While picking up a pencil to write, the amount of forces and torques applied by our fingers on the pencil change continuously. For a robot, assessing the correct magnitude of force or torque required in each instruction is indeed a non-trivial task. Infact, to hold the pencil (step 2) with fingers in a manner that it is firm enough not to slip out but still can be rotated to a perfect angle by applying an appropriate amount of torque is quite challenging. To me steps 2, 7 and 13 seem the most difficult ones for a robot to execute. In step 7, difficulty lies in estimating the torque required for a perfect rotation, meanwhile the magnitude of force acting on the pencil also changes so as to allow it undergoe a rotation easily, making the entire task even more complicated. Step 13 again requires correct amount of pressure (which varies from symbol to symbol), and several minute rotations (orientation of the pencil held might change slightly with every new symbol) to trace locus defined by characters perfectly.
The explicit or automatic aspects of execution are those parts of the algorithm that can be hard coded in the robot. For example, determining the location of the pencil and precise calculations of the trajectory the arm follows to reach that location. Implicit aspect here is the machine learning part of the algorithm, where a robot after several executions learns (reinforcement learning) the correct magnitudes of force and torque needed to grasp the pencil. This intuitive kind of a learning is gained implicitly through experiences and hence cannot be hard coded. The robot here can associate a chunk to a certain magnitude of force, torque, arm velocity etc. so as to retrieve from memory its corresponding effect, that is success or failure in grasping the pencil.
'Reward' based learning, more correctly termed as reinforcement learning evidently dominates the human learning process. These rewards can very strongly drive/motivate a person towards a task. However, this reward needn't be an explicit goal or achievement. It can very much be a matter of internal satisfication or pleasure to a person. In case of fire-fighter, the very idea of successfully extinguishing the fire might give him a sense of satisfaction of having completed his job. A fire fighter in the initial stages might be given certain explicit instructions on how to deal with different kinds of fire but his major learning is 'reward' based. As an amateur, he begins by applying several strategies to extinguish the fire. The eventual success or failure of these strategies are implicity learnt by him and over time he uses the strategy that results in best outcome. This is when he becomes an expert.