Trait or State? A Closer Look at the Construct Validity of
the Amsterdam Sexual Pleasure Index (ASPI) in a
Psychophysiological Study
Laura SchutteUniversity of Amsterdam
Research Master Psychology
Student-number: 10002094
Internal supervisors: Arjen Noordhof and Vanessa van Ast, University of Amsterdam
External supervisor: Ellen Laan, AMC, department Sexology and Psychosomatic Gynecology Date: 17th of August 2017 – 25 EC
2 Abstract
Recently, a questionnaire named the Amsterdam Sexual Pleasure Index (ASPI) – was developed to measure the propensity to experience sexual pleasure. Sexual pleasure may be defined as the feeling of enjoyment from varying sexual activities either with partner or alone. The aim of this study was to further explore the construct validity of the ASPI in a sample of women with and without sexual problems. First, it was investigated whether the ASPI measures sexual pleasure more as a trait rather than a state, by examining the effect of a neutral compared to an erotic context on the ASPI. Since the ASPI is assumed to measure a tendency (i.e. trait), it was hypothesized that this questionnaire is not sensitive to contextual influences. Second, to clarify its convergent validity, the ASPI was correlated with trait-like and theoretically related
measurements. Exploratorily, it was investigated whether arousal concordance predicted sexual pleasure in women. The evidence was inconclusive regarding the question whether the ASPI measures a trait or state. The ASPI was moderately correlated to sexual functioning, sexual distress, erotophilia and orgasm-consistency. Moreover, arousal concordance was no significant predictor of sexual pleasure. The construct validity of the ASPI remains to be investigated. However, in accordance with the initial validation study, the findings indicated that the propensity to experience sexual pleasure, as measured with the ASPI, is likely to be a reliable, stable and multi-faceted construct.
3 Table of Contents
Acknowledgement 4
1. Introduction 5
2. Methods 10
2.1. Participants: Inclusion and Exclusion Criteria 10
2.2. Measures and Materials 10
2.2.1. Questionnaires 10
2.2.2. Erotic Stimuli 13
2.2.3. Physiological Measures 13
2.3. Study Design 14
2.4. Procedure Neutral Context Condition 15
2.5. Procedure Erotic Context Condition 16
2.6. Data Reduction 16
2.7. Sampling Plan using the Bayesian Method 17
2.8. Data Analyses 17
3. Results 19
3.1. Sample Characteristics 19
3.2. Test of Context-Effect on ASPI (Hypothesis 1) 22
3.3. Analyses of ASPI’s Reliability and Convergent Validity (Hypothesis 2) 25 3.4. Predictive validity: Arousal Concordance and the ASPI (Hypothesis 3) 29
4. Discussion 30
5. References 34
Appendix A – Technical Details VPA Measurement 40
4 Acknowledgement
Writing this thesis has made me value practicing scientific research even more than I already did during the course of my studies. I learned that all aspects from the empirical cycle demand a proportional amount of time, energy and effort (even the smallest aspects like lay-outing text and tables). There is much more below the surface of a research paper than appears at first sight! Although my thesis process had not always been flawless, I did enjoy conceptualizing and conducting the research in the field of sexology. I want to thank all the people that helped me writing my thesis. First of all, I want to thank Ellen Laan for providing excellent supervision and feedback based on her extensive expertise and knowledge within the field of (clinical) psychology and sexology. Her colleague Marian Nievaard has also helped me a lot with the organizational and practical aspects doing this research. Also, I want to thank PhD-student Quinten Gronau, who has supported me with the Bayesian analyses in this study. Moreover, I am thankful for my UvA-supervisor Arjen Noordhof, who provided valuable feedback and was always willing to help during the somewhat messy process of writing this thesis. Next, I want to thank Bruno Boutin and Bert Molenkamp for the technical support they provided. Without Bruno (and the longitudinal-research program ‘Lotus’ he developed) I was not able to design the set-up of the research. In addition, I want to thank my colleague and co-research master student Marlene Werner, and all the people from the methods desk for their structure and statistical advises. Of course, I also want to thank my partner, friends and family for the mental support in the most stressful times. Last but not least, I want to thank the members of the thesis- and medical ethical committee for their specific instructions to improve and approve this study.
5 1. Introduction
Sexual pleasure is fun, healthy and important. Or isn’t it? Notably, the World Health Organization considers the possibility to obtain pleasurable sexual experiences a necessary requirement for sexual health (WHO, 2004). Its definition of sexual health stresses the presence of physical, emotional, mental and social wellbeing in relation to sexuality, besides the absence of sexual problems (WHO, 2004). Moreover, sexual wellbeing is likely to moderate sexual distress (Stephenson & Meston, 2015) and even seems to be related to overall happiness and quality of life (Laumann et al., 2006). However, most scientific studies have focused on sexual
dysfunctions, diseases and risks (e.g., low sexual desire, HIV prevention, sexual harassment) (Impett, Muise, & Breines, 2013). Although this focus has yielded valuable results, attention towards sexual pleasure and its underlying factors could offer directions on how to promote one’s sexual potential and health (Pascoal, Sanchez, Raposo, & Pechorro, 2016.)
But what exactly is sexual pleasure? Sexual pleasure may be defined as the psychological and/or physical sense of enjoyment obtained from any erotic stimulation and/or sexual
interaction (e.g., Abramson & Pinkerton, 1995; Phillpott, Knerr, & Boydell, 2006). Even though pleasure is often reported as an important goal for sex both in media and science (Graham, 2012; Rye & Meany, 2007), there have been very few scientific studies on its correlates, predictors and determinants (Laan, Bloemendaal, Gaasterland, & van Lunsen, in preparation).1 The little attention can be attributed to leading sociocultural conceptions, in which orgasm is regarded as synonymous with sexual pleasure (Masters & Johnson, 1966 cited in Opperman, Braun, Clarke, & Rogers, 2014). Only recently qualitative studies point out that the importance of orgasm is highly personal and variable (Opperman et al., 2014) and that other factors, such as emotional, cognitive and physical (e.g., sensory stimulation) components, also contribute to the experience of sexual pleasure in the context of both solitary and partnered sexuality (Goldey, Posh, Bell, & van Anders, 2016; Pascoal, Narciso, & Pereira, 2014). Thus, a broader scientific
conceptualization of sexual pleasure - and the role of orgasm herein - is warranted (Graham, 2012).
1
Sexual satisfaction, on the other hand, has been studied scientifically, mainly in the context of heterosexual
relationships. However, sexual satisfaction and sexual pleasure – although related (Pascoal et al., 2016) – can be considered two different concepts, since sexual satisfaction seems to be dependent on past (relational) experiences, an evaluation of costs and benefits (e.g., absence of problems), and what one thinks (s)he is entitled to have (Philippsohn & Hartmann, 2009; Van Lunsen & Laan, 2017). Thus, it is suggested that sexual pleasure would be the positively valued feelings stemming from sexual activity, irrespective of an evaluation of costs and benefits over time. Therefore, sexual pleasure should be measured differently than sexual satisfaction.
6 The Amsterdam Sexual Pleasure Index
A search of the literature indicates that a reliable and validated questionnaire about the concept of sexual pleasure is lacking. Two short scales concerning sexual pleasure do exist since recently, which are the Quality of Sexual Events (Sanders et al., 2013) and the Sexual Pleasure Scale (Pascoal et al., 2016). However, these scales do not tap into the possible aspects that constitute sexual pleasure, but try to determine the quality and extent of (physical and emotional) pleasure regarding recent sexual experiences. A more encompassing scale about the concept of sexual pleasure could reveal the specific aspects to focus or therapeutically intervene on, in order to stimulate one’s sexual experience and knowledge (Boul et al., 2009; Sanders et al., 2013). Accordingly, such a scale would prove useful and important for clinical and educational practices.
