Explaining the Esoteric Imagination

34 Pages·2017·0.41 MB·English

Aries – Journal for the Study
of Western Esotericism 17 (2017) 17–50
ARIES
brill.com/arie
Explaining the Esoteric Imagination
TowardsaTheoryofKataphaticPractice*
EgilAsprem
StockholmUniversity
[email protected]
Abstract
The imagination is central to esoteric practices, but so far scholars have shown lit-
tle interest in exploring cognitive theories of how the imagination works.The only
exceptionisTanyaLuhrmann’sinterpretivedrifttheoryandrelatedresearchonmental
imagerycultivation,whichhasbeenusedtoexplainthesubjectivepersuasivenessof
modernritualmagic.Thisarticledrawsonrecentworkintheneuroscienceofpercep-
tioninordertodevelopageneraltheoryofkataphatic(thatis,imagerybased)practice
thatgoesbeyondtheinterpretivedrifttheory.Mentalimageryisintimatelylinkedwith
perception.Drawingon“predictivecoding”theory,thearticlearguesthatkataphatic
practicesexploittheprobabilistic,expectation-basedwaythatthebrainprocessessen-
soryinformationandcreatesmodels(perceptions)oftheworld.Thisviewthrowslight
onawiderangeoffeaturesofkataphaticpractices,fromtheircontemplativeandcogni-
tiveaspects,totheirsocialorganizationanddemographicmake-up,totheirpageantry
andmaterialculture.Byconnectingreadilyobservablefeaturesofkataphaticpractice
tospecificneurocognitivemechanismsrelatedtoperceptuallearningandcognitive
processingofmentalimagery,thepredictivecodingparadigmalsocreatesopportuni-
tiesforcombininghistoricalresearchwithexperimentalapproachesinthestudyof
religion.IillustratehowthisframeworkmayenrichthestudyofWesternesotericism
inparticularbyapplyingittotheparadigmaticcaseof “astraltravel”asithasdevel-
opedfromtheGoldenDawntraditionofritualmagic,especiallyintheworkofAleister
Crowley.
* TheresearchforthisarticlewasmadepossiblebyaRubicongrantfromtheNetherlands
Organization for Scientific Research (nwo, project number 446-13-001), and a six-month
researchstayattheDepartmentofPhilosophyandReligiousStudies,NorwegianUniversityof
ScienceandTechnology.ThewritingwascompletedatStockholmUniversity.Iwishtothank
MarkusAltenaDavidsenandtwoanonymousreviewersforusefuladvice,suggestions,and
corrections.
© koninklijkebrillnv,leiden,2017 | doi:10.1163/15700593-01701002
18 asprem
Keywords
mentalimagery–predictivecoding–interpretivedrifttheory–kataphaticpractice–
astraltravel
1 Introduction:ExplainingtheEsotericImagination
Practicesthataimtoproducesubjectivelypowerfulexperiencesarecommon-
place in the history of esotericism. From conversations with angels through
crystalsanderoticencounterswithDivineSophia,toadventuresontheastral
plane and the channelling of ascended masters from the Pleiades, esoteric
practitionersoftenseekspecialknowledgethroughintimateexperienceswith
mediators. Scholars have long agreed that “imagination” is central to these
practices, and it has even been suggested that the imagination is a defining
characteristicof esotericismitself.1Whereveronestandsontheissueof defi-
nitions,itseemssafetosaythatesotericismhashistoricallybeenintertwined
withkataphaticspiritualpractices2—thatis,practicesthatfocusonsensing,
visualizing, and feeling the divine directly.3 Indeed, the kataphatic focus on
positive,personalexperienceofmediatorsgivestoesotericpracticesmuchof
theirheterodoxfeel.
Butwhatdoesitreallymeantosaythatesotericpracticesrelyontheimag-
ination? What is the imagination in the first place, and how does it help us
explainhowphenomenasuchasangelscrying,clairvoyance,orastralprojec-
tionwork?Howarewerelatingtheseeventstocategoriessuchas“dreams”,“hal-
lucinations”,“fantasy”,andplain-old“perception”?Esotericismscholarstendto
besilentonthesematters.Inthepresentarticle,Iwilldrawonrecentperspec-
tivesfromtheneuroscienceofperceptionandthecognitivescienceofreligion
inordertosuggestanexplanatorymodelforkataphaticpracticesingeneral.
