Chapter SEVEN IV.docx

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University of Toronto Scarborough
Steve Joordens

Chapter SEVEN LEARNING - Learning is shorthand for a collection of different techniques, procedures, and outcomes that produce changes in an organism’s behaviour. - Learning involves the acquisition of new knowledge, skills, or responses from experience that result in a relatively permanent change in the state of the learner. - The key ideas emphasized are: o Learning is based on experience o Learning produces changes in the organism o These changes are relatively permanent CLASSICAL CONDITIONING: ONE THING LEADS TO ANOTHER - Ivan Pavlov studied the digestive processes of laboratory animals by surgically implanting test tubes into the cheeks of dogs to measure their salivary responses to different kinds of foots - Classical conditioning, occurs when a neutral stimulus produces a response after being paired with a stimulus that naturally produces a response. - In his classic experiments, Pavlov showed that dogs learned to salivate to neutral stimuli such as a bell or a tone after that stimulus had been associated with another stimulus that naturally evokes salivation, such as food. THE DEVELOPMENT OF CLASSICAL CONDITIONING: PAVLOV’S EXPERIMENTS - He noticed that does that previously had been in the experiment began to produce a kind of “anticipatory” salivary response as soon as they were put in the harness, before any food was presented. - The dogs were behaving in line with the four basic elements of classical conditioning: o When the dogs were initially presented with a plate of food, they began to salivate. Pavlov called the presentation of food an unconditioned stimulus (US), or something that reliably produces a naturally occurring reaction in an organism. o He called the dogs’ salivation an unconditioned response (UR), or a reflexive reaction that is reliably produced by an unconditioned stimulus o Pavlov soon discovered that he could make the dogs salivate to stimuli that don’t usually make animals salivate, such as the sound of a buzzer. Pavlov paired the representation of food with the sound of a buzzer, the ticking of a metronome, the humming of a tuning fork, or the flash of a light. He then found that the dogs salivated to these stimuli, and each of which had become a conditioned stimulus (CS), or a stimulus that is initially neutral and produces no reliable response in an organism. o When the conditioned stimulus (CS), sound of a buzzer, is paired over time with the unconditioned stimulus (US), or the food, the animal will learn to associate food with the sound and eventually the CS is sufficient to produce a response, or salivation.  Pavlov called this the conditioned response (CR), or a reaction that resembles an unconditioned response but is produced by a conditioned stimulus.  The dogs’ salivation (CR) was eventually prompted by the sound of the buzzer (CS) alone because the sound of the buzzer and the food (US) had been associated so often in the past. The salivation, technically, is not a UR (the naturally occurring, reflexive reaction to the presentation of food) because it is produced instead by the CS (the sound of the buzzer). THE BASIC PRINICIPLES OF CLASSICAL CONDITIONING - As John B. Watson was proposing: An organism experiences events or stimuli that are observable and measured - Dogs learned to salivate to the sound of the buzzer, and there was no need to resort to explanations about why it had happened, what the dog wanted, or how the animal thought about the situation. - There was no need to consider the mind in this classical conditioning paradigm, which had appealed to Watson and the behaviourists. ACQUISITION - Learning through classical conditioning requires some period of association between the CS and US. - This period is called acquisition, or the phase of classical conditioning when the CS and the US are presented together. - During the initial phase of classical conditioning, typically there is a gradual increase in learning: It starts low, rises rapidly, and then slowly tapers off. - After learning has been established, the CS by itself will reliably elicit the CR. SECOND-ORDER CONDITIONING - After conditioning has been established, a phenomenon called second-order conditioning can be demonstrated: it is conditioning where the stimulus that functions as the US is actually the CS from an earlier procedure in which it acquired its ability to produce learning. - Second-order conditioning helps explain why some people desire money to the point that they hoard it and value it even more than the objects it purchases. EXTINCTION - QUESTION: What would happen if they continued to present the CS (tone) but stopped presenting the US (food)? - ANSWER: Behaviour declines abruptly and continues to drop until eventually the dog ceases to salivate to the sound of the tone. - This process is known as extinction, the gradual elimination of a learned response that occurs when the US is no longer presented SPONTANEOUS RECOVERY - QUESTION: Is a single session of extinction sufficient to knock out the CR completely, or is there some residual change in the dog’s behaviour so that the CR might reappear? - ANSWER: Pavlov extinguished the classically conditioned salivation response and then allowed the dogs to have a short rest period. - When they were brought back to the lab and presented with the CS again, they displayed spontaneous recovery, the tendency of a learned behaviour to recover from extinction