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Famous Psychology Experiments

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1 Famous Psychology Experiments
This presentation will take a look at some famous experiments in psychology. The experiments you’ll learn about fall under three broad categories: learning, social psychology, and brain disorders. Before we discuss specific experiments, let’s review some of the basics of psychological experimentation.

2 Ivan Pavlov Dog Classical Conditioning Experiments on dogs
Ivan Pavlov was a Russian scientist who specialized in studying the digestive system. He earned Russia’s first Nobel Prize in Pavlov became famous for his experiments in classical conditioning. In the 1890s and early 1900s, he conducted these experiments on dogs, whose digestive systems he had been studying. The next few slides will demonstrate these experiments and will explain how classical conditioning works. Classical Conditioning Experiments on dogs Smarty Pants: Nobel Prize Dog

3 Classical Conditioning and Pavlov’s Dogs: Hypothesis
Observations: Dogs salivate when food is placed in their mouths Dogs salivate at mere sight of food Hypothesis: Dogs can be trained, or conditioned, to salivate when exposed to an external (neutral) stimulus Pavlov observed that dogs salivated when he placed food into their mouths. He also noted that a dog would often salivate even if it just saw some food. The dog appeared to anticipate the feeling and taste of the food in its mouth. At first, Pavlov lamented that this salivation got in the way of his research on the dogs’ digestive systems. After thinking about the dogs’ reaction to the sight of food, however, he decided to focus his research on this phenomenon and to experiment with the dogs to see how their salivation response formed and changed. Pavlov hypothesized that dogs could learn to associate external stimuli, such as a sound or a touch, with food and would therefore salivate upon sensing those external stimuli.

4 Pavlov’s Methodology and Results
Present external (neutral) stimulus (bell) immediately before giving food. Order is important Results: After a few trials, the dog salivates upon hearing the bell Works with other stimuli as well Pavlov placed a dog in a small room and harnessed it so it couldn’t move around. He then attached a collection device to the dog’s mouth to measure how much the dog salivated. He began the experiment by ringing a bell and then immediately placing some food into the dog’s mouth. He measured the amount of saliva the dog excreted after each feeding. After repeating this bell-and-feeding sequence several times, Pavlov found that the dog would begin to salivate before it actually received the food. This confirmed his hypothesis. Pavlov achieved similar results when he tried other external stimuli, including a buzzer, a light, and touching the dog’s leg.

5 Classical Conditioning Components
CS-Conditioned Stimulus Learned trigger (initially neutral) UCS- Unconditioned Stimulus Automatically triggers a response UCR- Unconditioned Response Naturally occurring response CR- Conditioned Response Learned response

6 Altoid Theory – The Office
After viewing the clip be able to identify the components of classical conditioning.

7 Pavlov’s Conclusions Unconditioned Response (UCR)
Unconditioned Stimulus (UCS) Conditioned Response (CR) Conditioned Stimulus (CS) Pavlov came up with the following special terms to describe the results of his experiment: Unconditioned response (UCR): The salivation in response to the food is an unconditioned response. It is “unconditioned” because it’s a naturally occurring response that the dog does not have to learn. Unconditioned stimulus (UCS): The food is an unconditioned stimulus because it automatically triggers salivation in the dog. Again, the dog does not have to learn to salivate when it tastes food. Conditioned Response (CR): When the dog salivates in response to the bell or another external stimulus, it is exhibiting a conditioned response to that stimulus. The dog does not do this automatically but had to be conditioned to salivate without having food directly in its mouth. Conditioned Stimulus (CS): The bell and other external stimuli are “conditioned” because the dog has to learn to salivate in response to them. The overall process by which the dogs became conditioned to salivate when presented with the external stimuli (the bell, light, etc.) is called classical conditioning. because of because of

8 Continuing Pavlov’s Experiment
Other Aspects of Classical Conditioning Acquisition Learning the pairing CS+ UCS Making the association Extinction Represses CR (not eliminated) Spontaneous Recovery After extinction, time passes, recurring of the CR w/o UCS Generalization CR to stimuli that are similar Discrimination CR to a particular stimulus only Over the next few decades, Pavlov continued his experiment to learn more about how the dogs became conditioned to the external stimuli. He identified the following additional aspects of classical conditioning: Acquisition: There should be very little time between the presentation of the external stimulus (the bell) and the food. Also, if the food is presented before the bell rings, the dog does not become conditioned to salivate upon hearing the bell. Extinction: Once the dog has been conditioned, its conditioned salivation response will not last forever. The conditioned response (CR) gradually becomes less pronounced until it becomes “extinct.” Spontaneous Recovery: Interestingly, when Pavlov extinguished the conditioned response by not providing food with the bell, after a few hours the dogs would salivate at a weakened level upon hearing a bell, even if no food was presented. Generalization: The dogs salivated upon hearing the sound of bells that were similar to, but not the same as, the one to which Pavlov conditioned them to respond. Discrimination: Pavlov was also able to train his dogs to discriminate one sound from another and to respond to only one type of bell. Pavlov’s studies have had a significant impact on theories of learning in humans. Think about how each of Pavlov’s findings might relate to the ways in which people learn and react to their environment.

