3 - Classical Conditioning PDF

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In-depth module notes including an explanation of classical conditioning - its history and modern application to speech pathology....

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MODULE 2 – Classical Conditioning Learning: any relatively permanent change in the behaviour, thoughts and feelings of an organism that results from prior experience. Not all behaviour change is indicative of learning but may just be developments SIMPLE LEARNING: Habituation: decline in the tendency to respond to stimuli that have become familiar due to repeated exposure (eg. The tick of the clock) Adaptation: fitting in with the environment (eg. Shivering in cold conditions) Classical Conditioning: the learning process in which an originally neutral stimulus becomes associated with a particular physiological or emotional response that the stimulus did not originally reproduce. - Example: the smell of chocolate may become associated with the experience of eating chocolate chip cookies and cause you to feel hungry or your mouth to water. Ivan pavlov studied the mechanisms of classical conditioning after an experiment during which dogs smelled meat powder and started salivating. Over time, it was noticed that the dogs started salivating before they smelled the meat but only saw the owner or heard his footsteps. He continued to experiement using a buzzer: - First he made sure that the dog salivated when given meat powder. - Then he made sure that the dog did not normally salivate when a buzzer was sounded. - Third he sounded the buzzer and then immediately put the meat on the tray several times. - Fourth he sounded the buzzer without putting any meat on the tray and the dog still salivated because it had been conditioned to respond to the originally neutral stimulus of the buzzer through the pairing of the buzzer with the food. Components and timing of classical conditioning: 1. Star with an unconditioned stimulus (US) that elicits an automatic, unlearned physiological or emotional response (such as the meat powder) 2. The unconditioned response (UR) is the participant’s automatic, unlearned physiological response to this stimulus (such as the salivation) 3. Choose a stimulus that is originally neutral (such as the buzzer). 4. Pair your Stimulus and unconditioned stimulus so that they are associated. Eventually the stimulus becomes the conditioned stimulus (CS) and it alone with elicit the conditioned response (CR) (a learned pattern of behaviour that is typically similar or identical to the UR. Standard Conditioning: the onset of the CS comes directly before the US Delay conditioning: there us a long delay between the onset of the CS and the onset of the US. Trace conditioning: similar to delay condition , except the CS is terminated for a while before the US begins. Initially results are similar to those for the standard paradigm but eventually the animal learns that there will be a long delay from the onset of the CS to the onset of the US and so the CR does no appear until the CS has bee in effect for some time. Temporal Conditioning: the CS is given at fixed time intervals between the US presentations. So the animal learns that the US will occur at a given fixed time and begins to show the CR right before the presentation of the US. - Example: the child learns that her father will give a present every 7 days so the 7-day interval erves as the conditioned stimulus for learning when the present will be forthcoming. Typically ineffective as means of producing learning: Simultaneous conditioning: in which the conditioned and unconditioned stimuli occur at the same time. Backward conditioning: in which the conditioned stimulus occurs after the unconditioned stimulus. CONDITIONING REQUIRES: Temporal contiguity: If too long a time passes between the CS and US, conditioning will not take place because the organism will not associate one stimulus with the other. Therefore, the CS has to preceed the US by a small amount. (some originally thought this was all that was needed). Contingency: the dependent relationship between the occurrence of an unconditioned stimulus and the occurrence of a conditioned stimulus. (later it was thought that this was a key part of conditioning)

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Positive contingency: p(US|CS) is greater than p(US|no CS) In this case, the US is more likely when the CS occurs than when it does not. This procedure produces excitatory conditioning to the CS, as in ordinary delay conditioning. Neutral contingency: p(US|CS) = p(US|no CS) Here, the US is no more likely when the CS occurs than when it does not. This procedure fails to produce conditioning to the CS, even though, during the course of trials, the CS and US may be paired hundreds of times. Negative contingency: p(US|CS) is less than p(US|no CS) The US is less likely when the CS occurs than when it does not. This procedure produces inhibitory conditioning to the CS, as in backward conditioning.

