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SUPPORTINGINFORMATIONFeelingIt:AHigher-OrderTheoryofEmotionalConsciousness.JosephLeDouxandRichardBrownTableofContents PageNumberBox1:DefiningCorticalvs.SubcorticalCircuits 2Box2:TheConsciousnessPatients:HowNeurological 2CasesHelpedReviveInterestinConsciousnessasaScientificTopicBox3:MeasuringIntrospectiveConsciousnessUsing 3VerbalandotherReportingMethodsinHumansandOtherAnimalsBox4:NonconsciousCognition(EspeciallyNonconscious 7 WorkingMemory)Box5:RichversusSparseviewsonPhenomenologyof 10Perception Box6:RoleofAwarenessinFirst-OrderPhenomenal 12ConsciousnessBox7:Higher-OrderTheoriesandtheirRelationtoOther 15CognitiveTheoriesofConsciousnessBox8:PhenomenalConsciousnessinHigher-order 19ThoughtTheoriesofConsciousnessBox9:RelationalversusNon-RelationalHigher-Order 19TheoriesBox10:ResearchQuestions 21

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BOX1:DEFININGCORTICALVS.SUBCORTICALCIRCUITS.Forthepurposesofthisarticlewedistinguish“cortical”and“subcortical”

circuitsofthecerebralhemispheresinthefollowingway.“Cortical”isusedinreferencetolaminatedstructuresintheoutershell(i.e.thecortex)ofcerebralhemispheres.Particularemphasisisplacedoncorticalregionsthatcontributetosensoryprocessing(areasofvisualcortex)andhighercognitiveprocessing(especiallylateralandmedialprefrontalcortex,butalsoparietalandinsularcortex).“Subcortical”isusedtorefertostructuresthatliewithin,butunderneaththecorticalmantle,ofthecerebralhemispheres,andthatlackprominentorconsistentlamination.Circuitscenteredontheamygdalathatdetectinnateandlearnedthreatsandcontroltheexpressionofdefensivebehaviorsandsupportingphysiologicalresponsesinresponsetothesesstimuliareemphasized.BOX2:THECONSCIOUSNESSPATIENTS:HOWNEUROLOGICALCASESHELPEDREVIVEINTERESTINCONSCIOUSNESSASASCIENTIFICTOPIC

Consciousnesswasthenumberonepsychologicaltopicofinteresttophilosophersandpsychologistsuntiltheearly20thcentury1.Inanefforttomakepsychologyanobjectivescience,observablebehavior,ratherthaninnerstatesofmindknowableonlybyintrospection,cametobeemphasizedbyso-calledbehaviorists2,3.Theyfeltnoneedtogoinsidethe“blackbox.”Intheirview,behaviorcouldbeexplainedintermsofrelationsbetweenobservablestimuliandresponses,andneithermentalnorneuralexplanationswereneeded.Towardsmid-century,cognitivesciencebroughtthemindbacktopsychologybutnottheconsciousmindthatthebehavioristseliminated;thecognitivemindwasmoreaninformationprocessingsystem,ratherthatasystemofconsciousexperiences.Butbythe1960s,consciousnesshadbeguntomakeacomeback,inspiredinlargepartbyfindingsfrompatientswhohadundergonebrainsurgeryorwhohadsufferedbraininjuries.

Observationsofsplit-brainpatients,inwhomthecerebralcommissuresweresectionedinordertocontrolepilepsy4playedaparticularlypivotalroleinreawakeninginterestinconsciousnessasascientifictopic.Thesestudiesshowedthatconsciousexperiencesareinexorablytiedtolocalizedprocessesinthebrain—thelefthemispherecouldverballydescribestimulithatitsawbutdeniedseeingstimulipresentedtotherighthemisphere5.Thattherightsidehadprocessedthestimulusthatcouldnotbereportedonwasindicatedbysubject’sabilitytorespondnon-verballytothestimulus.Thiskindoffracturebetweenverbalandnon-verbalreportingremainsacornerstoneofconsciousnessresearchtoday(seeBox3).Inlaterstudiesofthesepatientsbehavioralresponsesweretriggeredfromtherighthemisphere,andthepatientwasthenaskedwhyhedidthat.Verbalreportsfromthelefthemisphereexplainedthebehaviorinwaysthatmadesomesensegivenwhatwasobserved(iftherighthemisphereproducedascratchingactionbythelefthand,thelefthemispheresaid,“Ihadanitch”).Butthesewerefabrications.Suchobservationssuggestedthataroleofconsciousnessistoexplainresponsesgeneratedbynon-consciousbrainsystems5,6.

Studiesofpatientswithamnesiaresultingfromdamagetothemedialtemporallobe(MTL)alsocontributedtotherevivalofinterestinconsciousness.

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MTLamnesiawasinitiallythoughttoreflectagloballossofmemory7butlaterstudiessuggestedthatmemorydeficitsweremorerestricted8.FurtherworkmadeitclearthatMTLmemorysyndromemainlyinvolvedtheinabilitytoformnewconsciouslyaccessiblememories.Thisledtotheideathatexplicitorconsciousmemoriesareanatomicallydistinctfrommemoriescreatedbynon-conscioussystemsthatareinvolvedinsensoryprocessing,motorcontrol,orconditioning9-12.

Patientswithdamagetotherightparietalcortexexhibitaclassicneurologicalsyndromecalledunilateralneglectinwhichtheyfailtonoticestimulipresentedintheleftvisualfield13.Asinsplit-brainpatients,iftwostimuliarepresented,oneineachvisualfield,onlythestimulusintherightvisualfieldisreported.Laterstudiesshowedthatparietalneglectpatientscouldstatewhethertwostimuliwerethesameordifferent,inspiteofonlybeingabletoreportontheidentityofthestimulusintherightvisualfield14.Neglectiscommonlythoughtofasanattentiondeficit15,16,aviewthatcontributedtocurrentinterestinparietalcortexaspartofthecognitivecircuitsthatunderlieconsciousexperiences17,18.

Arelatedsetoffindingscamefromstudiesofpatientswithdamagetotherightvisualcortex.Theseso-calledblindsightpatientsfailtoreportonleftvisualfieldstimulibutcanrespondbehaviorallytothesamestimuli19-22.Blindsightfindingshaveoftenbeencalleduponinstudiesoftheneuralbasisofconsciousnesstodemonstratethatitispossibleforonetorespondtovisualstimuliwithoutconsciouslyknowingwhatwasseen.Box2References1. BoringEG(1950)Ahistoryofexperimentalpsychology.NewYork:Appleton-Century-Crofts.2. WatsonJB(1925)Behaviorism.NewYork:W.W.Norton.3. SkinnerBF(1938)Thebehavioroforganisms:Anexperimentalanalysis.NewYork:Appleton-

Century-Crofts.4. GazzanigaMS,BogenJE,SperryRW(1962)Somefunctionaleffectsofsectioningthecerebral

commissuresinman.ProceedingsoftheNationalAcademyofSciencesUSA48:1765-1769.5. GazzanigaMS(1972)Onebrain-Twominds.AmericanScientist60:311-317.6. GazzanigaMS,LeDouxJE(1978)TheIntegratedMind.NewYork:Plenum.7. ScovilleWB,MilnerB(1957)Lossofrecentmemoryafterbilateralhippocampallesions.Journal

ofNeurologyandPsychiatry20:11-21.8. CorkinS(1968)Acquisitionofmotorskillafterbilateralmedialtemporallobeexcision.

Neuropsychologia6:255-265.9. MilnerB(1965)Memorydisturbancesafterbilateralhippocampallesionsinman.In:Cognitive

ProcessesandBrain(Milner,P.M.andGlickman,S.E.,eds)Princeton:VanNostrand.10. SquireL(1987)MemoryandBrain.NewYork:Oxford.11. SchacterDL(1998)Memoryandawareness.Science280:59-60.12. EichenbaumH(2002)Thecognitiveneuroscienceofmemory.NewYork:OxfordUniversity

Press.13. CritchleyM(1953)TheParietalLobes.London:EdwardArnold.14. VolpeBT,LeDouxJE,GazzanigaMS(1979)Informationprocessingofvisualstimuliinan

'extinguised'field.Nature282:722-724.15. HeilmanKM,ValensteinE,WatsonRT(2000)Neglectandrelateddisorders.SeminNeurol

20:463-470.16. MesulamMM(1981)Acorticalnetworkfordirectedattentionandunilateralneglect.AnnNeurol

10:309-325.17. VuilleumierP,ArmonyJL,ClarkeK,HusainM,DriverJ,DolanRJ(2002)Neuralresponseto

emotionalfaceswithandwithoutawareness:event-relatedfMRIinaparietalpatientwithvisualextinctionandspatialneglect.Neuropsychologia40:2156-2166.

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18. ReesG,WojciulikE,ClarkeK,HusainM,FrithC,DriverJ(2002)Neuralcorrelatesofconsciousandunconsciousvisioninparietalextinction.Neurocase8:387-393.

19. WeiskrantzL,WarringtonEK,SandersMD,MarshallJ(1974)Visualcapacityinthehemianopicfieldfollowingarestrictedoccipitalablation.Brain97:709-728.

