Sexual Desire Inventory

1. Abstract

The Sexual Desire Inventory (SDI) is an authoritative, brief self-administered psychometric questionnaire developed by Ilana P. Spector, Michael P. Carey, and Lynne Steinberg to evaluate and quantify human sexual desire. Historically, empirical research and clinical practice in sexology struggled with the accurate measurement of sexual desire, frequently conflating subjective desire with overt behavioral frequency (e.g., acts of intercourse or masturbation) or utilizing overly reductive single-item self-report queries. Recognizing that sexual desire operates as an intrinsically cognitive-affective motivational construct that is conceptually and empirically distinct from behavioral engagement, the SDI was designed to capture interest in sexual activity via the frequency and intensity of cognitive processing directed toward approaching or being receptive to sexual stimuli.

The inventory consists of two primary, theoretically driven subscales: Dyadic Sexual Desire (evaluating an individual’s interest in engaging in sexual activity with a partner) and Solitary Sexual Desire (assessing interest in engaging in sexual behavior by oneself, primarily via masturbation). Across its development and validation iterations, the instrument captures both the subjective frequency of sexual cognitions and the subjective strength or intensity of desire across various situational contexts. In its psychometric evaluation, the SDI has demonstrated outstanding internal consistency, with Cronbach’s alpha coefficients of .86 for the Dyadic subscale and .96 for the Solitary subscale, alongside a robust test-retest reliability coefficient of r = .76 over a 1-month period. Factor analyses confirm a clean two-factor orthogonal or oblique structure corresponding precisely to dyadic and solitary orientations. The instrument exhibits substantial construct, concurrent, and discriminant validity across diverse populations, including undergraduate cohorts, community couples, and geriatric long-term care residents, providing sex researchers and clinicians with an indispensable tool for individual profiling and dyadic discrepancy analysis.

2. Keywords

Sexual Desire Inventory, SDI, sexual desire, dyadic sexual desire, solitary sexual desire, sexology, sexual health assessment, psychometrics, libido, hypoactive sexual desire disorder, sexual discrepancy, marital therapy

3. Authors

The Sexual Desire Inventory was developed through collaborative psychometric and clinical research conducted by:

• Ilana P. Spector, Ph.D. — Behavioral Psychotherapy and Research Unit, Department of Psychiatry, Sir Mortimer B. Davis Jewish General Hospital, Montreal, Quebec, Canada; McGill University. (Correspondence: [email protected]).
• Michael P. Carey, Ph.D. — Department of Psychology, Syracuse University, Syracuse, New York, United States; currently affiliated with the Centers for Behavioral and Preventive Medicine, The Miriam Hospital and Brown University.
• Lynne Steinberg, Ph.D. — Department of Psychology, Oklahoma State University, Stillwater, Oklahoma, United States.

4. Purpose

The primary purpose of the Sexual Desire Inventory (SDI) is to provide an objective, reliable, and construct-valid operationalization of subjective sexual desire. Prior to the introduction of the SDI, sexologists, clinical psychologists, and marital therapists encountered persistent psychometric and conceptual hurdles. Early research within the tradition of Masters and Johnson or the diagnostic frameworks of the early Diagnostic and Statistical Manual of Mental Disorders (DSM) frequently assessed libido indirectly by measuring the frequency of overt sexual intercourse, orgasms, or masturbation. However, reliance on overt behavior as a proxy for desire is fundamentally flawed: individuals may frequently engage in partner-oriented sexual intercourse out of relational duty, partner gratification, or emotional reassurance in the total absence of intrinsic sexual desire. Conversely, individuals experiencing profound sexual longing and intense cognitive interest may exhibit zero sexual behavior due to physical disability, medical illness, partner unavailability, relationship distress, or restrictive sociocultural norms.

Alternatively, earlier psychometric scales often relied on global, unidimensional self-report questions, such as asking respondents to “rate your level of sexual desire from low to high.” Such monolithic questions fail to capture the multidimensional nuances of human motivational states and treat desire as an amorphous, homogeneous drive. The SDI was established to delineate sexual desire as a predominantly cognitive-motivational variable, defined specifically as an individual’s interest in or wish for sexual activity, quantified via the subjective volume, frequency, and intensity of thoughts oriented toward approaching or responding to sexual stimuli.

