BRADLEY and PETER J LANG University of Florida Gainesville USA Abstract Affective reactions to briefly presented pictures were investigated to determine whether fleeting stimuli engage the motivational systems mediating emotional responses Emotional ID: 39910
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Affectivereactionstobrieflypresentedpictures MAURIZIOCODISPOTI,MARGARETM.BRADLEY,PETERJ.LANGUniversityofFlorida,Gainesville,USAAffectivereactionstobrieflypresentedpictureswereinvestigatedtodeterminewhetherfleetingstimuliengagethemotivationalsystemsmediatingemotionalresponses.Emotionalandneutralpictureswerepresentedfor500ms;heartrate,skinconductance,corrugatorEMG,andtheevokedstartlereflexweremeasured.Thetimecourseofreflexmodulationwassimilartothatobtainedwithlongerpresentations,suggestingthatpictureprocessingcontinuesintheabsenceofasensorystimulus.Affectivereactionsfoundwithmoresustainedpresentationwerealsoobtained,withmorecorrugatorEMGactivityforunpleasantpictures,andgreaterskinconductancereactivityforemotionalpictures.Heartratemodulation,however,appearstorelyonthepresenceofasensorystimulus.Thedataalsosuggestthatbriefpresentationsofunpleasantpicturesmayresultinlessdefensiveactivationthansustainedpresentation.Emotion,Attention,Startle,Reflexmodulation,Prepulseinhibition,AffectViewingaffectivepictureselicitsanumberofphysiologicalreac-tionsincardiovascular,electrodermal,andsomaticsystems.Forinstance,skinconductanceresponsesarelargerwhenviewingemotionallyarousingpleasantorunpleasantpictures,comparedtoneutralpictures,whereascorrugatorEMGactivityandheartratevarywithaffectivevalence,withlargercorrugatorEMGresponsesandmoredeceleratoryheartrateresponseselicitedwhenviewingunpleasant,comparedtopleasant,pictures;thestartlereflexisalsomodulatedbytheaffectivecontentofpicturesseeBradley&Lang,2000a,foranoverview.Itisclearthataffectivepicturesareeffectivecuesinactivatingemotionalresponse.Theseaffectiveresponsepatternshavebeenobtainedwhenparticipantsviewpicturesforasustainedtimeperiode.g.,6sHere,weinvestigatedwhetherbriefpresentationsarealsoabletoengagethedefensiveandappetitivemotivationalsystemsthatmediateemotionalrespondingLang,Bradley,&Cuthbert,1997Pictureswerepresentedfor500msandskinconductance,heartrate,andcorrugatorEMGresponsesweremeasuredfor6sfol-lowingpictureonset.Predictionsareclear:Ifbriefpresentationsdonotactivatemotivationalsystems,themodulatorypatternsprevi-ouslyobtainedwillbeabsent.Ifbriefpresentationsaresufficient,theidenticalmodulatorypatternswillappear.Aparticularfocusisthepatternofreflexmodulationfollowingbriefpicturepresentations,giventhataffectivemodulationofthestartlereflexisusuallyobservedduringactiveviewingandseveralsecondsafterpictureonsetseeBradley,Cuthbert,&Lang,1999,forareview.Whenacousticstartleprobesarepresentedatdif-ferentonsetdelayswithina6-spicturepresentation,theblinkreflexremainsinhibitedforupto3safterpictureonset,andthemagnitudeanddurationofblinkinhibitionisgreaterforemotionalpleasantorunpleasantthanforneutralpicturesBradley,Cuth-bert,&Lang,1993.Wehaveinterpretedtheseunusuallyextendedªprepulseinhibitioneffectsºasreflectingdifferencesinpictureencoding,withaffectivelyengagingpicturesevidencingªnaturalselectiveattentionºÐdrawingmoreresourcesduringencoding,andforalongerdurationoftime,thanneutralpicturesBradley&Lang,2