Physiological and Subjective Sexual Arousal in Self-Identified

14 Pages·2011·0.44 MB·English

ArchSexBehav(2011)40:699–712
DOI10.1007/s10508-010-9671-7
ORIGINAL PAPER
Physiological and Subjective Sexual Arousal in Self-Identified
Asexual Women
LoriA.Brotto • MoragA.Yule
Received:27October2009/Revised:27July2010/Accepted:27July2010/Publishedonline:21September2010
(cid:2)SpringerScience+BusinessMedia,LLC2010
Abstract Asexuality can be defined as a lifelong lack of ofinteroceptiveawarenessamongasexuals.Takentogether,
sexualattraction.Empiricalresearchonasexualityrevealssig- thefindingssuggestnormalsubjectiveandphysiologicalsex-
nificantlylowerself-reportedsexualdesireandarousaland ualarousalcapacityinasexualwomenandchallengetheview
lowerratesofsexualactivity;however,thespeculationthat thatasexualityshouldbecharacterizedasasexualdysfunc-
there may also be an impaired psychophysiological sexual tion.
arousalresponsehasneverbeentested.Theaimofthisstudy
wastocomparegenital(vaginalpulseamplitude;VPA)and Keywords Asexuality(cid:2)Genitalarousal(cid:2)
subjectivesexualarousalinasexualandnon-asexualwomen. Vaginalpulseamplitude(cid:2)Hypoactivesexualdesiredisorder(cid:2)
Thirty-eight women between the ages of 19 and 55years Sexualattraction
(10heterosexual,10bisexual,11homosexual,and7asexual)
viewedneutralanderoticaudiovisualstimuliwhileVPAand
self-reportedsexualarousalandaffectweremeasured.There Introduction
werenosignificantgroupdifferencesintheincreasedVPA
and self-reported sexualarousal response to the erotic film Humanasexualityis,looselydefined,astheabsenceofsexual
betweenthegroups.Asexualsshowedsignificantlylesspositive attraction.Inthelastseveralyears,therehavebeenanumberof
affect, sensuality-sexual attraction, and self-reported auto- empiricalexaminationsfocusedonthedescriptionofasexu-
nomicarousaltotheeroticfilmcomparedtotheothergroups; alityandthecharacterizationofasexualindividuals.Theonly
however,therewerenogroupdifferencesinnegativeaffect existingstudytoexploretheprevalenceofasexualityfound
or anxiety. Genital-subjective sexual arousal concordance thatapproximately1%ofthepopulationreportalackofsexual
was significantly positive for the asexual women and non- attraction (Bogaert, 2004) and therefore likely identify as
significantfortheotherthreegroups,suggestinghigherlevels ‘‘asexual.’’Otherswhohavestudiedasexualityhaveemployed
differing definitions, including: a lack of sexual behavior
(Rothblum&Brehony,1993),alackofsexualorientation(Storms,
1980), and a lack of sexual desire or excitement (Prause &
Graham,2007).WiththeemergenceofGoogle,thisallowed
L.A.Brotto
individuals who previously had great difficulty finding and
DepartmentofObstetricsandGynaecology,UniversityofBritish
Columbia,Vancouver,BC,Canada interactingwithotherasexualsonlinetoeasilylocateoneanother
and develop an online group where questions and answers
M.A.Yule
couldbeposed,andexperiencescouldbesharedandexplored.
DepartmentofPsychology,UniversityofBritishColumbia,
Thelargestonlineweb-communityofasexuals,knownasthe
Vancouver,BC,Canada
AsexualityVisibilityand Education Network (AVEN), was
L.A.Brotto(&) foundedin2001byJay,andthegroupcametodefinethem-
DivisionofGynaecologicOncology,UniversityofBritish
selvesanotherway—focusingonthelackofsexualattraction
Columbia,2775LaurelSt.,6thFloor,Vancouver,BCV5Z1M9,
butaddingthat‘‘everyasexualexperiencessexualdesireand
Canada
e-mail:[email protected] arousalsomewhatdifferently’’(Jay,2003).
123
700 ArchSexBehav(2011)40:699–712
The development of this ‘‘community,’’ led by AVEN’s and that this might be due to a higher threshold for sexual
founder,Jay,hasfacilitatedtheemergenceofanonline‘‘asexual arousalintheformer.Ifthisweretrue,itwashypothesizedthat
identity’’(Scherrer, 2008), as the structure of AVEN’s pages theasexualswouldshowlowerscoresonameasureofsexual
werespecificallydesignedaround‘‘theprocessofidentityfor- arousability.AlowscoreontheSexualArousabilityInventory
mation’’(Jay,2003,p.6).Asthecuriousbutnot-yet-self-iden- (Hoon, Wincze, & Hoon, 1976) was the best predictor of
tified asexual navigated from‘‘static pages’’providing basic membership in the asexual compared to the sexual group.
informationandadefinitionofasexualitytotheinteractive‘‘web Moreover, low scores on the dyadic sexual desire and the
forum,’’ a collective identity of asexuality was thought to solitarysexualdesiresubscalesoftheSexualDesireInventory
emerge(Jay,2003;Scherrer,2008).Thelabelingandidentifi- (Spector, Carey, & Steinberg, 1996) as well as the sexual
cationofoneselfasasexualisamajoraimofAVENandthe excitationsubscaleoftheSexualInhibitionandSexualExci-
asexualitymovement,andlikelyrepresentssomethingakinto tation Scales (Janssen, Vorst, Finn, & Bancroft, 2002) also
thehomosexualityidentitymovementofthe1950sand1960s significantlypredictedasexualitygroupmembership.Thus,in
that was facilitated by the Mattachine society (Sears, 2006). additiontoPrauseandGraham’sspeculationsaboutlowdesire
Morethanavehicleforfacilitatingidentityformation,AVEN best differentiating asexuals from sexuals, it was, in fact,
isalsousedtotransformthiscollectiveidentityintocollective measures of arousability that best distinguished the groups.
action,providingeducationtothegreaterpublicwiththegoalof PrauseandGrahamsuggestedthatmeasuringsexualarousal
lesseningstigmaassociatedwithasexuality. withpsychophysiologicalinstrumentsmightfurtherelucidate
There has been a recent frenzy of media attention on iftheseobservedgroupdifferencesinarousalmightalsoapply
asexuality(e.g.,20/20,2006;CNNShowbizTonight,2006; toasexuals’sexualphysiologicalresponding.