The SDI serves several critical clinical and research functions:

• Clinical Diagnosis and Treatment Monitoring: The scale enables clinicians to diagnose conditions such as Hypoactive Sexual Desire Disorder (HSDD) and Female Sexual Interest/Arousal Disorder (FSIAD), disaggregating whether the client’s inhibition represents a global suppression of all sexual drive or a situation-specific relational inhibition limited to their partner.
• Assessment of Couple Desire Discrepancy: In marital and sex therapy, sexual desire discrepancy—where one partner desires sexual intimacy significantly more or less frequently than the other—is a major source of relational discord. The SDI allows therapists to calculate empirical discrepancy scores by comparing partners’ dyadic desire indices, providing an objective benchmark for clinical intervention.
• Theoretical Sexological Research: The SDI allows researchers to investigate how gender differences, neuroendocrine shifts, age-related transitions, and psychiatric illnesses differentially impact solitary versus dyadic manifestations of libido.
• Cross-Generational and Medical Studies: Because the items do not assume physical performance capacity, the inventory can be seamlessly administered to young adult populations, geriatric cohorts residing in long-term care facilities, and patients with chronic physical illnesses.

5. Psychological Construct

The psychological construct assessed by the Sexual Desire Inventory is sexual desire, conceptualized not as a reflexive biological physiological response (such as genital vasocongestion or erection), nor as an overt motor behavior, but as a cognitive-affective motivational appetite. The SDI delineates this construct across two distinct empirical dimensions:

Dyadic Sexual Desire

Dyadic sexual desire refers to an individual’s subjective interest in, longing for, or motivation to engage in sexual behavior with another person. This dimension is inherently interpersonal and relational. It encompasses not only the cognitive anticipation of mutual physical intimacy (such as caressing, oral sex, and intercourse) but also the psychological receptivity and responsiveness to external sexual stimuli embedded within social and romantic contexts.

Dyadic desire operates across varying levels of contextual evocative cues. The SDI measures dyadic desire across multiple ecological manifestations:

• Spontaneous Dyadic Cognitions: The habitual frequency with which sexual thoughts involving a partner arise into consciousness during daily living.
• Receptive and Contextual Desire: The intensity of sexual motivation triggered by romantic environments (e.g., romantic candle-lit dinners, intimate vacations) or proximity to attractive individuals in routine environments (e.g., at work, university, or social gatherings).
• Motivational Importance: The subjective personal value and psychological priority assigned to consummating sexual desire through shared relational activities.
• Self-Comparative Dyadic Desire: An individual’s metacognitive evaluation of their own relational sexual appetite relative to peers of the same age and gender.

Solitary Sexual Desire

Solitary sexual desire refers to an individual’s subjective interest in experiencing sexual pleasure and release independently, without the physical or emotional involvement of a partner. This dimension centers entirely on self-directed eroticism, typically expressed through masturbation, personal erotic fantasies, and self-touch.

Solitary desire represents an autonomous biological and psychological phenomenon that often functions independently of dyadic desire. A person may maintain robust solitary sexual desire while possessing negligible dyadic desire (for instance, in situations of severe marital conflict, relational detachment, or partner-specific resentment). Conversely, an individual deeply in love and desiring relational physical intimacy may exhibit minimal interest in solitary autoerotic activity due to personal preferences, moral prohibitions, or an exclusively interpersonal orientation to sexual gratification. The SDI evaluates solitary desire by assessing:

• Frequency of Autoerotic Longing: How often within the past month the respondent desired solitary sexual behavior.
• Intensity of Autoerotic Drive: The magnitude and strength of the internal urge to engage in solitary behavior.
• Perceived Importance: The degree to which self-directed sexual fulfillment is prioritized in the individual’s psychological life.
• Self-Comparative Solitary Desire: The individual’s normative estimation of their autoerotic drive relative to their peers.

6. Theoretical Framework

The development of the Sexual Desire Inventory is rooted in the evolution of theoretical models within modern sexology, particularly the paradigm shift from purely physiological models to triphasic and cognitive-emotional models of human sexuality.