001ThecurrentstudyutilizedthedesignofBradleyetal.,inwhichstartleprobesarepresentedatdifferentdelaysfollowingpictureonset.Ifearlyblinkinhibitionreflectsdifferencesinpictureencoding,weexpectedtofindsimilareffectsfollowingbriefpre-sentation,eventhoughacognitive,ratherthanasensory,repre-sentationservesasthestimulus.Thisisconsistentwithpriorresearchshowingthatencodingprocessescontinueunimpededwhenavisualstimulusisremoved,ifasecond,maskingstimulusisnotpresentedMassaro,1973.Alternatively,ifinhibitoryef-fectsontheblinkreflexearlyintheviewingintervalreflectoperationsspecificallyassociatedwithextractinginformationfromasensoryarray,theseinhibitoryeffectsshouldbeabsent,asthepictureisperceptuallyunavailableafter500ms.Whenviewingalongpicturepresentation,blinksarepotentiatedforunpleasant,comparedtopleasant,picturesbegin-ningaround500msafterpictureonsetBradley&Lang,2001andslightlyearlierifanaffect-relatedtaskisimposedVanman,Boehmelt,Dawson,&Schell,1996.Earlyaffectivemodulation ThisworkwassupportedinpartbyNationalInstituteofMentalHealthgrantsMH37757andMH43975andP50-MH52384,anNIMHBehavioralSciencegranttotheCenterfortheStudyofEmotionand,UniversityofFlorida,Gainesville,FL.Thesedatawerepresentedinpartasaposteratthe36thconventionoftheSocietyforPsychophysiologicalResearchinVancouver,Canada.dispoti,Bradley,&Lang,1996Addressreprintsrequeststo:MargaretM.Bradley,Box100165HSC,Gainesville,FL32610-0165,USA.Psychophysiology,38,474±478.CambridgeUniversityPress.PrintedintheUSA.Copyright2001SocietyforPsychophysiologicalResearch hasalsobeeninvestigatedbyGlobisch,Hamm,Stevens,&•hmanusingphobicsubjectsandbrief150mspicturesofsnakesorspiders.Subjectsreportinghighfearshowedsignificantstartlepotentiationat300mswhenviewingfearful,comparedtoneutral,pictures,whereaslow-fearsubjectsdidnot.Globischetal.con-cludethatfearresponsesareactivatedrapidly,withminimalstim-ulusinput.Here,westudiedstartlemodulationinnormalsubjectsafterviewingbriefpresentationsofawiderangeofbothpleasantandunpleasantpictures,assessingthepersistenceofreactionstocognitiveaffectiverepresentationsascomparedtoresponsepat-ternsevokedinpreviousresearchbyasustainedsensorystimulus.23femaleUniversityofFloridaintroductorypsychol-ogystudentsparticipatedaspartofaclassrequirement.Becauseofequipmentfailuresandorerrors,dataweremissingforoneormoredependentmeasuresforoneormoreparticipants.Finalsamplesizesineachanalysiswere:skinconductancelevel,corrugatorEMG,45;heartrate,49;startlereflexes,MaterialsandDesignThematerialsanddesignwereidenticaltothatdescribedinBrad-leyetal..Fifty-fourpictures18pleasant,18neutral,and18unpleasantwereselectedfromtheInternationalAffectivePic-tureSystemCenterfortheStudyofEmotionandAttention,.Elevenadditionalpicturesthatalsovariedinpleasantnessservedasfillerstimulionnonprobedtrialsonepresentedineveryblockofsixpictures.Theacousticstartlestimulusconsistedofa50-mspresentationofa103-dBwhitenoisewithinstantaneousrisetime,presentedbinaurallyoverheadphones.Eachpicturewaspresentedfor500ms,andstartleprobeswerepresentedeither300,800,1,300,1,800,2,800,or4,800msafterpictureonset.Thepictureswerearrangedinnineblocksofsix,suchthateachofthesixprobeconditionsoccurredonceineachblock,andpicturesofeachofthethreetypesofvalenceoccurredineachblock.Twopresentationordersvariedtheserialpositionofspecificpicturesacrosssubjects,andsixdifferenttimingorderscounter-balancedprobe-timingconditionforspecificpictures.TheslideswerepresentedusingaKodakEktagraphicIIIprojectorsituatedadjacenttotheexperimentalroom.Afterall54trialswerecompleted,ayes±norecognitiontestwasconductedtodeterminewhetherparticipantswereabletoidentifythepreviouslyseen,brieflypresentedpicturesaccurately.Inthisrecognitiontest,72pictures24pleasant,24neutral,24werepresentedfor500mseach:12picturesofeachtypeofvalencehadbeenseenearlierintheexperiment;12picturesofeachvalencewerenewstimulithathadnotbeenpresentedintheexperiment.ThesubjectwasinstructedtopressoneoftwobuttonsontheleftorrighthandcounterbalancedacrosssubjectsindicatingwhetherthepicturehadbeenseenearlierornotPhysiologicalRecordingandDataReductionTheeyeblinkcomponentofthestartleresponsewasmonitoredbymeasuringEMGactivityovertheorbicularisoculimusclebeneaththelefteye.TherawEMGsignalwasamplified,andfrequenciesbelow90Hzandabove250HzwerefilteredusingaCoulbournS75-01bioamplifier.TherawsignalwasrectifiedandintegratedusingaCoulbournS76-01contourfollowingintegrator,withanactualtimeconstantof123ms.BlinkEMGactivitywassampledat1000Hzfor50mspriortotheonsetofthestartleprobe,andfor250msfollowingprobeonset.Thestartledatawerereducedoff-lineusinganinteractiveMacIntoshprogramthatscoredeachtrialformagnitudeinanalogtodigitalunitsandonsetlatencyinmilliseconds,usinganalgorithmdevelopedbyGlobisch,Hamm,Schneider,andVaitlTheelectrocardiogramwasamplifiedwithaCoulbournS75-01bioamplifier,andheartratewasrecordedwithaSchmitttriggerthatinterruptedthecomputertomeasureeachR-Rintervaltothenearest1ms.Interbeatintervalswerereducedoff-linetoheartrateinbeatsperminuteinhalf-secondbins.Skinconductanceactivitywasmeasuredfromelectrodesplacedadjacentlyonthelefthypothenareminence,usingSensormedicsstandardelectrodesfilledwith0.05MNaClUnibasepaste.ThesignalwasrecordedonaCoulbournS71-22skinconductanceamplifiercalibratedtorecordarangeof0±40CorrugatorEMGactivitywasmeasuredusingSensormedicsminiatureelectrodesplacedabovethelefteye,usingtheplacementrecommendedbyFridlundandCacioppo.TherawEMGsignalwasamplified,andfrequenciesbelow90Hzandabove1000HzwerefilteredusingaCoulbournS75-01bioamplifier.Therawsignalwasamplifiedby30,000andthenrectifiedandinte-gratedusingaCoulbournS76-01contourfollowingintegrator,withatimeconstantof500ms.Afterfillingoutaconsentform,thesensorswereattached,andthesubjectwasinstructedthataseriesofslideswouldbepresentedforaverybriefperiod.Afixationpointwasprovidedinthecenterofthescreen,andthesubjectwasinstructedtocomfortablymaintainfixationonthispointthroughoutthestudy.Theyweretoldthatoccasionalnoisesheardovertheheadphonescouldbeignored.Afterallpictureswerepresented,the72-picturerecognitiontaskwaspresented.Datareductionandanalysis.Analysesofvariancewerecon-ductedonstartleblinkmagnitude,theaveragechangescoreviatedfroma1-sprepicturebaselineovera6-speriodafterpictureonsetforheartrateandcorrugatorEMGactivity,andthemaximumchangescoredeviatedfroma1-sprepicturebaselinebetween1and4spost-onsetforskinconductance.Significanteffectswereevaluatedat.05,andGreenhouse-Geissercor-rectionswereusedwhereappropriate.StartleReflexFigure1illustratesblinkmagnitudeatdifferentprobedelaysfol-lowingbriefpresentationsofpleasant,neutral,andunpleasant