Interesting, Important, and Classic Psychology Experiments

Milgram's Obedience to Authority    Zimbardo's Stanford Prisoners    Blascovich's Virtual Reality   

Rosenhan's Psychiatry    BF Skinner Operant Conditioning     Ivan Pavlov Classical Conditioning   

Henry Harlow's Attachment    Albert Bandura's Bobo Doll    Allan and Beatrice Gardner's Language Development   

 Jane Elliot's Blue Eyes Brown Eyes    Hermann Ebbinghaus's Memory

LINKS             REFERENCES

Stanley Milgram's Obedience to Authority

Social psychology was greatly enhanced by the experiment conducted by Stanly Milgram, a Yale University psychologist.  Milgram described this study in his book Obedience to Authority: An Experimental View (1974).  Milgram's study was intended to assess the likelihood that a subject would be willing to follow through on the instructions provided by an authority figure, even if the authority figure's commands are in conflict with the subject's moral views.  The following is a brief description of the method that Milgram used:

There were two subjects in the experiment, an actual subject and an actor pretending to be another subject.  The experimenter informed the subjects that they were going to be participants in a study to examine how effective punishment was for learning particular behaviors.  The subject was assigned the role of "teacher."  The actor was also assigned the role of "teacher" but claimed that his role was that of a "learner" so that the subject would believe that his role had been randomly assigned to him.  Both the subject and the actor were given a sample 45-volt electric shock administered by an apparatus strapped to the actor's chair.  The "teacher" was told to present simple memory tasks to the "leaner" and to administer an electric shock each time the learner made a mistake with the task. 

The "teacher" is then informed that the voltage of the shock would increase by 15 volts every time the "learner" made a mistake.  The "teacher" is not informed that no actual shocks are being administered to the "learner."  The actor pretended to experience discomfort and pain when the pretend "shocks" were administered.  When the shock level is set to 150 volts, the "learner" asks that the experiment be terminated.  He is told that the experiment requires him to continue.  The "learner" feigns greater levels of pain and discomfort as the experiment continues.  The "teacher" is told that the experimenter assumes all responsibility for the results of the study and for the safety of the "learner" if the "teacher" is hesitant to continue administering shocks to the "learner."

Prior to the experiment, Milgram asked psychiatrists what they believed the results of the study to be.  All of them believed that only a very few sadistic individuals would administer the maximum voltage level of shock to the "learner."  However, approximately 65% of subjects actually administer the maximum voltage shock (450 volts), even though some were uncomfortable doing so.  All subjects administered shocks up to at least 300 volts.  Other psychologists have repeated Milgram's experiment and found similar results.  Variations in testing conditions were tested.  For instance, subjects are more likely to administer the shock if the experimenter is present in the room with the subject.  Milgram's study brought ethical scientific experimentation to the forefront, and many current psychologists would consider Milgram's study to be unethical because of the subject's distress from their participation in the experiment.  However, Milgram would be able to argue against this point because 84% of his subjects rated their participation in the experiment as a positive experience and 15% considered it a neutral experiment.  Thus, only 1% of Milgram's subjects believe their participation in this study to be a negative experience!  Many subjects enjoyed this experience and thanked Milgram for allowing them to participate in this study. 

Milgram summed up in the article "The Perils of Obedience" (Milgram, 1974), writing:

"The legal and philosophic aspects of obedience are of enormous import, but they say very little about how most people behave in concrete situations. I set up a simple experiment at Yale University to test how much pain an ordinary citizen would inflict on another person simply because he was ordered to by an experimental scientist. Stark authority was pitted against the subjects' strongest moral imperatives against hurting others, and, with the subjects' ears ringing with the screams of the victims, authority won more often than not. The extreme willingness of adults to go to almost any lengths on the command of an authority constitutes the chief finding of the study and the fact most urgently demanding explanation."  (http://remus.rutgers.edu/~rhoads/PerilsofObedience.html)

Milgram began his experiments in July 1961, a year after the trial of Adolf Eichmann in Jerusalem. Milgram used his experiment to attempt to examine the answer to the question "Could it be that Eichmann, and his million accomplices in the Holocaust were just following orders? Could we call them all accomplices?" (Milgram, 1974).  Thomas Blass of the University of Maryland found that replications of Milgram's experiment have found that the percentage of subjects willing to administer electric shocks to another human subject ranged from 61% to 66% of subjects (Blass, 1999).

