Extramarital Behavioral Intentions Scale

Abstract

The Extramarital Behavioral Intentions Scale (EBIS) is a concise psychometric instrument designed to measure the subjective probability of an individual engaging in various forms of extramarital sex or involvement, should an opportunity arise. Developed by Bram Buunk, the scale is rooted in the theoretical framework of behavioral intention proposed by Fishbein and Ajzen (1975), which posits that intention is a strong predictor of future behavior. The EBIS consists of five items that cover a continuum of involvement, ranging from low-level acts like flirting to high-level acts such as establishing a long-term sexual relationship.

Respondents utilize a 7-point Likert-style response format, ranging from certainly no to certainly yes, with a midpoint formulated as uncertain. The scale typically requires no more than one to two minutes for completion, and items are summed to yield a single score, where higher scores indicate a higher likelihood of intended extramarital behavior.

Keywords

Extramarital Behavioral Intentions Scale, EBIS, extramarital sex, behavioral intention, marital relationships, sexual permissiveness, infidelity, psychological measurement, Buunk, Guttman scaling.

Authors

Bram Buunk (University of Nijmegen, The Netherlands).

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Purpose

The primary purpose of the Extramarital Behavioral Intentions Scale is to provide a standardized, predictive method for assessing an individual’s psychological readiness for future extramarital sexual involvement. Prior research frequently focused on correlating variables like marital dissatisfaction with actual extramarital behavior, but this approach made it difficult to establish the clear direction of causality (Buunk, 1980a).

By measuring the individual’s subjective behavioral intention, the scale aims to isolate the factors that predispose an individual toward extramarital activity, thereby offering a more robust assessment of the likelihood of involvement than retrospective self-reports of prior behavior or current relationship status.

Construct

The EBIS measures the psychological construct of Behavioral Intention as applied specifically to extramarital activities. This construct is derived from the theoretical foundation laid by Fishbein and Ajzen (1975), defining intention as the subjective probability that someone will exhibit a specific behavior if the opportunity presents itself. The theory suggests that high intentions are highly correlated with actual future behavior.

A fundamental assumption guiding the scale’s design is the existence of a Continuum of Extramarital Sexual Involvement. The five scale items are structured to represent this continuum, encompassing behaviors that vary in emotional and physical intimacy, from non-sexual (flirting) to fully committed sexual involvement (a long-term sexual relationship). This structure was later confirmed through Guttman scaling procedures.

Validity

The scale possesses strong evidence for concurrent validity. In a general population sample, scores on the EBIS correlated highly with the reported extent of extramarital experience during the previous year (r(250) = .74, p < .001). The scale also successfully differentiates between groups with varying levels of sexual permissiveness. Individuals in sexually open marriages scored significantly higher on the EBIS compared to both the average population sample (t(348) = 22.46, p < .001) and undergraduate students (t(478) = 15.16, p < .001).

Construct validity has been established through correlations with related psychological measures. The EBIS shows predicted positive correlations with permissive attitudes toward extramarital sex, and negative correlations with scales measuring the desire for an exclusive relationship (r(250) = -.54, p < .001) and moral disapproval of extramarital sex (r(250) = -.65, p < .001). Furthermore, the scale correlates negatively with anticipated sexual jealousy and positively with Psychosexual Stimulation (Frenken, 1976), which measures the openness to sexual fantasies and perceptions.

The scale’s validity is further supported by evidence from the open marriage study, where respondents’ intentions correlated significantly with the intentions perceived by their spouses (r(50) = .53 for women; r(50) = .42 for men).

Reliability

The internal consistency of the EBIS is consistently high across diverse samples. The measure of internal consistency, Cronbach’s alpha, was reported as .91 in a sample representing the general Dutch population. Other reported alpha values include .73 among individuals who had previously been involved in extramarital relationships, .75 in a sexually open marriage sample, and .87 among undergraduate students.

