Logan: Basic Principles of Learning SENSORY CONDITIONING If two stimuli, neither of which elicits a distinct overt response, are repeatedly paired in temporal sequence, an association will be formed between them. The paradigm for sensory conditioning is precisely the same as for classical conditioning except that there is no unconditional stimulus in the sense of eliciting an overt, observable reflexive response. For xample, a tone might be presented slightly before a light even though neither naturally leads to any specific response. It has been shown in the case of human subjects that subsequently presenting the first of these stimuli may lead to the report of a conditioned sensation of the other. The person reports "seeing" the light when the tone is sounded. With non-human subjects, the technique must obviously involve some nonverbal way of determining whether sensory conditioning has occurred. The procedure is known as SENSORY PRECONDITIONING and requires several stages. The first stage is just as described above; two stimuli such as a tone and a light are paired in temporal sequence. Next, the second of these stimuli is used as the antecedent stimulus for classical conditioning. For example, the light could be paired with food in order to condition salivation to that stimulus. The final test stage is to present the other stimulus, in this case the tone, and observe whether a conditioned salivary response occurs. The bulk of the empirical evidence suggests that it does occur, which is interpreted as indicating that an association was formed during the first stage. The assumption is that the occurrence of the conditioned response is mediated by a conditioned sensation. There are good reasons to view sensory conditioning as essentially a form of classical conditioning. For one thing, they are the same operationally since they both involve the repeated paired presentation of two stimuli without regard to the organism's behavior. Further, the relevant principles appear to be comparable. For example, the effect of the interstimulus interval between S1 and S2 shows an optimal condition similar to that found with pure classical conditioning. But we should not jump automatically to the conclusion that sensory conditioning is a cognitive (S-S) process. The behavioristic theorists contend that even a tone or a light, while not eliciting an overt movement, does elicit some orienting, investigatory, observing, and perceiving responses and it is actually these that are being conditioned. Since these postulated responses are not readily observable, it is difficult to prove or to disprove the behavioristic analysis. Whenever its basis, sensory conditioning very probably occurs in many learning situations. For example, rats benefit from simply being allowed to explore a maze without any obvious reward. This is called LATENT LEARNING because such conditioning only becomes apparent when reward is introduced and formal training begins. Apparently, rats can learn something about the design of a maze from mere exposure to it. Indeed, rats show some learning after having been pulled though a maze on a little cart. In similar fashion, you may learn directions to a person's home as a result of being driven there. There is also some evidence of STIMULUS PREDIFFERENTIATION. Exposing an organism to stimuli between which a discrimination must later be acquired facilitates such learning. The range of these phenomena is not well known because they are difficult to determine in unambiguous ways. Nevertheless, it is probably safe to assume that organisms generally learn about the regularities of stimulus events in their spatial and temporal environment. A special case of sensory conditioning is the phenomenon of COMPOUNDING. If two stimuli, such as two tones, or two lights, or a tone and a light, are presented simultaneously together and this compound stimulus event is shortly followed by a US such as food, a CR will initially develop to each element presented separately as well as to the compound of the two elements together. With sufficient training, however, only the compound and not the elements alone will elicit the CR. It is not just that the elements have become associated with each other, they have become integrated into a functionally single stimulus. The phenomenon of compounding is very close to the Gestalt view, according to which any stimulus is an indivisible whole, and the whole is more than the sum of its parts. A person's face, for example, may indeed have elements (eyes, nose, mouth, etc.) But we see the face as a unique, integrated configuration. From a Gestalt perspective, compounding is immediate and automatic; we naturally perceive events that occur together as being a single event. Certainly we are familiar with sensory conditioning in everyday affairs. You are likely to notice if a woman has a new hairdo or a man has grown a beard because your past sensory experiences involving that person include certain expectations as to her or his appearance. And when there are regularities in nature, such as thunder and lightning, and smoke and fire, we learn these as a direct consequence of sensory conditioning. We sometimes make mistakes in this regard, however. For example, you may feel perfectly confident that you heard a person say something that was not actually said simply because the other sensory stimuli in the environment, including that contextual cues of other words being said at the time, elicited a conditioned sensation that overshadowed the actual verbal stimulus. TERMS: Sensory conditioning, cognition, contiguity (s-s), discrimination, latent learning, mediation, sensory preconditioning, stimulus predifferentiation, antecedent stimulus, unconditioned stimulus.