Based on information found at the website http://www.cba.uri.edu/Faculty/dellabitta/mr415s98/EthicEtcLinks/Milgram.htm and  http://www3.niu.edu/acad/psych/Millis/History/2003/stanley_milgram.htm

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Phillip Zimbardo's Stanford Prisoner's Experiment

The Stanford Prison Experiment was a landmark psychological study.  It was conducted in 1971 by Philip Zimbardo of Stanford University and examined the study of human being's responses to being captive.  In particular, it examined the real world circumstances of prison life.   Subjects were assigned to play the role of either a "prisoner" or a "guard".  "Guards" were given sticks and sunglasses, while "prisoners" were arrested by the police.  They were shackled and transported to the basement of the psychology department at Stanford, which had been transformed into a temporary prison. Several "guards" became progressively more sadistic as time went on, torturing "prisoners."  This sadism was particularly noticeable at night when "guards" thought that the cameras were off and their behavior would not be witnessed.  Zimbardo lost control over his study.  A riot ensued among the "prisoners" and "prisoners" developed psychosomatic illnesses after being denied "parole." 

The study was originally intended for a two-week time period; however, it had to be shut down after six days due to concerns about the well-being and safety of the "prisoners."  Even Zimbardo truly took on the role of a "prison warden" rather than his intended role of a social psychologist.  Even though the experiment was intended to examine human behavior in captivity, its result has been used to human's tendency to be obedient and impressionable when provided with a legitimizing ideology and social and institutional support. Cognitive dissonance theory and the power of authority were also demonstrated in Zimbardo's study.

Based on ideas from http://www.zimbardo.com  and http://www.prisonexp.org/

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Jim Blascovich Pioneering Virtual Reality Experimentation

Jim Blascovich is the co-director of the Research Center for Virtual Environments and Behavior at the University of California, Santa Barbara. At this center, they use virtual reality (VR) to explore different psychological processes. Virtual reality experimentation adds to the external validity of an experiment by bringing the experimental situation closer to the real world situation. This increases the odds that you can correctly generalize from the experiment to the external world. Participants act unrestrictively and in real time with the virtual world.

In the area of Social Psychology, topics that are currently being researched include the ability of a computer agent to persuade the participant. Results indicate that participants were more persuaded by the computer agent of the same sex. There is also research on risk-taking and conformity in which the participant plays a Blackjack in a virtual casino. The researchers are also studying aggression in a very immersive way. They have participants play a VR violent video game while measuring cardiovascular and hemodynamic patterns, and then have the participant fill out a self-report of aggression. The researchers measure aggression using self-report, observed behaviors, and physiological data.

Within the more cognitive domain researcher are interested in spatial cognition and the ability of the participant to navigate themselves around the virtual environment. Current research is being done on cognitive mapping, the flexibility of spatial knowledge, and perceptual cues. Interestingly, they are also investigating how witnesses to crimes identify the perpetrator in a lineup.

The center aims to also address societal concerns such as violence desensitization through television, video games, and other media outputs. They eventually aim to use their research to change policy on these issues through experimental research.  The center also offers a training institute over the summer for diverse professionals in the fields of psychology and other related fields. This training seminar trains researchers to use VR technology and develop new ideas for VR research.

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David Rosenhan's Validity of Psychiatry

David Rosenhan conducted an experiment to prove the validity of psychiatry in 1972.  Rosenhan and eight graduate students attempted to feign mental illnesses to see if they would be admitted to a mental hospital.  All nine subjects stopped engaging in proper self-care or personal hygiene behaviors.  All nine individuals presented that they were hearing voices that were saying "thud" and were admitted to different hospital across the United States with diagnoses of paranoid schizophrenia.  When admitted, all nine subjects said that the voices had stopped and that they were no longer experiencing problems.  They were confined to psychiatric wards for several days and were dispensed medication (which they "cheeked" and did not actually take).  Rosenhan found that the psychosocial history of the subjects were adjusted to fit their schizophrenic diagnoses.  After several days, the subjects' diagnoses were declared to be in remission and they were discharged.   Rosenhan published his controversial findings in Science. Many advocates for psychiatry argued that a patient faking a medical emergency could receive treatment in a hospital emergency room.  However, many opponents, such as Robert Spitzer, argued that psychiatry was a lax field.  Lauren Slater repeated Rosenhan's study in 2003.  She attempted to be admitted to several psychiatric hospitals.  She failed to be admitted to any of them; however, she was prescribed antipsychotic and antidepressant medication. 

Based on information provided by http://www.holah.karoo.net/rosenhan.htm

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B.F. Skinner's Operant Conditioning

Skinner is most well known for his methodological advances and his laboratory inventions. Skinner used his operant conditioning chamber to introduce free operant techniques.  In his apparatus, rats responded and received food at their own pace. Skinner used this new variable of response rate, which was recorded by a cumulative recorder. This allowed for less laborious and more precise measurements.  Skinner uncovered one of his most important contributions, the intermittent reinforcement schedule, by accident. Initially, one press of the level allowed the release of one pellet of food.  However, the lever often broke and allowed for several presses of the lever to not be followed by food. Skinner found that the animals would continue working for some time before stopping. This technique was used to uncover properties of behavior and to develop different schedules of reinforcement (i.e., fixed interval, fixed ration, variable interval, variable ratio - each administering reinforcement after a different number of times. Skinner's initiation of this area of research has led to a greater understanding of a variety of behaviors, such as  gambling and drug use.  Schedules of reinforcement are also essential for behavioral therapies. 