20. WeiskrantzL(1986)Blindsight:Acasestudyandimplications.Oxford:ClarendonPress.21. CoweyA,StoerigP(1991)Theneurobiologyofblindsight.TrendsNeurosci14:140-145.22. WeiskrantzL(1997)Consciousnesslostandfound:Aneuropsychologicalexploration.NewYork:

OxfordUniversityPress.BOX3:MEASURINGINTROSPECTIVECONSCIOUSNESSUSINGVERBALANDOTHERREPORTINGMETHODSINHUMANSANDOTHERANIMALS

Assessmentofconsciousnessrequiressomeformofself-reporting1,2.Humanscantypicallygiveeitheraverbaloranonverbalreportofinformationtowhichwehaveintrospectiveaccess,butcannotprovideaverbalreportofinformationthatisonlyprocessednonconsciously3-5.Verbalself-reportsarethusgenerallyagreedtobeusefulforassessingconsciousness,butineffectiveinassessingprocessesthatareimplicitorunconscious3-5.Non-verbalreportingistheonlyoptionforassessingnon-consciousprocessing,butislesssatisfactoryasameasureofconsciousnessbecauseitcanreflectbothprocessesoneisawareofandprocessesthatarenotintrospectivelyaccessible6.Fracturesbetweenconsciousandnonconsciousprocessesbyverbalandnonverbalresponseshavethusplayedakeyroleindemonstratingintrospectiveawareness7-14.

Thesepointsareillustratedbyfindingsinstudiesofpatientswithblindsight1,15-17orinpeoplewithhealthybrainstestedusingsubliminalstimulationtechniquessuchasbriefexposures18,visualmaking19-26,orcontinuousflashsuppression27,28toimpairconsciousperception.Inthesevariouskindsofstudies,peoplecanproduceeitherverbalornonverbalresponsestostimulipresentedinfreevisionbutcanonlyrespondnonverballyto“unseen”stimuli.

Whileverbalself-reportingisthusanimportanttoolinconsciousnessresearch,ithaslimitations.Itismostsuitableforassessingthecontentofimmediateexperiences,anditsusefulnessdecreasesasthetimebetweentheexperienceandthereportincreasesbecausedistortionsandfabricationscanenter3,4.Itisthuslessusefulforassessingthemotivationsunderlyingsomepastaction,bothbecauseofthedelayinthereport,andalsobecausemotivationsareoftennotconsciouslyavailableandverbalizable29-34.Self-reportalsohaslimits,whenusedalone,forassessingself-knowledgeaboutinnerexperiences,asopposedtothecontentofexperience.Anotherprocedure,post-decisionwagering,hasbeenproposedtobeanobjectivemeasureofconsciousnesssinceself-reportisnotrequested35.However,sincewageringdoesrequireintrospection,itsstatusasmoreobjectiveisquestionable5.Also,post-decisionwageringisbasedonmemoryandthuspotentiallysuffersfromdistortionsandfabrications.Ratingsofone’sconfidenceinperceptualdecisionsisthoughttobehelpfulasasupplementtoself-reportinmeta-cognitivedecisionmakingtasks36,especiallyifmadeconcurrentlywiththeexperience5.Currently,thevalueofconfidencemeasuresvs.verbalreportingasmeasuresofinnerawarenessisdebated2,5,37-39.

Someproposethatnonhumananimalshaveinnerexperiences,but,lackinglanguage,aresimplylessfacileintheirabilitytoreport.Buttheproblemisnotso

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simplydismissed.Sinceanimalscanonlygivenonverbalreports1,thereisnosecondreportingmethodthatcandistinguishnonconsciousfromconsciousprocessing.Nonverbalbehaviorissatisfactoryfordemonstratingthatananimalisconsciousinthesenseofbeingawakeandresponsivetostimuli.Itisalsosufficientfordemonstratingcognitivecapacitiessuchasworkingmemory,attention,metacognition,andproblemsolvingabilityandotherindicatorsofintelligentbehavior40.Whileconsciousnessdependsoncognitiveprocessing,notallcognitiveprocessing,includingworkingmemoryandmetacognition,leadstoconsciousexperience(seemaintext).

Decidingwhetheranon-verbalbehaviorreflectsconsciousvs.nonconsciouscognitiveprocessesrequiresnotonlythatthatthebehaviorbeexplainableintermsofconsciousprocesses,butalsothatnonconsciousexplanationsareinadequate41.Whilethereisanewwaveofenthusiasmfortheideaofanimalconsciousness42-47,mostoftheclaimsarebasedonfindingsshowingthatthebehaviorisplausiblyexplainedintermsofconsciousness;thealternativehypothesisislessoftenconsidered.Sincemanyaspectsofhumanbehaviorcanbeaccountedforbynonconsciousprocesses30,34,48,49,themostdirectwaytodrawthelinebetweenthepresenceandabsenceofintrospectiveconsciousnessisbycontrastingverbalandnonverbalreports,whichcannotbedoneinanimals.Behavioralevidenceforcognitivecapacitiesisnotnecessarilyevidenceforconsciousawarenessinanimalssincemuchofcognitionoccursnonconsciously.

Twopointsofclarificationneedtobemadeaboutanimalconsciousness.First,wedonotclaimthatnonhumanorganismslackinnerexperiences,butinsteadclaimthatbecauseofthedifficultyoffracturingconsciousandnonconsciousprocessinginnonverbalorganisms,thescienceofconsciousness,atleastfornow,ismostfruitfullypursedinhumans.Second,giventhatimportantaspectsofcognitiveprocessingoccurnonconsciouslyinhumans,evenifanimalsturnouttobelimitedtononconsciousprocesses,thiswouldnotmeanthattheyarereflexive“beastmachines”41,50,51.Someanimalsclearlyusesophisticatedcognitiveprocesses,manyofwhichfallintothecategoryofthecognitiveunconscious48toguidecomplexbehaviors.Box3References1. WeiskrantzL(1997)Consciousnesslostandfound:Aneuropsychologicalexploration.NewYork:

OxfordUniversityPress.2. OvergaardM,SandbergK(2014)Kindsofaccess:Differentmethodsforreportrevealdifferent

kindsofmetacognitiveaccess.In:TheCognitiveNeuroscienceofMetacognition(Fleming,S.M.andFrith,C.D.,eds),pp67-86:Springer-VerlagBerlinHeidelberg.

3. EriccsonKA,SimonH(1993)Protocolanalysis:Verbalreportsasdata.Cambridge,MA:MITPress.

4. WilsonTD(1994)THEPROPERPROTOCOL:ValidityandCompletenessofVerbalReports.PsychologicalScience5:249-252.

5. SethAK,DienesZ,CleeremansA,OvergaardM,PessoaL(2008)Measuringconsciousness:relatingbehaviouralandneurophysiologicalapproaches.TrendsCognSci12:314-321.PMC2767381.

6. LeDouxJE(2015)Anxious:Usingthebraintounderstandandtreatfearandanxiety.NewYork:Viking.

7. FrithC,PerryR,LumerE(1999)Theneuralcorrelatesofconsciousexperience:anexperimentalframework.TrendsinCognitiveSciences3:105-114.

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8. JackAI,ShalliceT(2001)Introspectivephysicalismasanapproachtothescienceofconsciousness.Cognition79:161-196.

9. DennettDC(1991)Consciousnessexplained.Boston:Little,BrownandCompany.10. JackendoffR(2007)Language,Consciousness,Culture:EssaysonMentalStructure.Cambridge:

MITPress.11. NaccacheL,DehaeneS(2007)Reportabilityandillusionsofphenomenalityinthelightofthe

globalneuronalworkspacemodel.BehavBrainSci30:518-520.12. SergentC,ReesG(2007)Consciousaccessoverflowsovertreport.BehavBrainSci30:523-524.13. KochC,TsuchiyaN(2007)Phenomenologywithoutconsciousaccessisaformofconsciousness

withouttop-downattention.BehavBrainSci30:509-510.14. NahmiasEA(2002)Verbalreportsonthecontentsofconsciousness:Reconsidering

intropectionistmethodology.Psyche8.15. WeiskrantzL(1986)Blindsight:Acasestudyandimplications.Oxford:ClarendonPress.16. CoweyA,StoerigP(1991)Theneurobiologyofblindsight.TrendsNeurosci14:140-145.17. WeiskrantzL,WarringtonEK,SandersMD,MarshallJ(1974)Visualcapacityinthehemianopic

fieldfollowingarestrictedoccipitalablation.Brain97:709-728.18. LazarusR,McClearyR(1951)Autonomicdiscriminationwithoutawareness:Astudyof

subception.PsychologicalReview58:113-122.19. MeriklePM(1982)Unconsciousperceptionrevisited.PerceptPsychophys31:298-301.20. CheesmanJ,MeriklePM(1986).Distinguishingconsciousfromunconsciousperceptual

processes.CanJPsychol40:343-67.21. MarcelAJ(1983)Consciousandunconsciousperception:experimentsonvisualmaskingand

wordrecognition.Cognitivepsychology15:197-237.22. GreenwaldAG,KlingerMR(1990)Visualmaskingandunconsciousprocessing:differences

betweenbackwardandsimultaneousmasking?MemCognit18:430-435.23. GreenwaldAG,KlingerMR,SchuhES(1995)Activationbymarginallyperceptible("subliminal")

stimuli:dissociationofunconsciousfromconsciouscognition.JExpPsycholGen124:22-42.24. BreitmeyerBG,OgmenH(2006)VisualMasking:TimeSlicesThroughConsciousand

UnconsciousVision.Oxford:OxfordUniversityPress.25. KouiderS,DehaeneS(2007)Levelsofprocessingduringnon-consciousperception:acritical

reviewofvisualmasking.PhilosophicaltransactionsoftheRoyalSocietyofLondonSeriesB,Biologicalsciences362:857-875.PMC2430002.

26. MacknikSL(2006)Visualmaskingapproachestovisualawareness.Progressinbrainresearch155:177-215.

27. YangE,BrascampJ,KangMS,BlakeR(2014)Ontheuseofcontinuousflashsuppressionforthestudyofvisualprocessingoutsideofawareness.Frontiersinpsychology5:724.PMC4093749.

28. LiHH,CarrascoM,HeegerDJ(2015)DeconstructingInterocularSuppression:AttentionandDivisiveNormalization.PLoSComputBiol11:e1004510.PMC4627721.

