemotionalStroopwasinitiallythemostwidelyusedtoolto
Procedural Moderators
investigatethreat-relatedattentionalbiasesinanxiety.However,it
Subliminal Versus Supraliminal Stimulus Presentation hasbeencriticizedwiththeargumentthatdelayedresponselaten-
cieswiththreat-relatedstimulimayresultfromlateprocessesthat
Research on the neural substrates of emotion has underscored are unrelated to attention (e.g., Algom, Chajut, & Lev, 2004;
the role of automatic processes in mediating anxiety and fear MacLeod, Mathews, & Tata, 1986). MacLeod et al. (1986) sug-
responses(e.g.,LeDoux,1996;Ohman,1993).Specifically,ithas gestedthatanxiousparticipantsmightprocessboththeneutraland
beensuggestedthatneuralstructuressensitivetosignsofbiolog- the threat-related meanings to the same degree but that the pres-
icallythreat-relevantstimulicandirectlytriggeranxietyresponses ence of the latter might intensify the negative affective state of
and draw attention toward the source of threat before conscious anxiousparticipantstoalevelwhereitimpairsreactiontime.De
perceptionandevaluationoccur.Moststudiesofthethreat-related RuiterandBrosschot(1994)furthersuggestedthatinterferenceby
bias in anxiety have involved clearly visible stimuli, typically threatstimuliintheemotionalStroopmightreflecteffortfulavoid-
presented for 500 ms or longer, an exposure time that allows the ance of processing threat cues rather than attentional capture by
stimuli to be consciously perceived. However, in a number of thesecues.
studies the critical stimuli were presented in conditions that pre- To overcome these problems MacLeod et al. (1986) designed
cluded conscious processing. In these studies, the stimuli were the dot-probe paradigm. In this task, two stimuli, one threat-
typicallypresentedforverybriefdurations(subliminalexposure) relatedandoneneutral,areshownbrieflyoneachtrial,andtheir
andwereimmediatelymasked.Suchbackwardmaskingisknown offsetisfollowedbyasmallprobeinthelocationjustoccupiedby
to interrupt sensory processing, thereby preventing the masked oneofthem.Participantsarerequiredtorespondasfastaspossible
stimulifromreachingawareness(e.g.,DiLollo,Enns,&Rensink, totheprobe.Onthebasisoftheattentionliterature(e.g.,Navon&
2000).Therationaleforusingsubliminalstimuliisthatthestruc- Margalit,1983),responselatenciesonthedot-probetaskareheld
tures underlying early, automatic, rather than later, conscious to provide a “snapshot” of the distribution of participants’ atten-
processingofthreatmaybeabnormallysensitiveinanxiousindi- tion, with faster responses to probes presented in the attended
viduals. relativetotheunattendedlocation.Attentionalbiastowardthreat
Findingathreat-relatedbiasinresponsetosupraliminalstimuli is revealed when participants are faster to respond to probes that
does not allow a distinction between the contributions of a pre- replacethreat-relatedratherthanneutralstimuli.
consciousbiasversusabiasthatrequiresawarenessofthethreat- Inthedot-probeparadigm,participantsarerequiredtorespond
ening stimulus. Finding a bias using subliminal stimuli can be to a neutral stimulus (the probe). Therefore, there is no concern
accountedforonlybyanearly,preconsciousbias. that delayed latencies may result from response bias or general
arousal. An additional advantage of this paradigm is that manip-
ulating stimulus onset asynchrony, that is, the time interval be-
Experimental Paradigms
tween presentation of the critical stimuli and presentation of the
Threemainexperimentalparadigmshavebeenusedtostudythe probe,allowsforinvestigatingthetimecourseofattentionalallo-
threat-related attentional bias in anxiety: emotional Stroop, dot- cation.
probe, and emotional spatial cuing. In the following paragraphs, In the dot-probe paradigm, the advantage in performance on
wedescribetheseparadigmsandthedifferenttheoreticalimplica- trials in which the target probe appears at the location of the
tions that arise from the use of each of them. Surprisingly, the threat-relatedstimulusmightresulteitherfromfasterengagement
visual search paradigm, a primary tool used to investigate atten- withthethreatstimulusorfromadifficultytodisengagefromit.
tionalprioritywhenseveralobjectscompeteforattention,hasbeen In order to determine the relative contributions of these two
only seldom used in the context of anxiety research (cf. Gilboa components of attention (Posner & Peterson, 1990) to the threat-
Schechtman, Foa, & Amir, 1999; Hadwin et al., 2003; Rinck, related attentional bias, a variant of Posner’s spatial cuing para-
Becker,Kellermann,&Roth,2003).Thus,ameta-analysisofthese digmhasbeenused.InPosner’sclassicalparadigm(Posner,1980),
studieswouldbepremature. acueappearsinoneoftwolocationsandisfollowedbyatarget
The emotional Stroop is a modified version of the classic presentedatthecuedlocationonamajorityofthetrials(valid-cue
color-naming Stroop interference paradigm (Stroop, 1935). The condition)andatthealternativelocationonaminorityofthetrials
4 BAR-HAIMETAL.
(invalid-cue condition). Performance in detecting or identifying consciousawareness(e.g.,Morris,Ohman,&Dolan,1998).Such
thetargetistypicallyfasteronvalidlycuedthanoninvalidlycued rapidrecognitionishighlyadaptive:Athreateningfaceisaclear
trials. Speeding on validly cued trials has been attributed to the sign of danger and should therefore be a good candidate for
benefitsofattentionalengagementwiththecuedlocation.Slowing capturing the attention of anxious individuals. Angry and fearful
on invalidly cued trials has been associated with the costs of facesfallintothecategoryofthreat-relatedstimuli,whereasneu-
havingtodisengageattentionfromthecuedlocation. tralorhappyfacesaretypicallyusedascontrolstimuli.
Stormark, Nordby, and Hugdahl (1995) adapted this paradigm
to the study of attentional allocation to emotionally valenced
Population-Related Variables in the Study of Threat-
stimulibymanipulatingtheemotionalcontentofthecue.Foxetal.
