Wearable sensor metric for fidgeting: screen engagement rather than interest causes NIMI of wrists and ankles

Measuring fidgeting is an important goal for the psychology of mind-wandering and for human computer interaction (HCI). Previous work measuring the movement of the head, torso and thigh during HCI has shown that engaging screen content leads to non-instrumental movement inhibition (NIMI). Camera-based methods for measuring wrist movements are limited by occlusions. Here we used a high pass filtered magnitude of wearable tri-axial accelerometer recordings during 2-minute passive HCI stimuli as a surrogate for movement of the wrists and ankles. With 24 seated, healthy volunteers experiencing HCI, this metric showed that wrists moved significantly more than ankles. We found that NIMI could be detected in the wrists and ankles; it distinguished extremes of interest and boredom via restlessness. We conclude that both free-willed and forced screen engagement can elicit NIMI of the wrists and ankles.