Sexual Desire Inventory

Abstract

The Sexual Desire Inventory (SDI) is an 11-item, self-administered questionnaire developed to provide a precise measure of sexual desire. Historically, sexologists faced difficulties measuring this construct accurately, often relying on indirect methods such as frequency of sexual behavior or broad self-reports like “rate your level of sexual desire.” These older methods were deemed inadequate because sexual desire is theoretically a multidimensional construct, and empirical data confirms that desire and behavior are not perfectly correlated.

The SDI overcomes these limitations by defining sexual desire as interest in sexual activity, measured primarily as a cognitive variable focusing on the amount and strength of thought directed toward approaching or being receptive to sexual stimuli. The development process involved clinical experience, theoretical modeling, and rigorous factor analysis. This analysis established two distinct dimensions of the construct: Dyadic Sexual Desire (interest in sexual activity with a partner) and Solitary Sexual Desire (interest in sexual activity by oneself). The instrument is suitable for measuring sexual desire in diverse groups, including younger and older adults, individuals, and couples, across both general and clinical populations.

Keywords

Sexual Desire Inventory, SDI, sexual desire, dyadic sexual desire, solitary sexual desire, psychometrics, sexology, sexual behavior, psychological assessment.

Authors

Ilana P. Spector, Michael P. Carey, Lynne Steinberg.

Purpose

The primary purpose of the Sexual Desire Inventory (SDI) is to provide a reliable and empirically validated self-report instrument for quantifying sexual desire. It was specifically developed to address the shortcomings of previous measures that failed to capture the cognitive and multidimensional nature of desire.

The scale serves both research and clinical objectives. In research, it facilitates the systematic collection of psychometric data related to sexual interest across varied demographic groups. Clinically, it is used to assess individuals presenting with sexual desire disorders. Furthermore, the SDI’s scoring protocol allows for the calculation of a desire discrepancy score when administered to couples, providing a valuable metric for understanding relational sexual dynamics.

Construct

The SDI measures the construct of Sexual Desire, which the developers defined as a cognitive variable—the amount and intensity of thoughts concerning sexual activity. This definition is critical as it separates the mental experience of desire from the physical act of behavior.

The instrument is structured around two empirically derived subscales, reflecting the multidimensional nature of the construct:

• Dyadic Sexual Desire: Measured by Items 1 through 8, this subscale captures interest in sexual activity involving a partner.
• Solitary Sexual Desire: Measured by Items 9 through 11, this subscale captures interest in sexual activity performed by oneself (e.g., masturbation).

Validity

Extensive evidence supports the validity of the SDI, encompassing factor, concurrent, and discriminant validity measures.

Factor Validity: Factor analyses confirmed the intended two-factor structure. Items 1–8 consistently demonstrated high loadings (greater than 0.45) on the dyadic factor, while Items 9–11 loaded highly on the solitary factor. Both factors yielded eigenvalues exceeding 1, confirming the statistical separation of the two dimensions (Spector et al., 1996).

Concurrent Validity: In a sample of 380 students, solitary sexual desire showed a strong positive correlation with the frequency of solitary sexual behavior (r = 0.80, p < 0.0001). It was also found to be negatively correlated with erotophilia (r = –0.28, p < 0.0001). Dyadic desire correlated positively with the frequency of dyadic sexual behavior (r = 0.34, p < 0.0001). The observed imperfect correlations between desire scores and behavior frequencies validate the SDI’s ability to measure desire as a cognitive entity, distinct from overt sexual activity.

A separate study on 40 couples provided further concurrent validity evidence. For females, dyadic desire correlated positively with relationship adjustment (r = 0.54, p < 0.001), sexual satisfaction (r = 0.63, p < 0.001), sexual daydreams (r = 0.53, p < 0.001), and sexual arousal (r = 0.71, p < 0.001). For males, dyadic sexual desire was significantly correlated only with sexual satisfaction (r = 0.36, p < 0.01). Discriminant validity was established by demonstrating that neither subscale correlates with social desirability (Spector, 1992).

Reliability

The reliability of the SDI has been demonstrated through measures of internal consistency and test-retest stability.

Internal Consistency: Internal consistency estimates, using Cronbach’s alpha coefficients, showed strong evidence of reliability (Spector et al., 1996). The Dyadic scale yielded an alpha coefficient of 0.86, and the Solitary scale achieved a coefficient of 0.96, indicating excellent internal consistency across both dimensions.

Test-Retest Reliability: The scale demonstrated stability over time with a test-retest reliability coefficient of r = 0.76 over a one-month interval (Carey, 1995).

Factor Analysis

The SDI’s structure was confirmed through factor analysis, which was crucial for establishing the multidimensional nature of sexual desire. The factor analysis results, published in 1996, clearly supported a two-factor model.

The analysis showed that items related to partner activity (Items 1–8) clustered together as the Dyadic Factor, and items related to self-activity (Items 9–11) clustered separately as the Solitary Factor. This empirical separation justifies the scoring method and confirms that sexual desire should not be treated as a unitary construct when measured.

Scoring

Scoring the SDI involves summing the scores for items corresponding to each factor:

• Dyadic Sexual Desire Score: Sum of scores from Items 1 through 8.
• Solitary Sexual Desire Score: Sum of scores from Items 9 through 11.

