Arms
experimental: Training Protocol 1 - Roll-Tilt Intervention First
Participants will complete a roll tilt training protocol previously shown to reduce roll tilt thresholds. The training stimulus parameters are as follows: stimulus size for 0.5 Hz roll tilt motion will be adjusted based upon subject responses using a 2-down, 1-up (2D/1U) staircase, and both auditory and visual feedback will be provided.The training protocol will be completed first, followed by the placebo intervention.
experimental: Training Protocol 1 - Placebo First
Participants will complete a roll tilt training protocol previously shown to reduce roll tilt thresholds. The training stimulus parameters are as follows: 0.5 Hz roll tilt motion, stimulus size will be adjusted based upon subject responses using a 2D/1U staircase, and both auditory and visual feedback will be provided. The placebo intervention will be completed first, followed by the roll tilt training intervention.
experimental: Training Protocol 2 - Y-Translation Intervention First
Participants will complete an inter-aural translation training protocol. The training stimulus parameters are as follows: 0.5 Hz inter-aural translation motion, stimulus size will be adjusted based upon subject responses using a 2-down, 1-up (2D/1U) staircase, and both auditory and visual feedback will be provided.The training protocol will be completed first, followed by the placebo intervention.
experimental: Training Protocol 2 - Placebo First
Participants will complete an inter-aural training protocol. The training stimulus parameters are as follows: 0.5 Hz inter-aural translation motion, stimulus size will be adjusted based upon subject responses using a 2D/1U staircase, and auditory and visual feedback will be provided. The placebo intervention will be completed first, followed by the training intervention.
experimental: Training Protocol 3 - Mixed Intervention First
Participants will complete a training protocol that includes half roll tilt and half inter-aural translation. The training stimulus parameters are as follows: 0.5 Hz inter-aural translation motion and 0.5Hz roll tilt, stimulus size will be adjusted based upon subject responses using 2-down, 1-up (2D/1U) staircases, and both auditory and visual feedback will be provided. The training protocol will be completed first, followed by the placebo intervention.
experimental: Training Protocol 3 - Placebo First
Participants will complete a training protocol that includes half roll tilt and half inter-aural translation. The training stimulus parameters are as follows: 0.5 Hz inter-aural translation motion and 0.5 Hz roll tilt, stimulus size will be adjusted based upon subject responses using 2D/1U staircases, and auditory and visual feedback will be provided. The placebo intervention will be completed first, followed by the training intervention.
Interventions
Roll Tilt Training
The participants will be tilted and asked to indicate their perceived direction of self-motion (e.g., left or right). Feedback will be provided to promote learning (i.e., improved perception of motion). Feedback will only be provided after the subject response, and thus vestibular (i.e., self-motion) perception is required to judge the direction of the tilt stimulus. After each trial, a three second period of rest will be given. Each day of training will include four blocks of one-hundred trials each. Testing will take place in the dark (except for aims where a visual cue is provided). Subjects will be seated on a motion platform with a 5-point harness and the head restrained. Insert earbuds (along with a white noise signal) will be used to reduce external noise. Subjects will always be asked to make a decision (e.g. left versus right) by pressing buttons with their left or right hands. If not certain, subjects are instructed to provide their best guess.
Translation Training
The participants will be translated and asked to indicate their perceived direction of self-motion (e.g., left or right). Feedback will be provided to promote learning (i.e., improved perception of motion). Feedback will only be provided after the subject responds, and thus vestibular (i.e., self-motion) perception is required to judge the direction of the translation stimulus. After each trial, a three second period of rest will be given. Each day of training will include four blocks of one hundred trials each. Testing will take place in the dark (except for aims where a visual cue is provided). Subjects will be seated on a motion platform with a 5-point harness and the head restrained. Insert earbuds (along with a white noise signal) will be used to reduce external noise. Subjects will always be asked to make a decision (e.g. left versus right) by pressing buttons with their left or right hands. If not certain, subjects are instructed to provide their best guess.
Both Tilt and Translation Training
The participants will be equally tilted and translated and asked to indicate their perceived direction of self-motion (e.g., left or right) . Feedback will be provided to promote learning (i.e., improved perception of motion). Feedback will only be provided after the subject responds. After each trial, a three second period of rest will be given. Each day of training will include four blocks; 2 blocks of roll tilt and 2 blocks of translation - one hundred trials each. Testing will take place in the dark (except for aims where a visual cue is provided). Subjects will be seated on a motion platform with a 5-point harness and the head restrained. Insert earbuds (along with a white noise signal) will be used to reduce external noise. Subjects will always be asked to make a decision (e.g. left versus right) by pressing buttons with their left or right hands. If not certain, subjects are instructed to provide their best guess.
Placebo Control
Participants will complete home-based exercises that are not associated with improving vestibular perception or balance (e.g. saccades, smooth pursuit). Participants will sit in a comfortable chair facing out into a living space. They will then find a stationary object to the right and to the left of themselves as well as above and below their line of sight. Without moving their heads, they will look back and forth and up and down between the objects. Participants will complete a total of 400 eye motions per day for six days.