ABSTRACT
The Pavlovian conditioned stimulus (CS) is frequently referred to as a "signal" that warns the animal of a forthcoming biologically important event. In an unpredictable world such information has obvious biological value by allowing the organism to allocate its time successfully to different biological functions. In a world where optimal utilization of information processing capacities is essential, spending time and energy learning more than once about the same thing should be avoided at all costs. Traditionally it was assumed that the contiguous pairing of a CS with a unconditioned stimulus (UCS) was sufficient to generate Pavlovian conditioning. Pavlovian certain signals paired with conspecific mates result in conditioned secretion of sexual hormones during the CS. A resolution of the "preference for signaled shock" phenomenon is difficult to find at present, although the laboratory situation in which it has been studied has obvious artificialities which might hide its adaptive significance.
