Sociosexual Orientation Inventory (SOI)

Abstract

The Sociosexual Orientation Inventory (SOI) is a widely recognized psychological measure used to quantify individual differences in sociosexuality. This construct reflects an individual’s willingness to engage in sexual activity outside the confines of a committed, long-term romantic relationship. Originally developed by Jeffry A. Simpson as a unidimensional scale, the instrument was subsequently revised into the nine-item SOI-R (Sociosexual Orientation Inventory–Revised) by Lars Penke and Jens B. Asendorpf to capture a more nuanced, three-dimensional structure.

The revised SOI-R distinguishes between behavioral, attitudinal, and desiderative aspects of sexual orientation toward uncommitted relationships. This instrument is foundational in evolutionary psychology and relationship science, offering robust predictive utility for various mating strategies and relational outcomes such as jealousy and relationship investment. By providing a differentiated, multi-factor measure, the SOI-R serves as a reliable assessment of a stable personality disposition related to sexual psychology.

Keywords

Sociosexuality, Mating Strategy, Casual Sex, Uncommitted Sex, Personality, Relationship Science, Sexual Attitudes

Authors

Jeffry A. Simpson (Original SOI), Lars Penke, Jens B. Asendorpf (SOI-R)

Purpose

The fundamental purpose of the SOI, particularly the enhanced SOI-R, is to precisely quantify an individual’s position along the spectrum of Sociosexual Orientation. This measurement moves beyond simple counts of sexual partners by integrating the cognitive and motivational components associated with engaging in casual sex, thereby providing a holistic view of this key dimension in human sexual psychology.

The scale is crucial for research exploring human mating strategies. Scores derived from the SOI-R predict important relational behaviors, including levels of relationship investment, propensity for partner switching, and patterns of jealousy. By offering a robust, multi-dimensional score, the instrument allows researchers to analyze how dispositional differences in sexual desires and attitudes influence complex social and romantic interactions, contributing significantly to the fields of sexual selection and relationship dynamics.

Construct

The central psychological construct measured is Sociosexual Orientation, which is conceptualized as a continuum. At one end is a highly restricted orientation (requiring deep emotional commitment prior to sexual activity), and at the other is a highly unrestricted orientation (comfort and willingness to engage in sex outside of commitment). The revised SOI-R refined this concept by isolating three distinct, yet correlated, factors:

• Behavioral Component: This assesses objective history of sexual activity, such as the number of partners within a specified time frame or the count of one-night stands. It reflects past actions related to uncommitted sex.

• Attitudinal Component: This measures the cognitive acceptance and comfort level regarding casual sex, reflecting personal beliefs (e.g., the statement “Sex without love is OK”).

• Desire Component: This captures the underlying motivational disposition, quantifying the frequency of sexual fantasies, arousal, and desire directed toward non-committed or newly met individuals in daily life.

Validity

Extensive research supporting the SOI-R demonstrates strong convergent validity, where scale scores correlate predictably with theoretically related measures, such as specific personality traits (e.g., scoring higher on Extraversion and Openness from the Big Five model) and biological indicators (e.g., testosterone levels). This alignment confirms the scale’s theoretical foundation within evolutionary and personality psychology.

Furthermore, the shift to a three-factor structure significantly enhanced construct validity compared to the original unidimensional SOI. This differentiation, supported by statistical analysis of validity, allows for a more nuanced measurement of sociosexual expression across behavioral, attitudinal, and desiderative domains, thereby improving the scale’s overall predictive power for various courtship and relational outcomes in cross-cultural and longitudinal studies.

Reliability

The Sociosexual Orientation Inventory generally exhibits good internal reliability. Studies across diverse samples consistently report acceptable to high Cronbach’s alpha coefficients, which are often calculated separately for the three distinct subscales (Behavior, Attitude, Desire). These coefficients routinely meet the stringent requirements of standard psychological research.

In addition to internal consistency, the instrument demonstrates robust test-retest reliability over time. This temporal stability is consistent with the theoretical conceptualization of sociosexuality as a stable, dispositional characteristic that significantly influences an individual’s long-term approach to mating and relationships.

Factor Analysis

While the original SOI was conceptualized as unidimensional, subsequent empirical work employing Factor Analysis led directly to the development of the nine-item SOI-R. Both Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA) have consistently provided strong statistical support for a robust three-factor solution, which successfully separates the scale items into the Behavior, Attitude, and Desire dimensions.

This validated three-factor structure is essential because it demonstrates that sociosexuality is not a monolithic construct. Instead, it is a complex trait where an individual’s behavioral history, cognitive acceptance, and underlying motivational desires can operate semi-independently. This structural enhancement provides researchers with the necessary precision to isolate specific facets of sociosexual orientation when investigating potential genetic, neurological, or environmental influences.

Instrument

Test Type: Self-Report Questionnaire

Format: Multiple-choice and Likert-type scales. The original SOI used 5-point scales, while the SOI-R utilizes specific numerical counts for behavior items and 9-point Likert scales for attitude and desire items.

Language Available: English (Original), widely translated and validated in numerous languages globally.

Population Group: General adult population, frequently utilized in research involving college students and dating populations.

Age Group: Adolescents and Adults (typically 18+).

Population Details: Used globally in diverse cultural settings to study sexual behavior, relationship formation, and personality differences, often within the framework of evolutionary psychology.

Test Methodology: Respondents provide self-assessments concerning their past sexual behavior, their comfort level with casual sexual encounters, and the frequency of sexual fantasies involving non-committed partners. Scoring is typically done either by calculating a single overall standardized sociosexuality score or by determining separate scores for the three SOI-R subscales (Behavior, Attitude, Desire).

