To optimize the setting for interactions between astronauts and on board computer control systems were the main objective of the Mental Workload and Performance Experiment (MWPE). The experiment focused on motor and cognitive skills associated with such interactions, and designed to understand the demands placed on the astronaut’s mental and physical capabilities during space flight and particularly while operating graphic input devices such as cursor keys, joysticks, and trackballs.
A second part of the investigation was the evaluation of mental function, reaction times, and physical responses of the astronauts during space flight. A portable microcomputer with a display monitor and keyboard were attached to the anthropometric workstation. The subject then followed a performance assessment program displayed on the computer monitor. The MWPE performance assessment test was based on the Fittsberg task, a combination of Fitts’ Law and Sternberg tasks, that combined tests of eye-hand-coordination and short-term memory, respectively.
The Fitts’ paradigm was developed to examine the control and accuracy of movement and was used to measure response execution. Subjects were required to manually acquire a target of a certain size and distance away from an initial cursor position as quickly and as accurately as possible. The Sternberg memory search task required the subject to determine if a displayed item was a member of a previously memorized set. Each memory set contained 1 or 4 letters. For each memory set, 8 test stimuli were presented. After a set of 12 memory sets were presented, the subjects were asked to move to the next input device. Three different devices were used: keyboard cursor keys, a two-axis joystick (rate-contol device), and a trackball (position-control device).
The microcomputer recorded the speed and accuracy of the movements and the time needed to interpret the instructions. These data were complemented by the crew’s evaluations of the equipment.
The four IML-1 astronauts participating in the MWPE experiment performed these activities 2-4 times before, and 4 times during their space flight to determine whether mental and physical performance were influenced by adaptation to microgravity.
The MWPE experiment showed a significant increase in movement time for all four subjects (movement time is the time the subject starts to move the cursor until the cursor reaches its target). In other words, a decrease in fine motor control performance was observed in the microgravity environment. To determine whether these changes were caused by the exposure to microgravity, a 7-day ground-based study was conducted under similar conditions. The motor control of the four subjects participating in the ground study did not change.
The Sternberg task tested the cognitive performance of the four astronauts while in space. No significant changes could be measured between preflight and inflight test results.
Evaluating the different input devices for control strategies, two main results were found: (1) in both up-down and left-right cardinal movement-directions, no differences in the movement times between the used devices were observed, and (2) in the diagonal target directions, a significant increase in movement time was noted for the joystick while the trackball basically did not differ from other conditions.
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