Goal-Directed and Habitual Control in Smokers

Abstract

Introduction: Harmful behavior such as smoking may reflect a disturbance in the balance of goal-directed and habitual control. Animal models suggest that habitual control develops after prolonged substance use. In this study, we investigated whether smokers (N = 49) differ from controls (N = 46) in the regulation of goal-directed and habitual behavior. It was also investigated whether individual differences in nicotine dependence levels were associated with habitual responding.

Methods: We used two different multistage instrumental learning tasks that consist of an instrumental learning phase, subsequent outcome devaluation, and a testing phase to measure the balance between goal-directed and habitual responding. The testing phases of these tasks occurred after either appetitive versus avoidance instrumental learning. The appetitive versus aversive instrumental learning stages in the two different tasks modeled positive versus negative reinforcement, respectively.

Results: Smokers and nonsmoking controls did not differ on habitual versus goal-directed control in either task. Individual differences in nicotine dependence within the group of smokers, however, were positively associated with habitual responding after appetitive instrumental learning. This effect seems to be due to impaired stimulus-outcome learning, thereby hampering goal-directed task performance and tipping the balance to habitual responding.

Conclusions: The current finding highlights the importance of individual differences within smokers. For future research, neuroimaging studies are suggested to further unravel the nature of the imbalance between goal-directed versus habitual control in severely dependent smokers by directly measuring activity in the corresponding brain systems.

Implications: Goal-directed versus habitual behavior in substance use and addiction is highly debated. This study investigated goal-directed versus habitual control in smokers. The findings suggest that smokers do not differ from controls in goal-directed versus habitual control. Individual differences in nicotine dependence within smokers, however, were positively associated with habitual responding after appetitive instrumental learning. This effect seems to be due to impaired stimulus-outcome learning, thereby hampering goal-directed task performance and tipping the balance to habitual responding. These findings add to the ongoing debate on habitual versus goal-directed control in addiction and emphasize the importance of individual differences within smokers.

Figure 1.

Appetitive instrumental learning task. (A) During the instrumental appetitive learning phase participants learn stimulus–response–outcome associations, which is stimulated by a reward system. (B) In the behavioral test of action-outcome learning, one of the two displayed outcomes is devalued. The participants are instructed to respond with the correct response that is associated with the outcome. (C) During the baseline test, participants are exposed to all six stimuli, of which two are devalued. After the stimuli exposure, stimuli appear on the screen one by one and participants are asked to respond with the learned correct response unless the stimulus is devalued. (D) In the slips-of-action test, all outcomes are shown to the participants. Two of these outcomes are devalued. After outcome presentation, the associated stimuli appear on the screen one by one. Participants are asked to respond with the correct learned response unless the associated outcome of the stimulus is devalued. Participants who have a stronger habit tendency will automatically respond to the stimuli with the learned response regardless the value of the associated outcome.

Figure 2.

Avoidance instrumental learning task. (A) First participants are exposed to the stimuli and the aversive noise in the associated ear to establish learning of the stimuli–outcome associations by means of Pavlovian conditioning. (B) During the first and extended instrumental avoidance learning phases, participants learn to avoid the aversive noise by giving the correct response associated with the Stimuli. The first instrumental avoidance learning phase consists of 12 trials and is followed by outcome devaluation (C) and the first extinction phase, that is, the baseline devaluation sensitivity test (D). After the baseline devaluation sensitivity test, the participants are overtrained in the extended instrumental avoidance learning phase in 120 trails. After the extended instrumental avoidance learning phase, there is again outcome devaluation (C) followed by the avoidance habit test (D). (C) During outcome devaluation one of the earplugs is removed so that the outcome to the corresponding stimulus is devalued, that is, participants will not hear the aversive noise if they do not respond to the corresponding stimulus in the extinction phases. (D) During the baseline devaluation sensitivity and avoidance habit test, participants are instructed to avoid the aversive noises. Participants who have a stronger habit tendency will continue to respond to the stimuli regardless the value of the associated outcome.