Related Bias in Anxiety
(2001) later used the emotional spatial cuing paradigm to inves-
tigateattentionalbiasrelatedtothreatinanxiety.Athreat-related
Clinically Diagnosed Anxiety Versus Nonclinical Self-
attentionalbiasisrevealedwhenvalidityeffects(performanceon
invalid-cuetrialsminusperformanceonvalid-cuetrials)arelarger Reported Anxiety
when the cue is threat related than when it has a neutral content.
Theattentionalbiasinanxietyhasbeeninvestigatedinindivid-
Moreover,avalence-relatedmodulationofperformanceonvalid-
ualswithdiagnosedanxietydisorders(clinicalpopulation)andin
cue trials indicates that the attentional bias occurs at the stage of
individuals who self-reported high levels of anxiety on question-
initialorientingofattention,whereassuchmodulationoninvalid-
naires (nonclinical population). As clinical participants typically
cuetrialsreflectsadifficultyindisengagingattentionfromthreat-
display more severe anxiety, it is reasonable to expect that they
related material after attention has been engaged. Unfortunately,
willshowlargerattentionalbiases.Inaddition,someauthorshave
the small number of studies that have distinguished between the
claimedthatevenwithsimilarlevelsofreportedanxiety,clinical
“engage” and “disengage” components of attention, and the fact
participants should display a larger bias due to qualitative differ-
thatthesecomponentswereinvariablyexaminedinwithin-subject
encesbetweenclinicalandnonclinicalanxiety(e.g.,Martin,Wil-
designs,precludedmeta-analyticexaminationofthisissue.
liams,&Clark,1991).
Aswiththedotprobe,intheemotionalspatialcuingparadigm
One should keep in mind, however, that in between-subjects
the target to which subjects respond is neutral with respect to
analyses(anxiousvs.control)forclinicalversusnonclinicalpop-
valence.Thus,thisparadigmisnotopentothealternativeaccount
ulations, control participants for the nonclinical populations are
of response bias in anxious participants. However, unlike the
oftenselectedforparticularlylowanxietyscores,whereascontrols
dot-probeparadigm,inwhichtheneutralandthreat-relatedstimuli
for clinical participants are a matched sample, usually selected
compete for the participants’ attention, in the emotional spatial
fromthegeneralpopulation.
cuingparadigmthevisualfieldcontainsjustonestimulus.Tothe
Threat-related biases have been investigated in a variety of
extentthatcompetitionamongdifferentstimulimightbeaprereq-
clinicalanxietydisorders(e.g.,GAD,PTSD,socialphobia,simple
uisite for threat-related attentional bias in anxiety to emerge, the
phobias, OCD, panic disorder). Although the different disorders
dot-probe task might be a more sensitive paradigm. Moreover,
present considerable differences in symptoms, time course, etiol-
whereas in the dot-probe paradigm, the valenced cue stimuli are
ogy,andprognosis,theyaretypicallyheldtobelongtothesame
utterly task irrelevant, in the emotional spatial cuing paradigm
overarching family of anxiety disorders. Finding that the threat-
participants are instructed to attend to the valenced cue (through
relatedattentionalbiasisreliablydetectedineachofthesedisor-
validityinstructions).Thisfactmayhamperthegeneralizabilityof
ders would reinforce the idea that attentional bias is a core com-
thefindingsgeneratedbytheemotionalspatialcuingparadigm,as
ponentofanxiety.Incontrast,iftheattentionalbiasisnotreliably
these might be contingent on the cue stimulus’s being task rele-
demonstrated in one or more of the disorders, this may be inter-
vant.
pretedasadivergenceofthisparticulardisorderfromthefamilyof
anxietydisorders(seethediscussionregardingOCDinSummer-
Words Versus Naturalistic Stimuli
feldt&Endler,1998).
Threat-related bias in anxiety has been initially investigated
usingwordstimuli,themeaningofwhichwaseitherthreatrelated Effect of Depression Comorbidity
or neutral. Reliance on verbal stimuli was criticized on several
grounds (e.g., Bradley et al., 1997). It is likely that anxious Anxiety and depression are frequently comorbid conditions
individualsspendmoretimethannonanxiousindividualsthinking (e.g.,Mineka,Watson,&Clark,1998).Despitecommonfeatures
aboutthreateningeventsorspeakingwithothersabouttheiranx- suchashighlevelsofnegativeaffectanddistress,thetwocondi-
iousfeelings.Asaresult,theverywordsusedasthreatstimuliare tions also present unique features such as exacerbated fear of
likely to be more primed in anxious participants than in nonanx- danger in anxiety and thoughts of failure and worthlessness in
ious control participants. Thus, the valence-related effects ob- depression.Withregardtocognitivebiases,ithasbeensuggested
served with words may reflect high familiarity and subjective thatanxietyisassociatedwithanattentionalbiastowardthreatand
frequency of use of the threat words rather than a threat-related depression is associated with greater elaboration of negative ma-
attentionalbias(McNally,Riemann,&Kim,1990). terial (Williams et al., 1997). Accordingly, patients with depres-
Threat-related and neutral pictures have been used to corrobo- sion do not generally show an attentional bias toward negative
ratethefindingsobtainedwithwordstimuli.Themostwidelyused informationandappeartodosoonlywithlongstimuliexposures
pictorialstimuliarehumanfacesdisplayingemotionexpressions. thatallowlater,elaborativeprocessingtooccur(Eizenmanetal.,
Recognitionoffacialexpressionisautomaticanddoesnotrequire 2003;seeMogg&Bradley,2005,foranextensivereview).
