Beyond the lab: a review on neurophysiological mental states assessment in real-world settings

Recent advancements in wearable, non-invasive neurophysiological sensors have increased interest in applying Human factors (HF) research beyond controlled laboratory settings. HF research aims to objectively quantify individuals' (alone or working in team) mental and emotional states to ensure safety, maintain good performances and prevent risks. These devices enable real time, unobtrusive monitoring of individuals in real-world environments, overcoming the limitations of traditional subjective assessments. Unlike self-reports, neurophysiological signals provide objective, real-time data, allowing for a more accurate and continuous understanding of mental states. This review examines the latest advancements over the past ten years in real-time monitoring of the most studied and operationally relevant mental states, including mental workload (MW), stress, attention, fatigue, drowsiness, and teamwork, by analyzing studies that contribute to research advancing toward real-world application direction. While wearable biosensors were used as one criterion for selecting studies, this review extends beyond device usage to explore crucial methodological aspects relevant to real-world applications, such as data quality, customized processing steps, and the robustness of results compared to traditional laboratory-grade devices. Thus, this review analyzes 123 articles exploring current advancements in real-time monitoring of MW, stress, attention, mental fatigue, drowsiness, and teamwork using wearable devices. The findings provide a comprehensive overview of methodology advancement toward real-time, objective individuals monitoring in real world settings.