Experimental procedures.

<p>A. Participants were seated in front of a computer display and grasped the apparatus between the thumb and the index. The device was equipped with strain gauges measuring the grip force (GF) and load force (LF) developed during the experiment. B. In the “motor” condition (M), an auditory tone prompted the participant to grip, lift and maintain the apparatus approximately 5 cm above the table. After 11 s, a second auditory tone prompted the participant to put down the apparatus on the table and to reposition their hand at rest next to the apparatus. During the task, the participants fixated a cross displayed at the centre of the computer display. C. In the “motor + cognitive” condition (M+C), participants performed a visual search and counting task concomitant to the motor task. At the first tone, a colour photograph including a house was displayed on the computer screen. The photograph was changed every 4 s. A total of 4 pictures were shown in each trial. Participants were asked to count the number of pictures in which a chimney and a car, or a chimney and a garage could be identified. They reported their answer verbally at the end of each trial.