Inclusion of Other in the Self Scale (IOS)

Social psychologist Arthur Aron and colleagues (1992) developed the single-item Inclusion of Other in the Self (IOS) scale to measure how close the respondent feels with another person or group. The IOS has been given to respondents as young as five years old (Cameron, 2006), as well as to teens and adults. It has also been used with respondents living on a low income and previously incarcerated respondents (Folk et al., 2016; Mashek, Cannaday, & Tangney, 2007). Respondents see seven pairs of circles that range from just touching to almost completely overlapping. One circle in each pair is labeled “self,” and the second circle is labeled “other.” Respondents choose one of the seven pairs to answer the question, “Which picture best describes your relationship with [this person/group]?” Researchers indicate what person or group the “other” circle stands for (e.g., “your romantic partner,” “your parents,” “your community,” etc.). 1 = no overlap; 2 = little overlap; 3 = some overlap; 4 = equal overlap; 5 = strong overlap; 6 = very strong overlap; 7 = most overlap.


Relationship Skills


1st Grade,
2nd Grade,
3rd Grade,
4th Grade,
5th Grade,
6th Grade,
7th Grade,
8th Grade,
9th Grade,
10th Grade,
11th Grade,
12th Grade,
Post secondary
Other Language/s
This assessment is completely pictorial and poses no language barriers.

Administration Information

<3 minutes

Access and Use


Arthur Aron 

Phone: (631) 632-7707

Open Access
Use in Research

Boelen, P. A., & Van den Hout, M. A. (2010). Inclusion of other in the self and breakup-related grief following relationship dissolution. Journal of Loss and Trauma15(6), 534-547.

Ledbetter, A. M. (2013). Relational maintenance and inclusion of the other in the self: Measure development and dyadic test of a self-expansion theory approach. Southern Communication Journal78(4), 289-310.

Rusbult, C. E., Martz, J. M., & Agnew, C. R. (1998). The investment model scale: Measuring commitment level, satisfaction level, quality of alternatives, and investment size. Personal Relationships5(4), 357-387.

Woosnam, K. M. (2010). The inclusion of other in the self (IOS) scale. Annals of Tourism Research37(3), 857-860.


Manual scoring
Psychometric References

Aron, A., Aron, E. N., & Smollan, D. (1992). Inclusion of Other in the Self Scale and the structure of interpersonal closeness. Journal of Personality and Social Psychology, 63(4), 596–612.

Gächter, S., Starmer, C., & Tufano, F. (2015). Measuring the closeness of relationships: a comprehensive evaluation of the Inclusion of the Other in the Self scale. PloS One10(6), e0129478.

Digital Continuous Version:

Le, B., Moss, W. B., & Mashek, D. (2007). Assessing relationship closeness online: Moving from an interval-scaled to continuous measure of including others in the self. Social Science Computer Review25(3), 405-409.



Item Type
Multiple choice

Psychometric Considerations

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