29. NisbettRE,WilsonTD(1977)Tellingmorethanwecanknow:Verbalreportsonmentalprocesses.PsychologicalReview84:231-259.

30. BarghJA,MorsellaE(2008)TheUnconsciousMind.Perspectivesonpsychologicalscience:ajournaloftheAssociationforPsychologicalScience3:73-79.PMC2440575.

31. BanajiMR,GreenwaldAG(1995)Implicitgenderstereotypinginjudgmentsoffame.JPersSocPsychol68:181-198.

32. DevosT,BanajiMR(2003)Implicitselfandidentity.AnnalsoftheNewYorkAcademyofSciences1001:177-211.

33. PhelpsEA,O'ConnorKJ,CunninghamWA,FunayamaES,GatenbyJC,GoreJC,BanajiMR(2000)Performanceonindirectmeasuresofraceevaluationpredictsamygdalaactivation.JCognNeurosci12:729-738.

34. HassinRR,UlemanJS,BarghJA(eds.)(2005)Thenewunconscious.NewYork:OxfordUniversityPress.

35. PersaudN,McLeodP,CoweyA(2007)Post-decisionwageringobjectivelymeasuresawareness.Natureneuroscience10:257-261.

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36. LauHC,PassinghamRE(2006)Relativeblindsightinnormalobserversandtheneuralcorrelateofvisualconsciousness.ProceedingsoftheNationalAcademyofSciencesoftheUnitedStatesofAmerica103:18763-18768.PMC1693736.

37. RosenthalD(2012)Higher-orderawareness,misrepresentationandfunction.PhilosophicaltransactionsoftheRoyalSocietyofLondonSeriesB,Biologicalsciences367:1424-1438.

38. Maniscalco B, Lau H (2016) The signal processing architecture underlying subjective reports of sensory awareness. Neurosci Conscious 2016. PMC4972343.

39. CorteseA,AmanoK,KoizumiA,KawatoM,LauH(2016)Multivoxelneurofeedbackselectivelymodulatesconfidencewithoutchangingperceptualperformance.NatCommun7:13669.

40. SmithJD(2009)Thestudyofanimalmetacognition.TrendsCognSci13:389-396.41. HeyesC(2008)Beastmachines?Questionsofanimalconsciousness.In:Frontiersof

Consciousness:Chichellelectures(Weiskrantz,L.andDavies,M.,eds),pp259-274Oxford:OxfordUniversityPress.

42. GrossM(2013)Elementsofconsciousnessinanimals.Currentbiology23:R981-983.43. BekoffM(2007)TheEmotionalLivesofAnimals:Aleadingscientistexploresanimaljoy,sorrow,

andempathy-andwhytheymatter.Novato,CA:NewWorldLibrary.44. PankseppJ(2012)TheArchaeologyofMind:NeuroevolutionaryOriginsofHumanEmotionNew

York:W.W.Norton&Company.45. deWaalF(2009)TheAgeofEmpathy:Nature'slessonsforakindersociety.NewYork:Three

RiversPress.46. EdelmanDB,SethAK(2009)Animalconsciousness:asyntheticapproach.TrendsNeurosci

32:476-484.47. LowP(2012)CambridgeDeclarationonConsciousnessinNon-HumanAnimals.(alsobyJ

Panksepp,DReiss,DEdelman,andBvanSwinderen,andCKoch).OriginallyretrievedonSept26,2013fromhttp://fcmconferenceorg/ChurchillCollege,UniversityofCambridge.Thislinkwassubsequentlyremoved.AsearchonDec24,2014,revealedthatthedocumentwasagainavailablethroughthislink:http://fcmconference.org/img/CambridgeDeclarationOnConsciousness.pdfIn:http://fcmconferenceorg/ChurchillCollege,UniversityofCambridge.

48. KihlstromJF(1987)TheCognitiveUnconscious.Science237:1445-1452.49. WilsonTD(2002)Strangerstoourselves:Self-insightandtheadaptiveunconscious.Cambridge,

MA:HarvardUniversityPress.50. DescartesR(1644)Principiaphilosophiae.GhentUniversity:apudLudovicumElzevirium.51. DickinsonA(2008)Whyaratisnotabeastmachine.In:FrontiersofConsciousness(Weiskrantz,

L.andDavies,M.,eds),pp275-288Oxford:OxfordUniversityPress.BOX4:NONCONSCIOUSCOGNITION(ESPECIALLYNONCONSCIOUSWORKINGMEMORY)

Cognitivetheoriesgenerallyassumethatinformationprocessingoccursnon-consciouslyuntilitisrenderedconsciousthroughprocessesthatinvolveworkingmemoryandattention.Thenon-consciousprocessingisoftenassumedtobesensoryinnature.However,considerableevidencehasbeguntoemergesuggestingthatcognitiveprocessesthatunderlieworkingmemoryrepresentationsinvolvingprefrontalandparietalareascanoccurwithoutgeneratingconsciouscontent1-15.

Block16acceptstheexistenceofnonconsciousworkingmemorybutquestionsit’scapacity.BasedontheworkofSotoetal9,hehasarguedthatnon-consciousrepresentationsinworkingmemoryaretooweaktoaccountfortheperformanceofsubjectsinstudiesofperceptualtemporarymemoryusingthepartialreportparadigm17,18.Butincontrasttopartialreportstudies,inwhichsubjectsarepresentedanarrayoflettersorshapesforvariousintervalsandthenpresentedwithacueafterthestimulusisnolongeravailable,Sotoetalused

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maskingtodegradethestimulusandpreventawarenessandreporting.Maskingandotherbriefstimuluspresentationsweakenthepercept19,20.Inaheadtoheadmatchupthisgivesconsciousprocessingasignificantedgepurelyonmethodologicalgrounds21.

Blockcounterssuchchallengesbycitingwork22,23suggestingthatevenwhentherepresentationsinworkingmemoryarerobusttheydonotlastlongenoughtoaccountforexistingfindings24.However,morerecentresearchshowsthatnon-conscioustemporaryretentioninvolvingprefrontalcortexprocessingcanlastconsiderablylongerthanpreviouslyreported,isresistanttodistraction,andisrelatedtoprospectiveaction1,25-27.Thesefindingsthusindicatethatnonconsciousworkingmemoryislong-lasting,robust,andcapableofguidingbehavior.

Butanotherfactormaybeatworkbesidesweakpercepts.Consciousexperienceofastimulusmayitselfmaketheunderlyinglower-orderrepresentationsmorerobust28,whatmightbelooselycalledconsciousamplification,whichmightsimplybeattentionalamplification,oflower-orderrepresentations.

Forthesereasons(weakperceptsandconsciousamplification),findingsthatworkingmemorycapacityisweakinconditionswithweakrepresentationsshouldnotbeusedtocastdoubtonhowrobustworkingmemoryiswhenitdealswithstrongrepresentations(likethekindproducedwhenoneconsciouslyexperiencesthestimulus).Toevaluatethecapacity/robustnessofnonconsciousworkingmemory,studiesofblindsightpatientsmightbemoreusefulthanmasking-typeproceduressincenonconsciousstimulusexposureslastingsecondscanbeused.

Theseissuescanbeconsideredfromanotherperspective.Long-termmemorystoredviathemedialtemporallobememorysystemisunconsciousuntilretrievedintoworkingmemory.21Thisclearlyshowshownon-consciouscognitive(asopposedtosensory)informationcanexistaslower-ordernon-consciousrepresentationthatisre-representedinworkingmemorycircuitstorenderitconscious.

Consciousawarenessisthusbasedonnon-consciousprocesses,andthereisnointrinsicreasonwhyallactivityinprefrontalcortexmustbeconscious.Inotherwords,non-consciousrepresentationsinprefrontalcortexcanberenderedconsciousbybeingre-representedinworkingmemory.Whetherthenon-consciousrepresentationinprefrontalcortexis“in”workingmemoryornotisadifferentquestion.Thepointisthatatheoryofconsciousawarenessisnotjustabouthowsensorystimulicometobeexperienced.Itisabouthowconsciousexperiencesinamoregeneralsensecomesabout.Sensoryconsciousnessisanexcellentstartingpoint29butshouldnotbealimitingfactorinabroadertheoreticalunderstandingofconsciousness.

Wethusproposethatevidencethatprocesseslikeattentionandworkingmemoryareimplicatedinsometaskdoesnotshowthatthetaskdependsonconsciousness.Becauseattentionandworkingmemorycanoperatenonconsciously,theseprocesses,whilenecessary,arenotsufficientforphenomenalexperience.Onlywhenthatnon-consciousinformationisre-representedintheappropriatewaydoesphenomenalawarenessoccur21,28.Asimilarviewhasrecentlybeenexpressedbyotherswhonotethatthephenomenalexperienceof

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informationinworkingmemoryinvolves,throughadditionaltop-downmodulation,thecreationofanadditionaldistinctrepresentationofmemorycontent30,31.Thisleavesopenthequestionofwhatistheappropriatehigher-orderrepresentationinworkingmemory.Inotherwords,prefrontalcircuitsthatcontributetoconsciousnessdonotconstituteasingularunifiedsystem19,20.Futureresearchwillneedtofurtherseparatethedifferentcognitiveprocessescontributedtobythesecircuits,assesstheircontributionstoawareness,anddeterminewhethersomecontributetononconsciousrepresentationsandotherstohigher-orderrepresentationsofthesethatrendertheprocessingconscious.Box4References1. SotoD,SilvantoJ(2014)Reappraisingtherelationshipbetweenworkingmemoryandconscious

awareness.TrendsCognSci18:520-525.2. CustersR,AartsH(2010)Theunconsciouswill:howthepursuitofgoalsoperatesoutsideof

consciousawareness.Science329:47-50.3. LauHC,PassinghamRE(2007)Unconsciousactivationofthecognitivecontrolsysteminthe

humanprefrontalcortex.JNeurosci27:5805-5811.4. DelCulA,DehaeneS,ReyesP,BravoE,SlachevskyA(2009)Causalroleofprefrontalcortexin

thethresholdforaccesstoconsciousness.Brain132:2531-2540.5. vanBoxtelJJ,TsuchiyaN,KochC(2010)Consciousnessandattention:onsufficiencyand

necessity.Frontiersinpsychology1:217.PMC3153822.6. vanGaalS,LammeVA(2012)Unconscioushigh-levelinformationprocessing:implicationfor

neurobiologicaltheoriesofconsciousness.TheNeuroscientist18:287-301.7. ThakralPP(2011)Theneuralsubstratesassociatedwithinattentionalblindness.Conscious

Cogn20:1768-1775.8. HassinRR,BarghJA,EngellAD,McCullochKC(2009)Implicitworkingmemory.ConsciousCogn

18:665-678.PMC2760263.9. SotoD,MantylaT,SilvantoJ(2011)Workingmemorywithoutconsciousness.Currentbiology:

CB21:R912-913.10. TsuchiyaN,KochC(2009)Therelationshipbetweenconsciousnessandattention.In:The

NeurologyofConsciousness(Laureys,S.andTononi,G.,eds),pp63-77NewYork:Elsevier.11. AnsorgeU,HorstmannG,ScharlauI(2011)Top-downcontingentfeature-specificorientingwith

andwithoutawarenessofthevisualinput.Advancesincognitivepsychology/UniversityofFinanceandManagementinWarsaw7:108-119.PMC3260021.