Inordertoillustratethemodelanddemonstrateitsusefulnesstohistoriansof
esotericismspecifically,thebulkofthearticle(Section5)isdevotedtoexplain-
ingaparticularlyparadigmaticcaseof esoterickataphaticpractice:theastral
1 Faivre,AccesstoWesternEsotericism,12.
2 SeeAsprem,‘EsotericismandtheScholasticImagination’.
3 Iamassumingakataphatic/apophaticdistinctionalongthelinesusedinthestudyofmys-
ticism.Onthisview,“kataphatic”(kataphasis,“affirmation”)referstotechniquesthatstress
theactivedevelopmentofmentalimageryandsensations,while“apophatic”(apophēmi,“to
deny”)referstoattemptstoquenchorstillthemindbystoppinganymentalcontentfrom
arising.Seee.g.Egan,‘ChristianApophaticandKataphaticMysticisms’.
Aries – Journal for the Study of Western Esotericism 17 (2017) 17–50
explaining the esoteric imagination 19
travelexercisesthathavebecomeastapleelementof occultistmagicdueto
thepopularizationofthemagicalsystemsoftheHermeticOrderoftheGolden
Dawnand,especially,AleisterCrowley.
Iconsider GoldenDawn-style practice,in whichI includeCrowley’selab-
orations,paradigmaticfortworeasons.First,ithasbeenatthecentreof the
debate about the psychologization of magic, and is therefore a key case in
studies of the shifting interpretations of imagery-based practices.4 Secondly,
GoldenDawnpracticeswereatthebasisofTanyaLuhrmann’sgroundbreaking
study,ThePersuasionsoftheWitch’sCraft(1989),whichisstill,ratheramazingly,
theonlymajorattempttoembedoccultistmagicalpracticeinanexplanatory
framework consistent with contemporary cognitive science.5 I will therefore
open this article by discussing Luhrmann’s “interpretive drift” theory (Sec-
tion2).IsharetwoimportantassumptionswithLuhrmann’swork.First,that
the relevant meaning of the term “imagination” is the ability to form men-
talimagery6—which,moreover,canbelongtoanyof theperceptualmodali-
tiesandnotonlyvision.Second,thatkataphaticpractices—esotericorother-
wise—providetechniquesforcultivatingmentalimagery.Inotherwords,kat-
aphaticpractitionersdonotjustlearntotalkinadifferentway,asconstruc-
tionistapproachessometimesinsist,butreallydoaltertheirexperientialreper-
toire.Talkingwithangels,ortravelingontheastralplane,areskillsthatcanbe
trained.Theobjectiveof anyexplanatorytheoryof kataphaticpracticemust
thereforebetounderstandthecausalfactorsthatallowsuchtrainingtotake
place,andtoidentifythematerial,bodily,andmentaltechniquesthatpracti-
tionershaveattheirdisposalinordertohonetheskill.
4 SeeespeciallyHanegraaff,‘HowMagicSurvivedtheDisenchantmentoftheWorld’;Asprem,
‘MagicNaturalized?’;Pasi,‘VarietiesofMagicalExperience’;Plaisance,‘IsraelRegardieand
thePsychologizationofEsotericDiscourse’.SeealsoOwen,ThePlaceofEnchantment,148–
185.
5 ButseeSledge,‘Between“Loagaeth”and“Cosening”’;Klaassen,‘SubjectiveExperienceand
the Practice of Medieval Ritual Magic’; Asprem, ‘Reverse-Engineering “Esotericism”’.The
situationis,ofcourse,differentifwelookatmagicasageneralconcept.SeeespeciallyJesper
Sørensen,ACognitiveTheoryofMagic.
6 “Imagination”isnotawell-definedtechnicaltermincurrentpsychologicalscience.Broadly
speaking,Idifferentiatetwomeaningsthatareanalytically(andprobablyneurologically)dis-
tinct:theabilitytocreatementalimagery,andtheabilitytocreatenovelrepresentations.The
pointinseparatingthesetwoisthatmentalimageryappearstobeaspecialkindofrepresen-
tation,thatisprocesseddifferentlyfrom,e.g.,linguisticorpropositionalrepresentations.For
asurveyoftheevidenceofimageryasaseparatekindofrepresentation,seeKosslyn,Thomp-
son,andGanis,TheCaseforMentalImagery.