Keywords

Sexual Attitude, Relationship Satisfaction, Mating Behavior, Evolutionary Psychology, Commitment, Dispositional Traits, SOI-R

Authors

Author ORCID Identifier: Not provided in source content.

Affiliation Email addresses: [email protected]

Correspondence Address: Lars Penke, University of Edinburgh, UK

Permissions & Fee and Test Year

The original Sociosexual Orientation Inventory (SOI) was first published by Jeffry A. Simpson in 1998. The revised and now standard version, the Sociosexual Orientation Inventory–Revised (SOI-R), was formally introduced by Lars Penke and Jens B. Asendorpf in 2008.

The scale is generally available for non-commercial academic research use without associated fees. However, researchers planning specific or commercial applications are strongly advised to seek permission from the corresponding author, Lars Penke. Detailed information regarding the SOI-R is available online at: http://www.larspenke.eu/en/research/soi-r.html

The instrument was found on page 176 of the 2007 dissertation by Tammy Lowery Zacchilli. The original PDF can be downloaded here: http://repositories.tdl.org/ttu-ir/bitstream/handle/2346/9978/Zacchilli_Tammy_Diss.pdf?sequence=1

Reference’s

• Simpson, J. A. (1998). Sociosexual Orientation Inventory. In C.M. Davis, W. L. Yarber, R. Bauserman, G. Schreer, & S. L. Davis (Eds.), Handbook of sexuality-related measures (pp. 565-566). Thousand Oaks, CA: Sage Publications.

• Penke, L., & Asendorpf, J. B. (2008). Beyond global sociosexual orientations: A more differentiated look at sociosexuality and its effects on courtship and romantic relationships. Journal of Personality and Social Psychology, 95, 1113-1135.

• Zacchilli, T. L. (2007). The Relationship Between Conflict and Communication, Sex, Relationship Satisfaction, and other Relational Variables in Dating Relationships. A Dissertation In EXPERIMENTAL PSYCHOLOGY. Texas Tech University.

• Further information regarding the SOI-R is available at: http://www.larspenke.eu/en/research/soi-r.html

Items of the Sociosexual Orientation Inventory (SOI)

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

Please answer all of the following questions honestly‚ both the questions dealing with behavior and the questions dealing with thoughts and attitudes.

1. With how many different partners have you had sex (sexual intercourse) within the past year?

(A) Zero‚ (B) One‚ (C) Two‚ (D) Three to Four‚ (E) Five or more

2. How many different partners do you foresee yourself ha‎ving sex with during the next five years? (Please give a specific‚ realistic estimate)

(A) Zero‚ (B) One‚ (C) Two‚ (D) Three to Four‚ (E) Five or more

3. With how many different partners have you had sex on one and only one occasion?

(A) Zero‚ (B) One‚ (C) Two‚ (D) Three to Four‚ (E) Five or more

4. How often do you fantasize about ha‎ving sex with someone other than your current dating partner?

(A) Never‚ (B) Once every 2 or 3 months‚ (C) Once every 2 or 3 weeks‚ (D) Once every 2 or 3 days‚ (E) Once or more every

For each statement:

A = Strongly disagree with the statement

B = Moderately disagree with the statement

C = Neutral-neither agree or disagree

D = Moderately agree with the statement

E = Strongly agree with the statement

5. Sex without love is OK.

6. I can imagine myself being comfortable and enjoying “casual” sex with different partners.

7. I would have to be closely attached to someone (both emotionally and psychologically) before I could feel comfortable and fully enjoy ha‎ving sex with him or her.

1. With how many different partners have you had sex within the past 12 months?

0‚ 1‚ 2‚ 3‚ 4‚ 5-6‚ 7-9‚ 10-19‚ 20 or more

2. With how many different partners have you had sexual intercourse on one and only one occasion?

0‚ 1‚ 2‚ 3‚ 4‚ 5-6‚ 7-9‚ 10-19‚ 20 or more

3. With how many different partners have you had sexual intercourse without ha‎ving an interest in a long-term committed relationship with this person?

0‚ 1‚ 2‚ 3‚ 4‚ 5-6‚ 7-9‚ 10-19‚ 20 or more

4. Sex without love is OK.

1 □ Strongly disagree 2 □ 3 □ 4 □ 5 □ 6 □ 7 □ 8 □ Strongly agree 9 □

5. I can imagine myself being comfortable and enjoying “casual” sex with different partners.

1 □ Strongly disagree 2 □ 3 □ 4 □ 5 □ 6 □ 7 □ 8 □ Strongly agree 9

6. I do not want to have sex with a person until I am sure that we will have a long-term‚ serious relationship.

1 □ Strongly disagree 2 □ 3 □ 4 □ 5 □ 6 □ 7 □ 8 □ Strongly agree 9 □

7. How often do you have fantasies about ha‎ving sex with someone you are not in a committed romantic relationship with?

□ 1 – never

□ 2 – very seldom

□ 3 – about once every two or three months

□ 4 – about once a month

□ 5 – about once every two weeks

□ 6 – about once a week

□ 7 – several times per week

□ 8 – nearly every day

□ 9 – at least once a day

8. How often do you experience sexual arousal when you are in contact with someone you are not in a committed romantic relationship with?

□ 1 – never

□ 2 – very seldom

□ 3 – about once every two or three months

□ 4 – about once a month

□ 5 – about once every two weeks

□ 6 – about once a week

□ 7 – several times per week

□ 8 – nearly every day

□ 9 – at least once a day

9. In everyday life‚ how often do you have spontaneous fantasies about ha‎ving sex with someone you have just met?

□ 1 – never

□ 2 – very seldom

□ 3 – about once every two or three months

□ 4 – about once a month

□ 5 – about once every two weeks

□ 6 – about once a week

□ 7 – several times per week

□ 8 – nearly every day

□ 9 – at least once a day