Transition from Masters & Johnson to Helen Singer Kaplan

In their classic human sexual response cycle, William Masters and Virginia Johnson (1966) conceptualized sexual response as a continuous sequence consisting of four physiological phases: Excitement, Plateau, Orgasm, and Resolution. While groundbreaking, their model was purely somatic, focusing on genital vasocongestion and muscular contractions. It conspicuously omitted an antecedent psychological phase: the motivational impulse to seek out sexual experiences.

In 1979, psychiatrist Helen Singer Kaplan reformulated this framework by proposing the Triphasic Model of Sexual Response, which established Desire as the critical first phase, followed by Excitement and Orgasm. Kaplan posited that desire is biologically driven by neurochemical networks in the limbic system but mediated extensively by psychological, cognitive, and relational variables. Without desire, the downstream physiological cascade of excitement and orgasm is rarely initiated spontaneously. The SDI was explicitly conceptualized within this Kaplanian framework, treating desire as a distinct mental state that precedes physical arousal.

Cognitive-Motivational and Dual-Control Perspectives

The SDI also aligns closely with contemporary cognitive theories of sexual function, such as those articulated by Stephen Levine and the later Dual Control Model proposed by John Bancroft and Erick Janssen. Levine characterized sexual desire as an amalgam of three distinct components: biological drive (neuroendocrine neurobiology), psychological wish (cognitive intentions and emotional readiness), and social motive (interpersonal willingness to join with a partner). The SDI primarily targets the psychological wish and social-relational motives through cognitive self-appraisal.

Furthermore, by structurally bifurcating the construct into dyadic and solitary domains, Spector, Carey, and Steinberg acknowledged that sexual motivation does not operate as an undifferentiated biological reservoir. Instead, human eroticism possesses distinct motivational pathways: one directed toward interpersonal affiliation, romantic bonding, and shared pleasure, and another directed toward individual stress reduction, localized sensory pleasure, and autonomous somatic release. This theoretical bifurcation resolved decades of contradictory findings where individuals in sexless marriages nonetheless reported active autoerotic fantasy lives.

7. Validity

The psychometric validity of the Sexual Desire Inventory has been empirically validated across multiple independent studies utilizing college students, adult community couples, and elderly residential populations.

Construct and Factorial Validity

During initial scale development, exploratory factor analyses confirmed that the SDI items cleanly loaded onto two separate factors corresponding to Dyadic Sexual Desire (Items 1–8) and Solitary Sexual Desire (Items 9–11). All dyadic items demonstrated robust factor loadings exceeding .45 on the dyadic dimension with negligible cross-loadings on the solitary dimension, and all solitary items loaded heavily on the solitary factor, confirming excellent construct demarcation.

Concurrent Validity

Concurrent validity was examined by correlating SDI subscale scores with actual behavioral frequencies and established sexological instruments in a primary sample of 380 undergraduate students (Spector et al., 1996):

• Solitary Desire and Behavior: The Solitary Sexual Desire subscale demonstrated a substantial positive correlation with the frequency of actual solitary sexual behavior (masturbation; r = .80, p < .0001). Furthermore, solitary desire correlated with erotophilia (r = −.28, p < .0001; Spector, 1992).
• Dyadic Desire and Behavior: Dyadic sexual desire was significantly correlated with the actual frequency of dyadic sexual behavior (r = .34, p < .0001).

Crucially, the moderate magnitude of the correlation between dyadic desire and dyadic behavior (r = .34) provides powerful empirical evidence for the authors’ foundational assertion: desire and behavior are far from isomorphic. If desire were simply a proxy for behavior, this coefficient would approach unity. The divergence indicates that relational sexual activity is heavily constrained or facilitated by situational, partner, and social variables, underscoring the absolute necessity of measuring desire independently.

