Inclusion of Other in the Self Scale and the structure of interpersonal closeness.

Key Points

• This research aims to assess the reliability and validity of the Inclusion of Other in the Self Scale in measuring interpersonal closeness.
• Two studies were conducted to evaluate the IOS Scale's reliability and validity.
• The IOS Scale was compared with the Relationship Closeness Inventory and the Sternberg Intimacy Scale.
• Test-retest reliability and predictive validity for relationship status were analyzed over a three-month period.
• The IOS Scale showed high test-retest reliability with minimal social desirability bias.
• Convergent validity was confirmed with established measures of intimacy and closeness.
• The scale predicted whether romantic relationships remained intact three months later.