A two-week perturbation EMA-experiment was carried out with palatal prostheses. Articulatory effort for five speakers was assessed by means of peak acceleration and jerk during the tongue tip gestures from /t/ towards /i, e, o, y, u/. After a period of no change speakers showed an increase in these values. Towards the end of the experiment the values decreased. The results are interpreted as three phases of carrying out changes in the internal model. At first, the complete production system is shifted in relation to the palatal change, afterwards speakers explore different production mechanisms which involves more articulatory effort. This second phase can be seen as a training of the internal model during which input-output pairs are tested with respect to their articulatory effort. In the third phase speakers start to select an optimal movement strategy to produce the sounds so that the values decrease.