Convergent Validity

In an investigation involving 40 married and cohabiting couples (Spector & Davies, 1995), the SDI displayed pronounced convergent associations with validated relationship and sexual indices, revealing remarkable gender differences:

• Female Dyadic Desire: Among women, dyadic desire correlated strongly with dyadic relationship adjustment on the Dyadic Adjustment Scale (Spanier, 1976; r = .54, p < .001), sexual satisfaction on the Index of Sexual Satisfaction (Hudson et al., 1981; r = .63, p < .001), cognitive sexual fantasy on the Sexual Daydreams Scale (Giambra, 1980; r = .53, p < .001), and subjective sexual arousability on the Sexual Arousal Inventory (Hoon et al., 1976; r = .71, p < .001).
• Male Dyadic Desire: In contrast, among men, dyadic sexual desire demonstrated a selective significant correlation with sexual satisfaction (r = .36, p < .01), exhibiting non-significant relationships with broader marital adjustment, suggesting that male dyadic desire may operate with greater autonomy from global relationship satisfaction than female dyadic desire.

Discriminant Validity

Discriminant validity was established by evaluating the relationship between the SDI and social desirability response biases. Spector (1992) demonstrated that neither the Dyadic nor the Solitary subscale correlated significantly with social desirability scales, demonstrating that respondents are willing to report low or high levels of autoerotic and partner-directed desire without yielding to impression management tendencies.

8. Reliability

The SDI demonstrates high reliability across both internal consistency and temporal stability paradigms.

Internal Consistency

In the seminal psychometric validation study conducted by Spector, Carey, and Steinberg (1996) involving 380 participants, internal consistency was evaluated using Cronbach’s alpha:

• Dyadic Sexual Desire Subscale (Items 1–8): Produced an alpha coefficient of α = .86, indicating strong homogeneity of items assessing interest in partner-related sexual encounters across diverse contextual triggers.
• Solitary Sexual Desire Subscale (Items 9–11): Yielded an outstanding alpha coefficient of α = .96, reflecting exceptional internal reliability for the assessment of autoerotic motivation.

Item-total correlations for both subscales consistently exceed .50, with no individual item removal leading to an elevation in the scale’s overall reliability coefficients.

Test-Retest Reliability

Temporal stability was empirically confirmed by Carey (1995) in a longitudinal test-retest administration over a standard 1-month referent interval. The study yielded an aggregate test-retest stability coefficient of r = .76. This finding indicates that while the SDI is sensitive to dynamic shifts in relational contexts and life stressors over extended periods, it captures a highly stable cognitive trait over medium-term timeframes.

9. Factor Analysis

The factorial structure of the SDI was rigorously established through exploratory and confirmatory factor analytic methodologies during scale construction.

Exploratory Factor Structure

The initial pool of candidate items was formulated based on expert consensus among clinical sexologists and pilot tested on 20 individuals to establish content validity and item comprehensibility. Subsequently, the instrument was administered to a calibration sample of 300 university students. Principal components analysis followed by orthogonal (Varimax) and oblique (Promax) rotations revealed a robust two-factor solution:

• Factor 1: Dyadic Sexual Desire: Accounted for the largest proportion of total variance with an initial eigenvalue well exceeding 1.0. Items 1 through 8 loaded robustly onto this factor, with all standardized factor loadings exceeding .45 (ranging up to .82). Cross-loadings onto the solitary dimension were negligible (< .20).
• Factor 2: Solitary Sexual Desire: Yielded an eigenvalue substantially exceeding 1.0. Items 9 through 11 exhibited exceptionally high factor loadings onto this dimension, with primary loadings surpassing .85.

Subsequent psychometric evaluations across geriatric cohorts (Spector & Fremeth, 1996) and community couple samples (Spector & Davies, 1995) have replicated this bifurcated dimensional architecture. Confirmatory factor analytic investigations have repeatedly demonstrated superior model fit indices (CFI > .95, RMSEA < .06) for the two-factor model relative to a unidimensional model, providing structural justification for computing distinct Dyadic and Solitary subscale scores.