9 John Watson and Rosalie Rayner: Hypothesis, Methodology, Results
Conditioned fear into an infant Presented a rat immediately followed by a loud noise, startling the baby + = After a few tries, Albert was afraid of the rat Following up on Pavlov’s work, in 1920 John Watson and Rosalie Rayner hypothesized that humans could be conditioned to have certain fears. In particular, they hypothesized that a human child could be conditioned to fear a rat. The child they studied was an 11-month-old boy named Albert B., or “Little Albert.” Before the experiment, Little Albert was not afraid of rats, but he was afraid of loud noises. Watson and Rayner began the experiment by showing Little Albert a white rat. As Albert reached for the rat, the experimenters pounded a hammer directly behind his head, startling Albert. After doing this several times, Albert became frightened and began to cry simply upon seeing the rat without any accompanying noise. Watson and Rayner had therefore successfully conditioned him to fear the rat. A few days after conditioning Little Albert to fear the rat, Watson and Rayner found that Albert had generalized his fears to other furry creatures, including a rabbit, a dog, a sealskin coat, or Santa Claus mask. He did not express fear when exposed to non-furry toys. Albert generalized his fears to other furry objects

10 Mary Cover Jones DAY 1 DAY 2 DAY 3 Colleague of Watson
Deconditioned 3-year-old Peter from his fears by gradually moving a rabbit (and other things) closer to him while he was eating DAY 1 DAY 2 DAY 3 In 1925, Mary Cover Jones (a colleague of Watson) hypothesized that she would be able to decondition a three-year-old boy named Peter from some of his fears, which included feathers, cotton, frogs, fish, rats, rabbits, and mechanical toys. She began by bringing a caged rabbit into the same room where Peter was having a snack in his highchair. The rabbit was far enough away that it did not bother Peter. The next day, she brought the rabbit increasingly closer to Peter until he began to become disturbed. On subsequent days, the rabbit was moved closer and closer to Peter’s highchair only to the point at which Peter became afraid, at which time they’d end the experiment for the day. Eventually, Peter was able to pet the rabbit, having been deconditioned from his fear. Jones was able to decondition most of Peter’s other fears in this manner. Watson and Rayner’s experiment with Little Albert showed that people can be conditioned to fear specific types of objects. Conversely, Jones suggested that people could be deconditioned from their fears. Similar methods are used today to help people overcome phobias.

11 B.F. Skinner and Operant Conditioning
B.F. Skinner had an enormous influence on psychology in general and on the field of psychology known as behaviorism in particular. His key theories were published in the early 1950s. As Pavlov’s experiments showed, classical conditioning involves associating a neutral external stimulus with a response that is generally automatic (such as salivating). Skinner’s research revealed the power of operant conditioning, which involves learning how to operate on one’s environment to elicit a particular stimulus (a reward) or to avoid a punishment. In operant conditioning, the subject controls his or her response. You will learn how this works in the next few slides. Classical conditioning involves an automatic response to a stimulus Operant conditioning involves learning how to control one’s response to elicit a reward or avoid a punishment

12 The “Skinner Box”: Skinner’s Hypothesis, Methodology, and Results
Rats placed in “Skinner boxes” Shaped to get closer and closer to the bar in order to receive food Eventually required to press the bar to receive food Food is a reinforcer Skinner hypothesized that rats could be trained to perform specific behaviors in order to receive a food reward. He placed the rats into what is technically called an “operant chamber” but became more commonly known as a “Skinner box.” The soundproof glass box contained a bar or a key that the rat could press down to receive food. This bar or key was hooked up to an instrument that recorded how many times the rat pressed it. Skinner used a process called “shaping” to teach the rats to press the bar for food. For example, if a rat approached the bar, he might initially give it a pellet of food as a reward for getting close to the bar. Skinner would gradually make the rat get closer to the bar before giving it food. Eventually, the rat learned that it had to press the bar in order to get any food. The food in this case is referred to as a “reinforcer,” since it reinforces the rat’s behavior of stepping closer to and eventually pressing the bar.

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