ATTENTIONALBIASINANXIETY:META-ANALYSIS 5
Itisnotclearatthispointhowanxietyanddepressioninteract clear theoretical and practical significance to the study of devel-
on measures of attentional bias. On the one hand, if depression- opmentalaspectsofthethreat-relatedbiasinanxiety.Surprisingly,
relatedeffectsarerevealedonlyatlaterstagesofprocessing,then however,onlyasmallnumberofstudieshavebeenpublishedwith
comorbidityofdepressionmightnotaffecttheattentionalbiasin childrenrelativetotheextensiveresearchwithadults.
anxiety. On the other hand, there have been reports that when Theconflictingfindingsintheextantliteraturehavegivenrise
clinical anxiety and depression coexist, the attentional bias is no todifferentproposalsastothedevelopmentalcourseoftheasso-
longerfound(e.g.,Mogg,Bradley,Williams,&Mathews,1993). ciationbetweenprocessingbiasesandanxiety.Forinstance,Kindt
Mogg,Bradley,andWilliams(1995)suggestedthattheattentional and colleagues (Kindt, Bierman, & Brosschot, 1997; Kindt,
bias in anxiety may reflect an individual’s readiness to orient Brosschot, & Everaerd, 1997) have suggested that both anxious
towardnegativestimuliinordertodealwithpotentialthreats,that and nonanxious young children show equal bias with respect to
is,amotivationalstate.Theyfurtherreasonedthatdepressionisan threat-relatedstimuli,andthatwhereasnonanxiouschildrenlearn
amotivationalstate,andthatdepressioncomorbiditymightthere- to inhibit this bias with increasing age, anxious children do not.
foreinhibitthemotivation-basedselectivitythatcharacterizesanx- Accordingtothisview,asignificantattentionalbiasisexpectedin
iety. Thus, assessing the potential effects of participants’ depres- both anxious and nonanxious young children (Kindt & van den
sion comorbidity may be of crucial importance for studies of Haut, 2001). Others (e.g., Martin, Horder, & Jones, 1992) have
threat-related bias in anxiety. In practice, however, many studies proposedthatthreat-relatedattentionalbiasesandanxietygohand
have failed to either report participants’ depression levels or to inhandfromveryearlyoninlife.Becauseoftherelativelysmall
covarythemoutfromtheattentionalbiaseffect. numberofstudiesandthelackoflongitudinalresearch,thepresent
meta-analysis only allowed us to compare the effect sizes of
studies with children versus adults on some of the studied mod-
State Versus Trait Anxiety
erators.
Threat-related attentional bias in anxiety has been investigated With the aforementioned considerations in mind, the purposes
mainly for trait anxiety and more seldom for state anxiety. Very ofthepresentmeta-analysiswereasfollows:First,wewantedto
fewstudieshavedirectlycomparedtheeffectsofstateversustrait assesstheoveralleffectsizeoftheattentionalbiasinanxietyinthe
anxiety on the attentional bias. Some of these have examined literature to date and to determine whether the bias is smaller,
which, of state or trait anxiety scores, were best correlated with absent,orawayfromthreatinnonanxiousparticipants.Second,we
attentional bias scores in clinically anxious individuals (e.g., wanted to provide a systematic evaluation of the effects of the
Mathews&MacLeod,1985;Mogg,Mathews,&Weinman,1989). majorvariablesalongwhichtheexistingstudiesonattentionalbias
Othershaveusednonclinicalparticipantsdifferinginlevelsoftrait in anxiety differ. With respect to procedural variables, we exam-
anxietyandeitherexperimentallyinducedstateanxiety(e.g.,Rich- ined whether subliminal stimuli exposure times result in smaller
ards, French, Johnson, Naparstek, & Williams, 1992) or took effect sizes than supraliminal stimuli exposure times, whether or
advantageofnaturallyoccurringstressfulevents(e.g.,MacLeod& not divergent results are found for the various paradigms, and
Rutherford,1992).Thesestudieshaveyieldedconflictingfindings whether naturalistic pictures produce a stronger bias than word
and have led to various proposals as to the relative roles of state stimuli.Withrespecttopopulation-relatedvariables,weexamined
and trait anxiety in the attentional bias. For instance, Broadbent whether clinically anxious participants display a larger bias than
andBroadbent(1988)suggestedthatthetwofactorsinteract,with high-anxious participants recruited from normative populations,
theeffectofstateanxietybeingsubstantiallylargerinindividuals whether or not the bias is characteristic of all anxiety disorders,
withhightraitanxietythaninindividualswithlowtraitanxiety.A andwhethereffectsizesforthreat-relatedbiasinanxiouschildren
somewhatdifferentproposalisthatwhereasstateanxietyandthe and adolescents are similar to those in anxious adults. The third
attentional bias are positively correlated in individuals with high purpose of the present study was to use the meta-analytic tool to
traitanxiety,theyarenegativelycorrelatedinindividualswithlow generatenewfindingsbyanalyzinginteractionsamongthediffer-
trait anxiety (Egloff & Hock, 2001). Others suggested that both entmoderators,whetherproceduralorpopulationrelated.
transientstress(irrespectiveoftraitanxiety)andenduringanxious
personalitycharacteristics(irrespectiveofstateanxiety)aresuffi- Method
cient to produce the attentional bias (Mogg, Mathews, Bird, &
Literature Base
Macgregor-Morris, 1990). Thus, how state and trait anxiety con-
tribute to threat-related attentional bias remains an unresolved Studies were collected through a search of the PsycInfo and PubMed
issue.Inthepresentmeta-analysiswecomparedtheeffectsizesof databases using the key words attention*, bias*, selective attention*,
Stroop, dot-probe, probe detection, Posner, spatial cueing, or visual
studiesusingstateversustraitanxietyasthegroupingvariableof
search, intersected with anxi* (anxiety), phob* (phobia), PTSD, OCD,
anxiety, but we did not examine the interaction between the two
panic,orGAD.Inaddition,thesedatabasesweresearchedwiththenames
factorsbecauseofalackofstudiesdirectlytacklingthisissue.
of researchers in the field to see whether there were additional relevant
publicationsfromtheseauthors.Thereferencesofalltheobtainedarticles
Children Versus Adult Participants aswellasofrelevantreviewarticles(e.g.,Dalgleish&Watts,1990;Mogg
&Bradley,1999b;Williamsetal.,1996)weresystematicallysearchedfor
Becauseanxietyishighlyprevalentinchildrenandadolescents additionalrelevantstudies.