FoxNewsDayside,2006;MontelWilliamsShow,2007;The Inamorerecentstudydesignedtoexploresexualresponse
View,2006;TuckerCarlson,2006),someofwhichhassug- anddistressinasexuals,187asexualmenandwomencom-
gested that asexual individuals experience a type of sexual pletedaweb-basedquestionnairefollowedbyin-depthtele-
dysfunction known as Hypoactive Sexual Desire Disorder phoneinterviewswithasubsetof15asexuals(Brottoetal.,
(HSDD),andthatthisgroupmayrepresentthepolarlowerend 2010).Amongthoseasexualswhohadbeensexuallyactivein
ofthedesirecontinuum(MontelWilliamsShow,2007).The thepast4weeks,womenshowedlowarousalscoresonthe
implications,ifthisassumptioniscorrect,aresignificantgiven FemaleSexualFunctionIndex(Rosenetal.,2000)compara-
thecurrentclimateofsexualpharmaceuticalsandincreasing bletoalargervalidationgroupofwomenwithFemaleSexual
concentrationondiagnosing,treating,andcuringlowsexual ArousalDisorder(FSAD;Wiegel,Meston,&Rosen,2005).
desire(Tiefer,2002,2006).Upontheasexual’spresentationto However, asexual men showed normal levels of erectile
thesextherapyclinic,perhapsattheinsistenceofadistressed functioning(theanalogueofarousalinmen)ontheInterna-
anddissatisfiedpartner,theremaybeaprematuretemptation tional Index of Erectile Functioning (Rosen et al., 1997),
on the part of the clinician to seek pharmaceutical and/or suggestingthatifarousalwasimpaired,itmightbeafeature
hormonal treatments for the lifelonglackofsexualinterest. onlyoffemaleandnotofmaleasexuality.Inthequalitative
However, the existing data suggest that asexuals do not phaseofthisstudy,severalasexualsspokeabouttheirgenitals
experiencedistressnorwanttobe‘‘fixed’’(Brotto,Knudson, insomewhattechnical,emotionallybarelanguageandmost
Inskip, Rhodes, & Erskine, 2010; Pagan Westfall, 2004), believed that they lacked a sexual arousal response (Brotto
makingasexualityfundamentallydifferentfromHSDD.And etal.,2010).
althoughasubgroupofwomenwithHSDDsimilarlyreport Althoughthislimitedresearchproposesthatgenitalsexual
being satisfiedwiththe prospect ofnever havingsex again, arousalinasexualsmightbeimpaired(alongwithself-repor-
what seems to separate this group from asexuals is that the ted desire), to date, there have been no studies of asexuals’
latter report never having experienced desire or sexual psychophysiological sexual response to a competent sexual
attractionwhereastheformermayhaveexperienceddesireat stimulus,andpriorstudiesthathavemeasuredsexualarousal
somepointbutthenlostit.Inreality,theprecisedelineation utilized a self-report questionnaire focused on retrospective
between lifelong HSDD and asexuality is unclear, and this recalloverafixedperiodoftime.Thus,theextenttowhich
‘‘grayzone’’requiresfurtherstudy. asexuals’self-reportsoflackofsexualarousalreflectsubjective
In one qualitative study with four asexuals, Prause and only,physiologicalonly,orbothaspectsofsexualrespondingis
Graham(2007)notedthatsexualarousal,inadditiontosexual unknown.
desire, might also be impaired. One female participant Sexualpsychophysiologicaltechniqueshavebeenusedin
expressedthatasexuallyexplicitfilmwouldhavenoeffecton researchthroughoutthetwentiethcentury,andmorerecently
hersexualarousal(thoughsexualarousalwasnotassessedin havebeenusedinstudiesofsexualorientation.Thefieldgained
that study). In a follow-up quantitative phase, Prause and widespreadinterestfollowingtheworkofMastersandJohnson
Grahamthereforepredictedthatasexualswouldreportlower (1966)whostudiedthesexualarousalpatternsoftheirpatients
levelsofsexualarousalcomparedtoagroupofnon-asexuals usingavarietyofphysiologicalmeasures.Inwomen,vaginal
123
ArchSexBehav(2011)40:699–712 701
photoplethysmography is one of several psychophysiological The concordance between subjective and psychophysio-
techniques (Sintchak & Geer, 1975). It involves a tampon- logical sexual arousal has been a very important and inter-
shaped,usuallyacrylic,probe,whichemitsinfraredlightand estingaspect ofstudy inthe vaginal photoplethysmography
providesanindexofabsorbedlightcorrespondingtothedegree literature.Thisresearchhasconsistentlyshownalowcorre-
ofgenitalcongestion.Thestudyofvaginalphotoplethysmog- lationbetween self-reported sexualarousal and VPAacross
raphyhasledtosomeimportantadvancesinourunderstanding numerous studies (as summarized in the meta-analysis by
ofwomen’ssexualresponse.Forexample,whereasmenshow Chivers,Seto,Lalumiere,Laan,&Grimbos,2010),andcon-
patternsofgenitalarousalthatcorrespondtotheirstatedsexual cludesthatwomenshowsignificantlylessgenital-subjective
orientation(Rieger,Chivers,&Bailey,2005),lesbianandhet- concordancethanmen.Intheirreview,Chiversetal.predicted
erosexualwomenshowedthesamedegreeofincreaseinvaginal thatconcordancewouldbelowwhenactualgenitalresponding
pulseamplitude(VPA;themoresensitiveandspecificindexin waslow.Itfollows,therefore,thatifVPAwaslowinasexual
vaginalphotoplethysmography),regardlessoftheirstatedsex- women,genital-subjectiveconcordancemightalsobelowdue
ualorientationandirrespectiveofthestimulishown—whether toinabilitytodetectchangesinbloodflow(Heiman,1977).
