Immersion vs. familiarity: A controlled experiment of software evolution visualization in virtual reality

Abstract Understanding how software systems evolve over time is a key challenge in software engineering. While traditional tools like GitHub offer detailed access to project history, their interface can be fragmented and cognitively demanding. Immersive environments, by contrast, offer new opportunities to visualize software evolution in ways that leverage spatial reasoning and embodied interaction. In this paper, we present a controlled experiment comparing an immersive virtual reality (VR) visualization with a conventional GitHub-based interface for analyzing software evolution across releases. Using the BabiaXR framework and the city metaphor, we built parallel environments where 32 participants explored two real-world Java projects and completed a set of analytical tasks related to structure, activity, and system core identification. Our findings show that participants in VR were not more accurate on average, but engaged more deeply with the data, took more time, and often relied on spatial cues to formulate richer insights. In contrast, participants using the on-screen interface completed tasks faster but occasionally reverted to external tools or skipped complex questions. Qualitative analysis revealed that immersive exploration supported deliberate reasoning, especially in open-ended and structural tasks. Notably, prior experience with VR or software visualization had no significant impact on performance, underscoring the accessibility of immersive tools even for novice users. These results suggest that immersive visualizations may not universally outperform traditional interfaces, but they offer unique cognitive benefits for specific types of software comprehension tasks. We discuss the implications for visualization design and outline future directions involving hybrid analytical environments and extended longitudinal studies.