Physiology in the wild: BEATmonitor enables multi-participant PPG recording across naturalistic environments

Poster presented at Society of Psychophysiological Research, Halifax, Nova Scotia, Canada 14–17 October 2026 Name: Maya Flannery School/Affiliation: McMaster University Co-Authors: Lauren Fink

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Physiological recordings capture implicit responses, such as emotions, immersion, and attention, to dynamic stimuli; yet sensors are often expensive, invasive, and limited to laboratory settings requiring trained personnel. These constraints limit most studies to single participants in artificial environments with synthetic stimuli, reducing ecological validity. Thus, we developed BEATmonitor, a framework for recording blood pulse activity via photoplethysmography (PPG) from multiple participants in naturalistic environments. BEATmonitor uses inexpensive open-source hardware and software to record timestamped heart rate and raw PPG sensor data, with optional accelerometer and survey response data, and includes a remote dashboard controlling 1–100 watches for time-synchronization, data-transfer, and event triggering by a single operator. BEATmonitor has been used in 16 live-event studies (i.e., music concerts, dance and theatre performances, sports broadcasts, film screenings, and political debate) with up to 100 simultaneous participants. It has also been used in smaller-group contexts including an art gallery exhibition, music therapy with autistic youth, and dance therapy for the elderly. We present a performance evaluation focusing on timestamp synchronization accuracy, and heart rate and PPG quality in the environments mentioned above. BEATmonitor is open-source and inexpensive, enabling scalable, reproducible physiological recording across participant groups, settings, and populations previously inaccessible to psychophysiology research.