Aries – Journal for the Study of Western Esotericism 17 (2017) 17–50
20 asprem
Pursuingthisobjectivetakesmebeyondinterpretivedrift,toarecentneu-
rocognitive theory of perception known as predictive coding (Section 3).7
According to this view, perception is a guessing game. Rather than passively
recordingincomingsensedata,thebrainandthenervoussystemactivelytries
topredictchangesintheenvironmentbyproducingmodelsthatareconstantly
testedagainstexperience.Theperceptsthatweexperiencearethemodelsthat
bestexplainthebody’scurrentsituation.Theyarethebrain’sbestguessesof
whatisoutthere,basedonpreviousexperienceandcurrentpredictiveperfor-
mance.Iarguethatthispredictionmodel,whichhasrecentlybeenembraced
by some researchers in the cognitive science of religion,8 provides an ideal
framework for making sense of mental imagery cultivation (Section 4).This
modelexplicitlyrelatesmentalimagerytotheperceptualprocess,andembeds
perception itself in a generalized model of expectation-based learning. The
predictivecodingframeworkmakesitpossibletodemonstratehowkataphatic
practicesexploitthewaythebrainprocessessensoryinformation.Aftershow-
inghowwecanusetheseprinciplestopaycloserattentiontolittle-discussed
aspectsofastraltravelpractice(Section5),Iclosewithadiscussionofthenew
linesofresearchthatareopenedupbythisapproach(Section6).
2 TheCultivationofImaginationandtheInnerSenses
2.1 TheTheoryofInterpretiveDrift
Framedbytherationalitydebateinanthropology,LuhrmanncastPersuasions
asthestudyof‘acaseinwhichapparentlyirrationalbeliefsareheldbyappar-
entlyrationalpeople,’withanaimto‘identifytheelementswhichseemimpor-
tant to explaining how they do so’.9The theoretical objective was to explain
howhumansarecapableofexperiencingandunderstandingtheworldinrad-
icallydifferentways.Luhrmannfollowededucated,middleclassEnglishpeo-
plethatjoinedsmallmagicalgroups,describedherownparticipationinthe
coursesandexercisesthatwereprescribedtoaspirants,andstudiedhowpar-
ticipantsacquirednewskillsthateventuallyturnedthemintoaccomplished
7 Foraparticularlyluciddiscussionbyaleadingphilosopherofmind,seeClark,‘Whatever
Next?’
8 Schjoedtetal.,‘CognitiveResourceDepletioninReligiousInteractions’;Andersenetal.,‘Mys-
ticalExperienceintheLab’;TavesandAsprem,‘ExperienceasEvent’.SeealsoMarkússon,
‘IndicesintheDark’(thisissue),foranapplicationofthesameframeworktoawhollydiffer-
entproblem.
9 Luhrmann,PersuasionsoftheWitch’sCraft,13.
Aries – Journal for the Study of Western Esotericism 17 (2017) 17–50
explaining the esoteric imagination 21
magicians. Luhrmann described this learning process as “interpretive drift”,
definingitas‘theslowshiftinsomeone’smannerofinterpretingevents,mak-
ingsenseofexperiences,andrespondingtotheworld’.10
Onemightgettheimpressionthatthelearningprocessprovidesinterpre-
tationsof“raw”experiencesthat“justhappen”,butthiswouldbeanincorrect
reading.AsLuhrmannshowedinthechapteronvisualizationpractices—and
in more recent research, as we shall soon see—the specific techniques that
buddingkataphaticpractitionersaretaughtbringthemtopayattentiontothe
contentof theirownmindsandtoavarietyof bodilysensationsinwaysthat
resultinentirelynovelkindsofexperience.11Theprocessofbecomingamagi-
ciandoesnotonlyresultinadriftofinterpretations,butintherebuildingofthe
practitioner’sexperientialworld.Anexplanatorytheoryofthelearningprocess
must therefore account for how and why certain practices can effect lasting
changesinpeople’sexternalandinternalperceptions.
2.2 MentalImageryCultivationasanObjectofResearch
The cultivation of mental imagery has been on the radar of psychologically
informed anthropologists since Richard Noll published a seminal article on
the subject in 1985.12 Noll’s paradigm influenced the interpretive drift the-
ory, but Luhrmann and colleagues have pushed this line of research further
in more recent work.13Their “Spiritual Disciplines Project” investigated how
CharismaticChristianslearntohearthevoiceofGod,focusingonthehypoth-
esisthatkataphaticprayertechniqueswithaheavyemphasisonseeing,feel-
ing, and talking with Jesus may have an effect on practitioners’ abilities to
form mental imagery, as well as increase their chances of reporting sponta-
neous experiences that they appraise as spiritually significant. It should be
notedthat“imagery”,inthiscontext,doesnotreferto visualrepresentations
alone.Luhrmannandcolleaguesprefertalkingabout“innersensecultivation”
