2Psychological Science How can we differentiate between uniformed opinions and examined conclusions?The science of psychology helps make these examined conclusions, which leads to our understanding of how people feel, think, and act as they do!Psychology 7e in Modules
3Thinking Critically with Psychological Science The Need for Psychological ScienceThe limits of Intuition and Common SenseThe Scientific AttitudeThe Scientific Method
4Thinking Critically … Description The Case Study The Survey Naturalistic Observation
5Thinking Critically … Correlation Correlation and Causation Illusory CorrelationPerceiving Order in Random EventsPsychology 7e in Modules
6Thinking Critically … Experimentation Exploring Cause and Effect Evaluating TherapiesIndependent and Dependent VariablesPsychology 7e in Modules
7Thinking Critically … Statistical Reasoning FAQs About Psychology Describing DataMaking InferencesFAQs About PsychologyPsychology 7e in Modules
8What About Intuition & Common Sense? Many people believe that intuition and common sense are enough to bring forth answers regarding human nature.Why are the answers that flow from the scientific approach more reliable than those based on intuition and common sense?Intuition and common sense may aid queries, but they are not free of error.
9Limits of IntuitionPersonal interviewers may rely too much on their “gut feelings” when meeting with job applicants.Taxi/ Getty ImagesPsychology 7e in Modules
10Overconfidence We tend to think we know more than we do. 82% of U.S. drivers consider themselves to be in the top 30% of their group in terms of safety.81% of new business owners felt they had an excellent chance of their businesses succeeding. When asked about the success of their peers, the answer was only 39%. (Now that's overconfidence!!!)
11Overconfidence Sometimes we think we know more than we actually know. AnagramHow long do you think it would take to unscramble these anagrams?WREATWATERETYRNENTRYPeople said it would take about 10 seconds, yet on average they took about 3 minutes (Goranson, 1978).GRABEBARGE
12The Scientific Attitude The scientific attitude is composed of curiosity (passion for exploration), skepticism (doubting and questioning) and humility (ability to accept responsibility when wrong).Explain how the scientific attitude encourages critical thinking.Psychology 7e in Modules
13Critical thinking does not accept arguments and conclusions blindly. It examines assumptions, discerns hidden values, evaluates evidence and assesses conclusions.Courtesy of the James Randi Education FoundationThe Amazing RandiPsychology 7e in Modules
14Scientific MethodPsychologists, like all scientists, use the scientific method to construct theories that organize, summarize and simplify observations.Describe how psychological theories guide scientific research.Psychology 7e in Modules
15How Do Psychologists Ask & Answer Questions? Psychologists, like all scientists, use the scientific method to construct theories that organize, summarize and simplify observations.How do theories advance psychological science?
16For example, low self-esteem contributes to depression. TheoryA theory is an explanation that integrates principles and organizes and predicts behavior or events.For example, low self-esteem contributes to depression.
17People with low self-esteem are apt to feel more depressed. HypothesisA hypothesis is a testable prediction, often prompted by a theory, to enable us to accept, reject or revise the theory.People with low self-esteem are apt to feel more depressed.
18Research Observations Research would require us to administer tests of self-esteem and depression. Individuals who score low on a self-esteem test and high on a depression test would confirm our hypothesis.
20Case Studies A detailed picture of one or a few subjects. Tells us a great story…but is just descriptive research.Does not even give us correlation data.The ideal case study is John and Kate. Really interesting, but what does it tell us about families in general?
21Survey Method Most common type of study in psychology Measures correlationCheap and fastNeed a good random sampleLow-response rate
22Survey Random Sampling If each member of a population has an equal chance of inclusion into a sample, it is called a random sample (unbiased). If the survey sample is biased, its results are not valid.The fastest way to know about the marble color ratio is to blindly transfer a few into a smaller jar and count them.
23Sampling Identify the population you want to study. The sample must be representative of the population you want to study.GET A RANDOM SAMPLE.Stratified Sampling
24Naturalistic Observation Watch subjects in their natural environment.Do not manipulate the environment.The good is that there is no Hawthorne effect.The bad is that we can never really show cause and effect.
25Correlational MethodCorrelation expresses a relationship between two variable.Does not show causation.As more ice cream is eaten, more people are murdered.Does ice cream cause murder, or murder cause people to eat ice cream?
26Types of Correlation Negative Correlation Positive Correlation The variables go in opposite directions.Positive CorrelationThe variables go in the SAME direction.Studying and grades hopefully has a positive correlation.Heroin use and grades probably has a negative correlation.
27Correlation Coefficient A number that measures the strength of a relationship.Range is from -1 to +1The relationship gets weaker the closer you get to zero.Which is a stronger correlation?-.13 or +.38-.72 or +.59-.91 or +.04
28ScatterplotsPerfect positivecorrelation (+1.00)Scatterplot is a graph comprised of points that are generated by values of two variables. The slope of the points depicts the direction, while the amount of scatter depicts the strength of the relationship.
