Introduction

Orgasm is a psychophysiological response associated with an intense sensation and pleasure [1]. It has been defined as a cognitive process followed by the liberation and resolution of excitation [2]. Specifically, the subjective orgasm experience refers to its psychological appreciation and estimation [3]. The Multidimensional Model of the Subjective Orgasm Experience (MMSOE) [4] is a descriptive model that integrates the essential characteristics and the variability of the orgasm experience from a multicomponent approach. Its developers proposed three dimensions to theoretically describe the psychological orgasm experience: sensory, evaluative, and affective. Each dimension encompasses different orgasmic qualities described by adjectives [4]. Sharing the basic conception of the original model, Arcos-Romero et al. [5] have proposed a new Model of the Subjective Orgasm Experience (MSOE). The MSOE is integrated by four dimensions to describe the psychological orgasm experience in context of sexual relationship. Affective dimension refers to the emotions experienced during orgasm and includes adjectives, such as “satisfying” or “pleasurable”. Sensory dimension alludes to the perception of physiological sensations and includes items, such as “exploding” or “spreading”. Intimacy dimension reflects the intimate component of the orgasmic experience and includes items, such as “loving” or “tender”. Finally, rewards dimension refers to the reinforcing effect of the orgasm and includes adjectives, such as “relaxing” or “soothing”. The MSOE offers a conceptual framework to explain the psychological orgasm experience in context of sexual relationship; it is useful for both research and clinical purposes [5].

Sexual excitation and sexual arousal constitute different concepts. Sexual excitation is a complex phenomenon that implies physiological, psychological (cognitive–affective), and behavioral responses [6]. The subjective sexual arousal refers to the psychological perception of excitation, while the objective sexual arousal refers to the physiological or genital response [7]. On the one hand, The Dual Control Model (DCM) considers that sexual excitation is the result of the balance between excitatory and inhibitory mechanisms, being both relatively independent [8, 9]. As the DCM proposes [8, 10], sexual excitation can be understood as a trait. It refers to the individual propensity for sexual excitation [10]. An assumption of this model, referring to the trait, provides that individuals vary in their propensity for becoming sexually excited [9]. On the other hand, sexual arousal can be described as a state in response to sexual stimuli. This state occurs in a particular moment or a concrete sexual situation. It can be subjectively evaluated through self-reports and objectively registered through psychophysiological measures [11]. According to Handy et al. [12], in order to experience sexual arousal, it is necessary to be implicitly or explicitly aware of a sexual stimulus.

The association between orgasm and sexual excitation and sexual arousal has been previously established [13,14,15,16,17]. There is a tendency to relate the orgasm as a physiological response, without focus specifically on its psychological qualities or subjective experience [5]. Moreover, most research focuses on the study of the female orgasm, and there is a lack of specific works about the male orgasm experience [3]. Paterson et al. [13] pointed out that high levels of sexual excitation are associated with a greater orgasmic pleasure, probably making the orgasm more explosive and reducing the tension in both men and women. Stoléru et al. [14] indicated that the highest level of sexual arousal reached during any particular episode may vary to the orgasm in both sexes. Brody et al. [15] observed that a greater frequency of orgasms was associated with a greater excitation in women. Furthermore, there is an association between the subjective and objective sexual arousal of women and the orgasmic consistency when they are exposed to an erotic stimulus [16]. It has also been showed that a higher probability to reach an orgasm during a sexual intercourse is associated with a greater subjective and objective arousal in women [17].

The aim of this study is to provide validity evidence of the MSOE in context of sexual relationship proposed by Arcos-Romero et al. [5] within a laboratory study. The association between four dimensions of the subjective orgasm experience (affective, sensory, intimacy, and rewards) and three different types of sexual excitation experienced by men and women will be examined. These types of sexual excitation are the individual propensity for sexual excitation (trait), the subjective sexual arousal (state), and the objective sexual arousal (genital response). To do so, we will test the following hypotheses:

H1. The propensity for sexual excitation (trait), based on the DCM, will correlate with the dimensions of the subjective orgasm experience.

H2. The subjective sexual arousal experienced in response to an erotic stimulus (state), will correlate with the dimensions of the subjective orgasm experience.

H3. The objective sexual arousal experienced by men (erection) and women (VPA) in response to an erotic stimulus, will correlate with the dimensions of the subjective orgasm experience.

Methods

Participants

The sample was composed of 96 heterosexual participants (48 men and 48 women), with ages between 18 and 28 years. Mean age was 21.40 (SD = 2.89) and 20.04 (SD = 2.33) in men and women, respectively. All participants were Spanish undergraduate students. Exclusion criteria included: (a) having psychological disorders, sexual dysfunctions and/or medical problems; (b) medication use (e.g., antidepressants, antihypertensive); (c) drugs/alcohol use; and (d) history of sexual abuse.

Instruments and materials

Sociodemographic and Sexual History Questionnaire. This background questionnaire assessed sex, age, nationality, level of education, sexual orientation, relationship status, psychological, sexual or medical problems, pharmacological treatments, drugs/alcohol use, and sexual victimization.

