Final answer:
In operant conditioning, the subject's motivational state is defined by the consequences that follow their behavior, specifically through reinforcements that increase a behavior's frequency, or punishments that decrease it.
Step-by-step explanation:
In operant conditioning, the subject's motivational state is operationally defined by the consequences that follow their behavior. A core principle of operant conditioning, which was developed by psychologist B.F. Skinner, is that behaviors followed by positive consequences (reinforcements) tend to increase in frequency, whereas behaviors followed by negative consequences (punishments) are likely to decrease. Reinforcements can be positive, in the form of rewards, or negative, by the removal of an aversive stimulus. Punishments, conversely, decrease the likelihood of the behavioral response being repeated and can also be positive or negative. Skinner's experimental work, primarily with rats and pigeons in devices known as Skinner boxes, demonstrates the systematic study of how behaviors are modified by their consequences.
Operational definitions are crucial to measuring variables effectively to ensure consistency across studies. An example of this can be seen in how different studies might operationally define what constitutes a 'good' grade. Thus, in operant conditioning studies, the subject's motivational state can be operationally defined by the rewards or punishments that follow a specific behavior, as these consequences motivate the behavior to occur more or less frequently.