heterosexual,homosexual,ornon-humanprimate(Chivers, Theaimofthepresentstudywastocomparegenitaland
Rieger, Latty,& Bailey, 2004; Chivers, Seto, & Blanchard, subjectivesexualarousalinasampleofasexualwomenwith
2007). If such ‘‘target non-specificity’’ was a feature of all responses to women from other sexual orientation groups
women,includingasexuals,thenonemightpredictthatasexual (heterosexual, homosexual, and bisexual women). We pre-
women would show a similar degree of genital response to dicted lower levels of self-reported sexual arousal in the
stimulicomparedtoheterosexualandlesbianwomendespite asexual women compared to the other groups. Regarding
theirstatedpreferencefornosexualpartners. VPA, we predicted that if asexuality was characterized by
AnotherreasonwhyonemightpredictsimilarVPAresponses atypicalsexualresponses,thenwewouldfindlowerVPAin
inasexualwomencomparedtoothersexualorientationgroups the asexuals compared to the other three groups, but we
stemsfromtherecentfindingthatthemajority(77%)ofasex- hypothesized no significant group differences in VPA if
ual women had engaged in masturbation—the average fre- asexualitywasnotreflectiveofproblematicsexualrespond-
quencyofwhichwasonce/month(Brottoetal.,2010),aresult ing.Weincludedahomosexualandbisexualsampleofwomen
thatreplicatespreviousresearchindicatingthatasexualsdid basedontheconclusionsofChiversetal.(2004,2007)that
not differ significantly from non-asexuals in their desire to womenshowanon-targetspecificpatternofgenitalrespond-
masturbate (Prause & Graham, 2007).Although this specu- ing.Thus,weexpectedthatallgroupsofwomenwouldshow
lationisbasedonindirectreasoning,itispossiblethatbecause thesamepatternofVPAtotheheterosexualstimuli.Wealso
ahighlevelofgenitalarousalisnecessaryfororgasmtooccur explored the degree of concordance between genital and
(Bassonetal.,2003;Masters&Johnson,1966),andbecause subjective sexual arousal in each of these subgroups sepa-
orgasm is a positive reinforcer of masturbation (Herbenick rately.
etal.,2009),itmaybethatasexualsexperienceanormallevel
ofgenitalarousalwhich,inpart,providesincentivefortheir
masturbatoryactivity. Method
If,ontheotherhand,asexualitywassimplyonemanifes-
tationofalifelongsexualdysfunction,ashasbeensuggested Participants
bysome(seereviewofthistopicontheonlineasexualityblog
byPretzelboy,2009),thenonemighthypothesizelowerlevels A total of 38 women between the ages of 19 and 55years
ofsexualarousalwhilebeingtestedinacontrolledlaboratory participated in this study (10 heterosexual, 10 bisexual, 11
environmentwithpotentsexualstimuli.Thereissomelimited homosexual,and7asexual),andwereassignedtosexualori-
evidence for this assertion: In some select subgroups of entation group according to self-identification. Participants
women,thosewithself-reportedgenitalarousalimpairments were recruited through several separate avenues, including
were found to have significantly lower VPA compared to a postings on local websites (e.g., Craigslist), on the AVEN
sexuallyhealthycomparisongroup(Brotto,Basson,&Gorz- onlineweb-community,throughtheuniversity’shumansub-
alka, 2004; Pieterseetal.,2008; Wincze, Albert, &Bansal, jectpool,andthroughadvertisementsinthecommunity.The
1993),andwomenwithHSDDwerefoundtohavedifferent wordingofadvertisementsdiffereddependingonwhichsex-
patternsofactivationonfunctionalmagneticresonanceimag- ual orientation group was being targeted. Two separate ads
ingcomparedtowomenwithoutHSDD(Arnowetal.,2009). wereusedtotargetasexuals.Bothadsread,‘‘Doyouexperi-
Thus,ifasexualitywascharacterizedbyatypicalsexualresponse encealackofsexualattractiontowardsothers?’’and‘‘Doyou
intheformoflackofsexualexcitement,thenonemightpredict findithardtorelatewhenpeopletalkaboutsexualattraction?’’
significantly lower levels of physiological arousal in asexual Thefirstadalsoincludedthetext‘‘TheSexualHealthLabis
womencomparedtowomenofothersexualorientationgroups. looking for female participants who identify as asexual,
123
702 ArchSexBehav(2011)40:699–712
straight,lesbianorbisexualtotakepartinastudyonsexual desiredomainincludeditemssuchas‘‘Overthepast4weeks,
orientation.’’Thesecondaddeliberatelydidnotcontainany howoftendidyoufeelsexualdesireorinterest?’’Examples
referencetoself-identificationasasexual.Bothadsfurtherread of items from the arousal domain included:‘‘Over the past
‘‘Ifyoucanrelatetothestatementsabove,pleasecontactusfor 4weeks,howoftendidyoufeelsexuallyaroused(‘‘turnedon’’)
moreinformationaboutthisstudy.’’Themajorityofasexual duringsexualactivityorintercourse?’’and‘‘Overthepast4
women(N=6)wererecruitedviatheAVENwebsiteandone weeks,howconfidentwereyouaboutbecomingsexuallyaroused
asexualwomanwasrecruitedviathesecondad.Self-identi- duringsexualactivityorintercourse?’’Thetotal FSFIscore
ficationasasexualwasfurtherverifiedinpersonaccordingto was obtained by summing the scores from the individual
thefree-responseitemonthedemographicquestionnairethat domains,withhigherscoresonthismeasureindicatingbetter
askedwomentowritetheirsexualorientationstatus. levelsofsexualfunction.Ifonedomainsubtotalcouldnotbe
Theaverageageofparticipantswas28.1yearsforhetero- calculated(duetomissingitems),thenneithercouldtheFSFI
sexuals(SD=3.8),22.8yearsforbisexuals(SD=4.4),36.3 total score. The FSFI has been validated as an appropriate
years for homosexuals (SD=11.1), and 33.6 for asexuals tooltodifferentiatebetweenwomenwithandwithoutFSAD
(SD=9.9),andtherewasasignificantgroupdifferenceinage, (Wiegeletal.,2005),hasahighdegreeofinternalconsistency
F(3,34)=5.76,p\.01,withbisexualwomenbeingyounger (Cronbach’saof0.82andhigher),andhightest–retestreli-
than the other groups. There were no significant group dif- ability(r=.79–.86).Inlightofsomeconceptualandstatistical
ferencesinhighestlevelofeducationachieved,v2(3)=5.58, problemsidentifiedbyMeyer-BahlburgandDolezal(2007),
p\.05,withthemajorityofparticipants(100%ofhomosex- adjustmentsweremadetothescoringoftheFSFIinthecurrent
ual,90%ofbisexual,91%ofhomosexual,and86%ofasexual) study in that any woman who had not engaged in sexual
havingatleastsomepost-secondaryuniversityeducation. activity over the preceding month received‘‘missing value
Fiftypercentofheterosexuals,70%ofbisexuals,63%of codes’’foritemsinquiringaboutsexualresponseduringsexual
homosexuals,and28%ofasexualsindicatedthattheywere activity(asopposedtoreceivingazeroscore,whicherrone-
currentlyinacommittedrelationship,andtheseproportions ously inflates scores denoting dysfunction (Brotto, 2009)).