12. KieferM(2012)Executivecontroloverunconsciouscognition:attentionalsensitizationofunconsciousinformationprocessing.FrontHumNeurosci6:61.PMC3311241.

13. BorD,SethAK(2012)Consciousnessandtheprefrontalparietalnetwork:insightsfromattention,workingmemory,andchunking.Frontiersinpsychology3:63.PMC3298966.

14. CohenMA,CavanaghP,ChunMM,NakayamaK(2012)Theattentionalrequirementsofconsciousness.TrendsCognSci16:411-417.

15. PersaudN,DavidsonM,ManiscalcoB,MobbsD,PassinghamRE,CoweyA,LauH(2011)Awareness-relatedactivityinprefrontalandparietalcorticesinblindsightreflectsmorethansuperiorvisualperformance.NeuroImage58:605-611.

16. BlockN(2011)Perceptualconsciousnessoverflowscognitiveaccess.TrendsCognSci15:567-575.

17. SperlingG(1960)Theinformationavailableinbriefvisualpresentations.PsychologicalMonographs74:1-29.

18. SligteIG,ScholteHS,LammeVA(2008)Aretheremultiplevisualshort-termmemorystores?PLoSOne3:e1699.PMC2246033.

19. LauH,RosenthalD(2011)Empiricalsupportforhigher-ordertheoriesofconsciousawareness.TrendsCognSci15:365-373.

20. LauH,RosenthalD(2011)Thehigher-orderviewdoesnotrequireconsciouslyself-directedintrospection:responsetoMalach.TrendsCognSci15:508-509.

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21. LeDouxJE(2015)Anxious:Usingthebraintounderstandandtreatfearandanxiety.NewYork:Viking.

22. CarmelD,RaioC,PhelpsEA,CarrascoM(2011)Fastunconsciousfearconditioning.Journalofvision11:314-314.

23. RaioCM,CarmelD,CarrascoM,PhelpsEA(2012)Nonconsciousfearisquicklyacquiredbutswiftlyforgotten.Currentbiology:CB22:R477-479.

24. SligteIG,ScholteHS,LammeVA(2009)V4activitypredictsthestrengthofvisualshort-termmemoryrepresentations.JNeurosci29:7432-7438.

25. BergstromF,ErikssonJ(2014)Maintenanceofnon-consciouslypresentedinformationengagestheprefrontalcortex.FrontHumNeurosci8:938.PMC4240068.

26. PanY,LinB,ZhaoY,SotoD(2014)Workingmemorybiasingofvisualperceptionwithoutawareness.AttenPerceptPsychophys76:2051-2062.

27. ErikssonJ,VogelEK,LansnerA,BergstromF,NybergL(2015)NeurocognitiveArchitectureofWorkingMemory.Neuron88:33-46.PMC4605545.

28. BrownR(2014)Consciousnessdoesn'toverflowcognition.Frontiersinpsychology5:1399.PMC4255486.

29. CrickF,KochC(2003)Aframeworkforconsciousness.Natureneuroscience6:119-126.30. JacobJ,JacobsC,SilvantoJ(2015)Attention,workingmemory,andphenomenalexperienceof

WMcontent:memorylevelsdeterminedbydifferenttypesoftop-downmodulation.Frontiersinpsychology6:1603.PMC4610135.

31. JacobsC,SilvantoJ(2015)Howisworkingmemorycontentconsciouslyexperienced?The'consciouscopy'modelofWMintrospection.NeurosciBiobehavRev55:510-519.

BOX5:RICHVERSUSSPARSEVIEWSONPHENOMENOLOGYOFPERCEPTION

Ourconsciousexperienceoftheworldappearstoberichanddetailed.Yetevidencesuggeststhatlargechangesintheenvironmentcanfailtobedetected1.So-calledchangeblindnessfindingssuggestthatourconsciousexperiencemaybemuchsparserthanitappearstobe—wemayhavethefeelingthatthereisalotofdetailrepresentedinourconsciousexperience,butmaybethisisnotthecase.Thequestionofwhetherconsciousperceptionisrichorsparseisaheatedlydebatedtopicinconsciousnessresearchtoday.Thisisanimportantdebatedefinitiveevidenceinonedirectionortheotherwouldhaveimportantimplicationsforthebroaderdebateoverthenatureofconsciousness.

Block2,3isavocalproponentoftherichphenomenologyview.Hisargumentroughlytakesthefollowingform.Inexperimentswherepeopleareaskedtoverballyreportonwhattheysawduringabriefexposuretoagroupofstimuli4-6theytypicallysaytheysawtheentirearray2butcandescribeonlyafewoftheseitems.However,iftheyarecuedinacertainwayafterthestimulusisnolongerpresenttheyreportenoughitemstosuggestthattheymusthaveencodedallormostoftherelevantinformation.Forexample,inSperling’sclassicexperimentssubjectsarecuedwithanaudiotoneafterthearrayoflettersisnolongerpresent.Thisaudiotonecuesthemtonamethelettersineitherthetop(hightone),middle(middletone)orbottom(lowtone)rows.Subjectscangetallofmostofthelettersinthecuedrowsandsinceanyrowcouldhavebeencueditisinferredthatmostofthelettersandtheirspecificidentitieshadtoberepresentedpriortotheaudiocue.AccordingtoBlock,thissuggeststhatwehaverichconsciousphenomenologythatisdistinctfromourcognitiveaccesstoandabilitytoreportaboutit.Afterall,thesesubjectssaythattheyhaveaconsciousexperienceofallofthelettersandthattheyusethisconsciousexperiencetoguidetheirchoices2.Blockconcludesthatthereare

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stateswhicharephenomenallyconsciousbutunaccessedbycognitivesystems,andthusunreportable,andheusesthisevidencetoarguethatphenomenalconsciousnessexistsindependentofaccessconsciousness,whichreflectsintrospectionandcognitiveaccess(thispositionisdiscussedfurtherinBox6).

Block’spositionhasbeenchallengedbyresearcherswhoargueforadifferentinterpretationofthedata7-9.Inparticular,theopponentssuggestthatsubjectsmayhavesparseconsciousrepresentations(asreflectedinreports)butdetailedunconsciousrepresentations(thatcannotbereportedbutthatcanguidebehavior).BothBlock’sinterpretationofthedata,andtheinterpretationproposedbythecritics,areconsistentwiththereportsthatsubjectsgiveofseeingalloftheletters,etc.Onthesparsephenomenologyview(theviewofthecritics)subjectshaveadegradedconsciousexperienceofthelettersuntilthecuedirectstheirattentionandtheythenhaveadetailedconsciousexperienceoftherelevantrow.Subjectsmayconsciouslyexperienceenoughoftheletterstomakeittruethattheyfeltliketheysawthemall.Block’srichphenomenologyinterpretation,ontheotherhand,assumesthatonehasaphenomenallyconsciousexperienceofallofthelettersinthearraybutcanonlyaccessafewofthoseitems.Theserichrepresentations,accordingtoBlock,areaccessedenoughtonoticethattheyareletters,andtonoticehowmanylettersthereare;thereisphenomenallyconsciousdetailwhichcouldbeaccessed,butthatonecannotinthatmomentaccessinsuchawayastoreporttheirspecificidentities.Blockthusappealstoahypotheticalaccountofwhatitislikeforthesubjectstomakehiscase.

BronfmanetalhaverecentlyusedfindingsaboutcolorperceptiontoargueasimilarpointasBlock—thatcolorpropertiesinunattendedareasofperipheralvisionarephenomenallyexperiencedeventhoughunreportable3,10.Specifically,theypresentedsubjectswithanarrayoflettersthatvariedincolordiversityfromhightolow.Subjectswerepre-cued(thatis,thecuewasshownbeforetheonsetoftheletterarray)toattendtoaspecificrowandthenafterwardsapost-cueindicatedwhichletterfromthepre-cuedrowtheyshouldreport.Subjectswerealsoaskedtoestimatethecolordiversityinunattendedrows,whichtheywereabletodo,anddoingsodidnotinterferewiththeirabilitytorecallthepost-cuedletter.Theauthorstakethisasevidencethatphenomenalconsciousnesscanbeseparatedfromtheintrospectivemechanismsthatallowaccessandenablereport.However,asnotedabovefortheSperlinglettercuingtask,thedataarealsoconsistentwiththeviewthatnon-consciousinformationdrivestheperformanceofsubjects8,11,12.