TheInternationalAffectivePictureSystemLang,Bradley,&Cuth-bert,1999isavailableonCD-ROMandasphotographicslides.ThesestimulussetsandtechnicalmanualcanbeobtainedonrequestfromMar-garetM.BradleyorPeterJ.Lang,attheNIMHCenterfortheStudyofEmotionandAttention,Box100165HSC,UniversityofFlorida,Gaines-ville,FL32610-0165,USA.TheInternationalAffectivePictureSystemidentificationnumbersforunpleasantpicturesare1070,1090,1120,1300,2120,3000,3010,3100,3130,3150,3530,6020,6190,6200,6230,6370,9040,9490;forneutralpictures:2190,2200,5500,7000,7010,7020,7050,7080,7090,7100,7130,7150,7160,7170,7180,7500,7550,7700;forpleasantpictures:1600,2080,2250,4650,4660,4680,7200,7330,7350,8030,8080,8200,8510;4180,4210,4250,4290,and4310formales;4470,4490,4500,4520,and4550forfemales.Affectivereactions pictures.Probedelaygreatlyaffectedblinkmagnitude,5,22017.03.FollowingBradleyandLang,pairwisecomparisonswereconductedonblinkselicitedateachprobedelay,aswellasonblinksateachprobedelayandthoseelicitedduringtheintertrialComparedtoblinkselicitedatthelatestprobetime4,800ms,blinkselicitedat300,800,1,300,and1,800msafterpictureonsetweresignificantlyinhibited,1,4447.4,11.8,7.2,5.2,respectively,whereasthoseelicitedat2,800msafterpictureonsetwerenotsignificantlydifferentfromthoseatthelatestprobetime,1,441.Thesedatasuggestthatblinkswererelativelyinhibiteduntil2,800msafteronset.Thisconclu-sionwassupportedbytheITIcomparisons:Blinkselicitedfrom300to1,800msafterpictureonsetweresignificantlyinhibited,comparedtothoseelicitedduringITI,mean1,4442.7,25,7,17.8,9.4,for300,800,1,300,and1,800msprobes,respectively,whereasthoseelicitedat2,800and4,800msafterpictureonsetdidnotdifferfromITIblinks.Thedurationofinhibition,definedasthepointatwhichblinksnolongersignificantlydifferedfromthoseelicitedatalllatertimeseeBradley&Lang,2001waslongerwhenviewing2,800msorunpleasant2,800ms,comparedtoneutral1,300ms,pictures.ThesamepatternwasfoundwhencomparedtoITIblinks,inwhichblinksceasedbeingdifferentfromITIblinksat4,800msforpleasant,2,800msforunpleasantpictures,andat1,800msforneutralstimuli.Replicatingstudiesusinglongerpicturepresentations,thepleas-antnessofthepictureaffectedblinkmagnitude,2,88Largerstartlereflexeswereelicitedwhenprocessingunpleasant,comparedtopleasantpictures,1,4412.55,andinhibitedwhenviewingpleasant,comparedtoneutral,pictures,1,4413.86.Theseeffectsofpicturepleasantnessdidnotdependuponprobeposition,interaction1,andweresignificantevenattheearliestprobetime300ms,valence2,884.38;unpleasantversuspleasant,1,446.74;pleasantversusneutral,1,446.61.Comparedtoneutralpictures,however,blinkswerenotfacilitatedwhenviewingunpleasantstimuliatanyprobedelay.SkinConductanceReplicatingeffectsobtainedusingalongerviewinginterval,pic-turecontentaffectedskinconductancemagnitude,2,100seeFigure1,bottomleft.Largerincreasesinskinconduc-tancewereelicitedwhensubjectsprocessedemotionalpictureseitherpleasantorunpleasantcomparedtoneutralpictures,1,5036.85forunpleasantpicturesand1,5018.76forpleasantpictures.Nodifferenceswerefoundinskinconductancemagnitudewhenprocessingpleasant,comparedtounpleasant,CorrugatorEMGCorrugatorEMGchangesvariedwithpicturepleasantness,2,889.41,withlargerchangesoccurringwhenprocessingunpleasantpicturesmeanchange,com-paredtoeitherpleasantmeanchange1,44orneutralmaterialsmeanchange1,50.CorrugatorEMGactivitywasalsosignificantlylowerwhenprocessingpleasant,comparedtoneutral,1,50HeartRateHeartrateresponseasafunctionofpicturevalencediffereddra-maticallyfromthattypicallyobtainedduringa6-spicturepresen-seeFigure1,bottomright.Specifically,althoughaclassictriphasicwaveformGatchel&Lang,1973wasobtained,con-sistingofaninitialdeceleration,subsequentacceleration,andasecondarydecelerationtime,11,52822.72;cubictrend1,4825.23,averageheartratechangedidnotsignificantlyvarywiththeaffectivecontentofthepicture.RecognitionTaskPostexperimentalrecognitionaccuracywasquitehighforbothpreviouslypresentedandnewpictures,indicatingthatparticipantswereclearlyabletoencodeandlaterrecognizepicturespresentedforthebrief500msdurationusedinthecurrentstudy.Inmostways,affectivereactionsweresimilarforbrieflypresented500mspicturesasfoundpreviouslyusinglonger Unpleasantpicturesweredividedintoasubsetofhighandlowarousalmaterialstodeterminewhether,comparedtoneutralpictures,potentiationoccursforhighlyarousingunpleasantstimuli.Blinksfollowingbriefpre-sentation,however,werenotsignificantlypotentiatedevenwhenviewinghighlyarousingunpleasantpictures,unlikepreviousstudiesusingmoresustainedpicturepresentatione.g.,Bradley&Lang,2001 Figure1.Toppanel:Startleblinkmagnitudeforprobesdeliveredatdifferentdelaysaftera500-mspresentationofpleasant,neutral,orun-pleasantpictures.Bottomleftpanel:Skinconductancechangefor6sfollowingtheonsetofa500-mspicturepresentationforpleasant,neutral,andunpleasantpictures.Bottomrightpanel:Heartratechangefor6sfollowingtheonsetofa500-mspicturepresentationforpleasant,neutral,andunpleasantpictures.M.Codispoti,M.M.Bradley,andP.J.Lang tationintervals.Skinconductancechangesweresignificantlylargerforemotionallyarousingpleasantorunpleasantpictures,com-paredtoneutralpictures,andcorrugatorEMGactivitywasgreaterfollowingpresentationofunpleasant,comparedtopleasant,pic-e.g.,Lang,Bradley,Cuthbert,Hamm,1993.Thesedataareconsistentwiththeideathatabrieflypresentedpicture,intheabsenceofamaskingstimulus,effectivelyactivatesemotionalresponses.Ontheotherhand,heartratefollowingabriefpicturepresentationdifferedsubstantiallyfromamoresustainedpresen-tation:initialdecelerationwasminimal,andpicturevalencehadnodiscernibleeffect.Thesedatasuggestthatinitialheartratedecel-erationisassociatedspecificallywithsensorydetection1992;LaceyandLacey,1970,andthatheartrateisparticularlysensitivetotaskparameters,asnotedpreviouslyLang,Bradley,&Cuthbert,1990;Langetal.,1997ThedevelopmentofstartlemodulationwasalsosimilartothatfoundformoresustainedpresentationsBradleyetal.,1993Blinksweregenerallyinhibitedforupto3safterpictureonsetcomparedtoblinkselicitedintheITI,andthedurationoftheinhibitoryperiodwaslongerforemotional,comparedtoneutral,pictures.Findingbothoftheseeffectsfollowingbriefpicturepresentationsuggeststhatthestartlereflexcantapprocessesre-latedtopictureencoding,anddonotrelyonthepresenceofasensorystimulus.BradleyandLanginterprettherelativelylengthyªprepulseinhibitionºperiodduringpictureviewingasindicatingthatcomplexpicturestimuliinvolveamoreextendedencodingperiodthansimplerprepulsestimulie.g.,tonesorlightsinwhichinhibitionisusuallycompletebyaboutasecondafterstimulusonsetAnthony,1985.And,consistentwiththeideathatmotivationalactivationpromptsatypeofªnaturalselectiveatten-tion,ºaffectivepicturesdrawmoreheavilyonattentionalresourcesatencodingthandoneutralpictures.Supportingbothoftheseinterpretations,