(Albano, Chorpita, & Barlow, 2003), and because continuity of
Inclusion Criteria
trait anxiety from childhood to adulthood has been widely docu-
mented (e.g., Feehan, McGee, & Williams, 1993; Ferdinand & We used the following criteria to select studies for inclusion in the
Verhulst,1995;Pine,Cohen,Gurley,Brook,&Ma,1998),thereis meta-analysis:
6 BAR-HAIMETAL.
1. The study was published as a journal article in the English Coding System and Coding Decisions
languageuntilMay2005.
Weusedastandardcodingsystemtorateeverystudy(seeTable1).We
2. The study used one of the following experimental paradigms: coded sample size (N), whether the participants were children under 18
emotionalStroop,probedetection(ordot-probe)task,oraver- years of age or adults (age group), and whether the anxious group was
sionoftheemotionalspatialcuingtask.Therewereinsufficient clinicallydiagnosedorincludedparticipantswithhighself-reportedanxi-
visual search studies meeting the inclusion criteria as outlined ety (anxiety type). For clinical samples we noted the type of anxiety
latertoallowsystematicanalysis. disorder, and for self-reported anxiety, we noted the type of anxiety
measureused.Wecodedwhetherparticipantswithcomorbidmooddisor-
3. Thedifferencebetweenthreat-relatedandneutralstimulicould derwereincludedorexcludedfromeachsample(mooddisordercomor-
be assessed. Studies that compared threat-related stimuli with bidity).
stimuliotherthanneutral(e.g.,Mathews&MacLeod,1985,who Wecodedthetypeofparadigmused(i.e.,emotionalStroop,dotprobe,
contrasted reactions to negative stimuli with a combination of or emotional spatial cuing) and the type of stimuli presented in the
positive and neutral stimuli) were excluded from the meta- experiment (stimulus type; i.e., words or pictures). We also took into
analysis. Differences between threat-related stimuli and other accountwhetherthestimuliintheemotionalStroopparadigmwerepre-
emotionally valenced stimuli render the source of the bias un- sentedinablockeddesign(i.e.,stimulifromdifferentcategoriespresented
clear, because the observed behavior could stem from a bias withindifferentblocksoftrials)orrandomly(emotionalStroopdesign).
relatedtothethreatstimulusorfromabiasrelatedtotheother Finally,toassesstheeffectofstimulusexposuretime,wecodedwhether
emotionallyvalencedstimulus,orfromacombinationofboth.It thestimuliwerepresentedwithsubliminalorsupraliminalexposure.Be-
shouldbenotedthatthisselectioncriterionprecludesadistinc- cause several dot-probe studies were theoretically concerned with the
tionbetweentheeffectsofthreatinparticularversusemotionin effectsofvarioussupraliminalexposuretimes,wecreatedamoredetailed
general.Theinvestigationofthatdistinctioncallsforaseparate exposure time moderator variable for dot-probe studies (subliminal, 500
set of meta-analyses comparing neutral versus emotional non- ms,and1,000msorlonger).
threat stimuli, which is beyond the scope of the present study. Someadditionalcodingdecisionsweremade:
Similarly, studies comparing threat-related words to nonwords
(e.g., McNally, Riemann, Louro, Lukach, & Kim, 1992) were 1. Toenhancethepowerofmoderatoranalyses,instudiesinwhich
excluded because an observed bias in such studies might stem participantsweretestedonmorethanonelevelofamoderator
from a difference in semantic versus nonsemantic processing variable (e.g., participants were presented with both word and
ratherthanfromthevalenceofthethreatword. picturestimuli),weselectedthelevelthatincludedfeweroverall
samples for analysis. Specifically, we selected subliminal over
4. Thestudyincludedagroupofanxiousparticipantsselectedon supraliminal exposure times, state over trait anxiety, the dot-
thebasisofeitherclinicaldiagnosisorself-reportedhighanxiety probeparadigmovertheemotionalStroopparadigm,andpicture
on a questionnaire. Studies that formed anxiety groups based stimuli over word stimuli. In dot-probe studies not reporting
solely on experimental manipulations inducing anxiety in nor- subliminalexposuretimes,wepreferredlongerexposures(1,000
mative samples (e.g., Green, Rogers, & Elliman, 1995) were msorlonger)overexposuresof500ms.
excludedbecausetheanxiety-inducingproceduresdifferedcon-
siderably between studies and were typically not validated by 2. When data for the same participants were reported in two dif-
reliablemanipulationchecks. ferentstudies,onlyonestudywasselectedbasedonthecriteria
justmentioned.
5. Thestudyreporteddatathatallowedthecomputationofaneffect
size for at least one of the following outcome measures of 3. Ifasinglecontrolgroupwascomparedwithtwoormoreanxiety
attentionalbias:awithin-groupcomparisonforanxiouspartici- groupswithinthesamestudy,thenumberofcontrolparticipants
pants, a within-group comparison for control participants, or a inthereportedanalyseswassplitaccordinglytoavoidinflation
between-groups comparison. The within-group effects refer to ofthenumberofparticipants.
the bias measured as the difference between threat-related and
neutralconditionsreportedbystatisticssuchastorFvalues.The 4. Whenastudyassignedparticipantstomorethantwogroupsof
between-groupseffectreferstothebiasmeasuredasthediffer- anxietylevel(e.g.,low,medium,andhighanxiety),weselected
encebetweentheanxiousandcontrolgroupsontheaforemen- thetwoextremegroups.
