DATA and TOOLS for: Introducing IOS11 as an extended interactive version of the ‘Inclusion of Other in the Self’ scale to estimate relationship closeness

Provides data, analysis codes and the tools for Baader, Starmer, Tufano and Gaechter: " Introducing IOS11 as an extended interactive version of the ‘Inclusion of Other in the Self’ scale to estimate relationship closeness", Scientific Reports 14, April 2024, Article Number 8901. https://doi.org/10.1038/s41598-024-58042-6

ABSTRACT: The study of relationship closeness has a long history in psychology and is currently expanding across the social sciences, including economics. Estimating relationship closeness requires appropriate tools. Here, we introduce and test a tool for estimating relationship closeness: 'IOS11'. The IOS11 scale has an 11-point response scale, is a refinement of the widely used Inclusion-of-Other-in-the-Self scale. Our tool has three key features. First, the IOS11 scale is easy to understand and administer. Second, we provide a portable, interactive interface for the IOS11 scale, which can be used in lab and online studies. Third, and crucially, based on within-participant correlations of 751 individuals, we demonstrate strong validity of the IOS11 scale in terms of representing features of relationships captured by a range of more complex survey instruments. Based on these correlations we find that the IOS11 scale outperforms the IOS scale and performs as well as the related Oneness scale.