This is a generic term referring to drug-related stimuli. These are stimuli previously experienced during self-administration of that drug and it is generally assumed that these stimuli have been paired in some way with the drug effect. The stimuli can comprise external, internal, and cognitive stimuli; they can occur just before or long before drug intake. In the human, they can be described subjectively and usually increase the desire for the drug. The term is often used in clinical work to refer to stimuli that increase the risk for drug relapse in abstinent persons or the risk of continued drug intake in an active drug consumer. The actual word “cue” can be traced to its use in theatrical or musical pieces to indicate when an artist is to start playing part. In the learning literature, a cue is usually a signal that leads to reinforcement in one of two different ways: The cue can simply set the occasion for a reaction or act as...