Superstition in the Pigeon

One of Skinner's most famous experiments examined the way in which superstition developed in pigeons. He placed hungry pigeons in a cage attached to a mechanism that delivered food to the pigeon "at regular intervals with no reference whatsoever to the bird's behavior" (Skinner, 1947).  Pigeons associated chance actions that they performed at the time the food was delivered and repeated these actions because they wanted to receive more food.

"One bird was conditioned to turn counter-clockwise about the cage, making two or three turns between reinforcements. Another repeatedly thrust its head into one of the upper corners of the cage. A third developed a 'tossing' response, as if placing its head beneath an invisible bar and lifting it repeatedly. Two birds developed a pendulum motion of the head and body, in which the head was extended forward and swung from right to left with a sharp movement followed by a somewhat slower return." (Skinner, 1947). 

Skinner suggested that the pigeons believed that they were influencing the automatic mechanism with their "rituals" and that the experiment also shed light on human behavior:

"The experiment might be said to demonstrate a sort of superstition. The bird behaves as if there were a causal relation between its behavior and the presentation of food, although such a relation is lacking. There are many analogies in human behavior. Rituals for changing one's luck at cards are good examples. A few accidental connections between a ritual and favorable consequences suffice to set up and maintain the behavior in spite of many unreinforced instances. The bowler who has released a ball down the alley but continues to behave as if he were controlling it by twisting and turning his arm and shoulder is another case in point. These behaviors have, of course, no real effect upon one's luck or upon a ball half way down an alley, just as in the present case the food would appear as often if the pigeon did nothing -- or, more strictly speaking, did something else" (Skinner, 1947).

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Ivan Pavlov's Classical Conditioning

• Pavlov, a Russian Physiologist studying digestion, noticed that dogs salivated when they were presented with food.  He knew that if was normal for dogs to salivate when they eat because salivation is a reflexive behavior that aids in digestion.  However, Pavlov noticed that the dogs were salivating before they tasted the food.  Pavlov reasoned that this may be happening because the dogs had learned to associate the trainers, who brought them food, with the food itself.  He taught the dogs to salivate to a new stimulus (a bell).  Pavlov surgically altered the location of each dog’s salivary gland to make the secretions of saliva accessible.  He then attached tubes to the relocated salivary glands to measure precisely the amount of saliva produced by the food (the unconditional stimulus which produced the salivating response automatically).  Then he introduced a bell (the neutral stimulus), which is not necessarily related to salivation.  Pavlov measured the amount of saliva the dogs produced when a bell was rung by itself; the amount was negligible.  He then began the conditioning process by ringing the bell and immediately placing food in the dogs’ mouths.  After he did this several times, the dogs salivated in response to the sound of the bell alone.  Pavlov reasoned that the dogs had learned that the bell meant food was coming.  He termed the bell, which elicited salivation as a result of learning, a conditioned stimulus.  A conditioned stimulus is a neutral stimulus that, through repeated association with an unconditioned stimulus, becomes capable of eliciting a conditioned response.  He termed the salivation – the learned response to the sound of the bell – a conditioned response (the response elicited by a conditioned stimulus). 

  Importance of this experiment: Identified the process of classical conditioning, which occurs everyday in the world.  Had a major impact on theories and teachings involving learning and the ways in which responses are acquired.  Helped us realize that when classical conditioning occurs, behavior changes so emphasized the importance of this process.

  In 1903, Pavlov published his results calling this a "conditioned reflex," different from an innate reflex, such as yanking a hand back from a stovetop, in that it had to be learned. Pavlov called this learning process "conditioning." He also found that the conditioned reflex will be repressed, or become extinct, if the conditioned stimulus and the unconditioned stimulus are not paired repeatedly. If the bell rings repeatedly and no food appears, eventually the dog stops salivating at the bell.

        In 1904, Pavlov won the Nobel Prize for his work in Physiology and digestion. His ideas, however, played a large role in the development of the Behaviorist view of psychology, which was introduced by John Watson, in 1914.

Based on information from Gerow (1992)

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Henry Harlow and Emotional Attachment in Rhesus Monkeys

Harlow studied rhesus monkeys.  Harlow placed infant monkeys in cages along with two wire-covered shapes resembling adult monkeys.  One figure was covered with terry cloth; the other was left bare.  Both could be fitted with bottles to provide milk. 

In some cases, the wire mother surrogate had the bottle of milk; in other cases, the terry cloth mother had the bottle.  Harlow found that the infant monkeys clung to the terry-cloth mother surrogates whether or not they provided milk.  He concluded that the wire mother surrogate, even with a bottle of milk, could not provide the comfort that the terry-cloth mother surrogate could provide.