Safe to Stay: Psychological Safety Sustains Participation in Pull-based Open Source Projects

2025-04-24

AI Summary

Open-source projects lack formal organizational structures, relying instead on informal interpersonal interactions; yet how team psychological safety—the shared belief that the environment is safe for interpersonal risk-taking—affects contributor retention remains underexplored. Method: We propose the first scalable, behavior-based quantitative method to infer psychological safety from code review activities—specifically merge decisions, comment activity, interaction diversity, and mention patterns—and construct a Psychological Safety Index spanning over 60,000 pull requests. Contribution/Results: Using logistic regression while controlling for confounders (e.g., prior participation), we find that higher psychological safety significantly predicts both short-term (1-year) and long-term (4–5-year) contributor retention, with robust effect sizes. These findings establish psychological safety as an independent, critical determinant of sustainability in informal, collaboration-driven open-source ecosystems.

Technology Category

• Natural Language Processing: Safety and Robustness
• Multiagent Systems: Teamwork
• Cognitive Modeling & Cognitive Systems: Social Cognition And Interaction

Application Category

• Security and Privacy: Large-scale security measurements
• User Modeling, Personalization and Recommendation: Psychology-informed user models and recommender systems
• Search and Retrieval-Augmented AI: Web evaluation methodologies and metrics

Abstract

Psychological safety is the belief that team members can speak up or make mistakes without fear of negative consequences. While it is recognized as important in traditional software teams, its role in open-source development remains understudied. Yet, open-source contributors often collaborate without formal roles or structures, where interpersonal relationship can make or break participation. In this study, we examine whether team-level psychological safety, inferred from code review activities, is associated with contributors' continued participation in open-source projects. Code review is a central and collaborative activity in modern software development, which offers a rich context for observing team interactions. Based on 60,684 pull requests, we construct a psychological safety index using cues such as merge decisions, comment activity, interaction diversity, and mentions. We analyze its relationship with contributors' short-term (after 1 year) and long-term (after 4-5 years) sustained participation using three logistic regression models. Our findings show that contributors are more likely to remain active in repositories with higher levels of psychological safety. Psychological safety is positively associated with both short-term and future sustained participation. However, when prior participation is included, it becomes the stronger predictor of future sustained participation, while the effect of psychological safety becomes smaller. This study introduces a scalable approach to study psychological safety through pull request data and provides new evidence that it matters in open-source development.

Problem

• Examining psychological safety's impact on open-source contributor retention
• Measuring team-level psychological safety via code review interactions
• Analyzing long-term participation predictors in pull-based projects

Innovation

• Construct psychological safety index from pull requests
• Analyze participation using logistic regression models
• Link psychological safety to sustained contributor activity