This study concerns the adaptation of motor system when the production of movement was visually controlled through a video display. In human computer interaction, using digitized tablet to interact with a screen could lead to scale modifications. By using small specific size digitized tablet area, the amplitude of the movement perceived on the screen, is increased as compared to actual movement (gain). Moreover, theses scales modification are not constant according to movement direction when the ratio between the screen and the tablet is different. The goal of this experiment is to investigate adaptation to display altered gain in planar and control movements. To further understand about visuo-motor transformations, participants were instructed to perform aiming movements carried out on three digitized tablet area and two ratio conditions (same or different). Whatever the scale modification, the data reveals that the reaction and movement time is more important when the ratio between digitized tablet and screen are different. Theses results suggest that subjects spend more time to plan and control movement when the amplitude of the movement perceived on the screen changes according to direction movement. Moreover, results show an increase of movement time and error rate when the gain value increases. We hypothesize that control movement is less efficient when the gain value is too important. These results are discussed in view of Fitts law and speed accuracy tradeoffs.