Spanish version of the Orgasm Rating Scale (ORS) [5, 18]. It is a 25-item self-report adjective-rating scale that quantifies the subjective experience of orgasm in context of sexual relationship. Based on the MSOE [5], items are clustered into four dimensions: affective, sensory, intimacy, and rewards. The ORS uses a 6-point Likert scale, in which 0 indicates “does not describe it at all” and 5 indicates “describes it perfectly”. Internal consistency of the dimensions ranges from 0.93 (Sensory) to 0.78 (Intimacy). Regarding external validity, scores from the ORS positively correlated to sexual satisfaction and erotophilia. Regarding discriminant validity, the scale was useful to differentiate between individuals with orgasmic difficulties and individuals with no difficulties. In the present study, Cronbach’s alpha values for the four factors ranged from 0.86 (intimacy) to 0.93 (rewards) in men and from 0.80 (intimacy) to 0.93 (sensory) in women.

Spanish version of the Sexual Inhibition/Sexual Excitation Scales-Short Form (SIS/SES-SF) [19, 20]. It evaluates the individual propensity for becoming sexually excited or inhibited. The scale consists of 14 items distributed in three subscales: sexual excitation (SES), inhibition due to the threat of performance failure (SIS1), and inhibition due to the threat of performance consequences (SIS2). Cronbach’s alpha coefficients range between 0.60 (SIS2) and 0.72 (SES). Recently, Sierra et al. [21] reported that SES is a significant predictor of the subjective sexual arousal experienced by women in response to visual sexual stimuli. In the present study, in order to assess the sexual excitation as a trait, only SES was used. Cronbach’s alpha values in men and women were 0.78 and 0.61, respectively.

Ratings of Genital Sensations (RGS) [7, 22]. It evaluates the subjective sexual arousal as a state. RGS consists of 1 item that measures the level of genital sensations through an 11-item checklist scale, from 1 (no genital sensations) to 11 (multiple orgasm–repeated orgasmic release in a single sexual episode). High scores indicate greater subjective sexual arousal. Regarding the external validity, a previous study [7] reported significant correlations between the level of genital sensations and other sexual health variables (i.e., erotophilia, sexual excitation).

Genital response. Penile plethysmograph [23, 24] was used to measure the objective sexual arousal of men. This indium/gallium ring measures changes in penile circumference when an erection occurs. Vaginal photoplethysmograph [25,26,27] was used to measure the objective sexual arousal of women. This device measures the vaginal pulse amplitude (VPA). The Biopac MP 150 system with Acqknowledge software was used for data acquisition and processing. Genital responses were defined in terms of differences between scores from the sexual stimulus (erotic film) and the baseline stimulus (neutral film).

Visual stimuli materials: (a) a three-minute neutral content film (nature documentary); (b) a three-minute erotic content film (heterosexual couple having oral and vaginal sex followed by an orgasm). The ability of the erotic film to induce sexual activation was previously demonstrated in a pilot study [28].

Procedure

The study was previously approved by the Ethical Committee of Human Research from the University of Granada. University students were invited to participate in the study through flyers, posters placed at various locations, and ads posted on social networks (e.g., twitter, facebook). Regarding the inclusion criteria, participants had to be Spanish, between 18 and 28-year old, identified themselves as heterosexual, reported not to have psychological, sexual, or medical problems, not to use medication or drugs/alcohol, and not to have history of sexual abuse. In order to select the participants who met the inclusion criteria, an online questionnaire was used as screening. It included an informed consent, the background questionnaire, and the Spanish versions of the ORS and SES. Eligible participants were contacted and appointed to the laboratory by telephone. They were sent an email with information about the task, the appointment reminder, and a copy of the informed consent. At the human sexuality laboratory, the experimental task consisted of watching two films: (a) a three-minute neutral content film to have a baseline; (b) a three-minute erotic film to induce sexual activation. Simultaneously, genital response was registered. At the end of the erotic film sequence, participants were instructed to report their subjective sexual arousal (RGS). The average number of days between the screening and the arrival to the laboratory was ~10 days. An anonymous identification code for each participant was used. Participation was voluntary, participants did not receive rewards. The task included a written informed consent in which confidentiality and anonymity were guaranteed.

Results

First, descriptive statistics of the evaluated variables were calculated and differences across gender were examined (see Table 1). There were significant differences between men and women in scores from the sensory dimension of the subjective orgasm experience. This score was higher in women (t = −2.05; p < 0.05).

Table 1 Descriptive statistics of the evaluated variables
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Second, correlations between the four dimensions of the orgasm experience and the different types of sexual excitation (i.e., propensity, subjective, and objective) were analyzed. In men, the individual propensity for becoming sexually excited was positively correlated with all the dimensions of the orgasm experience, except intimacy. The significant correlations ranged from 0.39 (affective) to 0.41 (sensory). A positive correlation between the genital response and the intimacy dimension (r = 0.30, p < 0.05) was also found. In women, only the subjective sexual arousal positively correlated with the sensory dimension of the orgasm experience (r = 0.30, p < 0.05) (see Table 2).

