Perceptual Motor Deficits in Space (PMDIS) - 07.15.14
ISS Science for Everyone
Science Objectives for Everyone Perceptual Motor Deficits in Space (PMDIS) will investigate why astronauts experience difficulty with hand-eye coordination while on orbit. These measurements will be used to distinguish between three possible explanations: the brain not adapting to the near weightlessness of space; the difficulty of performing fine movements when floating in space; and stress due to factors such as space sickness and sleep deprivation. This experiment is a cooperative effort with the Canadian Space Agency.
Science Results for Everyone
All thumbs? This experiment sought to figure out why astronauts grow clumsy in space. Crew members used a stylus or joystick to aim at targets on a computer screen with their wrist either restrained or unrestrained and in combination with a spoken command. Researchers measured their speed and accuracy and found that performance was worst with the more mentally demanding dual task using the joystick. This suggests that hand-eye coordination loss is due to interacting stressors such as body stability, space sickness, and sleep deprivation all leading to cognitive overload. Hand-eye coordination loss can therefore be helped by appropriate training, task assignment, and equipment design.
Bristol Aerospace Limited, Winnipeg, Manitoba, Canada
Canadian Space Agency (CSA), Ottawa, Ontario, Canada
Sponsoring Space Agency
Canadian Space Agency (CSA)
ISS Expedition Duration
September 2006 - October 2007
Previous ISS Missions
PMDIS is a new experiment for microgravity research.
- PMDIS will attempt to distinguish between the three current theories for the initial decline in hand-eye coordination in space. The current explanations are as follows:
- The brain not adapting to the weightlessness of space.
- The difficulty of performing fine movements when floating in space.
- Stress due to factors such as space sickness and sleep deprivation.
Perceptual-Motor Deficits in Space (PMDIS) monitors the hand-eye coordination of astronauts in microgravity. PMDIS will measure the Shuttle astronaut's hand-eye coordination prior to docking with ISS (transition from 1-g to zero-g). Measurements will be taken while the astronaut's arm is securely supported or floating free in three conditions:
- Tapping targets on a computer screen with a stylus.
- Moving a cursor between the targets with a joystick.
- Performing these tasks while responding to tones with a button press.
This experiment will test the theory that the loss of eye-hand coordination during spaceflight is due to the disruption of certain neural circuits in the human brain, arising from a disruption in the vestibular system.
A mini-centrifuge with daily sessions has been suggested as a means for countering the physiological effects of long-term space flight, e.g., a Mars mission. This raises the possibility of continual changes in eye-hand coordination as the gravity signal changes on a daily basis. Understanding the cause of coordination loss is therefore critical to developing countermeasures.
Understanding how the brain adapts to physiological changes that the ISS crewmembers undergo will be applicable on Earth as well as space. The results from this experiment will give insight on how the brain overcomes stresses that are not normally part of the day-to-day life. This new information can be applied in many areas of research that deal with neurological diseases in order to provide improved treatments.
The PMDIS apparatus consists of a laptop computer with accessories. For the PMDIS measurements by the Shuttle's crew, the accessories include a joystick, a stylus and touchscreen, a pair of GFE-provided headphones for audio stimuli, and a Hand Reaction Switch box through which the astronaut responds to audio and visual stimuli. This experiment will have scheduling constraints. The crew may not exercise within 20 minutes before the session begins. The session must take place on the Shuttle Middeck.
During the PMDIS sessions, the crew will be seated on the middeck floor of the Space Shuttle, securely attach with a waist belt. Using a joystick connected to a laptop computer, the astronaut will move a display cursor between two targets. In other trials, the astronaut will tap targets on a touchscreen using a stylus. Also, the astronaut will listen to musical tones and press a button in response while hitting the targets to simulate multi-tasking.
In some early space experiments a loss of hand-eye coordination that could last for 2 to 3 weeks was observed in crewmembers. These losses were attributed to the absence of gravity interfering with normal brain activity. However, later experiments turned up little evidence in support of this so-called microgravity hypothesis. To test this hypothesis directly, the Perceptual Motor Deficits in Space (PMDIS) investigation was conducted with 5 ISS crewmembers on Expeditions 14 and 15 (September 2006 - October 2007). Crew participants practiced performing the experiment prior to actual data gathering to establish stable baseline performance. Data were collected at 30 days preflight, 71 to 94 hours after launch, and 30 days postflight. Testing consisted of aiming at targets on a computer screen with a stylus or a joystick and with the wrist either restrained or unrestrained. These aiming tasks were also performed in conjunction with auditory reaction time as a mentally demanding dual task. Both the speed and accuracy of movement were used to measure performance.
The results from PMDIS contradict the microgravity hypothesis because a major prediction of this hypothesis, that performance would be degraded using either the stylus or the joystick, was not supported. Rather, performance degradation only occurred with the more mentally demanding dual task using the joystick. These results suggest that the loss of hand-eye coordination in space can be attributed to a variety of interacting stressors which lead to cognitive overload. These factors include lack of body stability, degree of learning on the task and its complexity, space sickness, and sleep deprivation.
Thus impairment in hand-eye coordination is not a necessary condition of space flight. Understanding the link between sensory-motor degradation and mental and physical stressors plus how much cognitive resources are required to maintain performance in microgravity is important to developing mitigating strategies through appropriate training, task assignment, and equipment design, especially for future exploration-class missions (Fowler 2008).
Fowler B, Meehan S, Singhal A. Perceptual-Motor Performance and Associated Kinematics in Space. Human Factors. 2008 Dec; 50(6): 879-892.
Ground Based Results Publications
Fowler B, Manzey D. Summary of research issues in monitoring of mental and perceptual-motor performance and stress in space. Aviation, Space, and Environmental Medicine. 2000; 71 Suppl 9: A76-77.
Sturm T, von Richter A. Design and completion of the PMDIS/TRAC table. 54th International Astronautical Congress, Bremen, Germany; 2003 Sept 29 to Oct 3 2 pp.
Fowler B, Bock O, Comfort D. Is dual-task performance necessarily impaired in space?. Human Factors. 2000; 42: 318-326.
Fowler B, Comfort D, Bock O. A review of cognitive and perceptual-motor performance in space. Aviation, Space, and Environmental Medicine. 2000; 71(Suppl 9): A66-68.
Demonstration of the use and setup of the PMDIS hardware in the Destiny Lab mock up at Johnson Space Center (JSC) in Houston, TX. Image courtesy of NASA, Johnson Space Center.
+ View Larger Image
NASA Image: ISS014E09624 - Astronaut Suni Williams, Expedition 14 Flight Engineer, performs the Perceptual Motor Deficits in Space (PMDIS) shortly after STS-116/12A.1 docked with ISS in December 2006.
+ View Larger Image
NASA Image: ISS014E09626 - Expedition 14 Flight Engineer, Astronaut Suni Williams, performs the Perceptual Motor Deficits in Space (PMDIS). This investigation will test the hand-eye coordination of ISS crewmembers during their mission.
+ View Larger Image
NASA Image: S117E07031 - Astronaut Clayton Anderson, Expedition 15 Flight Engineer, works with the Perceptual-Motor Deficits in Space (PMDIS) experiment in the Destiny laboratory of the International Space Station while Space Shuttle Atlantis was docked with the station.
+ View Larger Image
NASA Image: S117E07092 - Astronaut Patrick Forrester, STS-117 Mission Specialist, works with the Perceptual-Motor Deficits in Space (PMDIS) experiment in the Destiny laboratory of the International Space Station while Space Shuttle Atlantis was docked with the station in June 2007.
+ View Larger Image