Ambulatory physiological measures obtained under naturalistic urban mobility conditions have acceptable reliability

Abstract

Ambulatory assessment methods in psychology and clinical neuroscience are powerful research tools for collecting data outside of the laboratory. These methods encompass physiological, behavioral, and self-report measures obtained while individuals navigate in real-world environments, thereby increasing the ecological validity of experimental approaches. Despite the recent increase in applications of ambulatory physiology, data on the reliability of these measures is still limited. To address this issue, twenty-six healthy participants (N = 15 female, 18-34 years) completed an urban walking route (2.1 km, 30 min walking duration, temperature M = 19.8{degrees} degree Celsius, Range = 12{degrees}-37{degrees} degrees Celsius) on two separate testing days, while GPS-location and ambulatory physiological measures (cardiovascular and electrodermal activity) were continuously recorded. Bootstrapped test-retest reliabilities of single measures and aggregate scores derived via principal component analysis (PCA) were computed. The first principal component (PC#1) accounted for 39% to 45% of variance across measures. PC#1 scores demonstrated an acceptable test-retest reliability (r = .60) across testing days, exceeding the reliabilities of most individual measures (heart rate: r = .53, heart rate variability: r = .50, skin conductance level: r = .53, no. of skin conductance responses: r = .28, skin conductance response amplitude: r = .60). Results confirm that ambulatory physiological measures recorded during naturalistic navigation in urban environments exhibit acceptable test-retest reliability, in particular when compound scores across physiological measures are analyzed, a prerequisite for applications in (clinical) psychology and digital health. Author summaryPsychophysiological assessments have been predominantly limited to controlled laboratory settings, leaving the reliability of field measurements unclear. In this study, we conducted a proof-of-concept investigation in N=26 healthy participants navigating the same urban route on two separate days. Cardiovascular and electrodermal activity were continuously recorded and combined with GPS-based location tracking. Psychophysiological measurements obtained under naturalistic urban mobility conditions showed acceptable test-retest reliability, in particular when multiple measures where combined into a compound score via principal component analysis. Shedding light on the reliability of ambulatory assessments in urban environments emphasizes the potential for psychophysiological measurements to contribute valuable insights beyond the constraints of traditional laboratory settings.