Connecting the dots: How users understand and diagnose smart home ecosystems

Smart homes are evolving into complex ecosystems, but their inner workings often remain opaque to users, limiting their ability to troubleshoot and customise the technology. The distributed and hidden components make it challenging for users to understand how these systems work. To design interfaces that enable intuitive troubleshooting for non-experts, we first need a clear understanding of how they form mental models and instinctively diagnose issues. We conducted three iterative vignette studies with realistic smart home scenarios to explore how users perceive interconnectivity in smart home ecosystems and how system complexity impacts their troubleshooting approaches. We identified common smart home topologies envisioned by users and categorised their diagnostic strategies. Our findings show that while users view their smart homes as hierarchical, their mental models are often incomplete, and current interfaces favour functional models, hiding the connections in the system. We provide seven actionable takeaways for designing interfaces that improve user understanding and troubleshooting capabilities.