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PSYC chapter7.doc

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Simon Fraser University
PSYC 100
Natasha Ghosh

CHAPTER 7. Learning andAdaptation: The Role of Experience Habituation is a decrease in response to a repeated stimulus. -serves a key adaptive function -different from sensory adaptation -simple form of learning that occurs within the central nervous system, not within the sensory neurons. e.g. you habituate to the feeling of your clothing against your skin. That tactile information has been presented continuously with no important consequences, so you no longer notice it. If, however, there is reason to become aware of skin sensations, perhaps because of a wasp or a mosquito in your vicinity, you suddenly become keenly aware. Sensitization is an increase in response to a repeated stimulus. e.g. when touched a metal door handle, and received a static electric shock. If you then touch another metal object and receive a second shock, you will jump a little more, pull your hand back a little more quickly Its purpose is to increase responses to a potentially dangerous stimulus. Learning is a process by which experience produces a relatively enduring change in an organism's behaviour or capabilities. Learning is measured by changes in performance. Learning involves adapting to the environment. Historically, behaviourists focused on the processes by which organisms learn, and ethologists focused on the adaptive significance of learning. Today, these two perspectives have crossed paths, and more attention is paid also to how mental processes and cultural environments influence learning. Habituation is a decrease in the strength of a response to a repeated stimulus. It may be the simplest form of learning. CLASSICAL CONDITIONING: ASSOCIATING ONE STIMULUS WITH ANOTHER Classical conditioning involves learning an association between stimuli. PAVLOV'S PIONEERING RESEARCH The dogs began to salivate before the food was presented, such as when they heard the footsteps of the approaching experimenter. Dogs have a natural reflex to salivate to food but not to tones. Yet when a tone or other stimulus that ordinarily did not cause salivation was presented just before food powder was squirted directly into a dog's mouth, the sound of the tone alone soon made the dog salivate. Classical conditioning alerts organisms to stimuli that signal the impending arrival of an important event. BASIC PRINCIPLES Acquisition refers to the period during which a response is being learned. unconditioned stimulus (UCS): the food with no learning is required for the food to produce salivation, unconditioned response (UCR): salivation learning trial: the tone and the food are paired—each pairing In classical conditioning, after a neutral stimulus such as a tone is repeatedly associated with food (unconditioned stimulus), the tone becomes capable of eliciting a salivation response. The strength of the CR (salivation) increases during the acquisition phase as the CS (tone) and the UCS (food) are paired on each trial. During the extinction phase, only the CS is presented, and the strength of the CR decreases and finally disappears. Presentation of the CS elicits a weaker CR (spontaneous recovery) that extinguishes more quickly . Presenting the CS and UCS at the same time (simultaneous pairing) produces less rapid conditioning, does not occur at all, when the CS is presented after the UCS (backward pairing). Strongest when there are repeated CS-UCS pairings, the UCS is more intense, the sequence involves forward pairing, and the time interval between the CS and UCS is short. Extinction and Spontaneous Recovery Extinction: If the CS is presented repeatedly in the absence of the UCS, the CR weakens and eventually disappears Extinction trial: Each presentation of the CS without the UCS e.g.When Pavlov repeatedly presented the tone without the food, the dogs eventually stopped salivating to the tone . Spontaneous recovery: the reappearance of a previously extinguished CR after a rest period and without new learning trials Stimulus generalization: Stimuli similar to the initial CS elicit a CR. e.g.Adog that salivates to a medium-pitched tone is more likely to salivate to a new tone slightly different in pitch, than to a low- or high-pitched tone. Discrimination is demonstrated when a CR (such as an alarm reaction) occurs to one stimulus (a sound) but not to others. e.g. My mother feared dogs but I got a dog dissimilar to the large dog that bit her. And my mother's fear would display stimulus discrimination. Higher-order conditioning:Aneutral stimulus becomes a CS after being paired with an already established CS. Typically, a higher-order CS produces a CR that is weaker and extinguishes more rapidly. e.g. Present the black square just prior to sounding the tone but do not present any food. The square will become a CS and elicit salivation by itself. The tone is the CS1. The black square becomes the CS2. APPLICATIONS OF CLASSICAL CONDITIONING Acquiring and Overcoming Fear Fear could be conditioned-Baby Albert. Albert displayed no sign of fear to the white rat. But Albert was afraid of loud noises. After several rat–noise pairings, the sight of the white rat alone madeAlbert cry. Stimulus discrimination and generalization Albert displayed no fear when shown coloured blocks, but furry white or grey objects, such as a rabbit and a bearded Santa Claus mask, made him cry. Exposure therapies because their basic goal is to expose the phobic patient to the feared stimulus (CS) without any UCS, allowing extinction to occur. Using Exposure Training to Reduce Fear 1 Rabbit anywhere in room triggers fear 2 Rabbit 4 metres away tolerated ... 