Therefore, sexology researchers at the Academic Medical Centre (AMC) in Amsterdam recently developed a questionnaire to assess the individual propensity to experience sexual pleasure: the Amsterdam Sexual Pleasure Index (ASPI) (Laan et al., in preparation). Based on qualitative research about the various motivations people could have for sex, multiple aspects were deemed relevant for the concept of sexual pleasure, such as physical pleasure, emotional pleasure and intimacy, openness to sexual experiences and communication about sexual wishes (Higgins & Hirsch, 2008; Laan et al., in preparation). These aspects were incorporated into 52 items (reviewed by experts on sex research) that together compose the ASPI. The items reflect both solitary and partnered sexuality, and were carefully written to avoid implicit assumptions or reinforce normative ideas about (hetero)sexuality (Laan et al., in preparation). Moreover, the ASPI is designed to measure the positive feelings associated with sexual behavior in the broadest sense, regardless of situation, sexual orientation, gender or partner status. Thus, sexual pleasure is in this questionnaire conceptualized as a multifaceted, stable and (relatively) context independent construct.
According to the initial validation study with 431 participants (61% women and 39% men), the ASPI shows a five-component structure (Laan et al., in preparation). The components were labeled as follows: Partner Related Pleasure, Sexual Self-Efficacy, Arousal Enjoyment, Sexual and Body Confidence and Closeness/Intimacy. Moreover, the ASPI could discriminate between people with and without sexual dysfunctions: both men and women with sexual problems scored lower on the total score. In addition, the internal consistency of the total score was considered
excellent (Cronbach’s alpha = .94) and the test-retest reliability (with an interval of 10 days) was good (Spearman Rank correlation = .81).
7 research is needed to further explore the construct validity of the ASPI. Specifically, the pilot study was limited in studying the correlates and predictors of this questionnaire. Also, the pilot study did not clarify - considering the relatively short time between first and second completion - whether the ASPI measures the intended stable, context independent construct. Accordingly, the current study focused on investigating its contextual/situational independence, convergent validity and predictive validity in more detail.
Trait/State Theory
Since the ASPI is designed to measure a person’s propensity, or overall tendency, to experience sexual pleasure, it is assumedthat the ASPI measures sexual pleasure as a trait rather than a state. Namely, a trait can be defined as an intrinsic pattern, or tendency, to think, behave and/or feel in a certain way that is relatively stable over time and context (e.g., Funder, 1991; Spielberger, 1966). Long-lasting influences, such as genes, learning processes and societal standards, are assumed to contribute to the development of traits (e.g., Stark et al., 2012), whereasa state, which is an emotion, thought or behavior at a given moment, is largely determined by situational and fluctuating factors and is more transitory than a trait (Spielberger, 1966). Despite being relatively stable over time and context, traits are likely to interact with a situation, such that a trait
determines (the level of) corresponding state changes in a trait-relevant situation (e.g., Funder, 1991). A trait is in this sense also situation-specific. Thus, trait variance between individuals will only become visible in trait-relevant contexts.
To give an example regarding the field of sexology: a sexual trait requires the presence of a trait-congruent sexual stimulus, cue or context in order to affect the level of a certain sexual state (e.g., sexual arousal) (Endler, 1997).2 As such, former studies have indicated that sexual desire is dependent on the experience of sexual arousal, which is in turn dependent on the evaluation of a sexual cue or context (Singer & Toates, 1987). Successively, this evaluation is a product of experience, memory, physiological reactions and current context, reflecting both shorter and long-lasting influences (e.g., Baumeister, 2001; Stark et al., 2015).Thus, states result from the joint influence of many factors, among which enduring traits, situational cues and appraisal of those cues.
2 This interrelation is similar to the (sexual) incentive motivation model (Laan & Both, 2008; Singer & Toates, 1987),
which assumes that a sexual mood is the result of an interaction between a sexual response system, stimuli (incentives) and an evaluation of that system’s response in combination with these stimuli (Laan & Both, 2008).
8 Examining Construct Validity: Influence of Context
A questionnaire that measures a trait should not be strongly dependent on a specific moment, situation or context in which it is completed. Previous research with the State-Trait Anxiety Inventory (STAI) has illustrated the relative stability and flexibility of, respectively, a trait and a state in different contexts. When investigating the impact of surgery-induced stress, trait-anxiety remained stable, whereas state-anxiety decreased significantly postsurgery compared to
presurgery (Auerbach, 1973).
Therefore, to test whether the ASPI is stable, context independent construct (i.e. a reflection of a trait), it is examined whether or not there is variation in ASPI-scores between a neutral and an erotic context. It is hypothesized that there is no variation in ASPI-scores between these two contexts. However, when context does have an effect on the ASPI, this would indicate that a state is measured next to a trait. Thus, only when no context-effect is present, it can be assumed that the ASPI is solely a measurement tool for trait-level sexual pleasure and not (also) of state-level sexual pleasure.
Examining Construct Validity: Reliability and Convergent Validity
To further explore the construct validity of the ASPI, this study’s second research question concerns the reliability and convergent validity of this questionnaire (Campbell & Fiske, 1959; Cronbach & Meehl, 1955). In accordance with the pilot study, reliability is provided with determining internal consistency and test-retest reliability. Convergent validity is provided with moderate (both positive and negative) correlations between the ASPI and construct-related measures. Convergent validity is expected between the ASPI and five other research instruments: (i) the Female Sexual Functioning Index (FSFI), (ii) the Female Sexual Distress Scale-Revised (FSDS-R), (iii) the Sexual Opinion Survey (SOS), which measures the tendency for positive attitudes towards sexual stimuli (erotophilia) (Fisher, Byrne, White, & Kelley, 1988), (iv) the ECR-2010 anxiety subscale, which measures attachment anxiety – and (v) a questionnaire that measures orgasm consistency during a variety of sexual activities.
Respectively, (i) sexual functioning and (ii) sexual distress are expected to be moderately to highly related to the ASPI, such that individuals with better sexual functioning and lower sexual distress are more inclined to experience sexual pleasure. (iii) Positive sexual attitudes possibly influence the willingness to engage in sexual behaviors and the level of pleasure experienced during sexual activities. Accordingly, people score high on erotophilia, also would have a higher score on the ASPI. In addition, (iv) anxiously attached individuals probably have difficulties enjoying sex, as they are often preoccupied with intrusive thoughts about rejection
9 during sex (e.g., Butzer & Campbell, 2008), and thus,would have a lower score on the ASPI. Moreover, (v) since orgasm is often seen as a part (or even a goal) of sexual pleasure (Opperman et al., 2014), the correlation between the ASPI and the orgasm consistency questionnaire is expected to be high, such that people who are more likely to orgasm in sexual situations are also more likely to have a high score on the ASPI.
In addition, it is investigated exploratorily to what extent both genital and subjective arousal converge with a score on the ASPI. This will indicate how state sexual responses (i.e. bodily and mental arousal) are related to the propensity to experience sexual pleasure as measured with the ASPI. It is expected that the correlations would probably be moderate to high, since an arousal response in reaction to (positively valued) sexual stimuli is an integral part of healthy sexual functioning (e.g., Laan, Van Driel, & Van Lunsen, 2008), and therefore, possibly also of sexual pleasure. Moreover, when a person allows sexual arousal to intensify, there is more opportunity to enjoy the sensations, which would aid to the experience of sexual pleasure (Basson, 2005).