ThusthereiscurrentlyinsufficientreasontotaketheexperimentsdiscussedinthisBoxasprovidingevidencefortheclaimthatunaccessed,unreportable,richconsciousrepresentationsexist.Block’skeyappealtowhatitislikeforsubjectsintheseexperimentsisnotdecisive.Thesparsephenomenologypositionpredictsthatsubjectswillexperiencethearrayinapartialanddegradedwaybutthesegenericrepresentationsmaystilllabelthedegradedelementsasletters,perhapsevenashavingdeterminatedetail.Weconcludethatthesedatadonotallowdefinitiveconclusionsrelevanttothefirst-ordervs.higher-orderdebate.Box5References

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1. RensinkRA,O'ReganJK(1997)TOSEEORNOTTOSEE:TheNeedforAttentiontoPerceiveChangesinScenes.PsychologicalScience8:368-373.

2. BlockN(2007)Consciousness,accessibility,andthemeshbetweenpsychologyandneuroscience.BehavBrainSci30:481-499;discussion499-548.

3. BlockN(2014)Richconsciousperceptionoutsidefocalattention.TrendsCognSci18:445-447.4. SperlingG(1960)Theinformationavailableinbriefvisualpresentations.Psychological

Monographs74:1-29.5. LandmanR,SpekreijseH,LammeVA(2003)Largecapacitystorageofintegratedobjectsbefore

changeblindness.VisionRes43:149-164.6. SligteIG,ScholteHS,LammeVA(2008)Aretheremultiplevisualshort-termmemorystores?

PLoSOne3:e1699.PMC2246033.7. KouiderS,deGardelleV,SackurJ,DupouxE(2010)Howrichisconsciousness?Thepartial

awarenesshypothesis.TrendsCognSci14:301-307.8. BrownR(2012)Themythofphenomenologicaloverflow.ConsciousCogn21:599-604.9. PhillipsIB(2011)PerceptionandIconicMemory:WhatSperlingDoesn'tShow.Mind&Language

26:381-411.10. BronfmanZZ,BrezisN,JacobsonH,UsherM(2014)Weseemorethanwecanreport:"costfree"

colorphenomenalityoutsidefocalattention.PsycholSci25:1394-1403.11. BrownR(2014)Consciousnessdoesn'toverflowcognition.Frontiersinpsychology5:1399.

PMC4255486.12. PhillipsI(2016)Nowatershedforoverflow:Recentworkontherichnessofconsciousness.

PhilosophicalPsychology29:236-249.Box6:RoleofAwarenessinFirst-OrderPhenomenalConsciousness

First-orderphenomenalconsciousnesshasthatawkwardpropertyofbeingaconsciousexperiencethatyouarenotawareof.TogetaroundthisproblemBlock,aleadingproponentoffirst-ordertheory,hasintroducedthenotionof“awarenessaccess”1.Indoingso,heacknowledgesthatsomekindofawarenessofourfirst-orderstatesisanecessarycomponentofphenomenalconsciousness,buthedeniesthattherelevantkindofawarenessisanythinglikethecognitivekindinvokedinhigher-ordertheories.

OnesuggestionBlockmakesisthatsomekindofdeflationaryawarenessmaysuffice.ThedeflationarynotionisinspiredbyremarksofErnestSosa2whonotesthatonesmilesone’sownsmilesbutthesmilingisnotsomethinginadditiontothesmile.Justhavingthesmileisitselfsmilingthesmile.So,onthedeflationaryview,sayingaconsciousstateisoneweareawareofitisabitlikesayingthatsmilingisalwayssmilingone’sownsmile.Thatis,onthedeflationaryview,weareconsciousofourfirst-orderstatesbutnotbecauseofanykindofdistincthigher-orderawareness.Tohavethestateistobeconsciousofit,andnothingelseisrequired.

Theproblemwiththisviewisthatitisunabletodistinguishconsciousstatesfromnon-consciousstates.Infact,thiskindofdeflationaryawarenessseemstoaccompanyeverystateofthebrain,whichthen,wouldmakeallbrainstatesphenomenallyconscious(andtomakemattersworse,ifweallowthattherearephenomenallyconsciousstatesthatarenotcognitivelyaccessedwemightnotevenbeabletotellthattheseconsciousstatesarethere!).Asaresult,deflationaryawarenessdoesnotseemtosolvetheunawarenatureoffirst-orderphenomenalconsciousness.

ArelatedalternativesuggestedbyBlock1isthatsame-orderawarenessmightdothejob.Thetraditionaldistinctionbetweenfirstandhigher-order

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representationalcontentsisadistinctionbetweenwhatkindsofthingsarebeingrepresented.First-ordercontentsrepresentstatesoftheenvironmentandhigher-ordercontentsrepresentothermentalstates.Onthetraditionalhigher-ordertheorythesetwodistinctkindsofrepresentationalcontentscorrespondtonumericallydistinctrepresentationalstates(atleasttwo,inthesimplestcase).Withsame-orderawareness,thereisonephenomenallyconsciousstatethatrepresentsitself3.Thatis,thereissaidtobeonestate,apartofwhichcanbeunderstoodashavingfirst-ordercontentandanotherpartofthesamestatewiththeappropriatehigher-ordercontent.Same-ordertheoriesthusendorsetheviewthatsomekindofinnerawarenessisrequiredforphenomenalconsciousness,likehigher-ordertheories,butdenythatthisisbecausetherearetwostates,oneofwhichrepresentstheother.

Butwhatkindofself-representationisatstakehere?Ifthehigher-orderpartofthestateturnsouttobesomethingcognitivethenthisisjustavariantofthekindofawarenessinvokedbythehigher-orderapproachandsowouldnotconstituteagenuinealternative.Blockwantsanotionofself-representationthatisnon-cognitive,andthusnotanythinglikerepresentationsinvokedbyglobalworkspacetheories,higher-ordertheories,orrepresentationaltheoriesingeneral1.Butwhatthatcouldpossiblyberemainsunclearatthispoint.Blockhasspeculatedthattheremaybeanotionofself-representationthatisrobustenoughtosatisfythecommitmentthatawarenessiscruciallyboundupinphenomenalconsciousnessandalsotheconstraintthatitbenon-cognitivebuthedoesn’thimselfofferanaccountwhatthatwouldbelike.

Whenpushed,Block4hasgesturedtowardwhathasrecentlybeencalledtheJoint-DeterminationView5,6,7.Onthiskindofviewthefirst-orderandhigher-orderstatesjointlydeterminethenatureofone’sphenomenalconsciousness.If,toillustrate,onewereseeingpurple,thenonewouldhaveafirst-orderstaterepresentingpurpleintheworldandahigher-orderstaterepresentingthatthefirstorderstateisreliable,somethingwemightexpresswith‘IamvividlyperceivingthecontentofrepresentationF’6.Byitselfthefirst-orderrepresentationofpurpleresultsinnoconsciousexperiencebutwhenonebecomesawareofoneselfasbeinginthatstate,byhavingthehigher-orderdecisionprocess‘judge’thefirst-orderstatetobereliable,onehasaphenomenallyconsciouspurpleexperience.Whenonehasjustthehigher-orderstatethejoint-determinationviewstillclaimsthatonewillhaveaphenomenallyconsciousexperience.Itwillappeartothesubjectasthoughtheyarehavingaveryvividexperiencebutwithoutanyspecificqualityenteringintotheexperience.Thoughconsistentwiththedataandnotwithoutitsadvantages,thejoint-determinationviewabandonstheexplanatoryprojectofthehigher-orderapproachinthatitisnotabletoexplainwhytheconsciouspurpleexperienceisexperiencedaspurpleasopposedtoanyotherquality,ornoneatall(forfurtherdiscussionofthisissue,see6,7).

Partofthestrengthofthehigher-orderapproachingeneralisthatitappealstowell-definedcognitiveprocesseswithknownneuralunderpinningsintheexplanationofwhatinnerawarenessamountsto.Theseprocesses,inturn,arepostulatedalreadyintheoriesaimedatexplainingmentalfunctioning,andareseeminglyneededindependentlyinordertoexplainhowperceptionworks.Itisthusnaturaltoextendthemtootherpsychologicalphenomenalikeconsciousness.

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Thealternative,perhaps,isakindofacquaintance.Onthisviewonemightpostulatetheexistenceofbasicqualitativeproperties,likered,andsoon,andthenarguethatwhenthesequalitiesareconsciouswecometobedirectlyacquaintedwiththem7.Thoughthisisapossibilityitcomeswiththeheavypriceofpostulatingthatmentalqualitiesarebasiccomponentsofreality,whichamountstosomethinglikepanpsychism.

Panpsychismhasbeentakenseriouslybyseveralauthorsrecently8,9.Oneversionofthisviewholdsthatthementalqualities,qualia,likered,thesoundofabell,anger,etc.arefundamentalelementsofrealitylikemassandchargeare.Inadditiontothefundamentalmentalqualitiesonewouldalsoneedtopostulateaprimitivenotionofawarenessthatwasnotexplainableintermsofthefunctioningofthesystem.Whiletheseviewsarenotruledoutaprioriwefeeltheycomeattoosteepacost;especiallywhenwehavemorephysicallyamenablecandidatesthathavenotbeenruledout.

Thusitappearsthatifwetrulywanttoabandoncognitiveaccesswemustalsoabandontheviewthatconsciousnesscanbeexplainedatthepsychologicallevel.Thisisadrasticmovewhichisnotmandatedbythecurrentdata.Wehavecognitivenotionsofawarenesswhichneedtobepostulatedinordertoexplainmentalfunctioning.Theseprocessescanalsobeusedtoexplainphenomenalconsciousnessandunlessthereissomethingwrongabouttheaccountweoughtnottoabandonitforspeculativemetaphysicalpositionsthataremoreextravagant.Box6References1. BlockN(2007)Consciousness,accessibility,andthemeshbetweenpsychologyand

neuroscience.BehavBrainSci30:481-499;discussion499-548.2. SosaE(2002)PrivilegedAccess.In:Consciousness:Newphilosophicalperspectives(Smith,Q.

andJokic,A.,eds),pp273-294Oxford:OxfordUniversityPress.3. KriegelU(2009)SubjectiveConsciousness:Aself-representationaltheory.Oxford:Oxford

UniversityPress.4. BlockN(2011)ResponsetoRosenthalandWeisberg.Analysis71:443-448.5. LauH(2008)Ahigher-orderBayesiandecisiontheoryofconsciousness.In:Modelsofbrainand

mind:Physical,Computational,andPsychologicalApproaches(Banerjee,R.andChakrabarti,B.K.,eds),pp35-48Oxford:Elsevier.

