Discriminative effects of compound drug stimuli: a focus on attention

Discrimination research has increasingly used compound stimuli emerging from drugs acting through multiple neurotransmitter systems or from injections of drug mixtures that approximate "street-wise" drug-taking behaviors. Accompanying this trend has been an interest in the role of cognitive factors in drug discrimination learning. Accounts of multidimensional drug stimuli have focused mainly on specific neuronal mechanisms, and have largely ignored the contribution of stimulus information to the perception of internal events or to the selection processes, heretofore called attention mechanisms, which may underlie the observer's idiosyncratic response to drug administration. It is argued here that research in drug discrimination may benefit from a more detailed consideration of the processes by which an observer interacts with the emergent stimulus properties of drug administration. Therapeutic intervention initiatives may critically depend on knowing the interactions between the specific attributes of the drug experience that capture the attention of the individual and that may later acquire stimulus control over complex drug-taking behaviors.