George is using positive punishment.
Operant Conditioning represents a learning process through which the strength of a behavior is modified by reward or punishment. The most significant researcher in area of Operant Conditioning was B.F. Skinner. Skinner stated in his research that the learning process can be modified by reinforcement (reward) and punishment. In this case, George is using punishment to modify the behavior of his son. This kind of punishment is called positive punishment as George is spanking his son and directly punishing him. Negative punishment would be If George took something that pleases his son.