Physiological measures of operators' mental state in supervisory process control tasks: a scoping review

Physiological measures are often used to assess the mental state of human operators in supervisory process control tasks. However, the diversity of research approaches creates a heterogeneous landscape of empirical evidence. To map existing evidence and provide guidance to researchers and practitioners, this paper systematically reviews 109 empirical studies that report relationships between peripheral nervous system measures and mental state dimensions (e.g. mental workload, mental fatigue, stress, and vigilance) of interest. Ocular and electrocardiac measures were the most prominent measures across application fields. Most studies sought to validate such measures for reliable assessments of cognitive task demands and time on task, with measures of pupil size receiving the most empirical support. In comparison, less research examined the utility of physiological measures in predicting human task performance. This approach is discussed as an opportunity to focus on operators' individual response to cognitive task demands and to advance the state of research. Physiological measures can provide the basis for dynamic operator assistance in supervisory process control tasks. This review synthesises the existing evidence, highlighting both the aggregated empirical support and the heterogeneity of the results. To advance the status quo, a larger emphasis on physiological measures as predictors of operator performance is needed.Abbreviations: HF/E: Human factors and ergonomics; CNS: Central nervous system; PNS: Peripheral nervous system; HR: Heart rate; HRV: Heart rate variability; IBI: Interbeat interval; AVNN: Average of RR intervals; SDRR: Standard deviation of RR intervals; CVRR: Coefficient of variation in RR intervals; RMSSD: Root mean square of successive; pNNX: Percentage of successive RR intervals; MAD: Median absolute deviation; LF: Power of the low-frequency; MF: Power of the mid-frequency; HF: Power of the high-frequency; TP: Total power.