Verticality Perception During Off-Vertical Axis Rotation

Abstract

During prolonged rotation about a tilted yaw axis, often referred to as off-vertical axis rotation (OVAR), a percept of being translated along a conical path slowly emerges as the sense of rotation subsides. Recently, we found that these perceptual changes are consistent with a canal–otolith interaction model that attributes the illusory translation percept to improper interpretation of the ambiguous otolith signals. The model further predicts that the illusory translation percept must be accompanied by slowly worsening tilt underestimates. Here, we tested this prediction in six subjects by measuring the time course of the subjective visual vertical (SVV) during OVAR stimulation at three different tilt-rotation speed combinations, in complete darkness. Throughout the 2-min run, at each left-ear-down and right-ear-down position, the subject indicated whether a briefly flashed line deviated clockwise or counterclockwise from vertical to determine the SVV with an adaptive staircase procedure. Typically, SVV errors indicating tilt underestimation were already present at rotation onset and then increased exponentially to an asymptotic value, reached at about 60 s after rotation onset. The initial error in the SVV was highly correlated to the response error in a static tilt control experiment. The subsequent increase in error depended on both rotation speed and OVAR tilt angle, in a manner predicted by the canal–otolith interaction model. We conclude that verticality misjudgments during OVAR reflect a dynamic component linked to canal–otolith interaction, superimposed on a tilt-related component that is also expressed under stationary conditions.

Interaural self-motion linear velocity thresholds are shifted by roll vection

“…Studies (Vingerhoets et al 2006, 2007) have reported that human translation perception during off-vertical axis rotation (OVAR) can be modeled by adding a leaky integrator (time constant of 40 ms) to Merfeld’s model (Merfeld and Zupan 2002) to convert estimated linear acceleration to estimated linear velocity. Another model includes internal models and dynamics similar to those discussed above but additionally includes the influence of dynamic visual cues (Zupan et al 2002).…”

Analysis of human spatial perception during lunar landing

“…A small out-the-window-view of the stars passing by will play a minor role in orientation perception, and as a result, astronauts will be forced to depend significantly on their vestibular system and the cockpit displays. For each of the simulations performed in this paper, the gains were determined from data from simple human perception experiments [8,17].…”

“…Within these models the general framework is defined theoretically and then the set of gains is adjusted to help the model fit experimental test cases [8,17,18].…”

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