after a rest period. - This recovery takes place even though there have not been any additional associations between the CS and US - Some spontaneous recovery of the conditioned response even takes place in what is essentially a second extinction session after another period of rest. GENERALIZATION AND DISCRIMINATION - The phenomenon of generalization tends to take place, when the CR is observed even though the CS is slightly different from the original one used during acquisition. - This means that the conditioning “generalizes” to stimuli that are similar to the SC used during the original training. - The more the new stimulus changes, the less conditioned responding is observed. - When an organism generalizes to a new stimulus, two things are happening. o First, by responding to the new stimulus used during generalization testing, the organism demonstrates that it recognizes the similarity between the original CS and the new stimulus. o Second, by displaying diminished responding to that new stimulus, it also tells us that it notices a difference between the two stimuli.  The organism shows discrimination, or the capacity to distinguish between similar but distinct stimuli. CONDITIONED EMOTIONAL RESPONSES: THE CASE OF LITTLE ALBERT - Classical conditioning demonstrates that durable, substantial changes in behaviour can be achieved simply by setting up the proper conditions. - By skillfully associating a naturally occurring US with an appropriate CS, and organism can learn to perform a variety of behaviours, often after relatively few acquisition trials. - There is no reference to an organism’s wanting to learn the behaviour, willingness to do it, thinking about the situation, or reasoning through the available options. - In the situation of Little Albert, a US (the loud sound) was paired with a CS (the presence of the rat) such that the CS all by itself was sufficient to produce the CR (a fearful reaction). - Watson’s goal was: o First, he wanted to show that a relatively complex reaction could be conditioned using Pavlovian techniques o Second, he wanted to show that emotional responses such as fear and anxiety could be produced by classical conditioning and therefore need not be the product of deeper unconscious processes or early life experiences as Freud and his followers had argued - Watson proposed that fears could be learned, just like any other behaviour o Third, Watson wanted to confirm that conditioning could be applied to humans as well as to other animals. A DEEPER UNDERSTANDING OF CLASSICAL CONDITIONING - The mechanisms of classical conditioning: the cognitive, neural, and evolutionary elements THE COGNITIVIE ELEMENTS OF CLASSICAL CONDITIONING - QUESTION: Why didn’t Pavlov’s dogs salivate to Pavlov? - ANSWER: Maybe classical conditioning isn’t such an unthinking, mechanical process as behaviourists assumed. - Somehow, Pavlov’s dogs were sensitive to the fact that Pavlov was not a reliable indicator of the arrival of food. - Pavlov was linked with the arrival of food, but he was also linked with other activities that had nothing to do with food, including checking on the apparatus, bringing the dog from the kennel to the laboratory, and standing around and talking with his assistants. - Robert Rescorla and Allan Wagner were the first to theorize that classical conditioning only occurs when an animal has learned to set up an expectation. - The sound of a tone, because of its systematic pairing with food, served to set up this cognitive state for the laboratory dogs; Pavlov, because of the lack of any reliable link with food, did not. - The Rescorla-Wagner model introduced a cognitive component that accounted for a variety of classical- conditioning phenomena that were difficult to understand from a simple behaviourist point of view. o The model predicted that conditioning would be easier when the CS was an unfamiliar event than when it was familiar - The Role of Consciousness. o In the Rescorla-Wagner model, the cognitive elements are not necessarily conscious. o Rather, they likely reflect the operation of nonconscious associative mechanisms that do more than just record co-occurrences of events – they link those co-occurrences to prior experiences, generating an expectation. o In delay conditioning, the CS is a tone that is followed immediately by the US, a puff of air, which elicits an eyeblink response. Importantly, the tone and air puff overlap in time – the air puff follows the tone, but the tone remains on when the air puff is delivered. Then, the tone and air puff end at the same time. After a few pairings of the tone and air puff, conditioning occurs and the one alone elicits and eyeblink response. o Trace conditioning uses the identical procedures, with one difference: In trace conditioning, there is a brief interval of time after the tone ends and the air puff is delivered. - Researchers have suggested that classical conditioning draws on implicit but not explicit memory. - Delay conditioning does not require awareness of the contingency between the tone and the air puff, whereas trace conditioning does. - Implications for Patients in a Vegetative State. o fMRI studies have shown that some of them exhibit brain activity that may reflect conscious processing of spoken stimuli. - Implications for Understanding Schizophrenia. o Conditioning procedures are being used to study the relationship between hallucinations and reality, as often occurs in patients with schizophrenia. THE NEURAL ELEMENTS OF CLASSICAL CONDITIONING - A