At the time that they did this experiment, Berridge and his colleagues thought that dopamine was necessary for any type of pleasure. They agreed with Wise, whose view had become the conventional wisdom. So, they expected that the rats wouldn’t be able to enjoy their meals: if dopamine was required for pleasure, the animals shouldn’t be capable of liking even the most sumptuous food, since they had virtually no dopamine. Without dopamine, they shouldn’t like or be pleased by anything, in fact.
