Ronald was the subject of an experiment for alcoholics. every time ronald had a drink, it was mixed with a nausea-inducing agent, which made him sick. after experiencing this pattern for several weeks, ronald started to dislike alcohol immensely. he did not drink for seven months. however, one day as he was walking past a new bar, ronald experienced an overwhelming desire to drink. in this scenario, ronald's sudden desire to drink best illustrates the concept of _____ in classical conditioning.