Abstract
The goal of this thesis was to determine the role of dynamic gravitational cues on human spatial orientation and control of vehicle equilibrium. Participants were seated in a device simulating a vehicle with dynamics of an inverted pendulum. Participants used a joystick to align themselves with the direction of balance(DOB). They also used the joystick by pressing its trigger button to indicate being aligned with DOB. Participants performed the roll balancing task while pitched backwards to 35o,45o,50o,55o,60o,65o,70o,75o,80o,85o, and 90o relative to the direction of gravitational vertical(DOG). The DOB of all pitch conditions was set to 0o in the roll plane. The 0o reference angular position is the roll position that is parallel with the DOG at 0o pitch. Pitch did not have a significant effect on the mean indicated and achieved angle of the participants. An increase in participants’ pitch was shown to increase the achieved standard deviation, but not the indicated standard deviation. Pitch did not affect participants’ perception of the DOB, but affected participants’ ability to maneuver the vehicle. Participants will deflect the joystick if they perceive orientation at an incorrect position. Using participants’ joystick information, I was able look at the thresholds of the semicircular canals signals and the integration of semicircular canals. My results indicate that semicircular canal thresholds for angular velocity decrease as pitch increased. However, the threshold for CNS integration of semicircular canals increased as pitch increased. This may indicate that otolith information may modulate CNS integration of semicircular canals, influencing achieved standard deviation.