Examining Construct Validity: Potential Predictive Validity
A third and final research question regarding the construct validity of the ASPI was formulated, and was tested exploratorily: how does arousal concordance (i.e. the agreement between genital and self-reported subjective sexual arousal) predict the ASPI-score? Previous research has shown that the level of genital arousal is less in concordance with the level of self-reported subjective sexual arousal in women than in men, and is highly variable between women (e.g., Chivers, Seto, Lalumière, Laan & Grimbos, 2010). These findings have long been established, but researchers have only recently begun to explore the moderators and mediators of the variation in arousal concordance (Suschinsky, Dawson & Chivers, 2017). Although the findings diverge, several studies indicate that arousal concordance is related to healthy sexual functioning (i.e. sexually functional women seem to show more arousal concordance than sexually dysfunctional women) and frequency of orgasms in women (Brody, 2007; Brotto & Chivers, 2016). Therefore, arousal concordance could be a relevant predictor of sexual pleasure. In this study it was examined whether the extent of arousal concordance differed between symptomatic and non-symptomatic women, and whether it could predict sexual pleasure. Accordingly, this third research question contributes, while preliminary, to the predictive validity of the ASPI.
10 Aim
In short, this research is directed at investigating the construct validity of the ASPI in more detail, regarding (a) contextual/situational independence (since the ASPI is conceptualized as a trait) (b) the internal consistency, test-retest reliability over context and the convergent validity of the ASPI, and (c) the exploratory predictive validity in relation to arousal concordance.
In this study, the erotic context was designed as a controlled situation in which genital- and subjective arousal was induced through erotic film-exposure and genital vibration.
Moreover, this study was conducted with a convenience sample of only female heterosexual participants (with and without sexual problems) in order to reduce costs, time and any possible experimenter bias on the sexual arousal response of a participant, since the investigators of this study were also female.
2. Methods 2.1. Participants: Inclusion and Exclusion Criteria
For this study, both women with and without sexual problems were recruited via advertisement flyers, website links, social media and the database of the Sexology department at the AMC. Inclusion and exclusion criteria were assessed by means of a short online screening
questionnaire. Inclusion criteria consisted of being 18 years or older, having had heterosexual experience (stimulation of genitalia) and willing to look at erotic, heterosexual film-clips.
Exclusion criteria consisted of pregnancy six months prior to study start, chronic disease, vaginal infection, oophorectomy/radiation of the ovaries, vaginal surgery, and diagnosis of mental illness. Eligible participants were randomly divided in either the neutral- or erotic context
condition (conditions were counterbalanced, see Figure 1). Participants that partook in the erotic context condition, were compensated €10 + travel costs. The Medical Research Ethics
Committee (MREC) of the AMC approved this study.
2.2 Measures and Materials 2.2.1. Questionnaires
Amsterdam Sexual Pleasure Index (ASPI)
The ASPI is a self-report questionnaire of sexual pleasure with 52 items measured on a 6-point Likert scale, varying from 0 (“strongly disagree”) to 5 (“strongly agree”). The pilot study indicated that the ASPI consists of five subscales: Partner Related Pleasure (i.e. pleasure from presence or interaction with partner), Sexual Self-Efficacy (i.e. perceived ability to gain sexual pleasure), Arousal Enjoyment (i.e. physical and psychological pleasure from being sexually
11 excited), Sexual and Body Confidence (i.e. feeling secure and attractive during sex) and
Closeness/Intimacy (i.e. sexual pleasure in relation to intimacy during sex). The total score ranges from 0-260 with higher scores representing a higher propensity towards experiencing sexual pleasure. An example item is: “I enjoy it when my body reacts to sexual stimuli”. ‘Sex’ is defined as all sexual activities that could result in arousal or pleasure, with a (casual) partner or alone. Internal consistency is considered excellent (Cronbach’s alpha = .94) and the test-retest reliability was good (Cronbach’s alpha = .81).
Female Sexual Function Index (FSFI)
The FSFI (Rosen et al., 2000) is a brief self-report measure of female sexual functioning. It has 19 items on a Likert scale alternately ranging from 1 (“almost always or always”) to 5 (“almost never or never”), 1(“very strong”) to 5 (“very weak/not present”), and from 1 (“very content”) to 6 (“very discontent”). The questionnaire is composed of six subscales: Desire, Arousal, Lubrication, Orgasm, Satisfaction, and Pain. The total score ranges from 2-36 with higher scores representing better sexual functioning. A cut-off score of 26.55 is used to discriminate between sexually functional (non-symptomatic) and dysfunctional (symptomatic) women, with a total score lower than 26.55 representing sexual dysfunction (Wiegel, Meston & Rosen, 2005). Internal consistency is considered very good (Cronbach’s alpha= .72 to .98) and test-retest reliability is good (correlations range from .71 to .90).
Female Sexual Distress Scale-Revised (FSDS-R)
The FSDS-R (Derogatis, Rosen, Leiblum, Burnett, & Heiman, 2002; Ter Kuile, Brauer & Laan, 2006) consists of 13 questions on a 5-point Likert scale ranging from 0 (“never”) to 4 (“always”). This self-report measurement is used to assess sexual function-related distress. Higher scores represent more sexual function-related distress (total score range 0-48). An example item is: “How often did you feel sad about your sex life”? Total scores higher than 11 (cut-off value) indicate clinically significant sexual function-related distress: this score represents sexual dysfunctioning together with a total score lower than 26.55 on the FSFI (Ter Kuile et al., 2006). Internal consistency and test-retest reliability (interval-duration: unknown) are considered very good (Cronbach’s alpha= .93 and Pearson’s correlation = .93, respectively).
Sexual Opinion Survey (SOS)
The SOS is a self-report measurement of sexual attitudes (Fisher et al., 1988). It consists of 21 items indicating the disposition to react to sexual cues along a negative-positive dimension of
12 affect and evaluation. Agreement or disagreement for a particular item can be indicated on a 7-point Likert scale varying from 1 (“totally disagree”) to 7 (“totally agree”). Every item expresses an affective-evaluative response to a sexual situation or activity. An example item is: “Seeing a pornographic movie would be sexually arousing to me”. The total SOS-score ranges from 0-126, with higher scores indicating more positive attitudes towards sexuality, which is suggested to indicate ‘erotophilia’. Lower scores on the SOS are suggested to represent ‘erotophobia’. The Dutch translation had a good internal consistency (Cronbach’s alpha = .81).
Experiences in Close Relationships Scale-2010 – anxiety subscale (ECR-2010)
The anxiety subscale of the ECR-2010 (Sibley, Fischer, & Liu, 2005) is used to assess adult attachment anxiety, which reflects an individual’s predisposition towards anxiety and vigilance concerning rejection and abandonment. The items are employed on a 7-point Likert scale ranging from 0 (“strongly disagree”) to 6 (“strongly agree”). An example item is: “I often worry about my relationships”. Higher scores represent more attachment anxiety (total score range: 0-108). Previous studies found good internal consistency (Cronbach’s alpha =.83).
Orgasm Consistency Questionnaire (OCQ)
This questionnaire about orgasm consistency consists of 18 statements that explore how often on average an orgasm is experienced during various, both solitary and dyadic, sexual activities, such as “masturbation (with focus on the clitoris) without vibrator”. These statements are inspired on questions designed by Brody and colleagues (e.g., Brody & Costa, 2008) and are expanded with questions asking specifically about anal activities and the use of toys such as vibrators and dildos (Anthony, Laan & Spiering, 2012). The items are employed on a 5-point Likert scale ranging from 0
(“never”) to 4 (“always”). Higher scores represent higher orgasm consistency (total score range 0 – 72). This is no validated questionnaire.
Sexual Arousal Questionnaire (SAQ)
The SAQ (Laan et al., 2008) consists of 25 items and is used to assess subjective sexual arousal and both negative and positive affective responses to the neutral and erotic film-fragments. The items are employed on a 7-point Likert scale that ranges from 1 (“not at all”) to 7 (“intensely”). This is an adapted version of the commonly used Film Scale by Heiman and Rowland (1983). It consists of five scales: (subjective experience of mental) sexual arousal (Cronbach’s alpha = .87); (subjective experience of) genital sensations (Cronbach’s alpha = .96); sensuality (Cronbach’s
13 alpha = .73); positive affect (Cronbach’s alpha = .93); and negative affect (Cronbach’s alpha = .65), with higher scores indicating a stronger experience of affect (Laan et al., 2008).
