Famous Psychology Experiments

Famous Psychology Experiments

Hypothesis • Scientific method • Hypothesis formulation =

Operationalization • Operationalization: to put an experiment into a form that allows researchers to test the hypothesis • Independent variable: the variable that researchers control • Dependent variable: the variable that researchers are studying • What other questions should the researchers ask? Independent variable Dependent variable

Operationalization (continued) • Confounding variables • Reliability • Validity SCARY = ? What makes a movie scary? How can we tell if a child has had a nightmare? What else might cause nightmares?

Conducting the experiment Experimenting, Recording Results, Conclusion Recording the results Drawing conclusions does cause

Correlation vs. Causation Correlation versus causation: just because two things are related doesn’t mean one thing caused the other Just because happened happened and then doesn’t necessarily mean that caused

Replication and Theory Development • Replication • Theory development = Experiment 1 results = Experiment 2 results = Experiment 3 results = THEORY:

Learning Experiments

Ivan Pavlov • Classical conditioning • Experiments on dogs

Pavlov’s Conclusions Unconditioned Stimulus (UCS) Conditioned Response (CR) Conditioned Stimulus (CS) Unconditioned Response (UCR) because of because of

Continuing Pavlov’s Experiment • Acquisition • Extinction • Spontaneous Recovery • Generalization • Discrimination Other Aspects of Classical Conditioning

John Watson and Rosalie Rayner: Hypothesis, Methodology, Results • Conditioned fear into an infant • After a few tries, Albert was afraid of the rat • Presented a rat immediately followed by a loud noise, startling the baby + = • Albert generalized his fears to other furry objects

Mary Cover Jones • 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

B.F. Skinner and Operant Conditioning • 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

Rates and Types of Reinforcement: Additional Experiments Fixed-ratio: food given after a fixed number of responses Variable-ratio: number of responses required to get food changes each time Fixed-interval: food given after a certain amount of time elapses Variable-interval: amount of time required to get food changes each time

Negative Reinforcement and Punishment Negative reinforcement: Removing an unpleasant stimulus Punishment 1. Introducing an unpleasant stimulus 1. Unpleasant stimulus = 2. Withholding a pleasant stimulus 2. Removal of unpleasant stimulus =

Albert Bandura: Hypothesis • Believed we learn through observation and imitation • Hypothesized that children would imitate aggressive behavior they observed =

Bandura’s Results EFFECT OF OBSERVED CONSEQUENCE ON IMITATIVE BEHAVIOR • Children in the aggression-punished group expressed the fewest aggressive behaviors toward the Bobo dolls • Children in the other two groups expressed an equal number of aggressive behaviors and were more aggressive than children in the aggression-punished group

Bandura’s Experiment, continued • Children promised rewards for imitating the adult in the film • Now, all three groups were equally aggressive • Children had learned the aggressive behavior from the film, but those who saw the adults being punished were less likely to act aggressively + = Viewing aggressive behavior Rewards for imitation Aggressive behavior

Allen and Beatrix Gardner: WashoeHypothesis • Hypothesized that Washoe could learn American Sign Language

Gardner and Gardner: Methodology • Began to train Washoe at the age of 11 months • Training continued for 51 months • Washoe was treated like a deaf human child: lots of toys, routines, plenty of attention • Washoe learned 151 signs during this period

Gardner and Gardner: Results • Washoe learned by: • Having the Gardners placing her hands into the correct sign • Observation and imitation • Washoe was able to use her language skills to express emotions Washoe learned to sign “toothbrush”: move the index finger horizontally back and forth across the mouth to simulate brushing

Gardner and Gardner: Results • Washoe eventually learned nearly 250 signs • Gardners’ hypothesis supported

Elizabeth Loftus and John Palmer: Memory Experiment and Hypothesis • Hypothesis: People will remember a car accident differently if given different language cues (words) about the accident

Loftus and Palmer: Results • People reported the fastest speeds if the researchers had used the word “smashed” in the question • From fastest to slowest reported speeds: smashed, collided, bumped, hit, and contacted groups

Loftus and Palmer: Results • One week later, subjects were asked if they had seen broken glass • 32% of subjects asked the “smashed” question said yes; 14% of subjects asked the “hit” question said yes