differed significantly, v2(3)=10.21, p\.05, with asexuals Missingcodeditemswerethenexcludedfromthecalculation
beingleastlikelytobeinarelationship.Themajority(70–90% oftheFSFItotalscoreandwerenotincludedinthecalculation
acrossgroups)identifiedthemselvesasEuropean/Canadian. ofthemeanforthatsubscaleacrossallparticipants.
DetailedAssessmentofSexualArousal(DASA)
Measures
TheDASAisanunpublishedquestionnairethathasbeenfound
DemographicInformation tosignificantlydifferentiateaspectsofsexualarousalinwomen
with arousal difficulties (Basson & Brotto, 2003). Subscales
Participantswereaskedtocompletedemographicinformation include:mentalexcitement,genitaltingling/throbbing,genital
on ethnicity, sex/gender, sexual orientation, occupation, wetness, and pleasant genital sensations, with each subscale
annualincome,education,presenceofsexualconcerns,rela- assessinglevelofarousalinresponsetoavarietyofdifferent
tionshipstatus,numberofsexualandromanticpartners,and formsofsexualstimulation(e.g.,fromverbal/writtenstimulito
masturbationfrequency.Allquestionswereinafree-response breaststimulationtovariousformsofgenitalstimulation).Items
formatgiventhefindingthatasexualsresponddifferentlyto wereratedona1–7Likertscalefrom(1)lowto(7)intense.
forced choice versus free response formats in answering
questionsaboutgenderandsexualorientation(Brottoetal., SexualDesireInventory(SDI)
2010; Prause & Graham, 2007), apart from questions per-
taining to education, relationship status, and masturbation TheSDI(Spectoretal.,1996)isa15-itemself-administered
frequency,whichhadforced-choiceresponseoptions. questionnaire intended to be a specific measure of sexual
desire.UnliketheFSFIsubscaleofdesire,whichfocuseson
frequencyandintensityoffeelingdesire,theSDIattemptsto
FemaleSexualFunctionIndex(FSFI) captureacognitive(ratherthanbehavioral)aspectofsexual
desire,andproducesatotalSDIscoreaswellasdyadicand
TheFSFI(Rosenetal.,2000)isa19-itemscaleassessingsix solitarydesiresubscalescores.Individualsnotinarelationship
domainsofsexualfunction:desire,subjectivearousal,lubri- areabletoreceiveascoreonthedyadicsubscale,astheitems
cation, orgasm, satisfaction, and pain during sexual activity focusonsexualthoughtsanddesiresinvolvingapartner,and
overthepastmonth.Itemswereratedona6-pointscale,with notsexualbehavior,asillustratedwiththefollowingitemon
lowerscoresindicatinglowerlevelsofsexualfunctioning,and the SDI:‘‘During the past month, how often have you had
azeroscoreindicatingnosexualactivityinthepastmonth.The sexual thoughts involving a partner?’’ The SDI has been
123
ArchSexBehav(2011)40:699–712 703
validatedwithnon-clinicalpopulationsofhealthywomenand joined by accompanying background music). A 1-min seg-
men.Itemswereratedonan8-pointscale,withhigherscores mentinwhichtheword‘‘Relax’’wasdisplayedonthetelevi-
indicatingbetterlevelsofsexualdesire. sion screen with no audio output preceded these films.
Participantswatchedoneoftwofilmsets,eachcontaininga
FilmScale neutral and erotic segment, and previous research has sup-
portedthesimilarityofwomen’sarousaltoandratingsofthese
TheFilmScale(Heiman&Rowland,1983)isa34-itemself- twofilmsets(Brotto,Basson,&Luria,2008).
reportquestionnairethatassessesperceptionofgenitalsexual
arousal(e.g.,warmthingenitals,genitalpulsingorthrobbing), Procedure
subjectivesexualarousal(e.g.,turnedon),autonomicarousal
(e.g.,fasterbreathing,fasterheartbeat),anxiety,positiveaffect Our university’s clinical research ethics board approved all
(e.g.,pleasure,interested,excited),negativeaffect(e.g.,wor- procedures.Participantsrespondingtocommunityandonline
ried, angry, disgusted), and sensuality-sexual attraction (e.g., advertisementstookpartinatelephonescreeningprocesswith
sensuous,adesiretobeclosetosomeone,sexuallyattractive)in onetrainedfemaleresearchassistantinwhichtheproceduresof
responsetosexualstimuli.Itemswereratedona7-pointLikert the study were described and any questions answered. They
scalefrom(1)notatallto(7)intenselyinwhichparticipants weretoldthattheywouldbewatchingheterosexualfilmsand
indicated how much they endorsed each item at the present that if this were objectionable to them, they could withdraw
moment. fromthestudy.Nonewithdrewfollowingthetelephonescreen-
ing.Thepurposeofthescreeningwasalsotoensurethatwomen
PsychophysiologicalRecording inthe‘‘probableasexual’’groupdidnotmeetcriteriaforHSDD.