tionedeffect,reportedwithbetween-groupsstatisticssuchastor
Fvalues,orsometimesasacorrelationbetweenthebiasscore 5. Whendifferentintensitylevelsofthreatstimuliwereusedinone
andtheanxietyscoreonaquestionnaire. study(e.g.,mildthreatandhighthreat),wecalculatedaneffect
sizethatreflectedtheaverageofthetwoconditions.Although
6. In cases in which an effect was reported as nonsignificant but differenttheoriespostulatedifferentassumptionsconcerningthe
exact statistics were not provided, we calculated an estimated effectofthreatlevelonthemagnitudeanddirectionofbiasin
effectsizeassumingp(cid:1).50,inordertoensurearepresentative anxiousandincontrolparticipants(foradiscussiononthistopic,
sampleofoutcomes(Cooper&Hedges,1994).Thisprocedure seeMogg,McNamara,etal.,2000;Wilson&MacLeod,2003),
was used only when enough information was provided (e.g., most studies have used only one level of threat, and levels of
tables,figures)todeterminethedirectionoftheeffect,anditwas threat are hardly comparable across studies. Thus, when mild-
usedin25.6%ofthebetween-groupsoutcomes,in17.9%ofthe andhigh-threatstimuliareusedinthesamestudy,itispractically
within-anxious-group outcomes, and in 40.2% of the within- impossibletodeterminewhichofthetwothreatlevelsismore
control-groupoutcomes. compatible with the “‘single”‘ level of threat stimuli used in
otherstudies.Forthesereasons,wechosetoaveragetheeffects
Thelistedcriteriaresultedintheselectionof172studies(including4,031 ofdifferentintensitiesofthreatinsteadofchoosingoneoverthe
participantsintotal),publishedbetweenFebruary1986andMay2005. other.
ATTENTIONALBIASINANXIETY:META-ANALYSIS 7
Table1
CodingSystemforIndividualStudies
Variable Codingdescription
Population
Nanxious Samplesizeforwhichawithin-anxious-groupeffectisreported
Ncontrol Samplesizeforwhichawithin-control-groupeffectisreported
Agegroup 0(cid:1)children(under18yearsofage)
1(cid:1)adults
Anxietytype 0(cid:1)clinicallydiagnoseddisorders
1(cid:1)highself-reportedanxiety
Typeofanxietydisorder 0(cid:1)generalizedanxietydisorder
1(cid:1)obsessive–compulsivedisorder
2(cid:1)panicdisorder
3(cid:1)post-traumaticstressdisorder
4(cid:1)socialphobia
5(cid:1)simplephobia
Typeofanxietymeasure 0(cid:1)traitanxiety(State-TraitAnxietyInventory)
(self-reportingsamples) 1(cid:1)stateanxiety(State-TraitAnxietyInventory)
2(cid:1)other
Moodcomorbidity 0(cid:1)participantswithcomorbidmooddisorderwereexcluded
1(cid:1)participantswithcomorbidmooddisorderwereincluded
Experimentalprocedure
Paradigm 0(cid:1)emotionalStroop
1(cid:1)dotprobe
2(cid:1)modifiedPosner
Exposuretime,general 0(cid:1)subliminal
1(cid:1)supraliminal
Exposuretime,dotprobe 0(cid:1)subliminal
1(cid:1)500ms
2(cid:1)(cid:1)1,000ms
Stimulustype 0(cid:1)words
1(cid:1)pictures
Stroopdesign 0(cid:1)blocked
1(cid:1)random
6. When more than one type of threat-related stimuli were pre- thewithin-groupanalyses,apositivesignoftheeffectsizevalueindicates
sented(e.g.,physicalthreatandsocialthreat)thetypeofthreat that attention is biased toward threat-related stimuli. For the between-
mostcongruenttothestudiedanxietygroupwasselected(e.g., groups analyses, a positive sign of d indicates that the attentional bias
forparticipantswithsocialphobia,weselectedthesocialthreat towardthreatislargerinanxiousparticipantsthanincontrolparticipants.
dataoverthephysicalthreatdata).Incasesinwhichtwothreat All analyses and computations were carried out using Comprehensive
categorieswereequallyrelevanttothestudiedgroupofpartici- Meta-Analysissoftware,Version2.002(Biostat,Englewood,NJ).
pants,wecalculatedaneffectsizethatreflectedtheaverageof Becausemostofourdatasetswereheterogeneousintheireffectsizes,
the two effects. For example, Brosschot, de Ruiter, and Kindt andbecauserandomeffectsmodelsaresomewhatmoreconservativethan
(1999) studied the threat-related bias in high- and low-trait- fixed effects parameters in such cases, combined effect sizes and their
anxious participants, who were presented with social threat confidenceintervals(CIs)arepresentedinthecontextofrandomeffects
words and physical threat words, both equally relevant to the models.Foradetaileddiscussionofthisissue,seeBakermans-Kranenburg,
general concept of trait anxiety. Thus, the average of the two
vanIJzendoorn,andJuffer(2003).
effectsizeswascomputedforfurtheranalyses.
Screeningtheentiredatasetforoutliersrevealedonestudy(Vasey,El
Hag,&Daleiden,1996)thatyieldedaneffectsizethatwaslargerthan3
7. When studies involved therapy or any kind of experimental
standarddeviationsfromthegroupmeansofeachofthemajoreffectsize
manipulation and measured selective attention to threat before
categoriesusedinthismeta-analysis(withinanxiousgroup,withincontrol
andafterthemanipulation,weincludedthedataemanatingfrom
group,andbetweengroups),andwasthusremovedfromfurtheranalyses.
thepretestmeasurement.
