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How Wearable Sensors Can Improve Ecological Validity

Tuesday, May 16, 2017   • Posted by Erika Vázquez

Ecological validity, the quest to create a study atmosphere that best represents a subject’s habitat in order to capture data that reflects natural behavior, is getting a lot easier to achieve thanks to wearable biosensors.

Wearable sensors and mobile technology enable study participants to move comfortably in unrestricted settings. This opens the possibilities for research protocols, inviting naturalistic settings and activities, and ultimately leading to more actionable and representative data.

Oklahoma State University researchers evaluated the feasibility of a novel methodology for assessing “physiology, behavior, and psychosocial variables.” The study used two objective sensors (a Zephyr BioHarness and an Actigraph wActiSleep-BT monitor) and a mobile app to monitor each subject’s daily routine over a 20-day period.

Also aiming to achieve a higher level of ecological validity, researchers from Washington State University built an ambulation circuit in a physical rehabilitation inpatient hospital to simulate everyday activities (transitioning from sit to stand, walking on different surfaces, getting in and out of a car). Physical therapy patients wore Inertial Measurement Units (Shimmer3) as they completed the ambulatory circuit right after they were physically capable, and one week later, near their scheduled time of discharge. The study aimed to analyze the ability of IMUs in an ecological environment to quantify changes throughout patient recovery.

The Oklahoma study results suggest that wearable sensors combined with ecological momentary assessment technologies (in this case, app questionnaires) are capable data-generating tools for developing “dynamical systems models of high value health behaviors such as sedentary activity, moderate to vigorous physical activity, sleep, and diet.” Additionally, results indicate that “a wearable sensor holds promise for linking subjective feeling states with physiological data and has the potential for informing intervention development.”

The Washington researchers affirmed their choice of sensors, pointing to the superior ability of IMUs to unobtrusively track “changes in movement because they can be attached to any position on the body.” The study found that utilizing wearable sensors in an ecological environment is a “powerful, objective method for quantifying changes over the course of inpatient rehabilitation.”

Washington investigators stated that future research efforts “can focus on providing individualized, clinically relevant post-care assessment.” In Oklahoma, researchers noted the necessity of subject willingness to wear sensors for extended periods of time. In future iterations they hope to improve compliance and data accuracy with “advancements in the comfort and adherence” of sensors.

By combining naturalistic environments and unobtrusive sensors, researchers are able to capture subject data that is representative of daily life and more ecologically valid than data confined to a traditional lab setting.