29ScatterplotsPerfect negativecorrelation (-1.00)No relationship (0.00)The Scatterplot on the left shows a negative correlation, while the one on the right shows no relationship between the two variables.
31ScatterplotThe Scatterplot below shows the relationship between height and temperament in people. There is a moderate positive correlation of
32ExampleAs the graph below (taken from the Church of the Flying Spaghetti Monster website) shows, two things have happened since the early 19th-century: one is that the number of pirates has declined, the other is that global average temperatures have risen.If correlation implied causation, we would be able to infer a connection between these two events. It is not the case, however, that global warming is an effect of the decline in piracy. Neither is the decline in piracy the result of increasing temperatures. Mere correlation does not imply a causal connection.
33Correlation = not Causation Real-World ExampleNestle, the makers of the breakfast cereal Shredded Wheat, once ran an advertising campaign in which the key phrase was this:“People who eat Shredded Wheat tend to have healthy hearts.”This is very carefully phrased. It does not explicitly state that there is any causal connection between eating Shredded Wheat and having a healthy heart, but it invites viewers of the advertisements to make the connection; the implication is there. Whether or not there is any such connection, the mere fact that the two things are correlated does not prove that there is such a connection.
34Correlation and Causation Correlation does not mean causation!or
35Disconfirming evidence Illusory CorrelationThe perception of a relationship where no relationship actually exists. Parents conceive children after adoption.Confirming evidenceDisconfirming evidenceDo notadoptAdoptDo not conceiveConceiveWhat are illusory correlations? Do flip the coin activity.Michael Newman Jr./ Photo Edit
36Given random data, we look for order and meaningful patterns. Order in Random EventsGiven random data, we look for order and meaningful patterns.Your chances of being dealt either of these hands is precisely the same: 1 in 2,598,960.
37Order in Random EventsGiven large numbers of random outcomes, a few are likely to express order.Jerry Telfer/ San Francisco ChronicleAngelo and Maria Gallina won two California lottery games on the same day.
38Exploring Cause and Effect ExperimentationExploring Cause and EffectLike other sciences, experimentation is the backbone of psychological research. Experiments isolate causes and their effects.How do experiments, powered by random assignment, clarify cause and effect?
39Exploring Cause & Effect Many factors influence our behavior. Experiments (1) manipulate factors that interest us, while other factors are kept under (2) control.Effects generated by manipulated factors isolate cause and effect relationships.
40Experimental Method Looking to prove causal relationships. Cause = EffectLaboratory v. Field ExperimentsSmoking causes health issues.
41Experimental vs. Control Groups Experimental GroupThe group exposed to manipulation of the independent variableE.g. receives the DROW-Z’sControl GroupGroup NOT exposed to manipulation of the independent variable; used for COMPARISONE.g. does NOT receive DROW-Z’sMay instead receive a PLACEBORandom assignment to groupsAll subjects have an equal chance of being in either the control group or experimental group!
42Operational Definitions, Etc. What are we measuring and how?How are we defining VARIABLES (IV/DV)?Allows experiment to be replicated by othersE.g. what is a “better” night’s sleep?Sample Size: the bigger the better!What is the difference between groups?Replication?
43Double-blind Procedure Evaluating TherapiesDouble-blind ProcedureIn evaluating drug therapies, patients and experimenter’s assistants should remain unaware of which patients had the real treatment and which patients had the placebo treatment.
44Random AssignmentOnce you have a random sample, randomly assigning them into two groups helps control for confounding variables.Experimental Group v. Control Group.Group Matching
45Independent Variable Whatever is being manipulated in the experiment. Hopefully the independent variable brings about change.If there is a drug in an experiment, the drug is almost always the independent variable.
46Dependent Variable Whatever is being measured in the experiment. It is dependent on the independent variable.The dependent variable would be the effect of the drug.
47Operational Definitions Explain what you mean in your hypothesis.How will the variables be measured in “real life” terms.How you operationalize the variables will tell us if the study is valid and reliable.Let’s say your hypothesis is that chocolate causes violent behavior.What do you mean by chocolate?What do you mean by violent behavior?
48Beware of Confounding Variables The object of an experiment is to prove that A causes B.A confounding variable is anything that could cause change in B, that is not A.If I wanted to prove that smoking causes heart issues, what are some confounding variables?Lifestyle and family history may also effect the heart.
49Hawthorne Effect But even the control group may experience changes. Just the fact that you know you are in an experiment can cause change.Whether the lights were brighter or dimmer, production went up in the Hawthorne electric plant.