werecentlyfounddifferentialERPactivityasafunctionofstimuluscomplexity,withactivityrapidlyreturningtowithinabout1swhenviewingblankslides,whereaspictureviewingelicitedsustainedpositivitythatwasaccentuatedforemotional,comparedtoneutral,stimuliCodispoti,Bradley,Cuthbert,Montebarocci,&Lang,1998Blinkswerealsolargerwhenviewingunpleasant,comparedtopleasant,pictures.Nonetheless,affectivemodulationdifferedininterestingwaysfromthatobtainedwithlongerpicturepresenta-tions.Forinstance,anumberofdifferentstudieshavefoundgreaterblinkinhibitionearlyintheviewingintervalforemotional,comparedtoneutral,picturesBradleyetal.,1993;Bradley&Lang,2001,Experiment3;Levenston,Patrick,Bradley,&Lang,.Withbriefpresentation,however,blinkswerelargerforunpleasant,comparedtopleasant,pictures,evenattheearliestprobedelay.BradleyandLangnotethatspecifictaskparametersÐsuchaspresentationdurationÐmayaffectthetimecourseofaffectivemodulation.Here,itsuggeststhatbriefpresen-tationmayaccelerateaffectiveprocessing;alternatively,atten-tionalresponses,forexample,associatedwithscanning,couldaffectmodulationfoundwithlongerpicturepresentations.Second,whereasGlobischetal.foundthatblinkre-flexesweresignificantlypotentiatedwhenviewingunpleasant,comparedtoneutral,picturesforphobicsubjectsviewingbrieflypresentedfearmaterial,differencesinblinkmagnitudeforunpleas-antandneutralpictureswerenotobtainedhere.BradleyandLangrecentlyproposedatwo-processaccountofstartlepoten-tiation,suggestingthatblinkselicitedwhenviewingunpleasantpicturesreflecttheneteffectofafacilitatoryprocessduetoandaninhibitoryprocessduetogreaterattentionAchangeineitherprocesscanaffectblinkpotentiationforun-pleasantpictures.Ifabriefpresentationisconsideredanalogoustoadistantratherthanimminentpredator,thedefensecascadeLangetal.,1997predictslessintensedefensiveactiva-tion,whichleadstovigilanceandorientedattention,bothofwhichwilldecreasedefensivestartlepotentiation.Takentogether,thedataindicatethattheemotionalreactionstoaffectivepicturesgenerallyfoundduringsustainedperceptualpro-cessingalsooccurwhenpicturesarebrieflypresented.Inindexingemotionalcontent,onlytheheartrateresponseappearstodependonsustainedsensoryinput.ResultsforcorrugatorEMGactivity,skinconductance,andmodulationofthestartlereflexallsuggestthataquickglimpseissufficienttoeffectivelyengagethemoti-vationalsystemsthatmediateemotion.Anthony,B.J..Intheblinkofaneye:Implicationsofreflexmodificationforinformationprocessing.InP.K.Ackles,J.R.Jennings,&M.G.H.ColesAdvancesinpsychophysiologyVol.1,pp.167±218.Greenwich,CT:JAIPress.Bradley,M.M.,Cuthbert,B.N.,&LangP.J..Picturesasprepulse:Attentionandemotioninstartlemodification.541±545.Bradley,M.M.,Cuthbert,B.N.,&Lang,P.J..Affectandthestartlereflex.InM.E.Dawson,A.Schell,&A.Boehmeltmodification:Implicationsforneuroscience,cognitivescienceandclin-icalsciencepp.157±183.Stanford,CA:Cambridge.Bradley,M.M.,&Lang,P.J..Measuringemotion:Behavior,feelingandphysiology.InR.Lane&L.Nadelneuroscienceofemotionpp.242±276.NewYork:OxfordUniversityBradley,M.M.,&Lang,P.J..Orientingandemotion:Prepulseandaffectivemodulationofstartleinapictureparadigm.Manuscriptsub-mittedforpublication.CenterfortheStudyofEmotionandAttentioninternationalaffectivepicturesystem:Digitizedphotographs.Gaines-ville,FL:TheCenterforResearch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