Continuous sexual subjective arousal (CSA)
To assess (change in) subjective sexual arousal during the erotic film-clips, a continuous measure of subjective arousal was implemented in this study. A mechanical lever – the “arousometer” – produced a continuous DC signal calibrated to indicate a 0-10 scale (Laan & Everaerd, 1995). A software program written in MatLab detects the position of the lever (Technical Support, Department of Psychology, University of Amsterdam). Subjects were instructed to use this lever to indicate how aroused they were feeling during both erotic film-clips, with 0 signaling no genital sexual arousal and 10 indicating maximum genital sexual arousal. The lever was connected to a corresponding bar on the TV monitor so that subjects did not need to look away from the screen in order to monitor their level of sexual arousal.
Demographic information and sexual history questionnaire
These questionnaires assess demographic information and, among others, the frequency and variety of sexual behaviors and experiences. Also, questions about the experience in the laboratory (erotic context condition) and negative sexual experiences were queried.
2.2.2. Erotic Stimuli
The audiovisual fragments consisted of two neutral and two erotic film-clips in total. Each fragment took approximately 3-4 minutes. The neutral film-clips depicted excerpts of geographic documentaries about underwater life. The erotic film-clips consisted of two fragments varying in erotic intensity: one low erotic fragment depicting a heterosexual couple engaging in cunnilingus and one high erotic fragment depicting intercourse between the same couple. They differed in content to avoid habituation and reduction of genital sexual arousal. The film-clips are more female-centered than conventional erotic movies (Both, Spiering, Everaerd, & Laan, 2004), which are known to significantly increase vaginal vasocongestion and subjective sexual arousal (Laan et al., 2008). The high erotic film-clip was accompanied by clitoral vibration.
2.2.3. Physiological Measures
Vaginal photoplethysmograph (Vaginal Pulse Amplitude: VPA)
To assess genital arousal, vaginal pulse amplitude (VPA) was measured using vaginal photoplethysmography, developed by Bert Molenkamp (Technical Support, Department of
14 Psychology, University of Amsterdam). VPA fluctuations reflect phasic changes in the blood content of the illuminated vaginal capillary bed of the vaginal wall at each heartbeat, with greater amplitudes indicating increased vasocongestion (Laan et al., 2008, p.1425). This is currently the most sensitive, specific and reliable measure of vaginal vasocongestion (Laan et al., 2008). Depth of the probe and orientation of the light source were controlled by a device (a 9 x 2-cm US Food and Drug Administration [FDA]-approved perspex plate; ODV Rubber en kunststoffen,
Zaandam, the Netherlands) attached to the cable within 5 centimeter of the optical sensor (Laan et al., 2008). The device was sterilized using plasma sterilization, performed by Clinium, an authorized sterilization laboratory. For more technical details about the VPA-measurements, see Appendix A.
Clitoral vibrator
The clitoral vibrator consists of a rubber stopper 2 centimeter in diameter, which contains the vibrator. The vibrator is mounted on a flexible metal strap lined with washable lycra cloth. The design of the vibrator does not compromise the VPA measurements (Peterson, Janssen, & Laan, 2010). The subject was instructed to place the rubber stopper against the clitoris. Participants were able to adjust the level of vibration with a small remote control, but were advised to keep the vibration as high as was possible and pleasurable. Participants received clitoral vibration during the high erotic film-clip to induce high sexual genital arousal and (state) sexual pleasure.
2.3. Study Design
The design of this study consisted of an online and laboratory part with a minimum interval of two weeks. The online part was set up as the neutral context condition, the laboratory part as the erotic context condition. A detailed description of the study design will follow below:
Before participation, the participants received detailed information about the aim and procedures of the study via a website-link received from advertisements. After giving informed consent online, eligibility was determined by means of a short screening questionnaire. Eligible participants were then randomly divided in either the ‘Neutral First’ or ‘Lab First’ group by means of a safe computer-survey system called ‘Lotus’ (a web tool to build and manage online longitudinal research), which also assigns each participant an individual subject ID. When divided in the ‘Lab First’ group, participants were only requested to make an appointment for the erotic context condition in the laboratory. The appointment was made without the interval of two weeks: it could be made as soon as possible. The participants were informed that they would receive the ASPI and other questionnaires two weeks after they had visited the erotic
15 context condition. Appointments were made such that participants were not menstruating at the time of the lab-appointment. Three days before the lab-appointment participants received an email-reminder. See Figure 1 for a graphic illustration of the design.
Note: *Two weeks post erotic context condition participants receive an email with an invite to complete the online
neutral context condition. **Right after neutral context condition participants are asked to schedule a lab appointment minimally two weeks later.
Figure 1. Flow chart of study design. `
2.4. Procedure Neutral Context Condition
When divided in the ‘Neutral First’ group, the participants were led to ‘Qualtrics’ (an online survey system) and received the following questionnaires in random order: FSFI, FSDS-R, SOS, ECR-2010, demographic and orgasm consistency questionnaire. Also, they were shown a neutral film-clip before they were asked to fill in the SAQ - to assess experienced affect/subjective sexual arousal - and the ASPI. After completion of the questionnaires participants were asked to schedule an appointment - at least two weeks later - for the laboratory session.
16 2.5. Procedure Erotic Context Condition
Upon arrival in the laboratory, participants were (again) required to give written informed consent, after receiving detailed information about the study. It was also stressed that
participants could withdraw any moment without consequences and that they were assured of privacy, anonymity and confidentiality. Subsequently, instructions to attach the vaginal
plethysmograph and clitoral vibrator, and use of the “arousometer”, the experimenter took the participants to an adjacent, sound-attenuated room. After the experimenter had left the room, participants attached the genital devices in private. Once participants were ready (i.e. had attached the vaginal probe/clitoral vibrator and were seated in the reclining chair), they could press a button on a response box to start the testing procedure. The experimenter monitored the testing procedure via the lab-computer in the adjacent room.
Firstly, participants were required to fill in the SAQ to assess experience of affect and arousal after they watched a neutral film-clip as a baseline-measurement. Participants could answer this questionnaire by pressing 1 of 7 buttons, which corresponded to the 7 answer categories that were shown underneath each question on the TV monitor. Once a question was answered, the next question was presented. Subsequently, participants were exposed to both erotic film-clips of three minutes each that differed in erotic intensity to induce high sexual arousal and to avoid both restriction of range and habituation.
After the first erotic film-clip, participants were informed that they were about to receive clitoral vibration. The experimenter manually controlled the onset of the clitoral vibrator during the second erotic-clip. Immediately after exposure to the second erotic-film clip, the SAQ and the ASPI were administered via the TV monitor and response box, to make sure participants would be likely to be in a sexually aroused state while filling in these questionnaires. Upon finishing these questionnaires, participants could remove the genital devices, and were asked to fill the sexual history questionnaire (with one open-ended question) on paper, which was present in the testing room. Lastly, participants could refresh themselves in the testing room, before entering the room of the experimenter, were a brief exit interview took place. The experimenter asked the participants if they had ever experienced physical and/or sexual abuse according to a protocol that addresses questions about negative sexual experiences. If participants reported a history of sexual abuse, the investigator offered the possibility to schedule an appointment at the clinic of Sexology at the AMC.