Todoso,aseriesofquestionsbasedontheDSM-IV-TRcriteria
Genitalarousalwasmeasuredusingthevaginalphotoplethys- for HSDD (American Psychiatric Association, 2000) were
mographandtheVPAsignalwastheprimaryendpointgiven askedbyatrainedinterviewer.Althoughwomenmayhavemet
that it is a sensitive and specific measure of genital arousal criterionA(i.e.,absent/deficientdesireforsexualactivity),none
(Laan,Everaerd,&Evers,1995).Asinglevaginalprobe(Behav- met criterion B (i.e., marked distress). Women in the other
ioral Technology Inc., Salt Lake City, UT) measured VPA, sexualorientationgroupsweresimilarlyaskediftheyexperi-
whichwasmonitoredthroughoutexposuretoeachneutraland encedanysexualdifficultieswiththeintentthatanywomanwho
erotic film segment. VPA was recorded on a personal com- didwouldbeexcluded;nonemetthisexclusioncriterion.
puter(HPPentiumMLaptop),whichcollected,converted(from Participants were tested from 2008 to 2009 in a psycho-
analogtodigital,usingaModelMP150WSWdataacquisition physiologicalresearchroomlocatedintheuniversityhospital,
unit[BIOPACSystems,Inc.]),andtransformeddata,usingthe whichcontainedacomfortablerecliningchair,twobookcases,
softwareprogramAcqKnowledgeIII,Version3.8.1(BIOPAC alargescreenTV,anintercom,andasinkwithsmallcupboard
Systems,Inc.,SantaBarbara,CA).Thesignalwasband-pass unit. A thin blanket was placed over the seating areaofthe
filtered(0.5–30Hz)andasamplingrateof200samples/swas chair.Followingwrittenconsent,participantsweretestedbya
usedforVPAthroughouttheneutralanderoticfilmexposure. femaleresearcher.
Artifactsmoothingtookplacefollowingvisualinspectionofthe Next, participants completed the questionnaire battery in
databyaninvestigatorwhowasblindtothesexualorientation the private psychophysiology room and were provided with
groupoftheparticipant,anddataweresubsequentlyanalyzedin further instructions about the vaginal photoplethysmograph
30-ssegments.ForanalysesofVPA,wecomparedthefirstthree andtheremainderoftheprocedures.Theresearcherthenleft
30-ssegmentsoftheneutralconditiontothelastfive30-sseg- theroomwhileparticipantsinsertedtheprobeandinformedthe
mentsoftheeroticcondition.Theprobewasdisinfectedina researcheroftheirreadinessviaintercom.Inordertohabituate
solutionofCidexOPA(ortho-phthalaldehyde0.55%),ahigh to the testing environment, participants were encouraged to
leveldisinfectant(AdvancedSterilizationProducts,Irvine,CA, relaxonacomfortablerecliningchairfora10minperiodafter
USA),promptlyfollowingeachsession. theprobewasinsertedbutbeforewatchingthevideosegments.
Subjectivesexualarousalandaffectwereassessedattheendof
SexualStimuli theadaptationperiodusingtheFilmScale.
FollowingthecompletionoftheFilmScale,thevideosequence
Participantsvieweda3-minneutralfilm(eitheradocumentary began.Theaudiocomponentwasdeliveredviawirelesshead-
aboutleimakingoratravelogueaboutHawaii)followedbyan phones.Immediatelyafterthevideosequence,participantsfil-
8-min erotic film (a Candida Royalle, female-friendly film ledoutasecondFilmScale,whichaskedthemtoevaluatehow
consisting of progressively increasing sexual intensity of theyfeltduringthelast(erotic)film.Theyweretheninstructed
heterosexualmanualgenitalstimulation,oralsex,andpenile- toremovetheprobeandmeettheresearcherinaseparateroom
vaginal intercourse clips which were spliced together and wheretheyhadtheirfinger-lengthsmeasuredusingastandard
123
704 ArchSexBehav(2011)40:699–712
computerscanner(datanotpresentedhere).Participantswere scored significantly lower than every other group of women,
debriefedandprovidedwitheither$20remunerationor2course with no significant between-group differences between the
credits,dependingonrecruitmentmethod. heterosexual,homosexual,orbisexualwomen(Table1).
DuetooneparticipantnotcompletingtheSDI,information
StatisticalAnalyses ondesireforsolitaryanddyadicsexwasbasedonsixasexuals.
OntheSDIDyadicsubscale,theoverallANOVAwassignifi-
Baselinegroupcomparisonsusedanalysisofvariance(ANOVA) cant,F(3,33)=12.83,p\.001,withaTukey’stestshowing
followedbytheTukey’smultiplecomparisonstestincasesofa significantlylowerdyadicdesireintheasexualscomparedto
significant overalleffect. Giventhesignificantgroup differ- theheterosexual(p\.001),homosexual(p\.001),andbisex-
enceinage,weconductedarepeatedmeasureANOVAwith ual(p\.001)women.TheoverallANOVAwasnotsignifi-
age as the covariate (ANCOVA) for all sexual arousal end- cantontheSDISolitarysubscale,F(3,33)\1,indicatingno
points.TherewasnosignificantFilmxAgeinteraction,p[ significantgroupdifferencesindesireforsolitarysexualactiv-
.05.Wethusdidnotcovaryforageinremaininganalysesand ity(Table1).
insteadconductedaseriesofGroup9FilmANOVAs.Effect Duringtheneutralbaselineperiod,therewerenosignificant
sizesforallrepeatedmeasuresanalyseswerecalculatedwith groupdifferencesonanymeasureofsubjectivesexualarousal,
thepartialeta-squared(g2). affect,orperceivedautonomicarousalontheFilmScale,all
ps[.05.
Results PhysiologicalSexualArousal
MeasuresofSexualFunction There was a significant main effect of Film on VPA, F(7,
231)=30.77,p\.001,partialg2=0.48,suchthattheerotic
Due to incomplete data from one asexual, information on film increased VPA in all groups. There was no significant
masturbationfrequencywasbasedonsixasexuals.Therewere Group9Film interaction, F(21, 231)\1, partial g2=0.04
no significant group differences in masturbation frequency, (Fig.1).