6. Brown,R(2012).TheBrainanditsStates.InShimonEdelman,TomerFekete&NetaZach(eds.),BeinginTime:DynamicalModelsofPhenomenalExperience.JohnBenjamins.pp.211-238.

7. ManiscalcoB,LauH(2016)Thesignalprocessingarchitectureunderlyingsubjectivereportsofsensoryawareness.NeurosciConscious2016.PMC4972343.

8. ChalmersD(2015)PanpsychismandPanprotopsychism.In:ConsciousnessinthePhysicalWorld:PerspectivesonRussellianMonism(Alter,T.andNagasawa,Y.,eds),pp246-276Oxford:OxfordUniversityPress.

9. TononiG,KochC(2015)Consciousness:here,thereandeverywhere?PhilosophicaltransactionsoftheRoyalSocietyofLondonSeriesB,Biologicalsciences370.PMC4387509.

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BOX7:HIGHER-ORDERTHEORIESANDTHEIRRELATIONTOOTHERCOGNITIVETHEORIESOFCONSCIOUSNESS

Itisimportanttomakeadistinctionbetweentheneuralnotionofhigher-ordertheory,whichassumesthatlower-orderneuralrepresentations(sayinvisualcortex)arenot,ontheirown,equivalenttointrospectiveawareness,fromphilosophicalversionsofhigher-ordertheory,suchashigher-orderthoughttheory,whichspecificallyrequireaformofhigher-orderinnerawarenessforphenomenalconsciousness.Thus,theoriesbasedonattentionand/orworkingmemory1-12,orprocessingbyaglobalworkspace13-17,orinterpretationofexperience18,19canbeconstruedashigher-orderintheneuralsenseofrequiringmorethansensoryprocessinginorderforconsciousnesstooccur(seeTable1forasummaryofcognitivetheoriesofconsciousness).

Forexample,Rosenthalarguesthatglobalworkspaceandattentionaltheories,whichcalluponhigher-orderneuralareasbutnothigher-orderawareness,arefirst-ordertheories20.OtherssympathetictoGlobalWorkspacetheorieshavearguedthattheglobalstatesthemselvesamounttoakindofhigher-orderawareness21.InfactBaarshimself,theoriginatorofGlobalWorkspaceTheory,suggeststhattheglobalworkspacemayonlybeanecessaryconditionforconsciousness14.Sufficiencymayrequireaccessbyanexecutiveself-system,andthissoundsalotlikeakindofhigher-orderawareness.Thus,inthisway,everytheoryofconsciousnesscanbeseenaseitherahigher-orfirst-ordertheory.Anytheoryofconsciousnesscanbeinterpretedasinvokingakindofhigher-orderawareness,inwhichcaseitisaversionofhigher-ordertheory,oritwilldenyaroleforanysuchawareness,inwhichcaseitwillbeafirst-ordertheory.

StudieslikethoseofLauandPassingham22providesomesupportforthepredictionbythehigher-ordertheorists.Itdoesseemthatwecangeneratecaseswheretaskperformanceismatched,asmeasuredbyameasureliked’,andyetsubjectsseemtohavedifferingconsciousexperiences22.Ifthisissothenitseemstocountagainstfirst-orderversionsofglobalworkspace.AsLauandRosenthal23noteitispossibleforaglobalworkspacetheoristtoposittwodistinctchannels--oneforconsciouscontentsandoneforunconsciousprocesses.ButcomputermodelsoftheLauandPassinghamdatasetsuggestthatglobalworkspacetheoriesdonotcapturetheknowndataaswellasthemodelsembodyingahigher-orderstructure.24ThekeyclaimofthesekindofdualchannelGlobalWorkspacemodelsisthataconsciousandanunconsciouschannelworktogethertoexplainboththetaskperformanceandthesubjectivereportswhilethehierarchicalmodelspositthattaskperformanceismostlydrivenbyfirst-orderstatesandsubjectivereportsaretheresultoflatestagehigher-orderprocesses.

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Table1:OverviewContemporaryTheoriesofConsciousnessFirst-OrderTheoryPremise:thepresenceofastateissufficientfortheconsciousexperienceofthatstate.ConsciousnessconsistsinouterawarenessRepresentativeProponents:NedBlocka,VictorLammeb,FredDretskec,MichaelTyedHigher-OrderTheoryPremise:thepresenceofastateisnotsufficientfortheconsciousexperienceofthatstate.Thestatemustbere-representedbyanadditional(higher-order)state.ConsciousnessconsistsininnerawarenessRepresentativeProponents:DavidRosenthale,JoshWeisbergf,RichardBrowng,HakwanLauhGlobalWorkspaceTheoryPremise:consciousnessresultsfromthebroadcastingofastatethroughoutaglobalprocessingnetworkRepresentativeProponents:StanislasDehaenei,Jean-PierreChangeuxi,BernardBaarsjIntegratedInformationTheoryPremise:consciousnessisinherentinintegratedinformationRepresentativeProponents:GiulioTononik,ChristofKochkOtherCognitiveTheoriesPremise:consciousnessresultsfromcognitiveprocessessuchasattention,workingmemory,metacognition,interpretationofexperienceRepresentativeProponents:JessePrinzl,DanielSchachterm,ChrisFrithn,MichaelGazzanigao

Table1Referencesa. BlockN(2007)Consciousness,accessibility,andthemeshbetweenpsychologyandneuroscience.

BehavBrainSci30(5-6):481-499;discussion499-548.b. LammeVAF(2005)Independentneuraldefinitionsofvisualawarenessandattention.Cognitive

PenetrabilityofPerception:Attention,Action,Strategies,andBottom-UpConstraints,edRaftopoulosA(NovaSciencePublishers,NewYork),pp171-191.

c. DretskeF(1995)NaturalizingtheMind.Cambridge,MA:MITPress.d. TyeM(2000)Consciousness,Color,andContent.Cambridge,MA:MITPress.e. RosenthalDM(2005)Consciousnessandmind.Oxford:OxfordUniversityPress.f. WeisbergJ(2011)Misrepresentingconsciousness.PhilosophicalStudies154:409-433.g. BrownR(2012)Themythofphenomenologicaloverflow.Consciousnessandcognition21:599-

604.h. LauH,RosenthalD(2011)Thehigher-orderviewdoesnotrequireconsciouslyself-directed

introspection:responsetoMalach.TrendsCognSci15:508-509.i. DehaeneS,ChangeuxJP(2011)Experimentalandtheoreticalapproachestoconscious

processing.Neuron70:200-227.j. BaarsBJ(2005)Globalworkspacetheoryofconsciousness:towardacognitiveneuroscienceof

humanexperience.ProgBrainRes150:45-53.k. TononiG,BolyM,MassiminiM,KochC(2016)Integratedinformationtheory:from

consciousnesstoitsphysicalsubstrate.NatRevNeurosci17:450-461.l. PrinzJJ(2012)TheConsciousBrain:HowAttentionEngendersExperience.NewYork:Oxford

UniversityPress.m.SchacterDL(1998)Memoryandawareness.Science280:59-60.n. FrithC,PerryR,LumerE(1999)Theneuralcorrelatesofconsciousexperience:anexperimental

framework.TrendsinCognitiveSciences3:105-114.o. GazzanigaMS(2012)Who'sinCharge?:FreeWillandtheScienceoftheBrain.NewYork:Ecco.

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Table2:SomeVariantsofHigher-OrderTheory

TraditionalHigher-OrderThought(HOT)TheoryPremise:athought-likementalstatemakesoneawareofoneselfasbeinginafirst-orderstate,byrepresentingoneselfasbeinginthatstate,therebymakingthefirstorderstateconscious.RoleofEmptyHigher-OrderStates?Higher-orderstatesrefertonon-existentfirst-orderstates,whichcanbethoughtofastheconsciousstate(thestateonerepresentsoneselfasbeingin).RepresentativeProponents:DavidRosenthalaa,JoshWeisbergbbHigher-OrderRepresentationofaRepresentation(HOROR)TheoryPremise:athought-likementalstatemakesoneawareofoneselfasbeinginafirst-orderstate,byrepresentingoneselfasbeinginthatstate,andthisconstitutesphenomenalconsciousness.RoleofEmptyHigher-OrderStates?Appropriatehigher-orderstatesarephenomenallyconscious.RepresentativeProponents:RichardBrowncc,JosephLeDouxdd

Same-Order(SO)TheoryPremise:amentalstatereferringto,orrepresenting,itself,isaconsciousstate.Thiscomplexstate,consistingofaworlddirectedcomponentandaself-referentialcomponent,constitutesthesubjectbeingawareoftheconsciousstate.Empty-Higher-OrderThoughts?Theseareirrelevant.Whenthefirst-ordercomponentismissingthereisnoresultingconsciousstate.RepresentativeProponents:UriahKriegelee,RoccoGennaroff,RobertVanGulickgg

Joint-Determination(JD)TheoryPremise:Ahigher-ordercognitivedecisionprocesswherebyanincomingfirst-orderperceptualsignalis‘judged’tobereliable(ornot)isaconsciousstate.Theresultingphenomenalconsciousnessdependsjointlyonthenatureofthefirst-ordersignalandthe‘judgement’bythehigher-orderprocess.EmptyHigher-OrderStates?Whenfirst-ordercomponentismissingthereisstillconsciousexperienceassociatedwiththehigher-orderelementalone,butthisconsciousexperienceispartialordegradedwithoutthefirst-orderelement.RepresentativeProponents:HakwanLauhh

Table2Referencesaa. RosenthalDM(2005)Consciousnessandmind.Oxford:OxfordUniversityPress.bb. WeisbergJ(2011)Misrepresentingconsciousness.PhilosophicalStudies154:409-433.cc. BrownR(2015)TheHORORtheoryofphenomenalconsciousness.PhilosophicalStudies

172:1783-1794.dd. LeDouxJE(2015)Anxious:Usingthebraintounderstandandtreatfearandanxiety.NewYork:

Viking.ee. KriegelU(2012)Precisofsubjectiveconsciousness:aself-representationaltheory.