The scale demonstrates acceptable stability over time, with a 3-month test-retest reliability of r(100) = .70 (p < .001) observed in the open marriage sample. Crucially, the EBIS fulfills the requirements of a Guttman scale, indicating that the items form a cumulative, unidimensional hierarchy. The coefficient of scalability was .78, and the coefficient of reproducibility was .92, confirming the structured continuum of intended behavior.

Factor Analysis

Formal factor analysis (Exploratory or Confirmatory) is not reported in the source documentation. Instead, the scale’s underlying structure was validated using Guttman scaling, which addresses the scalability and unidimensionality of items intended to form a cumulative hierarchy. The successful Guttman analysis confirms that the EBIS measures a single dimension of extramarital involvement intention.

The established order of the items along this cumulative continuum (Buunk, 1980a) reflects increasing levels of intended intimacy and commitment: flirting, followed by falling in love, light petting, sexual intercourse, and finally, a long-term sexual relationship. This order suggests that an individual intending to engage in a higher-level behavior is also likely to intend to engage in all preceding, lower-level behaviors.

Instrument

Test Type: Self-report questionnaire measuring behavioral intention.

Format: 5 items utilizing a 7-point Likert-type scale, where options are spelled out literally (e.g., “certainly no” to “certainly yes”).

Language Available: Dutch (Original development language).

Population Group: Adults in committed relationships (e.g., married or cohabiting individuals).

Age Group: Adults (Samples included undergraduate students and general population adults).

Population Details: Used across diverse populations, including the general Dutch population, individuals involved in extramarital relationships, and those in sexually open marriages.

Test Methodology: Respondents are asked to indicate the probability of engaging in each specific behavior if an opportunity were to present itself. The items are simply summed, with no reverse scoring required. Higher total scores indicate a greater intention to engage in extramarital sex.

Keywords

Behavioral intention theory, extramarital affairs, infidelity risk, sexual attitudes, Guttman scale, marital dynamics, psychological assessment, Bram Buunk, Cronbach’s alpha.

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Authors

Author ORCID Identifier: Not provided in source content.

Affiliation Email addresses: [email protected]

Correspondence Address: Bram Buunk, Department of Psychology, University of Groningen, Grote Kruisstraat 2/1, 9712 TS Groningen, The Netherlands.

Permissions & Fee and Test Year

Test Year: Circa 1980 (Based on initial publication date, Buunk, 1980a).

Permissions & Fee: Information regarding current permissions and usage fees is not detailed in the source material. Researchers seeking to utilize the scale must contact the corresponding author, Bram Buunk, for authorization.

Reference’s

• Bell, R. R., Turner, S., & Rosen, L. (1975). A multivariate analysis of female extramarital coitus. Journal of Marriage and the Family, 37, 375-384.

• Buunk, B. (1980a). Extramarital sex in the Netherlands: Motivations in social and marital context. Alternative Lifestyles, 3, 11-39.

• Buunk, B. (1980b). Sexually open marriages. Ground rules for countering potential threats to marriage. Alternative Lifestyles, 3, 312-328.

• Buunk, B. (1981). De samenhang van attitudes en sociale normen met de intentie tot buitenechtelijke sex [The relationships between extramarital behavioral intentions and attitudes and social norms]. Nederlands Tidschrift voor de Psychologie, 36, 165-170.

• Buunk, B. (1982). Anticipated sexual jealousy: Its relationships to self-esteem, dependency and reciprocity. Personality and Social Psychology Bulletin, 8, 310-316.

• Fishbein, M., & Ajzen, I. (1975). Belief, attitude, intention, and behavior. Reading, MA: Addison Wesley.

• Frenken, J. (1976). Afkeer van seksualiteit [Aversion to sexuality]. Beventer: Van Loghum Slaterus.

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Items of the Extramarital Behavioral Intentions Scale

Would you engage in the following behavior with another man/woman if the opportunity were to present itself?

1. flirting

   1. certainly not

   2. probably not

   3. maybe not

   4. uncertain

   5. maybe yes

   6. probably yes

   7. certainly yes

2. sexual intercourse a

3. light petting

4. a long-term sexual relationship

5. falling in love

a The seven response options are repeated for each item.