 The first subject takes a seat at the experimental set-up, the second one on an aircraft seat. The tested subject is then equipped with ear-phones plugged into a laptop. It helps to focus the attention on the tasks which are accompanied with acoustic signals. Recording devices are then adjusted to the subject by a standard calibration procedure, done by the test-operator. Before entering the first parabola the subject executes the same two grasping-tasks on level flight. After the first test parabola, during each 0g period it has to execute the grasping movements in one of each task - 4 parabolas task L with five episodes each, 10 parabolas task E with two episodes each. Entering the 0g phase the operator starts the test by a click on the keyboard, afterwards the tasks stop automatically. During 1g and 1,8g phases the test is interrupted. After the 15th parabola the subjects switch places and the second one starts with the tests during the 0g phases. On level flight back to the airport it executes the same two tasks again as control condition. 