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Thinking Critically With Psychological Science Psychological Science 1. How can we differentiate between uniformed opinions and examined conclusions? 2. The science of psychology helps make these examined conclusions, which leads to our understanding of how people feel, think, and act as they do! 2 Thinking Critically with Psychological Science The Need for Psychological Science The limits of Intuition and Common Sense The Scientific Attitude The Scientific Method 3 Thinking Critically … Description The Case Study The Survey Naturalistic Observation 4 Thinking Critically … Correlation Correlation and Causation Illusory Correlation Perceiving Order in Random Events 5 Thinking Critically … Experimentation Exploring Cause and Effect Evaluating Therapies Independent and Dependent Variables 6 Thinking Critically … Statistical Reasoning Describing Data Making Inferences FAQs About Psychology 7 What About Intuition & Common Sense? Many people believe that intuition and common sense are enough to bring forth answers regarding human nature. Intuition and common sense may aid queries, but they are not free of error. Limits of Intuition Personal interviewers may rely too much on their “gut feelings” when meeting with job applicants. Taxi/ Getty Images 9 Overconfidence • 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!!!) Overconfidence Sometimes we think we know more than we actually know. How long do you think it would take to unscramble these anagrams? People said it would take about 10 seconds, yet on average they took about 3 minutes (Goranson, 1978). Anagram WREAT WATER ETYRN ENTRY GRABE BARGE The Scientific Attitude The scientific attitude is composed of curiosity (passion for exploration), skepticism (doubting and questioning) and humility (ability to accept responsibility when wrong). 12 Critical Thinking Courtesy of the James Randi Education Foundation Critical thinking does not accept arguments and conclusions blindly. It examines assumptions, discerns hidden values, evaluates evidence and assesses conclusions. The Amazing Randi 13 Scientific Method Psychologists, like all scientists, use the scientific method to construct theories that organize, summarize and simplify observations. 14 How Do Psychologists Ask & Answer Questions? Psychologists, like all scientists, use the scientific method to construct theories that organize, summarize and simplify observations. Theory A theory is an explanation that integrates principles and organizes and predicts behavior or events. For example, low self-esteem contributes to depression. Hypothesis A 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. Research 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. Research Process Case 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? Survey Method •Most common type of study in psychology •Measures correlation •Cheap and fast •Need a good random sample •Low-response rate Survey 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. Sampling • 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 Naturalistic 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. Correlational Method • Correlation 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? Types of Correlation Positive Correlation • The variables go in the SAME direction. Negative Correlation • The variables go in opposite directions. Studying and grades hopefully has a positive correlation. Heroin use and grades probably has a negative correlation. Correlation Coefficient • A number that measures the strength of a relationship. • Range is from -1 to +1 • The relationship gets weaker the closer you get to zero. Which is a stronger correlation? • -.13 or +.38 • -.72 or +.59 • -.91 or +.04 Scatterplots Perfect positive correlation (+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. Scatterplots Perfect negative correlation (-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. Data Data showing height and temperament in people. Scatterplot The Scatterplot below shows the relationship between height and temperament in people. There is a moderate positive correlation of +0.63. • • Example As 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. Correlation = not Causation • • • • Real-World Example Nestle, 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. Correlation and Causation Correlation does not mean causation! or Illusory Correlation The perception of a relationship where no relationship actually exists. Parents conceive children after adoption. Do not conceive Confirming evidence Disconfirming evidence Do not Disconfirming evidence adopt Confirming evidence Michael Newman Jr./ Photo Edit Adopt Conceive Order in Random Events Given 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. Order in Random Events Given large numbers of random outcomes, a few are likely to express order. Jerry Telfer/ San Francisco Chronicle Angelo and Maria Gallina won two California lottery games on the same day. Experimentation Exploring Cause and Effect Like other sciences, experimentation is the backbone of psychological research. Experiments isolate causes and their effects. Exploring 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. Experimental Method • Looking to prove causal relationships. • Cause = Effect • Laboratory v. Field Experiments Smoking causes health issues. Experimental vs. Control Groups • Experimental Group – The group exposed to manipulation of the independent variable – E.g. receives the DROW-Z’s • Control Group – Group NOT exposed to manipulation of the independent variable; used for COMPARISON – E.g. does NOT receive DROW-Z’s – May instead receive a PLACEBO • Random assignment to groups – All subjects have an equal chance of being in either the control group or experimental group! Operational Definitions, Etc. • Operational Definitions – What are we measuring and how? – How are we defining VARIABLES (IV/DV)? – Allows experiment to be replicated by others – E.g. what is a “better” night’s sleep? • Sample Size: the bigger the better! • What is the difference between groups? • Replication? Evaluating Therapies Double-blind Procedure In 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. Random Assignment • Once you have a random sample, randomly assigning them into two groups helps control for confounding variables. • Experimental Group v. Control Group. • Group Matching Independent 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. Dependent 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. Operational 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? Beware of Confounding Variables If I wanted to prove that smoking causes heart issues, what are some 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. Lifestyle and family history may also effect the heart. Hawthorne 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. Experimenter Bias • Another confounding variable. • Not a conscious act. • use Double-Blind Procedure to counter this Statistics • Recording the results from our studies. • Must use a common language so we all know what we are talking about. Descriptive Statistics • Just describes sets of data. • You might create a frequency distribution. • Frequency polygons or histograms. Measures 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. Central 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- Michael The 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. Normal Distribution In 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 Measures of Central Tendency A Skewed Distribution Distributions • 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) Measures of Variation Range: The difference between the highest and lowest scores in a distribution. Standard Deviation: A computed measure of how much scores vary around the mean. Descriptive Statistics: Measures of Variation • Range – the difference between the highest and lowest score in a distribution – What 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) 1. Calculate mean 2. Calculate each scores deviates from the mean 3. Square that difference 4. Add the sum of the squares 5. Divide by the number of scores in the distribution 6. Take square root of this 7. The number is equal to the value of ONE standard deviation Standard Deviation Descriptive Statistics: Measures of Variation • So what? – In a normal curve, this number reveals the percentage of scores that falls within a particular range – 68% fall within one standard deviation from the mean – 96% fall within two standard deviations from the mean – 99% fall within three standard deviations from the mean What must the standard deviation be for this distribution of IQ scores? Comparison Below is a comparison of different research methods. Illusion of Control That chance events are subject to personal control is an illusion of control fed by: 1. Illusory Correlation: the perception of a relationship where no relationship actually exists. 2. Regression Toward the Mean: the tendency for extremes of unusual scores or events to regress toward the average. Making Inferences A statistical statement of how frequently an obtained result occurred by experimental manipulation or by chance. Making Inferences When is an Observed Difference Reliable? 1. Representative samples are better than biased samples. 2. The less variation in the data, the more reliable (if variability is high in a distribution, the mean becomes less meaningful) 3. More cases are better than fewer cases. (ask 2 friends how they like the class vs. asking 25) Making Inferences When 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. Significant 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. Normal Distribution Statistical Significance • p = .05 • p = The probability that the results of the experiment were due to chance variations in the sample groups • Findings which have a p value above 5% don’t find those results valuable. • p = .01 is more statistically significant than p = .03 Frequently 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. FAQ Q2. 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 FAQ Q3. Why do psychologists study animals, and is it ethical to experiment on animals? Ans: Studying animals gives us the understanding of many behaviors that may have common biology across animals and humans. From animal studies, we have gained insights to devastating and fatal diseases. All researchers who deal with animal research are required to follow ethical guidelines in caring for these animals. D. Shapiro, © Wildlife Conservation Society FAQ Q4. 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. FAQ Q5. Is psychology free of value judgments? Ans: No. Psychology emerges from people who subscribe to a set of values and judgments. © Roger Shepard FAQ Q6. 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.