inordertohighlightthattheyareinterestedinimageryrelatedtoanyof the
perceptualmodalities(smell,hearing,touch,taste,andvision),includingthe
interoceptive,vestibular,andproprioceptive“bodilysenses”.14
10 Ibid.,12.
11 Ibid.,180–202.
12 Noll,‘MentalImageryCultivationasaCulturalPhenomenon’.
13 SeeLuhrmannandMorgain,‘PrayerasInnerSenseCultivation’;Luhrmann,Nusbaum,
andThisted,‘“Lord,TeachUstoPray”’;CassanitiandLuhrmann,‘TheCulturalKindling
ofSpiritualExperiences’;Luhrmann,WhenGodTalksBack.
14 Respectively,thesearethesenseofthebody’sautonomoussystems,likeheartbeat,respi-
ration,andthedigestivesystem(interoception),thesenseofbalance(vestibularsense),
Aries – Journal for the Study of Western Esotericism 17 (2017) 17–50
22 asprem
TheSpiritualDisciplinesProjecthasdocumentedthatkataphaticprayerhas
a measurable effect on people’s abilities to visualize and their likelihood of
reportingcertainkindsofanomalousexperiences.15However,theresearchhas
also shown that these techniques do not have the same effect on everyone:
Somepeoplearekataphatic“naturals”,whileothersneverlearntoseeorfeel
muchof thespiritualworld.Inparticular,theyfoundthatpeoplewhoscored
highly on tests of the personality trait “absorption” were much more likely
to get something out of kataphatic prayer techniques.16 Further support for
individualdifferenceeffectsarefoundinresearchonmentalimageryvividness
in general: personality factors such as schizotypy17 and fantasy proneness18
arealsoassociatedwithhigherreportedvividness,whilethereappearstobe
amodestgenderdifferenceinfavourofwomen.19Inotherwords,bothspecific
techniquesandindividualdifferencesarecausalfactorsthatinfluencemental
imageryability.
TheSpiritualDisciplinesProjecthasuncoveredanumberofintriguingcor-
relations between personality factors, spiritual practice, vividness of mental
imagery,andthepropensitytohallucinate,butitdoesnotprovideanexplana-
tory account of these connections.That is, it does not propose mechanisms
thatspecifyhowproximatecausesinteracttoproducetheeffects.20Inwhatfol-
lows,Iwillsuggestthattheneurocognitivepredictivecodingframework,asan
action-andexpectation-orientedtheoryofperceptuallearning,offerssuchan
account.Importantly,itdirectsourattentiontoaspectsofthetrainingprocess
thatgobeyondthosecoveredbyinnersensecultivationalone,andpinpoints
specificproximatecausesthatareinvolvedinsuchpractices.
andthesenseofbodyownership(proprioception).Foranuptodatediscussionofthese
(andrelated)aspectsofthesensorium,seeRitchieandCarruthers,‘TheBodilySenses’.
15 Foradetaileddiscussionof theprocedureandanalysisof theresults,seeLuhrmann,
Nusbaum,andThisted,‘“Lord,TeachUstoPray”’,164–171.
16 SeeespeciallyLuhrmann,Nusbaum,andThisted,‘TheAbsorptionHypothesis’.
17 Oerteletal.,‘MentalImageryVividnessasaTraitMarkeracrosstheSchizophreniaSpec-
trum’.
18 AlemananddeHaan,‘FantasyProneness,MentalImagery,andRealityMonitoring’.
19 IsaacandMarks,‘IndividualDifferencesinMentalImageryExperience’.
20 Iassumeacausal-mechanisticviewofexplanationalongthelinespresentedbyCraver
andTabery,‘MechanismsinScience’.Forin-depthdiscussions,seeAspremandTaves,
‘ExplanationandtheStudyof Religion’;TavesandAsprem,Explanation:APrimer.For
anaccessibleoverview,seealsoAspremandTaves,BuildingBlocksofHumanExperience
(url:http://bbhe.ucsb.edu/).