Oneadditionalstudy(Kyrios&Iob,1998)yieldedaneffectsizelargerthan
Intercoderreliabilityforthemoderatorvariableswasestablishedon15% 3standarddeviationsfromthemeaneffectsizeofthewithin-anxiety-group
of the articles included in the meta-analysis. Across the total variable data,andthisparticulareffectsizewasalsoexcludedfromfurtheranalyses.
matrix, kappas ranged from .69 to 1.00 (the mean kappa was .96). Dis- Therefore,thepresentmeta-analysiswasbasedon172samplesreportedin
agreementswereresolvedbydiscussion,andthefinalcodingreflectedthe 142journalarticles.These172studiesyielded323effects:112represent-
consensusbetweenthetwocoders. ingwithin-groupattentionalbiaseffectsinanxiousparticipants,87repre-
senting within-group attentional bias effects in control participants, and
Meta-Analytic Procedures 124 representing between-groups differences in attentional bias between
anxiousandcontrolgroups.Atabledescribingthe172studiesincludedin
Theeffectsizeindexweusedforalloutcomemeasuresinthepresent themeta-analysesmaybeobtainedfromusonrequest.
meta-analysisisCohen’sd,thatis,thedifferencebetweenthemeansof Theresultsareorganizedintothreemainsections.Inthefirstsection,we
twoconditionsorgroupsdividedbytheirpooledstandarddeviation.For focus on the effects of procedural variables, namely, stimulus exposure
8 BAR-HAIMETAL.
time, experimental paradigm, and stimulus type, and the interactions Does the Magnitude of Threat-Related Bias Vary as a
among them. In the second section, we describe effects of population- Function of Experimental Paradigm (Emotional Stroop,
relatedvariables,namely,clinicalversusnonclinicalanxiety,age,typeof
Dot Probe, Emotional Spatial Cuing)?
anxietydisorder,stateversustraitanxiety,andmooddisordercomorbidity,
andtheinteractionsamongthem.Inthethirdsection,wereportinteractions Anxious individuals displayed a significant threat-related bias
amongtheproceduralandpopulation-relatedmoderators. witheachofthetestedparadigms(k(cid:1)70,d(cid:1)0.49,CI(cid:1)0.43,
Foreachquestion,weassessedthemagnitudeofthecombinedwithin- 0.56,withemotionalStroop;k(cid:1)35,d(cid:1)0.37,CI(cid:1)0.28,0.46,
anxiety-group effect, the combined within-control-group effect, and the with dot probe; and k (cid:1) 7, d (cid:1) 0.43, CI (cid:1) 0.23, 0.64, with
differencebetweenthesetwoeffects.Inaddition,wecalculatedthemag-
emotionalspatialcuing).Controlparticipantsdidnotshowabias
nitude of the difference in threat-related bias between the anxious and
with any of the paradigms. In addition, the combined within-
controlgroupsusingtheeffectsizesofbetween-groupcomparisons.To-
subject effect sizes of anxious participants were significantly
gether,theseanalysesprovideacomprehensiveviewofthestateofaffairs
largerthanthoseofcontrolparticipantsforeachoftheparadigms.
regarding each of the pertinent questions. Table 2 provides combined
The between-groups comparisons revealed a similar pattern for
within-groupeffectsizes,CIs,pvalues,numberofstudies(k),andnumber
ofparticipants(n)thatwereincludedintheanalysesfortheanxietyand studiesusingtheemotionalStroop(k(cid:1)77,d(cid:1)0.45,CI(cid:1)0.36,
control groups. Table 3 provides the same data for the between-groups 0.54)andthoseusingthedot-probe(k(cid:1)44,d(cid:1)0.38,CI(cid:1)0.26,
analyses.Forbrevityreasons,onlytheessenceofthefindingsconcerning 0.50)paradigm.Bycontrast,thecombinedbetween-groupseffect
each of the focal questions is reported in the text. A full report of all sizeofstudiesusingtheemotionalspatialcuingparadigmwasnot
statisticsisprovidedinTables2and3. significant (k (cid:1) 4, d (cid:1) 0.009, CI (cid:1) –0.38, 0.40). It should be
noted,however,thatthelattercombinedeffectsizewasbasedon
four studies, two of which came from Broomfield and Turpin
Results
(2005),whoobtainednegativevalidityeffects(i.e.,fasterreaction
timesoninvalid-cuerelativetovalid-cuetrials).Inconclusion,the
Overall Effect of Threat-Related Bias dot-probeandemotional-Stroopparadigmswereequallyeffective
in uncovering the between-groups bias, and evidence from the
Across all the studies that reported within-group effects, the
emotionalspatialcuingparadigmwasequivocal.
combined effect size of the threat-related bias was significant in
anxiousparticipants(k(cid:1)112,n(cid:1)2,263,d(cid:1)0.45,p(cid:2).01,CI(cid:1)
Is the Threat-Related Bias Larger in Emotional Stroop
0.40, 0.49), and nonsignificant in nonanxious controls (k (cid:1) 87,
Studies Using Blocked Versus Random Designs?
n(cid:1)1,768,d(cid:1)–0.007,p(cid:1).85,CI(cid:1)–0.06,0.05).Thedifference
between the combined effect sizes of anxious and control partic- Although both blocked- and random-design emotional Stroop
ipantswassignificant(Q(cid:1)87.56,p(cid:2).01).Meta-analysisofthe studiesyieldedsignificanteffectsofthreat-relatedbiasinanxious
studiesthatreportedbetween-groupscomparisons(k(cid:1)125,n(cid:1) participants,blockedpresentationsproducedasignificantlylarger
2,963andn(cid:1)2,906foranxiousandcontrolparticipants,respec- combinedeffectsize(k(cid:1)31,d(cid:1)0.69,CI(cid:1)0.60,0.78)thandid
tively) indicated an overall difference between the two groups randomizedpresentations(k(cid:1)30,d(cid:1)0.35,CI(cid:1)0.26,0.44).Of
(d(cid:1)0.41,p(cid:2).01,CI(cid:1)0.34,0.48)thatwascomparabletothe interest, a small but significant combined effect size was also
within-group effect for anxious participants. Thus, a significant found for control participants in studies using a blocked design
threat-related bias was present in anxious participants but not in (k (cid:1) 18, d (cid:1) 0.21, CI (cid:1) 0.10, 0.31). Notwithstanding, the
nonanxiousparticipants. difference between anxious and nonanxious participants was sig-
nificantforbothpresentationmodes,asreflectedbythecontrasts
betweenthewithin-groupcombinedeffectsofanxiousandcontrol
Procedural Moderators
participantsandbythebetween-groupsanalyses.
Is Threat-Related Bias Stronger With Supraliminal
Do Threat-Related Picture Stimuli Yield Larger Bias
Exposure Times Than With Subliminal Exposure Times?