2.6. Data Reduction
17 computer program developed at the Department of Psychology at the University of Amsterdam. After artifact deletion, peak-to-trough amplitude was calculated for each remaining pulse, and averaged over 30-second epochs, resulting in 4 points in the baseline condition and 12 data-points in the erotic condition (6 data-data-points per erotic film-clip). Continuous sexual arousal (CSA) was sampled during both erotic film-clips and yielded 26 data-points in total, averaged over 15-second epochs. These were reduced to 6 data-points per erotic film-clip, which yielded eventually 12 data-points in total, enabling direct comparison with VPA.
2.7. Sampling Plan using the Bayesian Method
Since it was assumed that the ASPI score would not be susceptible to immediate contextual influences, a null-effect was expected. The Bayesian statistical method is considered more suitable for testing the expectation of a null-effect than the classical method. The Bayesian method is
conceptually different from the classical method, and does not (necessarily) rely on power to estimate a sufficient sample size, or on a binary and arbitrary decision like the p-value regarding the presence or absence of an effect. Namely, the Bayesian method handles a more continuous approach: the Bayes factor, which is an average likelihood ratio or ‘degree of belief’, indicates the relative strength of evidence for the null-hypothesis vis-à-vis the alternative hypothesis based on prior (pre-set) distributions for effect size under H1. As such, the data may be extreme under H0, but not likely under H1 either (Wagemakers et al., 2015). This is in contrast with the p-value, which does not distinguish evidence for the null from no evidence at all (Dienes, 2014). Moreover, the Bayes factor is updated in the light of the data that are coming in, and can be terminated at any point (Rouder, 2014). Therefore, the need for an a priori sample size is less relevant in the Bayesian paradigm. However, for this study we wanted, as a heuristic, to recruit a minimum of 20 participants in each between-subject condition: the counterbalanced context-order group (‘Neutral first’ vs. ‘Lab First’). A minimum of 40 participants that participated in both context conditions was expected to be feasible in the data collection period of 4 months.
2.8. Data Analyses
The data analyses consisted of several parts: analyses concerning the effect of context on the ASPI (hypothesis 1), analyses of reliability and convergent validity (hypothesis 2) and analyses concerning predictive validity of arousal concordance for the ASPI (hypothesis 3).
Hypothesis 1: The Effect of Context
18 whether the erotic clips induced a sexual (arousal) response, compared to the neutral film-clip in both the neutral- and erotic context condition: one way repeated measures ANOVA’s and pair-wise comparisons with Bonferroni correction were conducted. Self-reported subjective arousal was indicated with the mean of several SAQ-scales (i.e. ‘Subjective Sexual Arousal’ and ‘Perception of Genital Arousal’). Genital arousal was measured as VPA in millivolts. Since VPA does not have an absolute scale, differences relative to mean baseline were calculated; VPAlow, VPAhigh and VPAcombined were calculated by subtracting the mean of the baseline (neutral) clip of the mean from respectively, the low, high and combined (low + high) erotic film-clips. This provides indices of change in sexual responding and controls for between-subject differences in resting baseline (Laan & Everaerd, 1995).
Subsequently, a Bayesian paired samples t-test (two-tailed) was conducted to test whether context has an effect on the ASPI score. In addition, a Bayesian Repeated Measures ANOVA was conducted to examine whether the factors ‘context-order’ (counterbalanced between subjects), ‘sexual dysfunction’ (women with and without sexual problems) and ‘time-interval’ (time between context conditions) would be relevant for any influence of context on the ASPI-scores – (although this was not expected). The Bayesian analyses were conducted via JASP (Jeffreys’s Amazing Statistics Program), an open-source graphical program for statistical analysis
(see: https://jasp-stats.org/).
Hypothesis 2: Convergent Validity
Reliability was assessed with internal consistency (relationship between scale-items denoted with Cronbach’s Alpha) and test-retest reliability over context (Pearson’s correlation between ASPI-scales in neutral vs. erotic context condition). Convergent validity was determined by Pearson’s product–moment correlations between the ASPI-scales and the multiple questionnaires that were administered. In case a questionnaire or scale did not meet the normality assumption, Spearman rank correlation coefficients were calculated. According to Cohen (1969), a correlation of .1 denotes a weak relationship, a correlation of .3 denotes a moderate relationship and a correlation of .5 denotes a strong relationship between two constructs. These analyses were conducted using data of the largest sample available (N=42; data from the neutral context condition). To explore how state sexual arousal responses converge with the ASPI, correlations were determined between the total ASPI score and SAQ-subjective arousal, VPA and
continuous sexual arousal (CSA) - stemming from the “arousometer” - during the low (CSAlow), high (CSAhigh) and combined erotic film-clips (CSAcombined). These correlations were
19 erotic context condition).
Hypothesis 3: Predictive Validity
Arousal concordance was determined by calculating within-subject (individual) correlations between VPA and CSA over time (i.e. during the erotic film-clips). An independent-test was conducted to examine whether arousal concordance could discriminate between symptomatic- and non-symptomatic women in this study (based on the clinical cut-off scores of the both the FSFI and FSDS). Subsequently, exploratory linear regression analysis was conducted with arousal concordance as a predictor for ASPI score, to exploratorily test to what extent arousal
concordance can predict sexual pleasure.
3. Results 3.1. Sample Characteristics
In total, 43 participants partook in this study. Of the 43 participants, 30 women were willing to participate in both the neutral- and erotic context condition (and completed the ASPI two times). The physiologic data (i.e. VPA) of four participants could not be interpreted due to technical difficulties (no differences in VPA) and one because of a deviant arousal response (VPA decline during erotic film exposure). Therefore, physiologic data were available for 26 women.
See Table 1 and 2 for the sample characteristics, including sexual history. Of the 42 women in the neutral context condition, 13 (31%) reported sexual problems. This amount of women with sexual problems corresponds to the amount found in the general population (i.e. the ratio is 3:1 in the Netherlands, Kedde, 2012). The mean age of this sample was 29.55, ranging from 18 to 66 years (SD: 1.67). In addition, 85.7% was native Dutch and 52.4% denoted
20 Table 1. Sample characteristics regarding socio-demographic variables
Neutral + Erotic (N=30)
Only Neutral Condition (N=42) Mean (SE) or %
Age 29.87(2,09) Range 20-66 29.55(1,67) Range 18-66
Ethnicity Dutch 86.7 85.7 Hindu 3.3 2.4 Surinam - 2.4 Other 10 9.5 Education
Lower general secondary ed. 6.7 4.8 Intermediate vocational ed. 3.3 7.1 Senior general secondary ed. 13.3 11.9 College of advanced ed. 26.7 23.8 University 50.0 52.4 Religion None 70 69 Reformed 6.7 4.8 Catholic 6.7 9.5 Buddhist 3.3 2.4 Other 13.3 14.3 Number of children No children 87.6 88.1 1 child or more 13.3 11.9 Sexual Dysfunction∗ Present 11 (35.5%) 13 (31%) Absent 19 (61.3%) 29 (69%)
21 Table 2. Sexual experience as reported on the sexual history questionnaire
Erotic Context Condition (N=31)
Mean (SD) or N (%)
Partnership status
Exclusive Monogamous Relationship Non-exclusive relationship
No relationship
Partnership duration (months) Number of relationships Sexual Orientation
Heterosexual Bisexual Other
Past Sexual Experience
Sexarche (oral sex) Sexarche (coitus)
Number of one-night-stands
Number of sex partners (without condom) Number of sex partners (within last year) Experience with masturbation
Experience with manual sex (last 6 months) with partner Experience with fellatio (last 6 months) with partner
Experience with receiving cunnilingus (last 6 months) with partner Experience with coitus (last 6 months) with partner
Experience with anal sex (last 6 months) with partner Experience with erotic films
Experience with erotic reading material
Experience with sexual abuse/unwanted sex (N =30)
14 (45.2%) 6 (19.4%) 11 (35.5%) 42.45 (80.71) Range: 0 – 367 3.12 (1.94) Range 1 – 8 24 (77.4%) 6 (19.4%) 1 (3.2%) 16.94 (4.19) – Range 3 – 29 17.61 (3.14) - Range 14 – 29 11.3 (13.47) – Range 0 – 50 3.16 (3.8) – Range 0 – 20 2.84 (3.1) - Range 0 – 12 26 (83.9%) 19 (61.3%) 19 (61.3%) 17 (54.8%) 18 (58%) 6 (19.3%) 27 (87.1%) 28 (90.3%) 10 (33.4%)
22 3.2. Test of Context-Effect on ASPI (Hypothesis 1)
Manipulation Check
First, the results of the one way repeated measures ANOVA’s (Sphericity assumed) showed that the mean of subjective arousal and perception of genital arousal differed significantly between film-clips (F(2, 138.09) = 156.12 and F(2, 115.28) = 99.09, respectively, both p <.001). Post hoc tests using the Bonferroni correction revealed that watching the two erotic film-clips (partly in combination with vibration) elicited more self-reported subjective sexual arousal than the neutral film-clip in both the neutral context condition and in the erotic context condition, see Table 3 for SAQ means and SE. Therefore, it can be concluded that the erotic context in the laboratory significantly increased self-reported sexual arousal.