Aries – Journal for the Study of Western Esotericism 17 (2017) 17–50
explaining the esoteric imagination 23
3 ImageryastheMind’sHypothesis:APredictiveCodingAccount
ofImagination,Perception,andHallucination
The predictive coding framework holds that the content of our experience
istheresultof internallygeneratedmodelsratherthanpassiverecordingsof
whatis“outthere”.21Morespecifically,itholdsthattheseinternalmodelsare
predictions—theyarethebrain’sbestattemptsatguessingthebody’scurrent
situation.Contrarytotheold-schoolempiricistview,sensedatadoesnotpro-
viderawmaterialsforconsciousexperience;thesensorystream’sroleisrather
totestaspectsofmodelsgeneratedinsidethebrain.Thebrainguessesxabout
the world, and gets the rest of the body to test the prediction by acting on
theguessandturningtoexpectedstimuli.Ifexpectationsdonotworkout,an
errorsignalissentbacktothebrain.Whensuchsignalsarelow,thehypothe-
sisisconfirmedandwehaveastablepercept.Whenerrorsignalsincrease,the
predictionfailsandthebrainstartslookingfornewmodelsthatmightbetter
explainthesensorystream(seefig.1).
In short, predictive coding is a computing principle that is implemented
intheorganizationof thenervoussystem,whichprovidestheorganismwith
a cost-efficient strategy for interacting with a complex world. A distinctive
featureofthisstrategyisthatitusesprobabilitiesbasedonwhathashappened
inthepastinordertomake“guesses”(ormodels)of whatishappeningnow.
Technically,theseexpectationsareknownas“priorprobabilities”,orpriors.22
On this view, mental images are our stock of perceptual hypotheses, based
on expectations from past experience (i.e., priors).23 Like percepts, imagery
arisesasinternalmodelsinthecorticalareasresponsibleforagivenperceptual
modality—thus, a visual mental image will correlate with neural activity in
the visual cortex indistinguishable from the activation during visual percep-
21 The framework has been developed at the intersection of neuroscience, cybernetics,
andembodiedcognition,especiallyintheworkof KarlFristonandcollaborators.See
e.g.Friston,‘ATheoryofCorticalResponses’;idem,‘TheFree-EnergyPrinciple’;Friston
et al., ‘Perception as Hypotheses’. See also Rao and Ballard, ‘Predictive Coding in the
VisualCortex’;Corlett,Frith,andFletcher,‘FromDrugstoDeprivation’.Asystematicand
accessiblediscussionisavailableinClark,‘WhateverNext?’IbuildprimarilyonClark’s
philosophicallyprovocativeunderstanding,andrefertotheopenpeercommentariesto
hisarticleforfurtherreferences.
22 ThistermisliftedfromBayesianprobabilitystatistics,whichisthemathematicalframe-
workofpredictivecoding.
23 Clark,‘WhateverNext?’,197–199;idem,‘PerceivingasPredicting’.
Aries – Journal for the Study of Western Esotericism 17 (2017) 17–50
24 asprem
figure 1 Thesensoryprocessaccordingtopredictivecoding.Priorprobabilities(expectations)
informtheproductionofinternalmodelsthattrytoactivelyguess(infer)whatis
“outthere”.Thetopillustrationshowsasteadystatewhereaclearperceptisheldin
view.Thesecondillustrationshowsanoldhypothesisbeingrejectedandreplacedfor
anotheraserrorsignalsincrease.This,inturn,leadstoanupdateofthepriors.
Modelscorrespondingtothenewhypothesisaremorelikelytobegeneratedinthe
future.
tion.24Howvividlytheimageisexperienceddependsonhowwelltheseinter-
nal models suppress prediction error at a given moment—prediction error
beingthebrain’sindirectproxyforhowwelltheinternalmodelfitswiththe
outsideworld.25
The error signalling process is always imperfect. Mismatches between an
internal model (the image) and the world outside may happen when they
shouldn’t(leadingtofailuretorecognizefeaturesthatareactuallypresent,or
asearchformorefar-fetchedpatterns),ornothappenwhentheyshouldhave
(leading to misperceptions or hallucinations). Not only are imagination and
perceptionintimatelyrelatedtoeachother,then,buttheyalsostandonacon-
tinuumwithotherexperientialcategoriessuchasdreamsandhallucinations.
24 SeeRaoandBallard,‘PredictiveCodingintheVisualCortex’.SeealsoKosslynetal.,‘Visual
MentalImageryActivatesTopographicallyOrganizedVisualCortex’;Cuietal.,‘Vividness
ofMentalImagery’.
25 Clark,‘PerceivingasPredicting’.
Aries – Journal for the Study of Western Esotericism 17 (2017) 17–50
explaining the esoteric imagination 25
table 1 Keyconceptsofpredictivecoding
Term Meaning
Internal Corticalareasgeneratemodelsoftheexpectedactivityon
generative thelevelsbelowthemintheneuralhierarchy.Generative
model modelsarepredictivehypothesesofexpectedlower-level
activity,basedonpriorprobabilities.Theyaretested(and
updated)bytheprocessingofbottom-uperrorsignalsfrom
thesensoryperiphery.