12 Holds rabbit on lap 16 Fondles rabbit affectionately 17 Lets rabbit nibble his fingers Systematic desensitization, the patient learns muscular relaxation techniques and then is gradually exposed to the fear-provoking stimulus Another approach, flooding immediately exposes the person to the phobic stimulus. Conditioned Attraction: e.g.“It really turns me on when you wear that” Aversion therapy: decrease our arousal and attraction to stimuli e.g. To reduce an alcoholic's attraction to alcohol, the patient is given a drug that induces severe nausea when alcohol is consumed. virtual reality (VR). -VR exposure therapy has been found effective for treating phobias, such as spider phobias, and related anxiety disorders. - the client is able to confront the situation without anxiety - clients donned a VR helmet and visited a virtual kitchen. Gradually, over a series of trials, clients received increasing exposure to a virtual spider. e.g. they initially saw a virtual spider at a distance, later they came within arm's reach of a virtual spider, and eventually they were to touch the virtual spider. Standard exposure therapy -clients received real-world exposure to preflight activities e.g. they visited ticket counters and airport waiting rooms... and sat on a stationary plane while imagining flying. Neutral stimuli acquire favourable or unfavourable meaning (they become attractive or unattractive) by being paired with other stimuli that already elicit positive or negative attitudes. e.g. Advertising Classical conditioning involves pairing a neutral stimulus with an unconditioned stimulus (UCS) that elicits an unconditioned response (UCR). Through repeated pairing, the neutral stimulus becomes a conditioned stimulus (CS) that evokes a conditioned response (CR) similar to the original UCR. THORNDIKE'S LAW OF EFFECT Thorndike placed a hungry animal, such as a cat, inside the puzzle box. Food was put outside. It eventually stepped on the lever, opening the door. Performance slowly improved with repeated trials, and over time the cat learned to press the lever soon after the door was shut. Instrumental learning : eliminated responses that failed to open the door, and became more likely to perform actions that worked The law of effect : a response followed by an unsatisfying outcome will become less likely to occur. e.g. the school of behaviourism. SKINNER'SANALYSIS OF OPERANT CONDITIONING Operant conditioning (akin to Thorndike's instrumental learning) is a type of learning in which behaviour is influenced by its consequences Through operant conditioning, organisms generally learn to increase behaviours that benefit them and reduce behaviours that harm them. Reinforcement, a response is strengthened by an outcome that follows it. Punishment occurs when a response is weakened by outcomes Operant behaviour involves 3 kinds of events: (A) antecedents: stimuli that are present before a behaviour occurs (B) behaviours that the organism emits (C) consequences that follow the behaviours IF antecedent stimuli IF I say “Sit” (A) are present AND behaviour AND my dog Jessie sits, (B) is emitted, THEN consequence THEN she gets a tasty treat. (C) will occur. Contingencies: The relations betweenAand B, and between B and C In classical conditioning, the organism learns an association between two stimuli— the CS and UCS (e.g., a tone and food)—that occurs before the behaviour (e.g., salivation). In operant conditioning, the organism learns an association between behaviour and its consequences. Behaviour changes because of events that occur after it. Classical conditioning focuses on elicited behaviours(hidden). Operant conditioning focuses on emitted behaviours(upcoming) ANTECEDENT CONDITIONS: IDENTIFYING WHEN TO RESPOND In operant conditioning, the antecedent may be a general situation or specific stimulus. e.g. When the light is on, pressing the lever dispenses food, but when the light is off, no food is given. The rat will soon learn to press the lever only when the light is on. The light becomes a discriminative stimulus, a signal that a particular response will now produce certain consequences. 5 major operant processes. Positive Reinforcement: Behaviour is reinforced by desirable outcomes. e.g.Arat receives food for pressing a lever. We receive praise for a job well done. e.g. Food, drink, comforting physical contact, attention, praise, and money Negative Reinforcement: avoiding something we anticipate will be aversive—also is a good outcome. e.g. Children clean up their rooms to stop their parents' nagging, and we use umbrellas when it rains to avoid getting wet. Negative reinforcement:Aresponse is strengthened by the subsequent removal or avoidance of a stimulus Negative reinforcer: the stimulus that is removed or avoided Operant Extinction is the weakening and eventual disappearance of a response because it is no longer reinforced. e.g. If pressing a lever no longer results in food pellets, the rat eventually will stop making this response. Resistance to extinction is the degree to which non-reinforced responses persist. Operant extinction often provides a good alternative to punishment as a method for reducing undesirable behaviours. e.g. Mrs.Adams 's 4-year-old son, Pascal, delighted in misbehaving. She had tried to reason with him and began using physical punishment. Mrs.Adams started to use a procedure called “time out from positive reinforcement.” When Pascal misbehaved, Mrs.Adams ignored him for a specific period of time. She also began to reinforce Pascal's desirable