Self-motion perception is explored in several different ways at the Max Planck Institute for Biological Cybernetics. First, the perception of self-motion while moving through a space is investigated from a multi-sensory integration perspective looking at the contributions of visual, vestibular, and proprioceptive information. A second focus is on investigations of the illusion of self-motion - that is, how can we fool the user into believing that they are moving without having expensive technology to actually move them. Finally, self-motion perception during walking is studied with the specific aim of better simulating walking within an infinite plane through the development and testing of an omni-directional treadmill.

◘ Human locomotion and gait parameters
◘ Perception of self-motion in Virtual Reality
◘ Spatial updating during movement in two and three dimensions
◘ Perception and production of speed during self-motion
◘ Bayesian integration of visual and vestibular information
◘ Vection in a Large Screen Immersive Virtual Environment
◘ Vestibular Direction Detection Thresholds in the Horizontal Plane

Vestibular Direction Detection Thresholds in the Horizontal Plane

The perception of translational movements is an important part of selfmotion perception. We investigate how our vestibular system, specifically the otoliths which are responsible for detecting linear movements, processes such motion signals. This helps us to understand how we can provide a participant with directional motion cues on a motion simulator that are either not perceived or, on the other hand, correctly perceived but with a minimum amount of actual displacement.

Participants are blindfolded and are being moved either forward, backward, left or right (Figure 1). Afterwards they are asked to state the direction in which they felt the motion. By varying the amplitude of the movement, we can measure the direction detection thresholds and understand how these depend on several parameters, such as duration and shape of the motion profile. We found that the perception is not only dependent on the amplitude of the acceleration, but also on the rate of change of acceleration, namely the jerk.

Figure 1: The participant on the motion simulator is blindfolded, hears noise and feels wind
during the experimental trials to mask unintended environmental cues which could help
to solve the task cues which could help to solve the task.

The dynamics of the otolith system can be described with a linear model based on physiological considerations. By resorting to this model, we can predict the perceptual thresholds within a certain frequency range of movements with arbitrary shapes. Our results suggest that for lower frequencies humans are more sensitive to jerky movements compared to previous studies.

REFERENCE

◘ F. Soyka, H. Teufel, K. Beykirch, P. Robuffo Giordano, J. Butler, F. M. Nieuwenhuizen and H. H. Bülthoff: Does jerk have to be considered in linear motion simulation? Proceedings of the AIAA Modeling and Simulation Technologies Conference (Chicago 2009)