Loftus and Palmer: Results and Implications • People remember things differently depending on the language used to describe an event (e.g., “smashed” versus “hit”) • Misinformation effect

Social and Developmental Psychology Experiments The following experiments involve social and/or developmental psychology

HarryHarlow: Hypothesis • Harlow observed that monkeys became very attached to their blankets • Hypothesized that monkeys became attached to sources of nurturing, even if they did not provide food

Harlow’s Methodology and Results • Monkeys separated from their mothers in early infancy and raised in their own cages • Two artificial mothers: one wire and wood, one cloth - cloth mother - wire mother

Harlow’s Methodology and Results • Monkeys preferred the cloth “mother,” even when the wooden one provided food

Harlow’s Legacy • Bond of attachment between parent and child • A secure base from which to explore • The need for security remains with us throughout our lives

Stanley Schachter: Anxiety and Affiliation— Hypothesis and Methodology • Hypothesized increased anxiety makes people want to affiliate with other people • One group expected painful shocks; the other expected very mild shocks • Asked if they wanted to wait alone or with others produces a desire to affiliate with others =

Schachter: Results Expectation of severe shocks • People expecting painful shocks were more likely to want to be in groups • Seeking reassurance and distraction • Later studies: the expectation of pain leads to affiliation, but social anxiety does not made subjects want to wait in groups =

Solomon Asch: Hypothesis and Methodology • Conformity experiment • Subject asked to match one of three lines to a “standard line”; the answer was obvious

Conformity Normative social influence = conformity when we want to avoid rejection or gain acceptance

Milgram: Further Findings • Teachers most likely to obey perceived authority figures from prestigious institutions • More likely to obey instructions when “victim” was at a distance and depersonalized • More likely to obey without role models who defied the authority figure’s orders

Implications of Milgram’s Experiments • Obedience to authority can keep people from following their own morals and standards • Ordinary people can perform cruelties in the process of obeying authority figures in their daily lives • Incrementally increasing the level of shock made it more acceptable for the teachers to continue

Muzafer Sherif: Boy Scout “Robber’s Cave” Experiment, Stage 1 • 22 Boy Scouts divided into two equal groups • Stage 1: lived separately, developed their own rules and leadership • At end of stage 1, began to become aware of the other group

“Robber’s Cave” Experiment, Stage 2 • In stage 2, intense rivalry developed between the two groups • Researchers kept the scores close • Competed for prizes

“Robber’s Cave” Experiment, Stage 3 • Researchers tried to build peace between the two groups • Best way: working together toward common goals

Implications of Sherif’s Study • Peacebuilding worked well; boys ended up getting along • More difficult in other, unstaged conflicts

Altruism • Why didn’t Kitty Genovese’s neighbor’s call the police earlier or help her in some other way before it was too late?

John Darley and Bibb Latané: Hypothesis Hypothesized that people would be less likely to report smoke in a room if others were present

Darley and Latané : Methodology and Results • Placed subjects in rooms that filled with smoke • 75% of subjects reported smoke if they were alone; 10% if they were with confederates of the researchers; 38% if they were with other subjects

Darley and Latané In order for bystanders to help: • People have to notice the incident • People have to interpret the incident as urgent • People have to take responsibility for helping out But… • People are less likely to help if others are around

Darley and Latané • Pluralistic ignorance: people assume someone else will help • Epileptic seizure experiment

Darley and Latané • There are certain circumstances under which people are more likely to help someone in need

Philip Zimbardo:Stanford Prison Experiment Recruitment and Methodology • Wanted to learn about behaviors and feelings of prisoners or guards • Set up a phony prison in a university building • Recruited male college students to participate • Randomly assigned 24 participants to role of either prisoner or guard

Stanford Prison Experiment: Results • Prisoners staged a rebellion on the second day • Guards stepped up their harassment and treated rebellion “ringleaders” differently than the “good” prisoners • Prisoners told they couldn’t leave; many became anxious • Guards increased bullying tactics as they perceived prisoners to be a real threat • Zimbardo and his colleagues adapted to their roles

Famous Psychology Experiments