Prior A(Bayesian)statisticalconceptexpressingtheestimated
probability chanceofsomefutureobservationbasedonwhathas
happenedinthepast.Priorprobabilitiesareconstantly
updatedthroughfeedback-basedinteractionwiththe
environment(learning).
Errorsignal Errorsignalsrepresentamismatchbetweenanexpected
outcomeandanactualoutcome.Theytracktheinaccuracy
ofaninternallygeneratedmodelandtheactivitybelowitin
theneuralhierarchy,whichittriestomodel.
Top-down Predictionsproducedbyinternalmodelsaresignalled
processing downwardsintheneuralhierarchy,fromthecortextothe
sensoryandmotorsystems.Whentop-downprocessing
dominates,subjectsexperiencewhattheyexpect.Top-down
processingisassociatedwith,e.g.,unambiguousperception,
hypnoticinduction,pattern-recognition,hallucinations,and
dreams.
Bottom-up Errorsignalsaresentupwardsinthehierarchy,fromthe
processing sensoryperipherytowardthecortex.Whentheerrorsignal
isstrongandbottom-upprocessingdominates,subjects
willexperienceconstantlyshifting,novelperceptions
andthoughts.Bottom-upprocessingisassociatedwith,
e.g.,attention,learning,disorientation,confusion,and
paranoia.
Aries – Journal for the Study of Western Esotericism 17 (2017) 17–50
26 asprem
The predictive coding framework helps us specify some of the physiological
variablesthatmodulatesuchperception-likeexperiences,offeringimportant
cluestohowandwhymentalimagerymaytakeonperceptualqualities.
Some of the causal factors involved come to view when we look at the
moreextremecasesof alteredperception,suchashallucinations.Hallucina-
tionshaveusuallybeendefinedascompellinglyrealisticperceptionsthatoccur
without a corresponding external stimulus.26 The predictive coding model
complicatesthispicture,becauseitrejectstheviewthatperceptsarebuiltup
“bit by bit” from sense data. Both percepts and hallucinations are internally
generated predictions (mental images) that successfully suppress prediction
erroratagivenmoment.Inhallucinations,however,thishappensbecausethe
error monitoring process is impeded in ways that favour top-down process-
ing.27 This can happen in many ways. One is to cut off the external sensory
stream altogether, whether by removing external stimuli or by blocking the
processingofinformationfromthesensestothecentralnervoussystem.This
accountsforthehallucinatoryexperiencesassociatedwithsensorydeprivation
andsomeformsof visualimpairment(likeCharlesBonnetSyndrome),butit
alsooccursonaphysiologicallevelduringremsleep,whenthebrain’saccess
tosensoryandmotorsystemsisblocked.28Errormonitoringmayalsobedis-
ruptedbyinterferingwiththeneurotransmittersthatmediatebothtop-down
predictionsignalsandbottom-uperrorsignals.29Alterationsonthislevelare
apartofthepictureinhallucinationsinducedbydrugs,psychopathology,and
remsleepalike.
3.1 CultivationBeyondtheBrain:TheRoleofPatternedPracticesand
MaterialCulture
Mental imagery becomes more vivid when top-down processing outweighs
bottom-up processing of prediction errors. While sensory deprivation and
intakeofpsychotomimeticdrugsarecapableofjumblingthisbalanceinways
thatproducedramaticshiftsinperception,theeffectsaregenerallyshort-lived.
26 See,e.g.,Sacks,Hallucinations,ix–xi.
27 SeeespeciallyCorlett,Frith,andFletcher,‘FromDrugstoDeprivation’.
28 Seeibid.,523–526;HobsonandFriston,‘WakingandDreamingConsciousness’;cf.Hobson
andFriston,‘Consciousness,Dreams,andInference’.
29 Errorsignalsarethoughttobemediatedbyampaandgabareceptorswhiletop-down
predictionsaremediatedbynmdareceptors.Arangeofneurotransmitterssuchasdopa-
mine, acetylcholine, and serotonin, are thought to regulate the “gain” or “weight” on
thesesignals.Foradiscussion,seeespeciallyCorlett,Frith,andFletcher,‘FromDrugsto
Deprivation’,517–519.
Aries – Journal for the Study of Western Esotericism 17 (2017) 17–50