Friendship promiscuity as indexed by preferences for wide networks and intimacy with many friends: structure and validity of a new construct

Friendships help people achieve many fundamental adaptive functions. As such, one might theorize that humans are designed to seek out and maintain as many friendships as possible. However, with time and energy as finite resources, humans face a unique challenge in determining the number of friendships they can sustain - do they prioritize maximizing friendship quantity (potentially at the expense of investment in each friend, thus compromising friendship quality), or do they prioritize friendship quality (potentially at the expense of friendship quantity)? Here, we introduce the novel concept of friendship promiscuity – an individual difference in preference for a wide friendship network and desire for friendship intimacy – and develop a tool for measuring this trait. Across 5 studies (NTotal = 5,707), we created and confirmed the Friendship Promiscuity Scale’s factor structure, its test-retest reliability, and construct and discriminant validity. Critically, we demonstrate that the scale achieves measurement invariance across three geographically diverse countries and is associated with friend-seeking motivation and behaviors beyond relevant controls. The scale offers a novel method for assessing an unexplored aspe