Non-work-related movements in machine-paced and self-paced work: an industrial study.

Non-work related movements (NWRM) of 10 experienced industrial workers performing light repetitive work were observed under a variety of conditions. More NWRM were observed for (1) machine-paced versus self-paced operations; and (2) a task with high mental load versus one with a low mental load. In addition, the age of the worker was found to be negatively correlated with NWRM.