Chapter Outline

Chapter Outline

1. THE ACQUISITION OF THE CONDITIONED RESPONSE

   1. The Conditioning Paradigm

      1. Basic Components

         In classical (or Pavlovian) conditioning, there are four important elements. In a normal conditioning experiment, these include the pairing of a conditioned stimulus (CS)followed by the unconditioned stimulus (UCS). The UCS innately elicits an unconditioned response (UCR), which is known as the unconditioned reflex. After CS-UCS pairings in training, the CS comes to elicit the conditioned response (CR), which is evidence for the conditioned reflex. The CR becomes stronger with more CS-UCS trials until it reaches asymptotic level.

      2. The Conditioning of Hunger

         Conditioned hunger develops when a CS is followed by the occurrence of a deprivation condition, such as hunger, the CS acquires the ability to elicit hunger and feeding responses.

      3. The Conditioning of Fear

         When a CS is followed by the occurrence of a painful event, the CS acquires the ability to elicit fear and motivates the avoidance of adversity.

      4. Other Examples of Conditioned Responses

         The conditioning process is so pervasive that virtually any response of the body can be elicited by CSs that have been paired with UCSs. In many situations, more than one CR is conditioned.

   2. Conditioning Situations: Several techniques are used to measure the level of classical conditioning.

      1. Signtracking

         Brown and Jenkins conducted the first sign tracking experiment known as autoshaping. The researchers found that pigeons would peck a key light presented shortly before the delivery of food. The response to the key light occurred even though no activity was required to produce the food.

      2. Eyeblink Conditioning

         Eyeblink conditioning develops when rabbits receive repeated presentations of a tone CS and an air puff UCS delivered to the cornea of the eye, the tone CS will elicit a conditioned blink response. Strength of conditioning can be measured by computing the CR probability over trials.

      3. Fear Conditioning

         Fear conditioning is demonstrated in the conditioned emotional response (CER) paradigm. In this situation, a CS previously associated with shock, is presented while a rat is performing an instrumental response for food. The suppression of the instrumental behavior is assumed to reflect the influence of fear conditioning attached to the CS, and a suppression ratio can be computed as the number of responses during the CS compared to the number of responses during the CS plus the number of responses without the CS. A suppression ratio of 0.5 indicates that fear has not been conditioned, and a ratio of 0.0 indicates complete suppression of behavior or complete fear.

      4. Flavor Aversion Learning

         Animals can learn to associate a flavor with illness. For example, if rats taste saccharin and then are made sick, they acquire a flavor aversion and subsequently avoid the taste of the saccharin. The strength of the aversion is reflective of the classical conditioning process.

   3. Conditioning Paradigms: There are five different paradigms or procedures that are commonly used in Pavlovian conditioning. They differ with respect to how a CS is paired with a UCS.

      1. Delayed Conditioning

         In delayed conditioning, the onset of the CS precedes the onset of the UCS and termination of the CS occurs either with the onset of the UCS or during UCS presentation.

      2. Trace Conditioning

         In trace conditioning, the CS is presented and terminated prior to the onset of the UCS.

      3. Simultaneous Conditioning

         In simultaneous conditioning, the CS and the UCS have onsets at the same time.

      4. Backward Conditioning

         In backward conditioning, the UCS is presented and terminated before the onset of the CS.

      5. Temporal Conditioning

         In temporal conditioning, the UCS is presented at regular time intervals allowing the timing of the UCS to serve as the CS eliciting the CR.

   4. Conditions Affecting the Acquisition of a Conditioned Response: CS and UCS pairings do not automatically insure that a CR will be acquired. Several variables determine whether conditioning will be successful.

      1. Contiguity

         Contiguity refers to the closeness in time between the deliveries of the CS and the UCS.

      2. The Optimal CS-UCS Interval

         The optimal CS-UCS interval. For each response system, there is an optimal time between the onsets of the CS and UCS that supports conditioning.