10. Instrument / Measurement Tool

The operational characteristics and structural architecture of the Sexual Desire Inventory are summarized below:

• Instrument Name: Sexual Desire Inventory (SDI)
• Authors: Ilana P. Spector, Michael P. Carey, and Lynne Steinberg
• Administration Format: Self-administered paper-and-pencil or computerized questionnaire
• Completion Time: Approximately 3 to 5 minutes
• Target Population: Adults (validated across ages 18 to 85+, including clinical cohorts, community couples, and geriatric populations)
• Referent Timeframe: The preceding one month (“During the last month…”)
• Subscales:
  • Dyadic Sexual Desire Subscale: Items 1 through 8 (evaluates desire for sexual activity with a partner).
  • Solitary Sexual Desire Subscale: Items 9 through 11 (evaluates desire for solitary autoerotic activity).
  • Additional Exploratory/Descriptive Items: Item 12 (and Item 13) capture general desire latency/frequency parameters (e.g., length of time an individual can comfortably abstain from sexual activity).
• Response Modes:
  • Frequency Items (Items 1, 2, 9): Utilizes a 7-point Likert-type frequency scale anchored from 1 = “Not at all” to 7 = “More than once a day”.
  • Strength, Importance, and Comparative Items (Items 3–8, 10–11): Utilizes a 9-point Likert-type scale ranging from 0 to 8, anchored by descriptive endpoints (e.g., 0 = “No desire” / “Not at all important” / “Much less desire” to 8 = “Strong desire” / “Extremely important” / “Much more desire”).
• Scoring Procedures:
  • Dyadic Desire Score: Sum the numerical responses for Items 1 through 8. Higher scores reflect greater dyadic sexual interest and responsiveness.
  • Solitary Desire Score: Sum the numerical responses for Items 9 through 11. Higher scores indicate greater autoerotic desire.
  • Couple Discrepancy Score: In clinical assessment of couples, calculate the absolute difference between Partner A’s dyadic score and Partner B’s dyadic score (|Dyadic_{Partner A} − Dyadic_{Partner B}|).

11. Permissions & Fee and Test Year

The Sexual Desire Inventory was developed through doctoral and university-based clinical research between 1992 and 1995, with its primary psychometric validation study published in 1996 in the Journal of Sex & Marital Therapy. The scale is considered an open-access academic instrument for non-commercial scientific research and clinical practice, provided that the original authors and validation publications are cited appropriately. Researchers seeking to utilize the scale in large-scale commercial applications or proprietary clinical trials should contact the corresponding author, Dr. Ilana P. Spector, at the Sir Mortimer B. Davis Jewish General Hospital, Montreal, Quebec, Canada.

12. References

• Carey, M. P. (1995). Test-retest reliability of the Sexual Desire Inventory [Unpublished raw data]. Syracuse University, Syracuse, NY.
• Giambra, L. M. (1980). A factor analysis of the items of the Imaginal Processes Inventory. Journal of Clinical Psychology, 36(2), 383–409. https://doi.org/10.1007/BF01542081
• Hudson, W. W., Harrison, D. F., & Crosscup, P. C. (1981). A short-form scale to measure sexual discord in dyadic relationships. The Journal of Sex Research, 17(2), 157–174. https://doi.org/10.1080/00224498109551110
• Kaplan, H. S. (1979). Disorders of Sexual Desire and Other New Concepts and Techniques in Sex Therapy. Brunner/Mazel.
• Masters, W. H., & Johnson, V. E. (1966). Human Sexual Response. Little, Brown and Company.
• Spanier, G. B. (1976). Measuring dyadic adjustment: New scales for assessing the quality of marriage and similar dyads. Journal of Marriage and the Family, 38(1), 15–28. https://doi.org/10.2307/350547
• Spector, I. P. (1992). Development and psychometric evaluation of a measure of sexual desire (Doctoral dissertation, Syracuse University). Dissertation Abstracts International, 53, 5456B.
• Spector, I. P., Carey, M. P., & Steinberg, L. (1996). The Sexual Desire Inventory: Development, factor structure, and evidence of reliability. Journal of Sex & Marital Therapy, 22(3), 175–190. https://doi.org/10.1080/00926239608414655
• Spector, I. P., & Davies, S. (1995). The experience of sexual desire in couples [Unpublished manuscript]. Sir Mortimer B. Davis Jewish General Hospital, Montreal, QC.
• Spector, I. P., & Fremeth, S. M. (1996). Sexual behaviours and attitudes of geriatric residents in long-term care facilities. Journal of Sex & Marital Therapy, 22(4), 235–246. https://doi.org/10.1080/00926239608414660

13. Items of the Scale (Questionnaire)