From lab to life: Evaluating the reliability and validity of psychophysiological data from wearable devices in laboratory and ambulatory settings.

Despite the increasing popularity of ambulatory assessment, the reliability and validity of psychophysiological signals from wearable devices is unproven in daily life settings. We evaluated the reliability and validity of physiological signals (electrocardiogram, ECG; photoplethysmography, PPG; electrodermal activity, EDA) collected from two wearable devices (Movisens EcgMove4 and Empatica E4) in the lab (N = 67) and daily life (N = 20) among adults aged 18-64 with Mindware as the laboratory gold standard. Results revealed that both wearable devices' valid data rates in daily life were lower than in the laboratory (Movisens ECG 82.94 vs. 93.10%, Empatica PPG 8.79 vs. 26.14%, and Empatica EDA 41.16 vs. 42.67%, respectively). The poor valid data rates of Empatica PPG signals in the laboratory could be partially attributed to participants' hand movements (r = - .27, p = .03). In laboratory settings, heart rate (HR) derived from both wearable devices exhibited higher concurrent validity than heart rate variability (HRV) metrics (ICCs 0.98-1.00 vs. 0.75-0.97). The number of skin conductance responses (SCRs) derived from Empatica showed higher concurrent validity than skin conductance level (SCL, ICCs 0.38 vs. 0.09). Movisens EcgMove4 provided more reliable and valid HRV measurements than Empatica E4 in both laboratory (split-half reliability: 0.95-0.99 vs. 0.85-0.98; concurrent validity: 0.95-1.00 vs. 0.75-0.98; valid data rate: 93.10 vs. 26.14%) and ambulatory settings (split-half reliability: 0.99-1.00 vs. 0.89-0.98; valid data rate: 82.94 vs. 8.79%). Although the reliability and validity of wearable devices are improving, findings suggest researchers should select devices that yield consistently robust and valid data for their measures of interest.

Testing the Mindfulness-to-Meaning Theory in Daily Life.

Objectives: The Mindfulness-to-Meaning Theory (MMT) describes the processes through which mindfulness leads to enhanced eudaimonic wellbeing (indirectly via mediating processes such as increased decentering, reappraisal, positive affect, and savoring), but little is currently known about how these processes impact one another over short time periods (e.g., across several hours). The current study tested the MMT by measuring these variables repeatedly as they occur naturalistically in daily life. Method: Three hundred and forty-five community members aged 18-65 completed surveys on smartphones six times per day over seven days, assessing their current levels of decentering, reappraisal, positive affect, savoring, and wellbeing, as part of a larger study. Multilevel structural equation modeling in Mplus was used to analyze the nested data with mediation models. Results: There was a significant indirect effect through the proposed MMT pathway at the within-person level, with all variables measured concurrently. Lagged mediation examining prospective effects indicated that the full indirect MMT pathway was not significant in predicting later wellbeing, though some individual indirect pathways were significant prospectively. Follow-up analyses testing alternative temporal ordering suggested bidirectional effects of savoring and positive affect in explaining the mutual association between decentering and wellbeing. Conclusion: Overall, this study found support for hypothesized MMT processes in daily life and measured over short time periods, with evidence for bidirectional effects for some processes. However, reappraisal showed inconsistent effects, requiring further study and replication using ecological momentary assessment designs.