      3. A Bridge Between the CS and the UCS

         If a second stimulus is presented between the onset of the CS and the onset of the UCS, conditioning will occur despite a long temporal separation between the CS and UCS onsets.

      4. Long-delay Learning

         In flavor-aversion learning, an aversion develops to a CS paired with illness despite long intervals between the onset of the CS and the onset of the illness.

   5. The Influence of Intensity

      1. CS Intensity

         In general, increases in the intensity of the CS support higher levels of conditioning. Also, presentations of loud and soft auditory CSs can raise the level of conditioning to the loud CS and reduce the level to the soft CS.

      2. UCS Intensity

         The strength of the CR increases with more intense UCSs.

      3. The Salience of the CS

         Seligman proposed that evolution has shaped how sensitive species are to various CSs. With some CSs, learning occurs rapidly, demonstrating preparedness. For other CSs, learning is essentially impossible, demonstrating contrapreparedness. Salience refers to the tendency for a CS to be associated with a particular UCS.

      4. The Predictiveness of the CS

         The ability of a CS to elicit a CR depends not only on its pairing with the UCS, but also its ability to predict the UCS. Cue predictiveness is degraded if the CS sometimes is not followed by the UCS or if there is a second, more predictive CS.

      5. UCS-Alone Presentations

         Similarly, if the UCS sometimes occurs without the CS, learning is degraded.

      6. CS-Alone Presentations

         Even when groups are given the same number of CS-UCS trials, learning is degraded if the CS is presented without the UCS during training.

      7. The Redundancy of the CS

         If a CS is first trained to elicit a CR, and then that CS plus another CS are simultaneously presented before the UCS, the first CS can block conditioning to the second. This occurs because the second CS provides no new information for the animal.

2. EXTINCTION OF THE CONDITIONED RESPONSE A

   CR that is elicited in a variety of environmental situations can come to occur in only one situation, a process called stimulus narrowing, and involves extinction of the conditioned response.

   1. Extinction Paradigm: Extinction is a method that can eliminate CRs. After first conditioning a CS to elicit a CR, subsequently delivering the CS without the UCS extinguishes the CR.

   2. How Rapidly Does a Conditioned Response Extinguish?

      1. The Strength of the CR

         Three factors influence the extinction of the CR. One is the strength of conditioning. In general, the stronger the CS-CR bond, the slower the extinction of the CR. However, the correlation between the CR acquisition level and the resistance to extinction is not perfect.

      2. The Influence of Predictiveness

         When the CS is occasionally presented alone during acquisition, resistance to extinction is increased.

      3. Duration of CS

         Exposure As the duration of the CS exposure in extinction increases, the strength of the CR weakens.

   3. Spontaneous Recovery: Pavlov proposed that the extinction of the CR is caused by an inhibition process. Furthermore, the inhibitory state is only temporary allowing the return of the CR following extinction (spontaneous recovery). However, long-term extinction prevents the occurrence of spontaneous recovery.

   4. Other Inhibitory Processes: The inhibition of the CR can become permanent, a process Pavlov called conditioned inhibition.

      1. Conditioned Inhibition

         Conditioned inhibition is the ability of a stimulus (CS-) associated with the absence of the UCS to suppress responding to the CS+.

      2. External Inhibition

         External inhibition occurs when a novel stimulus is presented during conditioning and interferes with the occurrence of the CR.

      3. Latent Inhibition

         Latent inhibition retards conditioning of a CS. The procedure involves presenting the CS alone before the CS is paired with the UCS. But because CS preexposure also retards the development of conditioned inhibition, it is not clear just what is learned during CS preexposure.

      4. Inhibition of Delay

         The absence of responding to the CS until the end of the CS-UCS interval was called by Pavlov inhibition of delay.

      5. Disinhibition

         During extinction trials, the CR is stronger when a novel CS is presented, a process called disinhibition.

3. A CR WITHOUT A CS-UCS PAIRING?

   Several procedures exist that allow a CS, never directly paired with an UCS, to elicit a CR. These procedures include higher-order conditioning, sensory preconditioning, and vicarious conditioning.

