The behavioral economics of cigarette smoking: The concurrent presence of a substitute and an independent reinforcer

The present study examined the consumption of cigarettes and two alternative reinforcers in dependent smokers. Cigarette price (response requirement) increased across sessions while alternatives were available at a fixed price in four phases of availability: (1) cigarettes alone; (2) cigarettes and nicotine gum; (3) cigarettes and money; and (4) cigarettes, nicotine gum, and money. Cigarette consumption decreased with increasing price throughout. In the cigarette and nicotine gum phase, nicotine gum consumption increased with cigarette price, indicating nicotine gum to be a substitute for cigarettes. In the cigarette and money phase, money consumption increased slightly with cigarette price, indicating money to be an independent reinforcer for cigarettes. When all three reinforcers were present, money again served as an independent reinforcer. During this phase, nicotine gum consumption increased marginally, but the small magnitude of increase suggests that nicotine gum functioned as an independent reinforcer rather than a substitute. Cigarette consumption decreased modestly when nicotine gum was available, and to a larger extent when money or both alternatives were available. The results highlight the potential for an independent reinforcer such as money to be more effective at reducing drug use than a pharmacological substitute.