Difference in perception of angular displacement according to applied waveforms

Abstract

Conclusions: This study shows that the differences in the waveforms of angular rotation affect the perception and memory of angular displacement. Objectives: During daily life, when we turn our head during various activities, our brain calculates how much angular displacement our head has undergone. However, how we obtain an accurate estimation of this angular displacement remains unclarified. This study aims to clarify this issue by investigating the perception and memory of passive rotation for three different waveforms of angular velocity rotation (sinusoidal (sine), triangle, and step). Methods: Thirteen healthy young subjects sitting on a servo-controlled chair were passively rotated at 60° or 120° about the earth-vertical axis by using one of these three angular velocity waveforms. They then attempted to reproduce the rotation angle by rotating the chair in the same direction in which they had been passively rotated using a handheld controller. The gain (reproduced angle/passively rotated angle) was calculated and used for the evaluation of the perception and memory of angular rotation. Results: The gain for step rotation was larger than that for sine and triangle rotations, with statistical significance. This confirms that the difference in the waveforms of angular rotation affects the perception and memory of angular displacement.

Keywords::

• Earth-vertical rotation
• vestibular system
• reproduction test
• velocity profile

Acknowledgments

We are very grateful to the dedicated volunteers who participated in this study. We also thank the engineers of Tamagawa Seiki, Co. Ltd for their technical advice.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.