Pavlovian sign-tracking model of alcohol abuse

While poorly controlled alcohol drinking is a prominent symptom of alcohol abuse, its environmental determinants remain poorly understood. The Sign-Tracking Model (STM), developed by Tomie and his associates, postulates that poorly controlled alcohol drinking is due to the development of signal-directed behaviors induced by Pavlovian sign-tracking procedures. In laboratory studies of animal learning, presentation of the lever (conditioned stimulus, CS) followed by the presentation of the food (unconditioned stimulus, US) induces sign-tracking conditioned response (CR) performance, wherein rats approach and contact, then express consummatory-like responses (i.e., licking, gnawing, and chewing) directed at the lever CS. The Pavlovian sign-tracking CR is an involuntary acquired reflexive response. It is poorly controlled and elicited by the presentation of the CS. STM proposes that poorly controlled alcohol drinking in humans may be due to repeated pairings of the alcohol sipper (e.g., cocktail glass) CS with alcohol's rewarding effects US, resulting in sign-tracking CR performance. The cocktail glass CS will elicit Pavlovian sign-tracking CR performance of reflexive and involuntary alcohol intake. This paper reviews evidence in the Pavlovian conditioning literature that in animals the positive contingency between the alcohol sipper CS and alcohol US induces sign-tracking of alcohol drinking. Also reviewed is evidence that in human beings alcohol drinking is a direct function of the positive contingency between a particular alcohol glassware CS and alcohol US. Implications of these findings for the Sign-Tracking Model (STM) are discussed.