behaviours by paying attention to him. Soon thereafter, Pascal was no longer a rascal. Positive Punishment (or aversive punishment) involves actively applying aversive stimuli e.g. painful slaps, electric shock, and verbal reprimands e.g. Ateenager wears a new blouse, and her close friends show their facial expressions betray dislike and the student stops wearing the shirt. Produces rapid results, an important consideration when it is necessary to stop a particularly dangerous behaviour Punishment arouses negative emotions, such as fear and anger, which can produce dislike and avoidance of the person delivering the punishment. Positive physical punishment also may set a bad example. It amounts to control by aggression and can send a message to the recipient that such aggression is appropriate and effective. e.g. Children whose parents use physical punishment display more aggression in daycare centres and at school than do otherwise similar children who are not physically punished Negative Punishment: a response is weakened by the subsequent removal of a stimulus -involved depriving him of other stimuli that he desired (perhaps no TV) Primary reinforcers are stimuli, such as food and water, that an organism naturally finds reinforcing because they satisfy biological needs. Other stimuli can become secondary, or conditioned, reinforcers. Secondary reinforcers, including money and tokens, performance feedback, and grades are crucial in everyday life e.g. Money is a conditioned reinforcer. e.g.Comforting physical contact with a caretaker, some research suggests, may be a primary reinforcer. Secondary reinforcers illustrate how behaviour often depends on a combination of classical and operant conditioning. e.g. In dog training, correct responses are operantly reinforced with food. “Good dog.”-food pairing. “Good dog” elicits excitement (salivation, tail wagging). “Good dog” can be used as a secondary reinforcer. Primary consequence has its value because of biological importance. Secondary consequence has its importance because of learning. e.g. A cat would pull the petals off of flowers. My mother approached the problem by spraying her cat with a water mister whenever it attacked a flower (primary punishment). “No.”(secondary consequence) - being sprayed pairing Immediate consequence has a stronger effect than a delayed one. e.g.Training animals requires very quick reinforcement so that they associate the correct response The timing of consequences may have less influence on human behaviour because we are able to imagine future consequences. Children who display less ability to delay gratification show poorer adjustment. e.g. If you could have $100 right now, or $200 a year from now, Chronic(Long-term) drug use e.g. Chronic cigarette smokers experience increased tension as the level of nicotine in their blood drops after their last cigarette. When they smoke again, tension is reduced. Thus, smoking is negatively reinforced by the removal of unpleasant tension . Developmental delayed Sami is a shy 12-year-old boy. He is an example of Selective mutism: he does not talk. Shaping, involves reinforcing successive approximations toward a final response. This technique also is called the method of successive approximations. Chaining, is used to develop a sequence (chain) of responses by reinforcing each response with the opportunity to perform the next response. Chaining usually begins with the final response in the sequence and works backwards toward the first response GENERALIZATIONAND DISCRIMINATION In operant generalization, an operant response occurs to a new antecedent stimulus or situation that is similar to the original one. e.g.Ayoung child who touches a hot stovetop burner learns to avoid touching all burners. Discriminate between antecedent conditions. e.g. Children learn to raid the cookie jar only when the parents are not in the kitchen. Operant discrimination means that an operant response will occur to one antecedent stimulus but not to another. e.g.these antecedent stimuli—parents' presence or absence, bus markings—are called discriminative stimuli. e.g the sight of a police car exerts stimulus control over most people's driving behaviour. Schedules of reinforcement means different patterns and frequencies that reinforcement comes in. They have strong and predictable effects on learning, extinction, and performance The most basic distinction is between continuous and partial reinforcement. On a continuous reinforcement schedule, every response of a particular type is reinforced. e.g. Every press of the lever results in food pellets. Every toonie deposit in the pop machine results in a can of cool bubbly drink With partial reinforcement(or intermittent reinforcement), only some responses are reinforced. Partial reinforcement schedules can be categorized along two important dimensions. The first is ratio versus interval schedules. On ratio schedules, a certain percentage of responses is reinforced. e.g. we might decide to reinforce only 50 percent of the rat's lever presses with food. The key factor is that ratio schedules are based on the number of correct responses. More responses … more reinforcement. (In the workplace, it is called pay for performance.) On interval schedules, a certain amount of time must elapse between reinforcements, regardless of how many correct responses might occur during that interval. We might reinforce lever pressing only once per minute, no matter whether the rat presses the lever 5, 10, or 60 times. The key factor is that interval schedules are based on the passage of time.
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