Motion Perception Thresholds in Flight Simulation

Pilot perception models include detailed descriptions of the sensory dynamics involved in human spatial orientation. For example, the TNO Spatial Orientation model contains transfer functions of the visual and vestibular system (semicircular canals and otoliths). In our previous attempts to apply this model for the validation of simulator motion cues, we realized that the model did not yet account for perception thresholds. This means that any non-zero motion input to the model yields a non-zero output, assuming that the motion input falls within the sensors’ operational frequency range. Hence, the model did not adequately predict the effect of sub-threshold motion stimuli, or possible interactions between multiple stimuli near threshold level (e.g., visual-inertial). This paper provides a brief overview of motion perception thresholds found in the literature and from obtained in previous simulator studies. We will present psychophysical data showing how the combination of visual and inertial cues affects the perception threshold involved. The results suggest that a visual stimulus leads to an increased detection threshold for a concurrent inertial stimulus, without affecting the underlying transfer function of the vestibular sensors. This finding is the basis for a newly developed threshold model, which lays a general scheme for the modeling of sensory thresholds.