Comparing Four Technologies for Measuring Postural Micromovements During Monitor Engagement

Objective metrics of engagement are valuable for estimating user experience or progression through interactional narratives. Postural micromovements of seated individuals during computer engagement have been previously measured with magnetic field sensors and chair-mounted force matrix detection mats. Here we compare readings from a head-mounted accelerometer, single camera sagittal motion tracking, and force distribution changes using floor-mounted force plates against a Vicon 8-camera motion capture system. Measurements were recorded on five participants who were watching or interacting with a computer monitor. Our results show that sagittal and coronal plane measurements for Vicon, the accelerometer and the single camera produced nearly identical data, were precisely synchronized in time, and in many cases proportional in amplitude. None of the systems tested were able to match the Vicon's measurement of yaw.