Than Word Stimuli?
The combined effect sizes of threat-related bias in anxious
Therewasnodifferencebetweenthecombinedeffectsizeswith
participants were significant both for studies using subliminal
wordstimuliandpicturestimuli.Bothtypesofstimuliproduceda
exposuretimes(k(cid:1)20,d(cid:1)0.32,CI(cid:1)0.20,0.44)andforstudies significantthreat-relatedbiasinanxiousparticipants(k(cid:1)88,d(cid:1)
usingsupraliminalexposuretimes(k(cid:1)90,d(cid:1)0.48,CI(cid:1)0.42, 0.46, CI (cid:1) 0.40, 0.52, for words; k (cid:1) 24, d (cid:1) 0.43, CI (cid:1) 0.32,
0.54). Although the combined effect size was slightly larger for
0.54,forpictures)andnosignificantbiasinnonanxiouscontrols.
supraliminal than subliminal exposures, this difference was not There was a significant difference between anxious and control
significant.Controlparticipantsshowednobiaswitheitherexpo- participantswithbothwordstimuliandpicturestimuli.
suretime,andthecombinedeffectsforanxiousparticipantswere
significantly larger than those for control participants with both Experimental Paradigm (cid:3) Exposure Times
exposure times. Consistent with this finding, the between-groups
datarevealedasignificantdifferencebetweenanxiousandcontrol Doesthemagnitudeofthreat-relatedbiasdifferasafunctionof
participants for both exposure times (ks (cid:1) 27 and 98, ds (cid:1) 0.37 exposure times in dot-probe experiments? In dot-probe experi-
and0.42,CIs(cid:1)0.22,0.52,and0.34,0.50,forsubliminalandfor ments,anxiousparticipantsshowedasignificantthreat-relatedbias
supraliminalexposures,respectively). with all exposure times (k (cid:1) 5, d (cid:1) 0.65, CI (cid:1) 0.42, 0.88, for
ATTENTIONALBIASINANXIETY:META-ANALYSIS 9
subliminal exposures; k (cid:1) 18, d (cid:1) 0.31, CI (cid:1) 0.20, 0.43, for Anxious participants showed a significant combined effect size
500-ms exposures; and k (cid:1) 7, d (cid:1) 0.29, CI (cid:1) 0.11, 0.47, for withwords(k(cid:1)66,d(cid:1)0.51,CI(cid:1)0.44,0.58)andanonsignif-
exposures (cid:1) 1,000 ms), with no difference among the three icant combined effect size with pictures (k (cid:1) 4, d (cid:1) 0.24, CI (cid:1)
exposureconditions.However,subliminalexposures(k(cid:1)5,d(cid:1) –0.02, 0.50). However, the difference between the two types of
0.65, CI (cid:1) 0.42, 0.88) yielded a significantly larger effect than stimuliwasnonsignificant.Incontrolparticipants,thebiaswasnot
supraliminalexposures(500msandover,k(cid:1)25,d(cid:1)0.31,CI(cid:1) significantwithwords,andnotenoughemotionalStroopsamples
0.21, 0.40, Q (cid:1) 4.12, p (cid:2) .05). Nonanxious control participants usedpictures(k(cid:1)3).
didnotshowsignificanteffectswithsupraliminalexposures(500 The between-groups analyses revealed significant differences
ms and (cid:1) 1,000 ms) but did show a significant bias away from between anxious and control participants in emotional Stroop
threatwithsubliminalexposures(k(cid:1)4,d(cid:1)–0.28,CI(cid:1)–0.47, studiesthatusedwords(k(cid:1)71,d(cid:1)0.48,CI(cid:1)0.41,0.55)and
–0.09). In addition, the differences between anxious and control anonsignificantcombinedeffectsizeintheoppositedirectionfor
participantsweresignificantforsubliminaland500-msexposures studiesthatusedpictures(k(cid:1)5,d(cid:1)–0.25,CI(cid:1)–0.52,0.01).
but failed to reach significance with longer exposures ((cid:1) 1,000 Words produced significantly larger interference effect than did
ms). pictures(Q(cid:1)14.44,p(cid:2).01).
Does the magnitude of threat-related bias differ between sub- Dothreat-relatedpicturesyieldlargerbiaseffectsthanthreat-
liminal and supraliminal exposure times in emotional Stroop ex- related words within studies using the dot-probe paradigm?
periments? Subliminal and supraliminal stimulus exposures re- Threat-related bias in anxious participants was significant both
vealedsignificantcombinedeffectsizesinanxiousindividualsand withwords(k(cid:1)20,d(cid:1)0.35,CI(cid:1)0.25,0.46)andwithpictures
nonsignificantcombinedeffectsizesincontrols.Here,thethreat- (k(cid:1)15,d(cid:1)0.38,CI(cid:1)0.26,0.50),withnosignificantdifference
related bias in anxious participants was significantly larger with between the two. Of importance, nonanxious control participants
supraliminalexposures(k(cid:1)55,d(cid:1)0.57,CI(cid:1)0.50,0.64)than displayedasignificantbiasawayfromthreatinexperimentsusing
withsubliminalexposures(k(cid:1)15,d(cid:1)0.23,CI(cid:1)–0.10,0.35). words(k(cid:1)17,d(cid:1)–0.14,CI(cid:1)–0.23,–0.05),andnobiaswith
ComparisonbetweentheemotionalStroop,dot-probe,andemo- pictures.
tional spatial cuing paradigms with subliminal and supraliminal
exposuretimes. Noemotionalspatialcuingstudyusedsublimi-
nal exposures. Contrasting combined effect sizes between emo-
Population-Related Moderators
tionalStroopstudiesanddot-probestudieswithsubliminalexpo-
suresinanxiousparticipantsrevealedalargercombinedeffectsize
Is Threat-Related Bias Stronger in Clinically Anxious
fordot-probestudies(Q(cid:1)7.20,p(cid:2).01).Thesamecomparison
Participants Than in Participants With High Self-
withsupraliminalstimulusexposuresrevealedalargereffectsize
Reported Anxiety?
foremotionalStroopstudiesthanfordot-probestudies(Q(cid:1)8.85,
p(cid:2).01).Contrastsinvolvingtheemotionalspatialcuingparadigm
Threat-relatedbiaswassignificantinclinicallydiagnosedpop-
werenonsignificant. ulations (k (cid:1) 62, d (cid:1) 0.45, CI (cid:1) 0.38, 0.51) as well as in
populations with high self-reported anxiety (k (cid:1) 50, d (cid:1) 0.46,
Stimulus Type (cid:3) Exposure Times CI(cid:1)0.38,0.54).Thecombinedeffectsizesofthetwopopulations
didnotdiffer.