We do not learn simply because two stimuli happen to occur close together in time, but becase the first stimulus somehow predicts the second. Blocking effect: the failure of a second CS to become classically conditioned because the first CS blocks the second one in eliciting a CR. - For example: if a rat has already become able to predict the unconditioned stimulus via the sound, the light is redundant because it provides no new predictive. Negative acceleration: Learning tends to increase at a rate that slows down as the amount of learning increases. A gradual reduction in the amount of increase occurs over successive conditioning trials. The more learning that has taken place, the slower the pace of the subsequent learning. As the US becomes more predictable, there is less need to notice the contingent relationship between the US and the CS. Shown in a graph where the learning curve starts by rising quickly, then tapers off and eventually reaches an asymptote where the degree of learning peaks. However, the probability of a given performance reflecting learning, that is the likelihood of the occurrence of a CR, increases over learning trials. SUCCESSFUL CONDITIONG DEPENDS ON: - The salience (the degree of obviousness) of the stimuli. As the salience increases, so does the rate of learning. For example, a barely noticeable electric shock is likely to be much less salient and to result in a slower rate of learning. - The maximum stable level of conditioning that can be achieved for a given CS-US pairing. Each stimulus would have a distinctive curve. Some curves yield higher asymptotes than others. PHASES OF CLASSICAL CONDITIONING Acquisition phase: the CR strengthens and the occurrence of the response increases in likelihood. Eventually the CR reaches its asymptote. Extinction Phase: if the CS was presented in the absence of the US. For example, a buzzer that previously had preceded shock would no longer precede shock. Gradually the probability of the occurrence of the CR would decrease, eventually approaching zero. Tends to occur less rapidly than acquisition does. Spontaneous recovery phase: In which a CR reappears without any environmental prompting. The CR may be extinguished, but the memory of the learning has not been completely erased. The behaviour can still be elicited. Resuming a varies of trials after a period of rest after the extinction period results in a higher level of responding than before the rest period. Savings: occurs when, for a period of time, the CS and US are not linked and then the CS is presented again in the presence of the US. When the CS is again paired with the US, even if only briefly, the CR returns to levels approaching those at the asymptote of the acquisition phase. Time is saved in reaching the earlier level of learning. LEVELS OF CONDITIONING: First-order conditioning: whereby a CS is linked directly with a US. Second-order conditioning: when a second CS is linked to the first one. - Example: we have conditioned a fear response to the sound of a tone. Right before the tone, a light comes on so we might link the CR (fear), which is already linked to the first CS (the tone), to the second CS (the light) as well. Higher-order conditioning: where a CS is not directly linked with a US but rather is linked to an established CS.

Conditioning beyond the first order tends to be rather unstable and relatively more susceptible to extinction. Stimulus Generalisation: conditioning occurs in association not only with the exact CS but also with stimuli that are similar to it. - For example: changing the pitch of the buzzer will have only a barely perceptible effect on the CR, but the more the one is changed, the less the tone will elicit the CR. Stimulus discrimination: the mechanism whereby the CR becomes less probable as the new stimulus increasingly differs from the old one. As the difference between a new stimulus and the original CS increases, it becomes increasingly less likely that the CR will occur. Preparedness: some organisms have a preparedness to learn. The learn some associations more easily than others. The rate of learning is not fixed across all possible stimuli and responses, it can depend on the nature of both the stimulus and the response. Conditioned emotional responses (CERs): are classically conditioned feelings that an individual experiences in association with particular stimulus events. Counter-conditioning: a technique in which the positive association between a given US and a given CS is replaced with a negative one by the substitution of a new US that has a different UR. - Gradual exposure to feared object/situation to facilitate extinction of CS-CR.

FOR SPEECH PATHOLOGY: Language acquires its influence by being paired with other relevant stimulus event. Meanings have been developed by the pairing of the words with relevant events. 12 year old boy who stutters whenever he gives class presentations. Presence of classmates (NS) Occasional stuttuering (ucs) Embarrassment (UCR) Stuttering paired with the presence of the class mates Presence of classmates evokes embarrassment....