   1. Higher-Order Conditioning

      1. The Higher-Order Conditioning Paradigm

         A CS1 that has previously been paired with a UCS can support conditioning to a second CS (CS2) when the CS2 and CSl are paired together. Thus CS2, never directly paired with the UCS, still elicits a CR. This is higher-order conditioning.

      2. Research on Higher-Order

         Conditioning Higher-order conditioning is weaker than original (first-order) conditioning. Rescorla's research suggests that during second-order conditioning, the CS2-CS1 pairings not only condition CS2 to elicit the CR (excitation), but they also condition inhibition of the CR because the UCS is absent. Thus, as second-order conditioning trials proceed, there is initial excitatory conditioning of CS2, but eventually there is increased conditioned inhibition.

   2. Sensory Preconditioning

      1. The Sensory Preconditioning Paradigm

         The procedure for sensory preconditioning requires three phases. In phase 1, CS2 and CS1 are paired together. In phase 2, CS1 is paired with an US for conditioning. In phase 3, CS2 is presented alone and elicits the CR previously evoked by CSl.

      2. Research on Sensory

         Preconditioning Reliable sensory preconditioning occurs if, during the preliminary CS2-CS1 trials, the two CSs are separated by several seconds, and if there are only a few CS2-CS1 trials.

   3. Vicarious Conditioning

      1. Research on Vicarious Conditioning

         A CR can develop to a CS if a person observes another person experiencing the CS-UCS pairing. This is termed vicarious conditioning, and has also been observed in monkeys.

      2. The Importance of Arousal

         Vicarious conditioning requires that the observer be at least somewhat emotionally aroused while observing the CS-UCS pairing in the other person.

4. APPLICATIONS OF PAVLOVIAN CONDITIONING

   1. Systematic Desensitization: Systematic desensitization is a therapy based on Pavlovian conditioning procedures that can be effective in the elimination of conditioned fear and the reduction of phobic behavior.

      1. Original Animal Studies

         A central feature of systematic desensitization is a counterconditioning procedure, which involves the elimination of a CR when the CS is paired with an opponent or antagonistic UCS. According to Wolpe, the extinction is successful due to reciprocal inhibition, which assumes that only one emotional state can be experienced at a time. Wolpe first trained cats to fear an environment where a buzzer CS signalled shock. By letting the cats eat food in similar environments, the animals eventually lost their fear.

      2. Clinical Treatment

         Therapy involves cue-controlled relaxation in which the relaxation response is conditioned to a specific environmental event. Therapy also involves the construction of thematic hierarchies which refers to a listing of fear-inducing situations that are related to a basic theme. Additionally, a spatial-temporal hierarchy, which is a listing of activities related to a phobic object on the basis of time or physical distance, is also used. By remaining relaxed while imagining the lowest item in the hierarchy, the fear to that situation or object is counterconditioned. By then counterconditioning situations higher in the hierarchy, all situations may be counterconditioned.

      3. Clinical Effectiveness

         To test the effectiveness of the treatment, the individual must encounter the feared object. Treatment is effective to the extent that the person can tolerate the once-feared object or situation. For the therapy to work, patients must be able to imagine feared items on their hierarchy of feared situations. Virtual reality technology may enhance the success of systematic desensitization.

   2. Explorations for the Future

      1. An Intense Craving

         A drug addict experiences withdrawal after a period of abstinence. Additionally, environmental cues (CSs) that were previously paired with drug use can elicit conditioned withdrawal reactions. Thus, curing addictions might require extinction of these responses.

      2. The Conditioning of Immune System Suppression

         Ader and Cohen have demonstrated that Pavlovian procedures can produce conditioned immune system suppression. Their findings have important implications for the treatment of autoimmune disorders, such as lupus, in which the immune system is overactive. In other disorders, such as AIDS, in which the immune system is underactive, it may be possible to produce conditioned immune system enhancement.