Table 3. Effects of neutral and erotic film on discrete measures of subjective sexual arousal and perception of genital arousal as measured with the SAQ (N=30)
SAQ-arousal-scales Film-clip
Neutral (online) Neutral (lab) Erotic
Subjective arousal 1.40 (.16)a 1.91(.18)a 5.41 (.21)b
Perception of genital arousal 1.51 (.16) a 2.47 (.26) b 5.34 (.20) c
Note: Numbers in row with different superscript (a vs. b vs. c) differ significantly with p < .05. Data represent means
and SE. All items employed a 7-point response scale (1 = Not at all to 7 =Intensely). Higher numbers reflect more sexual arousal.
Second, the results of the one way repeated measures ANOVAs also showed that the mean of Sensuality and Positive Affect of the SAQ differed significantly between film-clips (F(2, 6.7) = 14.05, and F(2, 39.41) =38.96, respectively, both p <.001), whereas negative affect did not (F(2, .01) = .90, p =.41). Post hoc tests using the Bonferroni correction revealed that watching the two erotic film-clips (partly in combination with vibration) elicited more feelings of
sensuality and positive affect than the neutral film-clip in both the neutral context condition and in the erotic context condition, see Table 4. Therefore, it can be concluded that the erotic
23 Table 4. Effects of neutral and erotic film on discrete measures of sensuality, positive affect and negative affect from neutral to erotic film-clips (N=30)
SAQ-affect-scales Film-clip
Neutral (online) Neutral (lab) Erotic
Sensuality 3.20 (.15) a 3.57 (.14) a 4.16 (.19) b
Positive affect 2.62 (.19) a 3.75 (0.19) b 4.95 (.24) c
Negative affect 1.12 (.05) a 1.21 (.09) a 1.25 (.09) a
Note: Numbers in row with different superscript (a vs. b vs. c) differ significantly with p < .05. Data represent means
and SD. All items employed a 7-point response scale (1 = Not at all to 7 =Intensely). Higher numbers reflect more affect.
Third, the results of the one way repeated measures ANOVA’s with a Greenhouse-Geisser correction determined that the mean of genital arousal, as measured with VPA, differed significantly between film-clips (F(1.31, 15.25) = 128.94, p <.001. Post hoc tests using the
Bonferroni correction revealed that watching the two erotic film-clips elicited more genital sexual arousal than the neutral (baseline) film-clip (0.92 ± 0.11 mV VPA vs. 1.75 ± .19, respectively, p < .001). For VPA means and SE of all the film-clips in the erotic context condition, see Table 5. Therefore, it can be concluded that the erotic context in the laboratory significantly increased genital arousal. 3
Table 5. Effects of erotic film on vaginal pulse amplitude (VPA) (N=26)
Film-clip mV VPA (N=26) M (SE) Neutral .92 (.11) a Erotic (low) 1.44 (.17) b Erotic (high) 2.09 (.24) c Erotic (low+high) 1.75 (.19) d
Note: Numbers in column with different superscript (a vs. b vs. c vs. c) differ significantly with p < .001. All erotic film-clips compared to the neutral film-clip in erotic context condition (Post hoc pair wise comparisons).
3 It is important to note that this analysis only designates a general trend, since VPA is a relative scale (i.e. each
24 Comparison ASPI-Score in Neutral vs. Erotic Context Condition
In order to determine the effect of context on the ASPI-score, Bayesian analyses were
conducted. The results of the Bayesian paired samples t-test indicated that the Cauchy prior4 of 0.707 (i.e. a default, “user prior” in Figure 3) yielded an BF01 =1.362, which is ‘anecdotal
evidence’ (i.e. ‘weak/inconclusive’; Wagemakers et al., 2016)5, indicating that the data are equally likely under H1 and H0. The median and the 95% credible interval of the posterior density of the effect size is, respectively, -0.286 and [-0.65, 0.05]. In other words, the data are insensitive for one or the other theory; see Figure 3, 4 and 5.
Moreover, the results of the Bayesian Repeated Measures ANOVA indicated that every factor (i.e. ‘context-order’, ‘sexual dysfunction’ and ‘time-interval’) resulted in inconclusive evidence regarding each effect on ASPI-scores over conditions (data equally likely under H1 and H0;BF10 range 0.55 – 0.74for these factors). Therefore, there is no evidence that the effect of context on the ASPI differs for any of these factors.
Figure 3. Effect size under posterior and prior density under the alternative hypothesis according Bayesian paired samples t-test. Note: The circle represents the proportion wheel; a visual representation of the Bayes factor.
4 The Cauchy distribution is a t distribution with one degree of freedom. Compared to the normal distribution, the
Cauchy distribution has fatter tails (cited from Wagemakers, 2015, p.25)
5 A Bayes factor greater than 3 represents substantial evidence for the alternative, a value less than 1/3 substantial
25 Figure 4. The relative plausibility of the data
under H1 versus H0; according to three prior sizes. Note: Bayes factor = BF10 and its inverse BF01, grading the evidence that the data provide for H1 versus H0.
Figure 5. Development of the Bayes factor as the data come in using the user-defined prior + Robustness check. Note: Robustness check: Adds the results of the sequential analysis using the wide (scale = 1) and ultrawide prior (scale = sqrt(2)).
3.3. Analyses of ASPI’s Reliability and Convergent Validity (Hypothesis 2) Internal consistency
In accordance with the initial validation study, the internal consistency6 of the total score of the ASPI was considered excellent. The internal consistency of the subscales, Partner Related Pleasure, Sexual Self Efficacy, Arousal Enjoyment and Sexual and Body Confidence was good, and the internal consistency of the subscale Closeness/Intimacy was acceptable, see Table 6. The items 7, 36 and 50 did not correlate strongly (r ≤ .30) with the total score of the ASPI. 7 However, removing these items did not significantly increase Cronbach’s Alpha.
6 The internal consistency denotes the relationship between items of a questionnaire’s scale. Nunally (1978) denotes
an (Cronbach’s Alpha) α ≤ .5 as unacceptable, .5 < α < .6 as bad, .6 < α < .7 as questionable, .7 < α < .8 as acceptable, .8 < α < .9 as good and α ≥ .9 as very good.
