Editorial Review:

Recently, investigators have claimed that, whereas in many Pavlovian conditioning paradigms a conditioned stimulus (CS) elicits a conditioned response (CR) because it signals the occurrence of an unconditioned stimulus (US), in other paradigms a CS elicits a CR because it "sets the occasion" for the responding produced by another CS. In the first case, the CS is said to be a "simple CS", in the latter case CS is said to act as a facilitator, that is, an occasion setter. The group of experimental psychologists and theoreticians who authored the chapters in this book discuss the current status of data and theories concerning simple classical conditioning and occasion setting.