F(3,33)\1,withameanfrequencyofbetweenonetothree
timespermonth(Table1),andtheserateswerecomparableto Self-ReportedSexualArousal
thoseinapreviousstudyofmasturbationfrequencyinasex-
uals(Brottoetal.,2010).AccordingtotheFSFI,four(57%) Onsubjectivesexualarousal,therewasamaineffectofFilm,
outofsevenasexualshadbeensexuallyactive,eitheraloneor F(1, 34)=61.33, p\.001, partial g2=0.64, such that sub-
withapartner,inthepast4weeks.Thecorrespondingratesfor jective arousal increased after the eroticfilm.There was no
heterosexual,bisexual,andlesbianwomenwere:90,100,and significant Group9Film interaction, F(3, 34)\1, partial
82%.There wasa significantoverallANOVAeffectonthe g2=0.06 (Fig.2A). On perceived physical sexual arousal,
FSFIDesiresubscale,F(3,37)=8.67,p\.001.ATukey’stest therewasasignificantmaineffectofFilm,F(1,34)=101.34,
showedtheasexualwomentohavesignificantlylowerscores p\.001, partial g2=0.75, such that the erotic film signifi-
than the heterosexual (p=.001), bisexual (p\.001), and cantly increased reports of perceived genital arousal. There
homosexual(p=.011)women,withnoneoftheothergroups was also a marginally significant Group9Film interaction,
significantlydifferingfromoneanother.Therewerenosig- F(3, 34)=2.52, p=.075 which suggested that there was a
nificantoverallANOVAeffectsonFSFIArousal,F(3,31)= morerobustincreaseinperceivedgenitalarousalinthenon-
1.88;FSFILubrication,F(3,30)\1;FSFIOrgasm,F(3,31)\ asexualgroupscomparedtotheasexualgroup;however,the
1;FSFISatisfaction,F(3,25)=1.41;FSFIPain,F(3,22)\1; effectsizewassmall,partialg2=0.18(Fig.2b).Onthesen-
ortheFSFITotalScore,F(3,21)\1(Table1).Scoresonthe suality-sexualattractiondomainoftheFilmScale,therewasa
FSFI subscales of Desire, Arousal, and Lubrication in the significant Group9Film interaction, F(3, 34)=3.41, p=
presentstudywerealsocomparabletothoseofasexualwomen .028,partialg2=0.23,whichrevealedsignificantincreasesin
in previous research (Brotto et al., 2010); however, asexual sensuality-sexualattractionwithexposuretotheeroticfilmin
womeninthepresentstudyhadslightlyhigherscoresonthe the heterosexual, homosexual, and bisexual women but no
FSFIsubscalesofOrgasmandPainandslightlylowerscores significantchangeamongtheasexualwomen(Fig.2c).
ontheSatisfactionsubscale.
OntheDASA,therewasasignificantoverallANOVAfor Self-ReportedAffect
mentalsexualarousal,F(3,34)=15.79,p\.001;genitaltin-
gling/throbbing, F(3, 34)=12.44, p\.001; genital wetness, TherewasasignificantGroup9Filminteractiononpositive
F(3,33)=4.19,p=.013;andpleasantgenitalsensations,F(3, affect,F(3,34)=2.96,p=.046,partialg2=0.21,whichshowed
34)=12.51,p\.001.Foreachofthefoursubscales,asexuals thatonlythenon-asexualgroupsexperiencedasignificant
123
ArchSexBehav(2011)40:699–712 705
Table1 Sexualbehaviormeasuresasafunctionofgroup
Measure Group p
Heterosexual Bisexual Homosexual Asexual
(n=10) (n=10) (n=11) (n=7)
Masturbationi
Never 3(30%) 1(10%) 2(18.2%) 2(33.3%) ns
Fewtimes/year 1(10%) 2(20%) 3(27.3%) 1(16.7%)
Once/month 1(10%) 0(0%) 1(9.1%) 1(16.7%)
2–3/month 2(20%) 1(10%) 0(0%) 1(16.7%)
Once/week 0(0%) 0(0%) 3(27.3%) 0(0%)
2–4/week 2(20%) 6(60%) 2(18.2%) 0(0%)
Once/day 1(10%) 0(0%) 0(0%) 1(16.7%)
[Once/day 0(0%) 0(0%) 0(0%) 0(0%)
M(SD) M(SD) M(SD) M(SD)
FSFIdesirea 3.90(1.55) 4.38(1.23) 3.38(1.32) 1.37(0.29) \.01
FSFIarousalb 4.87(1.58) 4.77(1.20) 4.67(1.24) 3.00(1.82) ns
FSFIlubricationb 4.90(1.47) 5.22(1.22) 5.27(0.87) 4.60(1.14) ns
FSFIorgasmb 5.02(1.56) 4.76(1.40) 4.80(1.61) 4.30(1.58) ns
FSFIsatisfactionc,j 4.67(1.25) 4.67(1.30) 5.20(0.56) –h ns
FSFIpainb,j 5.45(0.83) 5.30(0.97) 5.20(1.60) –h ns
FSFItotalscored 28.61(7.15) 28.21(7.11) 28.47(7.23) –h ns
DASAmental 5.56(1.11) 5.29(0.67) 4.63(1.43) 2.19(0.76) \.001
arousale
DASAgenital 5.23(1.15) 5.27(0.91) 4.72(1.47) 2.21(0.81) \.001
tingling/throbbinge
DASAgenital 4.86(1.65) 4.56(1.32) 4.61(1.51) 2.48(1.43) \.01
wetnesse
DASApleasant 5.96(1.24) 5.64(0.79) 4.71(1.65) 2.28(1.41) \.001
genitalsensationse
SDIdyadici,f 39.30(14.58) 46.20(6.89) 38.27(13.96) 10.33(5.16) \.001
SDIsolitaryi,g 11.70(7.83) 11.80(6.83) 10.45(5.28) 7.00(6.20) ns
Absoluteranges:a1.2–6,b0–6,c0.8–6,d2–36,e1–7,f6–62,g2–23;hnotavailable;ibasedon6asexuals;jbasedon1asexualsodataarenotpresented
nsnon-significant
increase in positive affect with the erotic film (Fig.3a). On
1.00 negativeaffect,therewasneitheramaineffectofFilm,F(1,
34)\1, partial g2=0.02, nor a significant Group9Film
0.80 interaction,F(3,34)=1.71,partialg2=0.13(Fig.3b).Anxi-
V) 0.60 ety significantly decreased following exposure to the erotic
m filminallgroups,F(1,32)=10.07,p=.003,partialg2=0.24,
VPA ( 0.40 with no Group9Film interaction, F(3, 32)\1, partial g2=
0.04(Fig.3c).
