Past work on children's drawing from the "process oriented" approach focused more on how children draw without considering what and why they draw. Both what and why under the "product oriented" approach need to complement the question of how in order to understand children's drawing behaviour better. The work of this thesis focuses on the"process oriented" approach that deals with the motor process of children's drawing without neglecting the importance of the "product oriented" approach.This thesis seeks a better understanding on psychological processes involved in drawing and drawing development in children to study their drawing behaviour. This is why the thesis is reviewed under the theoretical framework of Adaptive Interaction. This framework (Chapter 2: Background and Theoretical Framework) studies children's drawing through a utility maximization approach that derives its explanatory power from three components of human behaviour; ecology, utility and information processing mechanisms.As such, it raises the following questions: (1)"How would children draw on a tablet given that they have cognitive and motor limitations?"; (2)"Why would children draw on a tablet given that there are limitations on tablet and drawing software?" The framework helps to provide an explanatory and predictive account of children's adaptation of drawing strategies on a tablet. The empirical work of the framework is conducted to answer the following research questions: (1)"How do children adapt their drawing strategies according to their own motor variability and to the limitations of tablet and drawing application?";(2)"How do a child adapt to the drawing actions according to his/her own motor variability?"; and (3)"Does adaptation to motor variability explain age-related changes in drawing performance?";To answer these questions, I conducted empirical studies (Chapter 3 to 6) to examine how children adapt their drawing actions to their own motor variability and to extrinsic motivations (rewards). My study consisted of drawing tasks that tested the model of movement planning based on the Statistical Decision Theory. The idea was to see how children act as ideal drawing planners when choosing movement trajectories on touch surfaces. I derived predictions of the hypothesis from children's drawing on a touch screen with regions carrying reward and penalties. When a penalty region is placed near to a target region, adults are known to alter their motor plan. In particular, they shift their aim point to avoid the penalty region. The model predicts shifts in subjects aim point in response to changes of reward and penalty structures within the drawing environment.The result of my studies show that children make near optimal adaptation to subjective rewards, their own cognitive and motor limitations and to the limitations of tablet and tablets drawing software. The work reported here shows that a child's strategies for drawing on a tablet can be understood as a Bayesian adaptation to movement variability, motivation and limitations of the...