Do threat-related pictures yield larger effects than threat-
related words with supraliminal exposures? With supraliminal
exposures, both words (k (cid:1) 72, d (cid:1) 0.51, CI (cid:1) 0.44, 0.57) and Does the Magnitude of Threat-Related Bias Differ as a
pictures(k(cid:1)20,d(cid:1)0.38,CI(cid:1)0.26,0.50)producedsignificant Function of Anxiety Disorder?
biaseffectsinanxious,butnotincontrolparticipants.Therewas
Wecomparedthecombinedeffectsizesofgroupsofstudiesthat
nodifferenceineffectsizesbetweenthetwotypesofstimuli.
focusedonspecificanxietydisordersusingthreatstimulithatwere
Do threat-related pictures yield larger effects than threat-
congruent with the concerns of the specific disorder studied. In-
related words with subliminal exposures? The findings with
cluded were studies of GAD (k (cid:1) 11), OCD (k (cid:1) 6), panic
subliminalstimulusexposureswereinconclusive.Analyseswithin
disorder(k(cid:1)7),PTSD(k(cid:1)22),socialphobia(k(cid:1)8),andsimple
the anxious group showed that subliminally presented pictures
produced a significantly larger combined effect size (k (cid:1) 4, d (cid:1) phobia (k (cid:1) 5). Tables 2 and 3 provide the detailed statistics of
0.65,CI(cid:1)0.42,0.89)thandidsubliminallypresentedwords(k(cid:1) thesecomparisons.Theresultsindicatethatthreat-relatedbiaswas
16,d(cid:1)0.24,CI(cid:1)0.15,0.34).Surprisingly,thecombinedeffect significant for all the clinical disorders tested, with effect sizes
rangingfrom0.36to0.59.Thecombinedeffectsizesdidnotdiffer
sizeofthebetween-groupscomparisonswassignificantforwords
(k(cid:1)21,d(cid:1)0.42,CI(cid:1)0.24,0.61),butnotforpictures(k(cid:1)6, amongthevariousdisorders.
d(cid:1)0.19,CI(cid:1)–0.17,0.54).Unfortunately,therewerenotenough
samples with subliminally presented pictures for control partici- Does Comorbidity Between Anxiety and Mood Disorders
pants(k(cid:1)3)toallowacompleteanalysisofthismatter. Affect the Magnitude of Threat-Related Bias in Clinically
Anxious Populations?
Experimental Paradigm (cid:3) Stimulus Type
The combined effect sizes of bias were significant both for
Dothreat-relatedpicturesyieldlargerbiaseffectsthanthreat- studies that excluded participants with comorbid mood disorders
related words in studies using the emotional Stroop paradigm? (k (cid:1) 17, d (cid:1) 0.43, CI (cid:1) 0.33, 0.53) and for studies that did not
10 BAR-HAIMETAL.
ol 01 0101 0101 0101 0101 0101 01 01011 01 0101 0101 0101
ntr p 00 0000 000001 0000 0000 0000100500 000000— 00—0000 0000 0000
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atedBiasesforAn Withinanxious d85%CI ****0.40,5 ****80.42,0.54****20.20,0.44 ****90.43,0.56****70.28,0.46**30.23,0.64 ****90.60,0.78****50.26,0.44 ****60.40,0.52****30.32,0.54 ****50.42,0.88****10.20,0.43*90.11,0.47**30.10,0.35****70.50,0.64 ****10.44,0.57****80.26,0.50****40.15,0.34****50.42,0.89 ****10.44,0.58(cid:4)40.02,0.50****50.25,0.46****80.26,0.50 ****50.38,0.51****60.38,0.54 ****60.37,0.66***50.25,0.65****00.34,0.66****60.27,0.46****90.43,0.74**60.43,0.74 ****30.33,0.53****70.38,0.56 ****50.42,0.88****80.28,0.48
Rel 0.4 0.40.3 0.40.30.4 0.60.3 0.40.4 0.60.30.20.20.5 0.50.30.20.6 0.50.20.30.3 0.40.4 0.50.40.50.30.50.3 0.40.4 0.60.3
at-
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hr 26
T N 2. 76 797 58 85 39134 3451 2581 67 260208 93 27
oup 1,8342 1,466513 6458 1,7946 93314331,13 1,4340366 1,3793827 1,3293 20717502012 3743 951
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Table2Meta-AnalyticResultsof Moderator Totaldataset StimulusexposuretimeSupraliminalSubliminalParadigmStroopDotprobePosnerStroopdesignBlockedRandomStimulustypeWordsPictures(cid:3)ParadigmExposureDotprobe—subliminalDotprobe—500ms(cid:2)Dotprobe—1,000msStroop—subliminalStroop—supraliminal(cid:3)StimulusTypeExposureSupraliminal—wordsSupraliminal—picturesSubliminal—wordsSubliminal—pictures(cid:3)StimulusTypeParadigmStroop—wordsStroop—picturesDotprobe—wordsDotprobe—pictures AnxietytypeClinicalanxietyHighself-reportedanxietTypeofanxietydisorderGADOCDPanicdisorderPTSDSocialphobiaSimplephobiaComorbidmooddisordersExcludedIncludedStatevs.traitanxietyStateTrait