0.20
neutral erotic
0.00 Self-ReportedAutonomicArousal
30 60 90 300 330 360 390 420
Time (s) TherewasasignificantinteractionbetweenGroupandFilmon
heterosexual bisexual homosexual asexual self-reported autonomic arousal, F(3, 34)=5.06, p=.005,
partialg2=0.31,aswellasamaineffectoferoticfilm,F(1,
Fig.1 Effectsofneutralanderoticstimulionvaginalpulseamplitude
34)=40.08,p\.001,partialg2=0.54.Multiplecomparison
(VPA) during the first 90s of neutral and last 150s of erotic film
conditions.Errorbarsindicatestandarderrorofmeasurement(SEM) revealedasignificantincreaseinautonomicarousalwiththe
123
706 ArchSexBehav(2011)40:699–712
Fig.2 Effectsofneutraland
neutral
eroticstimulionasubjective
sexualarousal,bself-reported erotic
physicalsexualarousal,and 5 5.5
a b
csensuality-sexualattraction
inheterosexual,bisexual, sal
u
homosexual,andasexual 4 o 4.4
women.Errorbarsindicate sal al ar
SEM u u
o x
exual ar 3 sical se 3.3
e s 2 phy 2.2
ctiv ed
ubje 1 port 1.1
S e
elf-r
S
0 0.0
heterosexual bisexual homosexual asexual heterosexual bisexual homosexual asexual
5
c
4
n
o
cti
a
Attr 3
al
u
x
e 2
S
y/
alit
u
ns 1
e
S
0
heterosexual bisexual homosexual asexual
Feriogt.i3cstEimffueclitsonofanpeoustirtaivleaanfdfect, a 5.5 b 2.0
neutral
bnegativeaffect,canxiety, 1.6
anddautonomicarousal ct 4.4 erotic ect
ihnomheoteseroxsueaxl,uaanl,dbaisseexxuuaall, e affe 3.3 ve aff 1.2
wSEoMmen.Errorbarsindicate Positiv 2.2 Negati 0.8
1.1 0.4
0 0
heterosexual bisexual homosexual asexual heterosexual bisexual homosexual asexual
c 3.5 d 5
2.8 al 4
s
u
o
y 2.1 ar 3
et c
xi mi
An 1.4 no 2
o
ut
0.7 A 1
0 0
heterosexual bisexual homosexual asexual heterosexual bisexual homosexual asexual
123
ArchSexBehav(2011)40:699–712 707
eroticfilminallgroupsexcepttheasexuals,wheretherewas
nosignificantincrease(Fig.3d).
Physiological-SubjectiveConcordance
Differencescoresbetweeneroticandneutralstimuluscondi-
tions were calculated for subjective sexual arousal and per-
ceivedphysicalsexualarousal.Apercentchangescorewas
calculatedfor VPA((erotic-neutral)/neutral).The Pearson
product-momentcorrelationwasthencalculatedbetweenthese
transformedvariablesandexaminedineachgroupseparately.
Amongtheasexualwomen,therewasastrongpositivecor-
relationbetweenVPAandsubjectivesexualarousal(p=.036)
andperceivedgenitalarousal(p=.05).Ascanbeseenbythe
scatterplots for the asexual women, these results were not
accountedforbyoutliers,andinstead,representarelatively
linear pattern (Fig.4). Correlations between VPA and self-
reportmeasureswerenotsignificantforanyoftheotherthree
subgroups(Table2).
Discussion
SummaryofFindings
Overall,thefindingsrevealednosignificantdifferencesbetween
asexualwomenandheterosexual,homosexual,orbisexual
womeninthegenitalarousalresponsetoaheterosexualaudio-
visualeroticstimulusinacontrolled,laboratoryenvironment.
Instead,allwomenshowedasignificantincreaseinresponseto
theeroticfilm.AmaineffectofFilmwasalsofoundforsub-
jectivesexualarousalinthatallgroupsshowedasignificant Fig.4 ScatterplotsofapercentchangeinVPAvs.subjectivesexual
arousal,andbpercentchangeinVPAvs.self-reportedphysicalsexual
increase,withnosignificantgroupdifferences.Onperceived
arousalforasexualwomen(n=7)
genital arousal, there was a trend towards a Group9Film
interactionsuchthattherewaslessofanincreaseamongthe
asexualscomparedtotheothergroups;however,thisdidnot GenitalArousalResponses
reachstatisticalsignificance.Giventhesmalleffectsize,this
effectmightnotbemagnifiedwithalargersample.Aspre- The lack of a significant Group9Film interaction on VPA
dicted,therewasasignificantGroup9Filminteractiononthe cannotonlybeattributedtolowsamplesizesgiventhatthe
sensuality-sexualattractiondomainoftheFilmScalesuchthat effect size (partial g2) was small. Nonetheless, these results
therewasasignificantincreasefollowingtheeroticfilminall shouldbereplicatedinalargersampleofasexuals.Inwomen,
groupsexcepttheasexualwomen. physiological measures such as VPA (Brotto et al., 2004;
On other self-report measures of affect, there was a sig- Pieterseetal.,2008)andfMRI(Arnowetal.,2009)havebeen
nificant Group9Film interaction for positive affect to the found to differentiate women with and without sexual dys-
eroticstimulussuchthatasexualsdidnotshowtheincreasein functioninsomestudiesbutnotinothers(Laan,vanDriel,&
positive affect with the erotic stimulus seen by the other vanLunsen,2008).Ourfindingslendsupporttothespecula-
groups.Therewerenomaineffectsofgrouporfilmonneg- tion(Bogaert,2006;Brottoetal.,2010;PaganWestfall,2004)
ativeaffect,andanxietydecreasedbyasimilarmagnitudefor thatasexualityisnotasexualdysfunction—orperhaps,more
allwomenwithexposuretotheeroticstimulus.Interestingly, precisely, it is not a disorder of sexual arousal. In studies
there was a significant Group9Film interaction for auto- exploringVPAdifferenceswithregardtosexualorientation,
nomicarousalinthatallwomenshowedasignificantincrease heterosexualandhomosexualwomendidnotdiffer,regardless
withtheeroticfilmexcepttheasexuals. ofthestimulustypeshown(Chivers&Bailey,2005;Chivers
123
708 ArchSexBehav(2011)40:699–712
Table2 Correlationsbetween
Perception p Subjective p
percentchangeinVPAand
ofgenital sexualarousal
perceptionofgenitalsexual
sexualarousal
arousalandsubjectivesexual
arousalasafunctionofgroup
Heterosexual r(9)=.327 ns r(9)=-.038 ns
Bisexual r(9)=-.229 ns r(9)=-.108 ns
Note:ValuesrepresentPearson Homosexual r(10)=-.392 ns r(10)=-.247 ns
productmomentcorrelation
Asexual r(6)=.753 .05 r(6)=.787 .036
coefficients.dfinparentheses
etal.,2004,2007;Peterson,Janssen,&Laan,2010).Thatasex- domainanalysis, lower scoreswould have been revealed in
ual women responded to heterosexual stimuli despite their thisgroup.