series of pioneering experiments conducted across several decades by Richard Thompson and his colleagues focused on eyeblink conditioning in the rabbit, and showed convincingly that the cerebellum is critical for both delay and trace conditioning. - Studies of patients with lesions to the cerebellum supported these findings. - The cerebellum is part of the hindbrain and plays an important role in motor skills and learning. - In contrast to the cerebellum, the hippocampus is important for trace conditioning but not delay conditioning. - More recent neuroimaging findings in healthy young adults show greater hippocampal activation during trace than delay conditioning, together with similar amounts of activation in the cerebellum during the two types of conditioning. - In addition to eyeblink conditioning, fear conditioning has been extensively studied. - The amygdala, particularly an area known as the central nucleus, is also critical for emotional conditioning. - The central nucleus of the amygdala plays a role in producing both of these outcomes through two distinct connections with other parts of the brain. - If connections linking the amygdala to the midbrain are disrupted, the rat does not exhibit the behavioural freezing response. - If the connections between the amygdala and the hypothalamus are served, the autonomic responses associated with fear cease. - Hence, the action of the amygdala is an essential element in fear conditioning, and its links with other areas of the brain are responsible for producing specific features of conditioning. THE EVOLUTIONARY ELEMENTS OF CLASSICAL CONDITIONING - Evolution and natural selection go hand in hand with adaptiveness: Behaviours that are adaptive allow an organism to survive and thrive in its environment. - Any species that forages or consumes a variety of foods needs to develop a mechanism by which it can learn to avoid any food that once made it ill. o There should be rapid learning that occurs in perhaps one or two trials. o Conditioning should be able to take place over very long intervals, perhaps up to several hours. Toxic substances often don’t cause illness immediately, so the organism would need to form an association between food and the illness over a longer term. o The organism should develop the aversion to the smell or taste of the food rather than its ingestion. Its more adaptive to reject a potentially toxic substance based on smell alone than it is to ingest it. o Learned aversions should occur more often with novel foods than familiar ones. It’s not adaptive for an animal to develop an aversion to everything it has eaten on the particular day it got sick. - Biological preparedness, is a propensity for learning particular kinds of associations over others, so that some behaviours are relatively easy to condition in some species but not others. OPERANT CONDITIONING: REINFORCEMENTS FROM THE ENVIRONMENT. - Operant conditioning, is a type of learning in which the consequences of an organism’s behaviour determine whether it will be repeated in the future. - The study of operant conditioning is the exploration of behaviours that are active. THE DEVELOPMENT OF OPERANT CONDITIONING: THE LAW OF EFFECT - Edward L. Thorndike’s research focused on instrumental behaviours, that is, behaviour that required an organism to do something, solve a problem, or otherwise manipulate elements of its environment. - Thorndike developed the law of effect, which states that behaviours that are followed by a “satisfying state of affairs” tend to be repeated and those that produce an “unpleasant state of affairs” are less likely to be repeated. - In Thorndike’s work, the behaviour of the animal determined what happened next. - If the behaviour was “correct”, the animal was rewarded with food. - Incorrect behaviours produced no results and the animal was stuck in the box until it performed the correct behaviour. B.F. SKINNER: THE ROLE OF REINFORCEMENT AND PUNISHMENT - B.F. Skinner coined the term operant behaviour to refer to behaviour that an organism produces that has some impact on the environment. - In Skinner’s system, all of these emitted behaviours “operated” on the environment in some manner, and the environment responded by providing events that either strengthened those behaviours (reinforced them) or made them less likely to occur (punished them). - A reinforce is any stimulus or even that functions to increase the likelihood of the behaviour that led to it - A punisher is any stimulus or event that functions to decrease the likelihood of the behaviour that led to it. - Positive reinforcement (where a rewarding stimulus is presented) - Negative reinforcement (where an unpleasant stimulus is removed) - Positive punishment ( where an unpleasant stimulus is administered) - Negative punishment (where a rewarding stimulus is removed) - Reinforcement is generally more effective than punishment in promoting learning. There are many reasons, but one reason is this: o Punishment signals that an unacceptable behaviour has occurred, but it doesn’t specify what should be done instead. PRIMARY AND SECONDARY REINFORCEMENT AND PUNISHMENT - Food, comfort, shelter, or warmth are examples of primary reinforcers because they help satisfy biological needs. - Handshakes, verbal approval, an encouraging grin, a bronze trophy, or money all serve powerful reinforcing functions. - We learn to perform a lot of behaviours based on reinforcements that have little or nothing to
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