PhilosophicalStudies159:443-445.ff. GennaroRJ(2011)TheConsciousnessParadox.Cambridge,MA:MITPress.gg. VanGulickR(2004)Higher-orderglobalstates(HOGS):Analternativehigher-ordermodelof

consciousness.In:Higher-OrderTheoriesofConsciousness:AnAnthology(Gennaro,R.J.,ed):JohnBenjamins.

hh. ManiscalcoB,LauH(2016)Thesignalprocessingarchitectureunderlyingsubjectivereportsofsensoryawareness.NeurosciConscious2016.PMC4972343.

Box7References1. ShalliceT(1988)Informationprocessingmodelsofconsciousness.In:Consciousnessin

contemporaryscience(Marcel,A.andBisiach,E.,eds),pp305-333Oxford:OxfordU.Press2. BaddeleyA(2000)Theepisodicbuffer:anewcomponentofworkingmemory?TrendsCognSci

4:417-423.

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3. SchacterDL(1989)Ontherelationbetweenmemoryandconsciousness:Dissociableinteractionsandconsciousexperience.In:Varietiesofmemoryandconsciousness:EssaysinhonourofEndelTulving(Roediger,H.L.I.andCraik,F.I.M.,eds),pp355-389Hillsdale,NJ:LawrenceErlbaumAssociates.

4. SchacterDL,BucknerRL,KoutstaalW(1998)Memory,consciousnessandneuroimaging.PhilosophicaltransactionsoftheRoyalSocietyofLondonSeriesB,Biologicalsciences353:1861-1878.

5. FrithCD(2008)Thesocialfunctionsofconsciousness.In:FrontiersofConsciousness:Chichelelectures(Weiskrantz,L.andDavies,M.,eds),pp225-244Oxford:OxfordUniversityPress.

6. PrinzJJ(2012)TheConsciousBrain:HowAttentionEngendersExperience.NewYork:OxfordUniversityPress.

7. CrickF,KochC(2003)Aframeworkforconsciousness.Natureneuroscience6:119-126.8. JacobsC,SilvantoJ(2015)Howisworkingmemorycontentconsciouslyexperienced?The

'consciouscopy'modelofWMintrospection.NeurosciBiobehavRev55:510-519.9. Johnson-LairdPN(1988)Thecomputerandthemind:Anintroductiontocognitivescience.

Cambridge,Mass.:HarvardUniversityPress.10. CohenMA,CavanaghP,ChunMM,NakayamaK(2012)Theattentionalrequirementsof

consciousness.TrendsCognSci16:411-417.11. BorD,SethAK(2012)Consciousnessandtheprefrontalparietalnetwork:insightsfrom

attention,workingmemory,andchunking.Frontiersinpsychology3:63.PMC3298966.12. BaarsBJ,FranklinS(2003)Howconsciousexperienceandworkingmemoryinteract.Trends

CognSci7:166-172.13. BaarsBJ(1988)ACognitiveTheoryofConsciousness.NewYork:CambridgeUniversityPress.14. BaarsBJ(2005)Globalworkspacetheoryofconsciousness:towardacognitiveneuroscienceof

humanexperience.Progressinbrainresearch150:45-53.15. McGovernK,BaarsBJ(2007)CognitiveTheoriesofConsciousness.In:TheCambridgeHandbook

ofConsciousness(Zelazo,P.D.etal.,eds),pp177-205NewYork:CambridgeUniversityPress.16. DehaeneS,ChangeuxJP(2011)Experimentalandtheoreticalapproachestoconscious

processing.Neuron70:200-227.17. DehaeneS,NaccacheL(2001)Towardsacognitiveneuroscienceofconsciousness:basic

evidenceandaworkspaceframework.Cognition79:1-37.18. GazzanigaMS(2008)Human:Thesciencebehindwhatmakesusunique.NewYork:Ecco.19. GazzanigaMS(2015)Talesfrombothsidesofthebrain:Alifeinneuroscience.NewYork:

Ecco/HarperCollins.20. RosenthalD(2012)Higher-orderawareness,misrepresentationandfunction.Philosophical

transactionsoftheRoyalSocietyofLondonSeriesB,Biologicalsciences367:1424-1438.21. VanGulickR(2004)Higher-orderglobalstates(HOGS):Analternativehigher-ordermodelof

consciousness.In:Higher-OrderTheoriesofConsciousness:AnAnthology(Gennaro,R.J.,ed):JohnBenjamins.

22. LauHC,PassinghamRE(2006)Relativeblindsightinnormalobserversandtheneuralcorrelateofvisualconsciousness.ProceedingsoftheNationalAcademyofSciencesoftheUnitedStatesofAmerica103:18763-18768.PMC1693736.

23. LauH,RosenthalD(2011)Empiricalsupportforhigher-ordertheoriesofconsciousawareness.TrendsCognSci15:365-373.

24. ManiscalcoB,LauH(2016)Thesignalprocessingarchitectureunderlyingsubjectivereportsofsensoryawareness.NeurosciConscious2016.PMC4972343.

BOX8:PHENOMENALCONSCIOUSNESSINHIGHER-ORDERTHOUGHTTHEORIESOFCONSCIOUSNESS

Somehigher-ordertheorists,likeDavidRosenthal,construe‘phenomenalconsciousness’asdenotingakindofconsciousnessthatsensoryqualitieshaveindependentlyofanykindofcognitiveawareness—thepropertiesbywhichwerepresentphysicalfeaturesliketheshapeorcolorofvisualstimuliorthepitchof

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sounds1.Higher-orderrepresentationthenmakesthefirst-orderstateconscious(seethearrowfromworkingmemorynetworkstovisualcortexinFigure2b).Rosenthaltakesthedebatebetweenhimselfandfirst-ordertheoristslikeBlocktobeaboutwhetherthesesensoryqualitiescanoccurindependentofconsciousness.AsRosenthalusestheterms,thereisnophenomenalconsciousness,sincethesensorypropertiesonlybecomeconsciousviahigher-orderstates.Construedthiswaytheexistenceofphenomenalconsciousnesswouldcountagainstanykindofhigher-ordertheory.Rosenthal,forexample,arguesthatpaincanoccurunconsciously,andwhenitdoesithasthesamequalitativecharacter(i.e.sensoryproperties)asitdoeswhenitisconscious,exceptitisnotlikeanythingforthesubject.Hemeansbythisthatthereisnokindofconsciousnessthattheseunconsciouspainshave.Rosenthalisobviouslynotafirst-ordertheorist,butratherheinterprets‘phenomenalconsciousness’tobeapositoffirst-ordertheories.However,inthemoregeneral,andlessrestricted,senseofphenomenalconsciousnessthatweemployhere,phenomenalconsciousnessisthecommonexplanatorytargetofbothhigher-orderandfirst-ordertheories.Useofthistheory-neutralsenseofphenomenalconsciousnessmakesphenomenalconsciousnesswhathigher-ordertheoryseekstoaccountfor.Box8References1. RosenthalD(2011)Exaggeratedreports:replytoBlock.Analysis71:431-437.BOX9:RELATIONALVERSUSNON-RELATIONALHIGHER-ORDERTHEORIES

Thepossibilityofamismatchbetweenthecontentoffirstandhigher-orderstateshaslongbeenthoughttoposeaproblemforhigher-ordertheories.Forinstance,ifonehasalower-orderstaterepresentingthatoneisseeingagreenleafandyet,forwhateverreason,comestohaveahigher-orderstaterepresentingthatoneisseeingaredleafwhatisitlikeforthesubject?Higher-ordertheoristshaveforthemostpartrespondedthatthisisnotatheoreticalpossibility.However,empiricalreasonssuggestthatthisactuallyhappensandthatitdoessoinawaythatfavorsaparticularkindofhigher-orderthoughttheory.

Forinstance,Brown1arguesthatwehavecasesofmismatchresultingfrominattentionalinflationandarareformofCharlesBonnettsyndrome.InsomerareformsofCharlesBonnettsyndromethereisextensivedamagetovisualcortexandyetsubject’sreportvividhallucinations.Evenifweassumethattheresidualcortexissufficientforsomefirst-orderrepresentationstosurviveitisreasonabletothinkthatthiswouldnotbeenoughtosupporttherichanddetailedconsciousexperiencethesesubjectsreport.Thusthislookslikeacasewherethereismoreintheconsciousexperienceofthesubjectthancanbeaccountedforbythefirst-orderstates.Ininattentionalinflationsubjectsseeminglyoverestimatetheirvisualphenomenologyinunattendedareas.Theymayreporthighconfidenceinseeingsomethinginanunattendedregioneventhoughtheremayhavebeennothingtosee(andviceversa)andwhentheirperformanceonunattendedstimuliisnotbetterthantoattendedstimuli.

