Acceleration effects on manual performance with isometric and displacement joysticks

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BACKGROUND: We have shown before that novice human subjects produce exaggerated isometric forces when exposed to three times normal terrestrial acceleration (+3 Gz), and that this deficit is compensated by intensive training in +3 Gz. We now investigate whether training in normal terrestrial gravity (normal G) is also effective. We further examine whether subjects in +3 Gz produce not only exaggerated forces, but also exaggerated hand displacements.

METHODS: Experiments were conducted in the stationary (normal G) or rotating (+3 Gz) gondola of a man-rated centrifuge. With their dominant hand, subjects produced either forces using an isometric joystick, or hand displacements using a regular joystick. Response directions and magnitudes were prescribed visually. In practice trials, subjects received continuous visual feedback about their performance, while in test trials they did not.

RESULTS: Subjects produced exaggerated forces in +3 Gz, whether or not they previously practiced the task in normal G. In contrast, subjects did not produce exaggerated hand displacements in +3 Gz.

DISCUSSION: Exaggerated force production in +3 Gz is not overcome by task practice in normal G, as opposed to task practice in +3 Gz. This might be an indication that pilot training should contain extended practice of force production during phases of increased gravity (+Gz) to avoid motor deficits during flight maneuvers inducing +Gz. Furthermore, the control of isometric and regular joysticks seems to be based on partly distinct neural mechanisms, with different +Gz dependence. Thus, against the background of motor performance during +Gz, regular sticks might be favorably compared to isometric sticks in high-performance aircrafts.

Original languageEnglish
JournalAviation, space, and environmental medicine
Issue number10
Pages (from-to)990-994
Number of pages5
Publication statusPublished - 01.10.2007

ID: 162901

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