7 Notably, three of these items (i.e. item 7: ‘I prefer to have sex when I feel connected to my partner’, item 36: ‘I enjoy sex more
than my partner does ’ and item 50: ‘In order to experience sexual pleasure, it doesn’t matter whether I feel connected to my partner’)
26 Table 6. Internal consistency of total score and subscales of the ASPI (N=42)
ASPI (all items) .96
Partner Related Pleasure .92
Sexual Self Efficacy .95
Arousal Enjoyment .87
Sexual and Body Confidence .83
Closeness/Intimacy .77
Note: All values represent Cronbach’s Alpha. Reverse coded items: 10, 11, 14, 24, 27, 32, 35, 36, 37, 40, 48 49 and
50).
Test-retest reliability – Correlation Between ASPI-scores Over Context
The test-retest reliability (with a minimum interval duration of two weeks) of the total score was excellent: r = .94, even though the ASPI was administered within different contexts (neutral vs. erotic). All correlations between scales were significant at p< .001. Only the retest-reliability of the subscale Closeness/Intimacy was questionable (r = .63). The mean test-retest reliability was .87, which indicates that the overall test consistency/stability of the ASPI over time was good. See Table 7 for mean scale scores and correlations between first and second completion of the ASPI.
Table 7. Mean scale scores and correlation between neutral and erotic context completion of the ASPI (N=30)
Scales ASPI (neutral
context) M(SD) ASPI (erotic context) M(SD) R (Pearson’s correlation)a ASPI Total 3.73 (0.70) 3.81 (0.55) .94*
Partner Related Pleasure 3.90 (0.71) 4.01 (0.61) .93*
Sexual Self Efficacy 3.38 (1.01) 3.44 (0.81) .97*
Arousal Enjoyment 3.94 (0.73) 4.02 (0.64) .84*
Sexual and Body
Confidence 3.59 (0.87) 3.72 (0.84) .89*
Closeness/Intimacy 3.99 (0.68) 3.98 (0.49) .63*
Note: *p < .001. a: The assumption of normality was met for the ASPI in both the neutral and erotic context
condition; D(30)= .15 and .08, p > .05. All items employed a 5-point response scale from 0 (“Totally disagree”) to 5 (“Totally agree”); higher numbers reflect more sexual pleasure/higher score on the subscale
27 Convergent validity
Convergent validity was determined by calculating the non-parametric Spearman Rank
correlation between the ASPI and the other questionnaires (FSFI, FSDS, SOS, ECR-2010 and OCQ). See Table 8 for the correlations between ASPI scales and the other questionnaires.
FSFI
In accordance with the initial validation study, there was a high positive correlation between the ASPI and FSFI, rs (42) =.68, p <. 01, indicating that the more sexual pleasure women are inclined to experience, the better their sexual functioning. Unlike the pilot study, the Closeness/Intimacy-subscale was not related to the FSFI.
FSDS-R
As predicted, there was a high negative correlation between the ASPI and FSDS-R, rs (42)= -.62, p < .01. Unexpectedly, the Arousal Enjoyment-subscale was not significantly related to the FSDS-R. Overall, women are less inclined to experience sexual pleasure when they experience more sexual distress.
SOS
As predicted, there was a moderate positive correlation between the ASPI and the SOS, rs (42) = .36, p < .01. Upon inspection, only the subscales Partner Related Pleasure and Arousal Enjoyment were significantly correlated with the SOS. Overall, the more sexual pleasure women are inclined to experience, attitudes towards sexuality tend to be more positive (i.e. erotophilia).
ECR-2010 – anxiety subscale
Against prediction, the ASPI, was not significantly correlated the ECR-2010-attachment anxiety scale, rs (42)= -.30, p > .05. Thus, women who experience fear of rejection and insecurity about proximity towards a partner, do not significantly experience less sexual pleasure.
Orgasm consistency questionnaire
As predicted, there was a moderate positive correlation between the ASPI and the OCQ, rs (42)= .40, p < .01. Unexpectedly, of all the ASPI- subscales, only ‘Sexual Self Efficacy’ was significantly correlated to the total score of the OCQ: rs (42)= .50, p < .01. Overall, the more sexual pleasure women are inclined to experience, the more often orgasms they tend experience during various sexual activities (both with a partner and alone).
28 Table 8.Correlations between ASPI scales and the FSFI, FSDS-R, SOS, ECR-2010 and OCQ
Scales FSFI FSDS-R SOS ECR-2010 OCQ
ASPI Total .68** -.62*** .36* -.30 .40**
Partner Related Pleasure .55** -.42** .61** -.21 .11
Sexual Self Efficacy 64** -.62*** .20 -.29 .50**
Arousal Enjoyment .45** -.22 .73** -.06 .18
Sexual and Body Confidence .47** -.52*** .33* (r) -.28* (r) .12
Closeness/Intimacy .07 -.35* -.13 -.09 .05
Note: Participants who did not experience coitus are included. ***p < .001 **p < .01, *p <. 05 Exploratory convergent validity
As can be seen in Table 9,there is a moderate to high significant correlation between the ASPI-total score and all arousal indices except for CSA and VPA during the high erotic film-clip and VPA during both erotic film-clips (probably because of a ceiling effect during the high erotic film-clip). The largest correlation was found between the ASPI and ‘subjective perception of genital arousal’ as measured with the SAQ (r = .57, p < .01).
Table 9. Correlations among the ASPI and subjective arousal (SAQ/CSA) and genital arousal (VPA)
Arousal Indices ASPI
Total Subjective arousal SAQ Subjective Arousal (rs) .44*
SAQ Genital Arousal .57**
CSAcombined .34* Continuous subjective arousal CSAlow .39* CSAhigh .25 VPAcombined (rs) .30
Genital arousal VPAlow (rs) .45*
VPAhigh (rs) .12
29 3.4. Predictive validity: Arousal Concordance and the ASPI (Hypothesis 3)
Arousal Concordance as Predictor of the ASPI
The within-subjects arousal concordance correlations ranged from -.56 to .87, of which 55,56% was significant. Upon individual inspection, it was concluded that each participant showed an increase in both subjective (CSA) and genital arousal (VPA) over the two erotic film-clips (i.e. restriction of range was absent; see Appendix B). The mean arousal concordance was r = .54. The exploratorily analyses pointed out that the extent of arousal concordance did not
significantly differ between symptomatic (M= .64, SE= .10) and non-symptomatic (M= .43, SE=.09) women (t(24) = -1.26, p = .22), nor did it predict the ASPI-score (i.e. the association between arousal concordance and the ASPI was non-significant, negative and non-linear: Adjusted R2 = .04), see Figure 5. Thus, concordance between genital and subjective arousal is not related to sexual functioning and does not significantly predict ‘the propensity to experience sexual pleasure’ as measured with the ASPI in this sample.
30 4. Discussion
The present study aimed to contribute to the validation of a recently developed sexual pleasure questionnaire (the Amsterdam Sexual Pleasure Index - ASPI) by means of both correlational and psychophysiological research in a small sample of women with and without sexual problems. The evidence is inconclusive with respect to whether or not the ASPI score is susceptible to erotic contextual influences (i.e. whether the ASPI measures a trait or a state). However, the findings that indicate good (test-retest) reliability and convergent validity with both trait-like and theoretically related constructs are of added value to the construct validity of this questionnaire.
Discussion of Context Effect
Temporal stability and situational or contextual independence are fundamental issues for the conceptualization of the ASPI as a trait questionnaire (Stark et al., 2015). However, the Bayesian analysis yielded neither strong evidence in favor of a context-effect nor strong evidence in favor of no effect. Therefore, the conclusion whether or not the ASPI might measure a state next to a trait, needs to be suspended. The data presented in this study can serve as a starting point to address the question of interest, and can be combined with new Bayesian data without compromising valid (statistical) conclusions (see Rouder, 2014).