For clinical work or research involving couples, a Desire Discrepancy Score can be calculated by subtracting the female partner’s dyadic score from the male partner’s dyadic score.

Instrument

Test Type: Self-administered questionnaire (Psychometric Scale).

Format: 11 core items. Items 1, 2, and 10 are frequency items utilizing a seven-option response format. The remaining eight strength items are rated on an 8-point Likert-type scale (ranging from 0 to 8). The time frame of reference is the last month. The scale typically takes less than 5 minutes to complete.

Language Available: English (Original development).

Population Group: General population and clinical samples.

Age Group: Younger adults (Mean age = 20.8) and older adults (Mean age = 82.5).

Population Details: Data has been collected from students, geriatric long-term care residents, and couples.

Test Methodology: Pencil-and-paper self-report, utilizing both frequency and intensity ratings.

Keywords

Psychological assessment, psychometric instrument, dyadic relationship, sexual function, geriatric samples, Likert scale, sexual health, desire discrepancy.

Authors

Author ORCID Identifier: Not provided in source material.

Affiliation Email addresses: [email protected] (For Ilana P. Spector).

Correspondence Address: Ilana P. Spector, Behavioral Psychotherapy and Research Unit, Department of Psychiatry, SMBD Jewish General Hospital, 4333 Cote St. Catherine Road, Montreal, Quebec, Canada, H3T 1E4.

Permissions & Fee and Test Year

The scale was developed and validated in the mid-1990s, with primary publication occurring in 1996 (Spector, Carey, & Steinberg). Specific commercial fee information is not provided in the source content. Requests for usage or permissions should be directed to the corresponding author.

Reference’s

Carey, M. P. (1995). [Test-retest reliability of the Sexual Desire Inventory.] Unpublished raw data.

Giambra, L. M. (1980). A factor analysis of the items of the Imaginal Processes Inventory. Journal of Clinical Psychology, 36, 383–409.

Hoon, E. F., Hoon, P. W., & Wincze, J. P. (1976). The SAI: An inventory for the measurement of female sexual arousability. Archives of Sexual Behavior, 5, 291–300.

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, 157–174.

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, 15–28.

Spector, I. P. (1992). Development and psychometric evaluation of a mea- sure of sexual desire. Unpublished doctoral dissertation, Syracuse University, New York.

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, 175–190.

Spector, I. P., & Davies, S. (1995). The experience of sexual desire in couples. Unpublished manuscript.

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, 235–246.

Items of the Sexual Desire Inventory

IMPORTANT: The following scale items must be preserved in their original language and must not be changed in any way.

This questionnaire asks about your level of sexual desire. By desire, we mean interest in or wish for sexual activity. For each item, please circle the number that best shows your thoughts and feelings. Your answers will be private and anonymous.

1. During the last month, how often would you have liked to engage in sexual activity with a partner (for example, touching each other’s genitals, giving or receiving oral stimulation, intercourse, etc.)?

   1. Not at all 4) Twice a week

   2. Once a month 5) 3 to 4 times a week

   3. Once every two weeks 6) Once a day

   4. Once a week 7) More than once a day

2. During the last month, how often have you had sexual thoughts involving a partner?

   1. Not at all 4) 3 to 4 times a week

   2. Once or twice a month 5) Once a day

   3. Once a week 6) A couple of times a day

   4. Twice a week 7) Many times a day

3. When you have sexual thoughts, how strong is your desire to engage in sexual behavior with a partner?

   0 1 2 3 4 5 6 7 8

   No desire Strong desire

4. When you first see an attractive person, how strong is your sexual desire?

   0 1 2 3 4 5 6 7 8

   No desire Strong desire

5. When you spend time with an attractive person (for example, at work or school), how strong is your sexual desire? 0 1 2 3 4 5 6 7 8

   No desire Strong desire

6. When you are in romantic situations (such as a candle-lit dinner, a walk on the beach, etc.), how strong is your sexual desire? 0 1 2 3 4 5 6 7 8

   No desire Strong desire

7. How strong is your desire to engage in sexual activity with a partner?

   0 1 2 3 4 5 6 7 8

   No desire Strong desire

8. How important is it for you to fulfill your sexual desire through activity with a partner?

   0 1 2 3 4 5 6 7 8

   Not at all Extremely

   important important

9. Compared to other people of your age and sex, how would you rate your desire to behave sexually with a partner? 0 1 2 3 4 5 6 7 8

   Much less Much more

   desire desire

10. During the last month, how often would you have liked to behave sexually by yourself (for example, masturbating, touching your genitals etc.)?

    1. Not at all 4) Twice a week

    2. Once a month 5) 3 to 4 times a week

    3. Once every two weeks 6) Once a day

    4. Once a week 7) More than once a day

11. How strong is your desire to engage in sexual behavior by yourself?

    0 1 2 3 4 5 6 7 8

    No desire Strong desire

12. How important is it for you to fulfill your desires to behave sexually by yourself?

    0 1 2 3 4 5 6 7 8

    Not at all Extremely

    important important

13. Compared to other people of your age and sex, how would you rate your desire to behave sexually by yourself? 0 1 2 3 4 5 6 7 8

    Much less Much more

    desire desire

14. How long could you go comfortably without having sexual activity of some kind?

    1. Forever 5) A week

    2. A year or two 6) A few days

    3. Several months 7) One day

    4. A month 8) Less than one day

    5. A few weeks