Table 2 Correlations between the dimensions of the orgasm experience, the propensity for sexual excitation, the subjective sexual arousal and the genital response
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Finally, regression analyses using the stepwise method were performed. In order to determine which type of sexual excitation was able to predict the dimensions of the MSOE, only the types of sexual excitation which previously significantly correlated with the orgasm dimensions were introduced.

For men, we performed four linear regression models. The four dimensions of the orgasm experience were the dependent variables. We introduced the propensity for becoming sexually excited and the genital response as predictor variables. Results showed that the propensity for sexual excitation was the only predictor of sensory (β = 0.41, p < 0.01), Affective (β = 0.40, p < 0.01), and rewards (β = 0.40, p < 0.05) dimensions. The sexual excitation as a trait explained 15.2%, 12.9%, and 10.5% of the sensory, affective, and rewards dimensions, respectively. Furthermore, genital response was able to predict the intimacy dimension of the orgasm experience (β = 0.30, p < 0.05). The objective sexual arousal explained 6.9% of the variance of the intimacy factor.

For women, results showed a single significant regression model, in which the subjective sexual arousal in response to a sexual stimulus explained 6.8% (β = 0.30, p < 0.05) of the variance of the sensory dimension of the orgasm experience.

Discussion

The aim of this study was to provide validity evidence of the MSOE that proposes four dimensions to describe the psychological experience of orgasm in context of sexual relationship [5]. To do so, correlations between the model components and three types of sexual excitation (i.e., propensity, subjective, and objective) were examined within a laboratory task.

Regarding the first hypothesis, the individual propensity for sexual excitation is associated with the orgasm experience only in men. It has been showed that sexual excitation as a trait is involved in the estimation of the subjective orgasm experience, being able to predict sensorial, emotional, and reinforcing aspects of the male orgasm. However, this association has not been found in women. Gender differences could be a possible explanation. The greater propensity for sexual excitation in men, compared with women [19, 20], could make this trait have a greater relation with other manifestations of sexual functioning such as the male orgasm experience. In this regard, it may also occur that items included in the SES scale are not equally relevant for both sexes, maybe some items are more representative of male sexual excitation rather than that of female [9, 29].

As hypothesized, whereas both variables might be considered similar, specifically referring to physical and sensory changes at sexual level, the subjective estimation of genital sensations is associated with the sensory dimension of the orgasm experience in women. However, the subjective sexual arousal is unrelated with the orgasm dimensions in men. It has been showed relevant gender differences only in the sensory dimension, in which mean score was higher in women. According to these findings, Mah and Binik [18] also indicated that women value more subjectively than men the sensory aspects of orgasm experience. Similarly to previous research [30], it is suggested that women are better able to describe their sensations during orgasm or that they are more in tune with their internal sensations.

Finally, regarding the third hypothesis, the genital response is only associated with the intimacy dimension of the male orgasm experience. However, the objective sexual arousal is not associated with any of the female orgasm dimensions. Once more, gender differences might provide an explanation to this finding. Generally, both sexual excitation [9] and orgasm experience [31] are more related with physical aspects in men and with psychological ones in women. Considering that, it is not surprising to find that the physical response experienced in exposure to an erotic stimulus is associated with male orgasm experience but not with the female one. Orgasm in men tends to acquire a manifest and voluntary character, due to the obvious physical responses such as erection and ejaculation, whereas orgasm in women is characterized by a reflex or automatic aspect, which is not usually so visible. Nevertheless, these results contrast with findings of other laboratory studies with female samples [16, 32], where direct associations between different aspects of orgasm and genital response have been shown.

In conclusion, this study provides validity evidence to the MSOE in context of sexual relationship in both men and women [5, 33]. The dimensions attributed to the orgasm experience proposed by this descriptive model are associated with different types of sexual excitation. The ability of different types of sexual excitation to predict qualities of the subjective orgasm experience is endorsed. Above all, differences across gender have been reflected. The link between the orgasm experience, the sexual excitation as a trait, and the physiological response predominates in men. The subjective estimation and psychological valuation of both orgasm experience and sexual arousal predominate in women. The validation of the MSOE provides a more delimited and exhaustive explanation of the orgasm experience applicable to both sexes. Theoretically, the model allows the study of the subjective orgasm experience from a new multicomponent approach, focusing specifically on the psychological qualities. In clinical field, the MSOE could be used as screening device for orgasmic difficulties. It can be use entirely or, if necessary, emphasizing some of its components. Its use for the research purpose in the area of human sexuality is endorsed.

As limitations, it should be noted that the sample was not randomly recruited, participants were exclusively young and heterosexual. Extrapolation of the obtained results to the general population would be difficult. Future studies might examine orgasm experience in other sexual contexts such as solitary masturbation. Furthermore, including samples with different sexual orientations and age ranges is recommended.