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Inamorecommonsensevein,DavidRosenthal2hasarguedthatthisisacommonoccurrenceinordinaryconsciousexperience.Hehassuggestedthatitisoftenthecasethatwhenweconsciouslyseesomethingasredwemaynotseeitasanexactshadeofred,thoughpresumablywerepresentitassomespecificshadeofredatthatlower-orderlevel.Iftheseviewsarecorrectthenmismatchbetweenlevelscannotbeaproblemforhigher-ordertheories;infactthesecasessuggestthatthemismatchbetweenlevelsgivesrisetoapredictionwhichisempiricallysupported.

Butwhataboutthearguablymoreextremecasewherethefirst-orderstateisaltogetherabsent?Inthese‘empty’higher-orderthoughtcasesthestatewhichthehigher-orderstaterepresentsismissingandsome,notablyNedBlock,havearguedthatthesekindsofcasesposeaseriouschallengetohigher-ordertheories.Thebasicideaofhischallengecanbebroughtoutbyaskingwhichstateitisthatisphenomenallyconscious?Thefirst-orderstatedoesnotexist(bystipulation)andsoitcannotbephenomenallyconscious.TheresponsebytheHORORtheoryistoarguethatthisshowsthatitisthehigher-orderstatewhichisphenomenallyconscious.Rosenthalhassuggestedthatinthesekindsofcasesitisthenotionalnon-existentfirst-orderstatewhichisphenomenallyconscious.Thissoundsveryoddtosomereadersbutallthathemeansbyitisthatthestatewhichisconsciousisthestatethatthehigher-orderthoughtattributestoone.Whilethismaysoundparadoxical–aconsciousstatethatdoesn’texist!-allthatitmeansisthatthestateoneseemstobeindoesnotactuallyoccur.Whilethismaybecorrectthereisstillastrongintuitivepulltotheclaimthatphenomenallyconsciousstatesmustexist.HORORtheoryisausefulalternativetothetraditionalapproachandanswerthatRosenthaldefends.OntheHORORtheoryitisthehigher-orderstatewhichisphenomenallyconscious.Notbecauseitisrepresentedbysomefurtherhigher-orderstate,thoughthatmayoccur,butbecauseitisthekindofstatethatallowsonetobeawareofone’sownmentallife,which,thetheoryclaims,isallthereistophenomenalconsciousness.Box9References1. Brown,Richard(2012).TheBrainanditsStates.InShimonEdelman,TomerFekete&NetaZach

(eds.),BeinginTime:DynamicalModelsofPhenomenalExperience.JohnBenjamins.pp.211-238.2. RosenthalD(2011)Exaggeratedreports:replytoBlock.Analysis71:431-437.BOX10:RESEARCHQUESTIONS

1. Damagetofirst-ordersubcorticalcircuits(includingdefensivesurvivalcircuits,suchasthoseinvolvingtheamygdala)disruptstheexpressionofobjective(behavioralandphysiological)responseselicitedbythreats.Thetheoryproposedheresuggeststhatpeoplewithsuchlesionsshouldstillexperiencefearfulfeelings,butthatthefeelingsmightbemuted.Someevidence,discussedinthepaper,supportstheconclusionthatfearfulfeelingscanpersistinpatientswithamygdaladamage,butthisshouldbestudiedfurther.Whetherquantitativechangesinfearfulexperiencesoccurwithamygdalalesionshasnotbeenstudied.Ifsuchchangesoccur,itwouldbe

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importanttodeterminewhethertheyareduetoalterationsofsignalswithinthebrainitselforoffeedbacksignalsfromthebody,orboth.Quantitativedifferencesmaybeespeciallyimportantinintense,trulyfearful,experienceswherebrainarousalandbodyfeedbackmaybeespeciallyprominent.However,forethicalreasons,experimentalsubjectscannotbeplacedinsituationsthatarouseintensefearfulorotheremotionalexperiences.Thisposeslimitsontheabilitytofullyaddresssuchquestionswithstandardmethodsandresearchpractices.

2. Activityinprefrontalcortexiscorrelatedwithintrospectiveawarenessofthreats.Weproposethatthesamecircuitryunderliestheexperienceof“fear”elicitedbythreats.Evidenceinvolvingstudiesofvisualmaskingandblindsightpatientsdiscussedinthepapersuggeststhatthisisthecase,butrelativelyfewstudieshaveobtainedreportsaboutfeelingsinstudiesinvolvingmaskedthreatsorblindsight.

3. Ourtheoryassumesarepresentational-hierarchicalrelationbetweenfirst-ordersubcorticalcircuits(e.g.amygdala)andhigher-ordercorticalcircuits(e.g.prefrontal)intheexperienceoffear.However,unlikeinperception,foremotionalexperiences,thelower-order(amygdala)andhigher-order(prefrontal)circuitsareactivatedinparallelbysensoryinputs,andthelower-orderstateisnotnecessaryforthehigher-orderstate(seeabove).Theamygdalastatesinourtheoryare,infact,oneofseveralfactorsthatthatcanbiaspatterncompletionofanemotionschemaandgiverisetothehigher-orderstateandtheexperienceoffear.Thecontributionofemotionschematoemotionalexperienceisrelativelyunexplored.Animportantquestioniswhetherandifsohowpatterncompletionleadstoaparticularemotionalexperiencewhenstimuliincompletelyactivateanemotionschema,suchasafearschema.Isthepresenceofathreat,identifiedviamemory,sufficienttogiverisetofear,orisamygdala-triggeredbrainarousal,orfeedbackfromamygdala-dependentbodyresponsesalsonecessary?Andifnotnecessary,whatdotheycontributetotheexperience,ifanything?

4. Nonconsciousworkingmemoryisoftenstudiedusingbriefstimulusexposures,asinmasking.Itisuncleartheextenttowhichlimitationsreportedinsomestudiesareduetotheuseofsuboptimalviewingconditionsinstudiesofnonconsciousprocessing.Nonconsciousconditionsinvolvebriefand/ormaskedexposuresorstimulithatcompetebetweentheeyes,whileconsciousprocessingusesconditionsthatallowunimpaired,richerprocessing.Inblindsightstudiesnonconsciousprocessingcanbestudiedusinglessrestrictedstimulusexposureconditions.Suchstudiesmightbemoresuitableforassessingthecapacityofnonconsciousworkingmemory.

5. Mostworkonthebrainbasisofconsciousnesshasinvolvedcorrelationsbetweenbrainactivityandmeasuresofconsciousness.Forexample,activityinlateralandmedialprefrontalcorticalareasisoftencorrelatedwith

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awareness.Recentworkhasattemptedtogobeyondsimplecorrelationand“decode”experiencefrommultivariatepatternanalysisofbrainactivity.Asofnowtheresultsaremixed.Isthisduetothelackofinvolvementoftheseareasintheexperienceortothefactthatexistingmethodsallowustoidentifycircuitsthatarenecessaryforconsciousexperiencebutdonotallowustodecodethecontentoftheexperience?Correlationsbetweenreportsofawarenessandneuralactivityinspecificareasareusefulbutdonotdemonstratethenecessityoftheactivityfortheexperience.Causalimplicationofareasrequiresconditionsthatinterferewithconsciousness.Whilestudiesofpeoplewithbraindamagearethetraditionalwaytoimplicatebrainareasinbrainfunction,lesionsdonotrespectanatomicalboundaries.Also,becausetheyarepermanent,lesionscanleadtocompensatorychangesinundamagedtissue.Somesuccesshasbeenhadindisruptingreportsofintrospectiveawarenessusingtranscranialmagneticstimulation.Systematicstudiesinwhichtheeffectsofstimulationofeachofthelateralandmedialprefrontalregionsthathavebeenimplicatedthroughcorrelationswouldbeuseful.Becausethekeyareasarewidelydistributedinlateralandmedialprefrontalcortex,negativeresultswithlocalizedstimulationmightneedtobefollowedupwithbroadercoverage.Atthesametime,improvedmethodsforstudyingcorrelationsmightmoreaccuratelypinpointwhichregionstotargetforspecifictasks.

6. Higher-ordertheoriesmakethepredictionthatoneshouldbeabletovarytheconsciousexperienceofasubjectbymanipulatinghigher-orderstatesandmaintainingfirst-orderstates.Converselytheyalsopredictthatoneshouldbeabletoholdtheconsciousexperienceofsubjectsconstantwhilevaryingfirst-orderstates.Someevidencesuggeststhisisthecasebutstudiesdirectlyaddressingthisissuewouldbehelpful.

7. Tofullyempiricallydifferentiatebetweenhigher-orderandglobalworkspacetheoriesofconsciousness(aswellasbetweenthevariantsofthesetheories)weneedtoknowmoreabouttheneuralunderpinningsofcognition.Inparticular,itisnecessarytobeabletodistinguishbetweentheneuralactivityassociatedwiththeglobalneuronalworkspacefromactivityassociatedwiththekindofhigher-orderawarenesspostulatedbyhigher-ordertheories.

8. Futureresearchwillneedassessthepossiblecontributionofdifferentlateralandmedialprefrontalcircuitstodeterminewhichcircuitsandcognitiveprocessescontributetononconsciousrepresentationsasopposedtopossiblehigher-orderrepresentationsofthesethatrendertheprocessingconscious.Inaddition,thequestionofwhetherdifferentaspectsofbothconsciousandnonconsciousprocessinginvolvedifferentsubcircuitsisimportant.

9. Discussionsofconsciousnesstendtoemphasizeprefrontalcircuits.Otherareas,especiallyparietalandinsularareas,arementionedinpassingbutarenotalwaysgivenasmuchconsideration.Futureworkshouldevaluatethese

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areassidebysidewithprefrontalareasinanefforttomoreaccuratelyidentifywhichcircuitscontributetowhichcognitiveprocessesunderlyingspecificaspectsofconsciousexperience.

10. Theroleoftheselfinconsciousness,includingemotionalconsciousness,isrelativelyunexplored,asistheneuralprocessesthatunderlieself-representations,includingself-schema.Thisisaripeareaforresearch.