This research provides a bridge between traditional analyses of simple conditioning and the study of more complex cognitive and organizational processes in behavior. Previous research has yielded a set of procedures and phenomena that capture many of the more cognitive aspects of learning while building on the simplicity of simple conditioning. In simple conditioning, an insignificant event, the conditioned stimulus (CS), comes to control behavior as the result of the formation of connections between neural representations of that CS and of another, biologically significant event, the unconditioned stimulus (US). Under some circumstances, an event acquires the ability to modulate the effectiveness of connections among other events. Although this modulatory process (called occasion-setting) is based on simple conditioning, it is functionally distinct, and in some cases follows different rules. This occasion-setting process has much in common, both neurally and behaviorally, with more complex memory phenomena studied by neuropsychologists. The present research uses a variety of conditional-discrimination tasks (those in which a CS signals one event in one circumstance but another event in another circumstance) to (1) more precisely specify the conditions under which occasion-setting occurs, including the development of mathematical models, (2) further explore what organisms actually learn about in conditional- discrimination tasks in which occasion-setting has been implicated, (3) examine the relation between simple Pavlovian conditioning (in which the CS signals the occurrence or nonoccurrence of the US), occasion-setting (in which an occasion- setter signals the validity of a relation between another CS and the US), and operant conditioning (in which a CS indicates when particular behavior will produce the US). The existence of occasion-setting suggests that important changes and expansions to our current theories of conditioning are in order. Those changes may well lead to a more profitable integration of relatively well-understood but simple conditioning phenomena and more complex but poorly understood phenomena of cognition. Furthermore, given the popularity of conditioning- based theories of phobias, eating disorders, substance abuse, and other socially-significant phenomena that are surely under conditional or contextual control (and hence more analogous to occasion-setting than to simple conditioning), it is important to understand the differences in the actions of simple conditioned stimuli and occasion-setters.
