Richard L. Solomon’s opponent process theory of emotions—also commonly referred to as the opponent process theory of acquired motivation—contends that the primary or initial reaction to an emotional event (State A) will be followed by an opposite secondary emotional state (State B). In other words, a stimulus that initially inspires displeasure will likely be followed by a pleasurable after-feeling and vice versa. The second important aspect of this theory is that after repeated exposure to the same emotional event, the State A reaction will begin to weaken, whereas the State B reaction will strengthen in intensity and duration. Thus, over time, the after-feeling can become the prevailing emotional experience associated with a particular stimulus event. One example of this phenomenon is how, for some people, an initial unpleasant fear aroused by a good roller-coaster ride becomes, over time, an enjoyable and much sought-after experience.