50Experimenter Bias Another confounding variable. Not a conscious act. use Double-Blind Procedure to counter this
51Statistics Recording the results from our studies. Must use a common language so we all know what we are talking about.
52Descriptive Statistics Just describes sets of data.You might create a frequency distribution.Frequency polygons or histograms.
53Measures of Central Tendency Mode: The most frequently occurring score in a distribution.Mean: The arithmetic average of scores in a distribution obtained by adding the scores and then dividing by the number of scores that were added together.Median: The middle score in a rank-ordered distribution.
54Central Tendency Mean, Median and Mode. Watch out for extreme scores or outliers.Let’s look at the salaries of the employees at Dunder Mifflen Paper in Scranton:$25,000-Pam$25,000- Kevin$25,000- Angela$100,000- Andy$100,000- Dwight$200,000- Jim$300,000- MichaelThe median salary looks good at $100,000.The mean salary also looks good at about $110,000.But the mode salary is only $25,000.Maybe not the best place to work.
55Normal DistributionIn a normal distribution, the mean, median of the central tendency are equal!i.e.Sample Data Set:1, 1, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 5, 5
56Measures of Central Tendency A Skewed Distribution
57Distributions Outliers skew distributions. If group has one high score, the curve has a positive skew (contains more low scores)If a group has a low outlier, the curve has a negative skew (contains more high scores)
58Measures of VariationRange: The difference between the highest and lowest scores in a distribution.Standard Deviation: A computed measure of how much scores vary around the mean.
59Descriptive Statistics: Measures of Variation Range – the difference between the highest and lowest score in a distributionWhat does it tell you?What DOESN’T it tell you?Standard Deviation – how much do scores vary from the mean in a distribution? (see table 1.4 in text p. 36)Calculate meanCalculate each scores deviates from the meanSquare that differenceAdd the sum of the squaresDivide by the number of scores in the distributionTake square root of thisThe number is equal to the value of ONE standard deviation
61Descriptive Statistics: Measures of Variation So what?In a normal curve, this number reveals the percentage of scores that falls within a particular range68% fall within one standard deviation from the mean96% fall within two standard deviations from the mean99% fall within three standard deviations from the meanWhat must the standard deviation be for this distribution of IQ scores?
62Below is a comparison of different research methods.
63Illusion of ControlThat chance events are subject to personal control is an illusion of control fed by:Illusory Correlation: the perception of a relationship where no relationship actually exists.Regression Toward the Mean: the tendency for extremes of unusual scores or events to regress toward the average.
64Making InferencesA statistical statement of how frequently an obtained result occurred by experimental manipulation or by chance.
65When is an Observed Difference Reliable? Making InferencesWhen is an Observed Difference Reliable?Representative samples are better than biased samples.The less variation in the data, the more reliable (if variability is high in a distribution, the mean becomes less meaningful)More cases are better than fewer cases. (ask 2 friends how they like the class vs. asking 25)What principles can guide our making generalizations from samples and deciding whether differences are significant?
66When is a Difference Significant? Making InferencesWhen is a Difference Significant?When sample averages are reliable and the difference between them is relatively large, we say the difference has statistical significance. It is probably not due to chance variation.For psychologists this difference is measured through alpha level set at 5 percent. If possibility of chance is above 5%, then study loses value.
67Significant Difference? What is the difference between the experiences of the control and the experimental groups?What is the chance that the difference happened due to chance?If it IS a significant difference, how important is that difference (e.g. difference between IQ scores of first- and later-born children is significant, but due to its very small value, it is not important.
69Statistical Significance Findings which have a p value above 5% don’t find those results valuable.p = .01 is more statistically significant than p = .03p = .05p = The probability that the results of the experiment were due to chance variations in the sample groups
70Frequently Asked Questions About Psychology Q1. Can laboratory experiments illuminate everyday life?Ans: Artificial laboratory conditions are created to study behavior in simplistic terms. The goal is to find underlying principles that govern behavior.
71Q2. Does behavior depend on one’s culture and gender? FAQQ2. Does behavior depend on one’s culture and gender?Ans: Even when specific attitudes and behaviors vary across cultures, as they often do, the underlying processes are much the same. Biology determines our sex, and culture further bends the genders. However, in many ways woman and man are similarly human.Ami Vitale/ Getty Images
73Q4. Is it ethical to experiment on people? FAQQ4. Is it ethical to experiment on people?Ans: Yes. Experiments that do not involve any kind of physical or psychological harm beyond normal levels encountered in daily life may be carried out.
75Q6. Is psychology potentially dangerous? FAQQ6. Is psychology potentially dangerous?Ans: It can be, but is not when practiced responsibly. The purpose of psychology is to help humanity with problems such as war, hunger, prejudice, crime, family dysfunction, etc.