Humans are a species that can thirst for and turn towards social relationships in times of stress. The need to belong perspective suggests that loneliness should promote an individual to seek social connections and thus enhance pro-social behavior. In contradiction, some research supports the social exclusion hypothesis, showing increased loneliness will decrease pro-social behavior. Furthermore, tend and befriend theory suggests enhanced prosocial behavior as a result of a stressor, specifically for women. Tend and befriend is also challenged by recent research finding pro-social behavior to manifest in men as a response to a stressor. The aim of the present study was to understand the influence of a relational stressor on pro-social behavior. Additionally, this study re-tested the suggestion that women would be more willing to act pro-socially in response to a stressor than men. The study took place across two discrete rounds of data collection: one in the laboratory and one out-of-laboratory. Results provided mix support for a sex difference in performance of a pro-social behavior. Furthermore, this study revealed mild support for the social exclusion hypothesis. Future research should seek to integrate a writing intervention focused on a personal experience with feeling lonely