Nonetheless, the finding that sexual arousal was clearly affected by the erotic context, whereas the ASPI was not (i.e. inconclusive evidence on the one hand, but good test-retest reliability over context on the other hand), suggests that the ASPI is likely to measure ‘the propensity to experience sexual pleasure’ as the intended trait-like (i.e. stable and context
independent) construct. The conceptual distinction between trait and state sexual pleasure might be able to elucidate which short and long-lasting processes (e.g., biological, sociocultural and learning processes) contribute to ‘the propensity to experience sexual pleasure’, and in turn, to (un)healthy sexual functioning (Boul, 2009). Furthermore, this distinction could be important for clinical practice, since a stable personality disposition (a trait) is less likely to be influenced by immediate contextual changes. Therefore, a trait probably needs different strategies to stimulate its development or alter its expression as opposed to a state. Thus, a validated trait sexual pleasure questionnaire might prove useful as a diagnostic instrument, to assess and offer suggestions for treatment of sexual dysfunctions over the long-term.
Discussion of Reliability and Convergent Validity
Another important issue for the conceptualization and construct validity of the ASPI is whether this questionnaire indeed measures sexual pleasure as a multi-faceted construct. The high internal
31 consistency of the total score and subscales denotes that the ASPI is a reliable construct, but might also indicate there is conceptual redundancy amongst the 52 items (Sanders et al., 2013). Accordingly, the question arises whether or not the subscales measure distinct aspects of sexual pleasure. Nonetheless, the analyses of convergent validity indicate the subscales might do so in fact, because sexual functioning (FSFI) and sexual distress (FSDS-R) were associated with almost all ASPI subscales, whereas orgasm-consistency (OCQ) and positive attitudes towards sexuality (SOS) only with one to three subscales, respectively.
Specifically, orgasm-consistency (OCQ) was related to no other ASPI subscale besides ‘Sexual Self Efficacy’. This suggests that ‘the self-perceived ability to gain sexual pleasure’, by means of communication and taking initiative, is the part of sexual pleasure that is likely to increase the likelihood of having orgasms across various sexual activities. This finding indicates that experiencing orgasms might not be central to the concept of sexual pleasure in heterosexual women, which goes against sociocultural conceptions (Opperman et al., 2014).
In addition, the subscale Closeness/Intimacy was, besides sexual distress (FSDS-R), not related to any other sexuality-related construct, which suggests that this component might be conceptually different and perhaps less contextually independent than the other components (e.g., depends possibly more on whether or not somebody has a long-term relationship). This finding, while preliminary, suggests that the items of this component might need revision to better tap into the emotional pleasure and intimacy aspect that was deemed relevant for the ASPI.
Moreover, the exploratorily analyses of convergent validity indicated that the ASPI is moderately to highly related to genital and subjective sexual arousal. The finding that the ASPI is related with these state sexual arousal responses, complies with the theory that a trait determines the level of corresponding state-changes (Endler, 1997; Funder, 1991). Therefore, this finding supports the assumption that the ASPI is a trait questionnaire. Overall, these findings indicate that sexual pleasure as measured with the ASPI is likely to be a reliable, stable and multi-faceted construct. However, more research is needed on whether all intended aspects are adequately covered, and whether the questionnaire could be made more parsimonious (i.e. less conceptually redundant) to facilitate its future use in clinical practice.
Discussion of predictive validity
In the context of the third, exploratorily, research question, it was examined whether arousal concordance (i.e. the agreement between genital and subjective arousal) was of any predictive value for sexual pleasure, to further explore the construct validity of the ASPI. First, as in line
32 with previous research, the findings indicate that arousal concordance was highly variable
between women (Chivers et al., 2010). Second, arousal concordance was not associated with sexual (dys)functioning, which contradicts some earlier research (e.g., Brody, 2007) Third, the findings, while preliminary, indicate that arousal concordance does not contribute to variation in ASPI-scores: there was not even a trend in that direction. Therefore, it might be possible that arousal concordance and sexual pleasure reflect different, unrelated aspects of the female sexuality. It might also be possible that arousal concordance might be a rather irrelevant or secondary construct to female sexuality. Thus, further research should elucidate the relevance (if any) of arousal concordance. More importantly, other possible predictors, correlates and
moderators of sexual pleasure as measured with the ASPI should be investigated, in order to assert that this questionnaire is a good, comprehensive research instrument.
Limitations
The findings must be interpreted with great caution, because there are several limitations associated with the current study. Several characteristics of the sample used in this study (that consisted of women only) could compromise the generalizability and reliability of the results. Firstly, although the current sample was representative and diverse in terms of age and amount of symptomatic women, it was more homogenous in other factors (e.g., education, ethnicity, sexual orientation). Second, the psychophysiological nature of this study often results in a volunteer bias, attracting participants with liberal attitudes towards sexuality.
Thirdly, the small sample size has probably affected the power of some analyses of this study. Namely, the goal of recruiting 40 participants, who would complete the ASPI in both the neutral- and erotic context, did fall short on an amount of 10 women. It turned out that
participants were difficult to motivate for a psychophysiological study that was compensated with only a little amount of money (10 euros)8. Although the Bayesian analyses might not (directly) suffer from low power (e.g., data can be sensitive in a low powered study; Dienes, 2008), the other analyses (those of convergent and predictive validity) might have. This could be problematic for the reliability of the results.
Other limitations concern the study design, which could have affected the findings in several ways. Firstly, the erotic context was situated in the laboratory, which is by definition an artificial situation that could, perhaps, disregard impact on certain sexual pleasure aspects (e.g., dyadic processes, such as feeling desired by one’s partner; Goldey et al., 2016). Secondly, state sexual arousal could already have significantly decreased when the ASPI was administered,
8 Noteworthy, most women who participated in this study were enthusiastic about the laboratory experiment, and all
33 because participants had to fill in the SAQ first, right after erotic-film exposure. As such, the erotic context would not have been able to affect the score. Thirdly, the instruction on the questionnaire to rate sexual pleasure ‘in general’ as opposed to ‘in this moment’, could possibly have reduced any effect of context on the ASPI, because this instruction makes participants explicitly think beyond the context they are in. In turn, these limitations might have decreased the
likelihood that the ASPI could have detected state sexual pleasure.
Future Directions
Multiple suggestions for future research can be proposed. First, it is recommended to look for other, less circuitous methods (that also could make use of larger sample sizes), to investigate whether the ASPI measures a trait rather than a state. For example, the extent of susceptibility to contextual influences can be compared between the ASPI and a newly developed state sexual pleasure questionnaire (for an example related to trait anxiety, see Auerbach, 1973). Another alternative to complex designs and invasive experiments is simply to study the test-retest
reliability with an interval of one or more years. This is a common method to study the temporal stability and contextual susceptibility of a trait-questionnaire, as has been illustrated with the Trait Sexual Motivation Questionnaire (see Stark et al., 2015).
In addition, a relatively new method is to adopt a network approach, which could contribute to the construct validity of the ASPI (Werner, 2016). This approach enables to elucidate which aspects are associated with and central to sexual pleasure in an individual, couple and in groups (e.g., clinical and non-clinical samples, LHBT- samples, women and men). It might also illustrate that the ASPI still requires improvement with regard to conceptual redundancy and coverage of relevant pleasure factors, and to what extent ‘the propensity to experience sexual pleasure’ is likely to differ between a solitary or dyadic context (see Goldey et al., 2016 for evidence that this difference might be relevant). Moreover, when all aspects are strongly related, directing treatment at one aspect is likely to improve the other aspects concurrently (Cramer & Borsboom, 2015). Thus, the use of network analyses and longitudinal research with respect to the ASPI – based on large samples from different populations – will not only specify the construct validity of this questionnaire, but also its clinical and educational value.
Conclusion
To conclude, a good, comprehensive questionnaire of sexual pleasure does currently not exist. Therefore, the ASPI has been developed and is, at present, being assessed on its psychometric qualities. It remains to be investigated whether the ASPI measures sexual pleasure more as a trait