statedpreferencefornosexualpartnersisconsistentwiththe Sinceallwomenwereincludedinanalysesoflaboratory-
targetnon-specificityseeninhetero-andhomosexualwomen. inducedsubjectivearousalandthisshowedanoverallsignif-
Specifically, work by Chivers et al. has consistently shown icantincrease,thissuggeststhat,regardlessofcurrentsexual
that,amongwomen,thereisthesame(strong)magnitudeof activity, asexual women are capable of experiencing sub-
VPA among different sexual orientation groups to stimuli jective sexualarousal inresponseto a sexualstimulus. One
depictingmale–male,female–female,andmale–femaleactor recentstudythatexaminedsubjectivesexualarousalbasedon
pairings,despitethefactthatself-reportedarousallevelscor- thedegreeof‘‘absorption’’(i.e.,theabilitytoimmerseoneself
respondedwiththestimulioftheirstatedpreference.Ourdata in a stimulus without being distracted by other competing
alsoshowedthatbisexualwomen—whopreviouslyhavenot stimuli;Koukounas&McCabe,1997)intheeroticfilmfound
beenthesubjectofVPAresearch–hadthesamemagnitudeof thatthosewomenwhoweregiveninstructionstobecomemore
VPAincreaseasallothergroups.Ifourspeculationthattarget absorbedinthefilmshowedhigherlevelsofsubjectivesexual
non-specificityisaphenomenonaspertinenttoasexualwomen arousalcomparedtothosewhowereinstructedtoviewasa
asitistowomenofothersexualorientationgroups,thenthis passiveobserver(Sheen&Koukounas,2009).Becauselackof
alsosuggeststhatconclusionsdrawnabouttheautomaticityof absorption has been associated with difficulties with infor-
women’ssexualresponding,whichmayhaveevolvedtobe mationprocessingandpossiblyattentionaldisruption(Cran-
adaptationstopromotefacilegenitalpenetrationandminimize ston-Cuebas&Barlow,1990),ourfindingssuggestthatthese
physicaldamage(Chiversetal.,2007),alsoextendtoasexual cognitiveandattentionalpathways,whichareimportantfor
women.Furthermore,one might alsospeculate that asexual sexualresponding,areintactinasexualwomen,andanystated
women’s VPA responses to male-male and female-female apathytowardssexualstimulioractivityisnotduetofaulty
eroticstimuliwouldbeasrobustastheircurrentlyobserved cognitiveorattentiveprocesses.
responsestomale-femalestimuli,andwouldnotdifferfrom There was a significant Group9Film interaction on sen-
heterosexualandhomosexualwomen. suality-sexual attraction in the predicted direction with all
womenexcepttheasexualsshowingasignificantincreaseto
SubjectiveArousalResponses theeroticstimulus.Theindividualitemscomprisingthissub-
scaleinclude:‘‘adesiretobeclosetosomeone’’and‘‘sexually
Therewerenosignificantgroupdifferencesinsexualarousal attractive.’’Giventhatasexualsdefinethemselvesaccordingto
whenmeasuredbytheself-reportFSFIorwhenmeasuredin alackofsexualattraction(Jay,2005),ourfindingssuggestthat
response to a laboratory stimulus. However, on the DASA, despiteasexuals’normalsexualarousalresponsetocompetent
which assessesdifferent components ofsexual arousal (i.e., stimuli,theydonotexperiencethecorrespondingmotivationto
mental sexual arousal vs. genital tingling vs. lubrication vs. directthatexcitementtowardsapotentialsexualmate.Clarity
pleasantgenitalsensations),asexualwomenreportedsignifi- onthismaybegleanedbyconsideringtheincentivemotivation
cantlylowerlevelsthantheotherthreegroups.Thesedatasug- modelofsexualresponse,whichpositsthateachindividualhas
gestthatwithacompetentsexualstimulus(suchasthecondi- asexualresponsesystemthatcanbeactivatedbycompetent
tions during the psychophysiological assessment), asexuals sexual stimuli (Both, Everaerd, & Laan, 2007; Everaerd &
showeda robustsubjectivesexualarousal responsethatdid Laan,1995).Acomponentofthemodelisthedispositionto
notsignificantlydifferfromnon-asexuals.Moreover,because respond to those stimuli with some form of sexual activity,
FSFIarousalratingswerebasedonlyonthose(asexuals)who which,inandofitself,thengeneratessexualdesire.This‘‘dis-
weresexuallyactive(57%),thelackofsignificantgroupdif- position’’islikelyinfluencedbycentralandperipheralneuro-
ferencessuggeststhatasexualitydoesnotinterferewithasex- transmitter-hormone interactions (Laan & Both, 2008), and
uallyactivewoman’sabilitytobecomearoused.Thearousal can be measured by reflexes of the Achilles tendon, reflect-
patterns of sexually inactive women are unknown, and it is ing an‘‘action tendency’’(Both, van Boxtel, Stekelenburg,
possiblethatifallwomenwereincludedintheFSFIarousal Everaerd,&Laan,2005).Themodelviewssexualdesireasan
123