Learning about associatively activated stimulus representations: Implications for acquired equivalence and perceptual learning

Pavlovian conditioning is taken to reflect the formation of links between the central representations of stimuli. A link will be formed when presentation of the relevant stimuli is scheduled in a way that ensures that two representations are activated concurrently. Once this has occurred, a representation can be activated not only by the occurrence of the appropriate stimulus but also by way of the link. Evidence is reviewed to suggest that activation produced by this second route is, in some ways, functionally equivalent to direct activation; in particular, an associatively activated representation (an image) appears capable of forming further associative links with other event representations. Learning about associatively activated stimulus representations may play a role in a range of phenomena. Its contribution to the following is discussed: sensory preconditioning, second-order conditioning, acquired equivalence and distinctiveness, equivalence class formation, and the perceptual learning effect. Finally, consideration is given to the way in which existing theories of associative learning might be modified in order to accommodate this process.