The Effect of Long Duration Hypogravity on the Perception of Self-Motion (VECTION) - 12.20.17

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ISS Science for Everyone

Science Objectives for Everyone
The objective of The Effect of Long Duration Hypogravity on the Perception of Self-Motion (VECTION) study is to determine to what extent an astronaut's ability to visually interpret motion, orientation, and distance may be disrupted in a microgravity environment, and how it may adapt, and how it may be changed upon return to Earth. Multiple experimental time points inflight and upon return to Earth allows for the adaptation and recovery process to be investigated.
Science Results for Everyone
Information Pending

The following content was provided by Laurence Harris, Ph.D., and is maintained in a database by the ISS Program Science Office.
Experiment Details

OpNom: Vection

Principal Investigator(s)
Laurence Harris, Ph.D., York University, Toronto, Ontario, Canada

Michael Jenkin, Ph.D., York University, Toronto, Ontario, Canada
Robert Allison, Ph.D., York University, Toronto, Ontario, Canada

York University, Toronto, Ontario, Canada

Sponsoring Space Agency
Canadian Space Agency (CSA)

Sponsoring Organization
Information Pending

Research Benefits
Space Exploration, Earth Benefits, Scientific Discovery

ISS Expedition Duration

Expeditions Assigned

Previous Missions
Information Pending

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Experiment Description

Research Overview

  • The broad goal of The Effect of Long Duration Hypogravity on the Perception of Self-Motion (VECTION) study is to determine how visual motion perception, perceived orientation, and the ability to estimate distances change between Earth normal (1-g) and a microgravity environment, and to help develop a mathematical model of how human self-motion perception is altered under long duration microgravity and its subsequent recovery upon return to Earth normal conditions.


On Earth humans use multiple senses to evaluate motion, body position, and the distance to objects. Signals from what we see, feel, and hear are combined with information about acceleration, including the linear acceleration due to gravity, from our inner ear (vestibular system). The Effect of Long Duration Hypogravity on the Perception of Self-Motion (VECTION) study looks at this process, and how gravity, or lack thereof, affects it.
The two main sensory contributors to establishing an estimate of motion are vision and proprioception including the vestibular system. Interaction between these senses is responsible for determining the direction and distance of travel, and to establish our orientation through recognition of the normal orientation of everyday objects and the structure of the scene. Relative movement between a person and the visual scene (“optic flow”) is processed by the brain to help estimate travel distance and direction of travel. The vestibular system comprises two parts: the otolith organs that respond to linear acceleration, and the semicircular canals that respond to angular acceleration. The otoliths sense linear acceleration, which includes gravity and changes in translational velocity. On Earth, the input from visual cues, the vestibular system and other sensory inputs, are processed by the central nervous system to allow us to navigate and interact with the world around us.
In space, gravity no longer acts on the vestibular system and other gravity detectors. Visual perception and touch sensations may also not be the same as on Earth (e.g., astronauts do not feel pressure on the feet that normally occurs when standing). When astronauts are in a microgravity environment, changes in sensory input may be misinterpreted, resulting in errors in the estimation of velocity, distance or orientation. It is thought that during long-duration missions adaptation to these changed sensory inputs occurs, whereby the lack of gravity input is reinterpreted. However, upon return to Earth the resumption of gravity stimulation of the vestibular system, and other gravity sensing detectors, can result in altered perception of motion, confusion regarding body orientation, and difficulty with estimating distances.

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Space Applications
Impairments in an astronaut’s ability to judge self-motion, assess their orientation, and estimate distances can have serious operational consequences. The VECTION project provides further knowledge of visual-vestibular interactions in space and on Earth, and will significantly improve safety wherever movement under microgravity conditions is required. Experimental outcomes may lead to suggestions about controlling vehicles in low-gravity environments, either as drivers, pilots, or under robotic tele-operations (e.g., robotic manipulations, Canadarm2, and Dextre).

Earth Applications
The ability to perceive self-motion is key to a wide range of tasks on Earth (e.g., driving a car, walking). Understanding the role that vision plays is vital to constructing environments that are perceived correctly. This is particularly important in the development of environments for those for whom navigation and gait are perturbed (e.g., Parkinsonism, vestibular damage). The VECTION study provides further knowledge to help understand the role of vision, and may lead to the generation of effective visual cues for safe movement within an environment. The study also helps with the design of operator/robotic interfaces in which vision is used to assess motion. How operators are oriented with respect to gravity may affect perceived self-motion, which may lead to recommendations concerning operator body orientation when remotely operating tools.

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Operational Requirements and Protocols

Each Baseline Data Collection (BDC) and inflight session consists of three experiments:
  1. The ability of the astronaut subjects to perceive self-motion based on visual motion cues is assessed by measuring how far a participant needs to "travel" in a simulated visual environment to reach a previously viewed target.
  2. Ambiguity in terms of translation and tilt is explored by measuring perceived orientation following a visually-simulated translation.
  3. The perception of distance in virtual reality and the influence of microgravity on the perception of distance, are evaluated through the comparison of the perceived length of a virtual object with a real world reference object.
All experiments are performed using a head mounted display (HMD) to elicit a sense of self-motion or view objects.
For pre-flight and post-flight BDCs two body orientations are tested, seated and supine. The supine body position removes gravity from acting along the long axis of the body and thus crudely simulates exposure to microgravity. For inflight sessions subjects are tested in one body orientation. Due to the lack of gravity inflight the vestibular system is not affected by different body orientations. Subjects inflight are tethered in place so that they do not drift into objects during testing.
One pre-flight BDC (Launch (L)-180/-60 days), two inflight sessions (L+ 3/6 days, L+ 80/100 days) and two post-flight BDCs (Return (R)+4/6 days, R+50/70 days) are scheduled. The multiple inflight and post-flight sessions allow for the adaptation to microgravity and recovery upon return to Earth to be explored.
Eye health and basic neurologic function are assessed for all time points by obtaining data from standard Medical Assessment tests. The use of medications which may affect vision or vestibular function are obtained from Medical logs.

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Decadal Survey Recommendations

Information Pending

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Results/More Information

Information Pending

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Related Websites

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