The Scientific Method. Myers PSYCHOLOGY. Chapter 1. Thinking Critically with. Psychological Science

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1 Myers PSYCHOLOGY Chapter 1 Thinking Critically with Psychological C1:1 Outline of Chapter 1 - The Need for Psychological The Scientific Attitude Naturalistic Observation - and Causation Illusory s C1:2 Independent and - Frequently Asked Questions About Psychology Limits of Intuition and Common Sense - Number of recent books by psychologists and others with titles such as: How we know what isn t so Why people believe weird things How mistakes of reason rule our minds - Partial list of some cognitive problems in right panel - Myers talks about a number of these here and elsewhere in book - People want them to be true C1:3 Failure to seek or use negative evidence Selective memory for positive results Inadequate thinking about alternatives - Use of weak evidence Overconfidence in intuition Excessive reliance on authority and tradition Overconfidence in anecdotes and case studies - Statistical/Research considerations Coincidence or chance Regression toward the mean Illusory correlations Placebo effect - Need for certainty - Craving the mysterious - Hindsight or after the fact reasoning - Circular reasoning C1:4 Limits of Intuition and Common Sense - Hindsight Bias: Tendency to believe, after learning outcome, that one could foresee it I-knew-it-all-along phenomenon Study of Hindsight Bias - Half handouts read: Researchers have found that people with HIGH self-confidence are more susceptible to flattery than those with low self-confidence. - Other half read: Researchers have found that people with LOW self-confidence are more susceptible to flattery than those with high self-confidence. - Both groups thought that they would have predicted outcome of study C1:5 The Scientific Attitude - Scientific Attitude Curiosity: wonder how world, including people, really works Skepticism: require rigorous evidence for truth claims Humility: willingness to reject our false beliefs given sufficient evidence - Critical Thinking Examines assumptions Discerns hidden values Evaluates evidence Entertains alternative explanations The Scientific Method C1:6 1

2 Scientific Method C1:7 - Theory Explanation using integrated set of principles that organizes and predicts observations - Hypothesis Testable prediction Often implied by (derived from) theory - Examples Dissonance theory: financial incentive and attitude toward boring task Inhibition and Childhood Development: Simon Says Scientific Method - Operational Definition Statement of procedures (operations) used to define research variables Example: Intelligence can be operationally defined as what intelligence test measures - Replication Repeating essence of research study to see whether basic finding generalizes to other subjects and circumstances Usually with different subjects in different situations and even cultures C1:8 Outline of Chapter 1 - The Need for Psychological The Scientific Attitude Naturalistic Observation - and Causation Illusory s C1:9 Independent and - Frequently Asked Questions About Psychology Description C1:10 - Psychologists describe behavior using Case Studies, Naturalistic Observation, and Surveys - Case Study Psychologists study one or more individuals in great depth in hope of revealing things true of us all (e.g., is language unique to humans) Dangers! e.g., smoker who lives to 100+ Case Study: Phineas Gage - Explosion drove tamping rod through skull and frontal lobes of brain - Phineas survived and initially seemed largely unaffected by incident - But, personality changed markedly: No longer Phineas Before accident: capable and efficient foreman, well-balanced C1:11 mind, shrewd smart business man After: fitful, irreverent, and grossly profane; little deference for his fellows; impatient and obstinate, yet capricious and vacillating C1:12 Description - Naturalistic Observation Observe and record behavior in naturally occurring situations without trying to manipulate and control situation 2

3 Description - Survey Technique to determine self-reported attitudes or behaviors of people C1:13 Wording s - Amount of TV viewing people report influenced by whether alternatives indicate low or high number of hours Representative, random sample of people! (Truman above) - False Consensus : Tendency to overestimate extent to which others share our beliefs and behaviors - Population: all cases in group, from which samples drawn for study - Random Sample: fairly represents population, each member has equal chance of inclusion (+1) C1:14 - Random Sampling If marbles of two colors are mixed well in large jar, the fastest way to know their ratio is to blindly transfer a few into a smaller one and count them Description C1:15 C1:16 Canadian Attitudes Toward Abortion C1:17 C1:18 3

4 Outline of Chapter 1 C1:19 - The Need for Psychological The Scientific Attitude Independent and Naturalistic Observation - Frequently Asked Questions - About Psychology and Causation Illusory s C1:20 - Given scores on two or more variables (e.g., IQ and GPA, years married and marital satisfaction, number of bystanders and likelihood of helping,., we can ask whether there is any relationship between pairs of scores Does GPA increase or decrease with IQ? Does satisfaction increase or decrease with years of marriage? Does helping increase or decrease with number of bystanders? - These questions concern s: consider height and temperament measures on next slide (+1) Data showing height and temperament in 20 men C1:21 C1:22 - Scatterplot Graphed cluster of dots, each of which represents values of two variables Slope of points suggests direction of relationship Amount of scatter suggests strength of correlation - Little scatter indicates high correlation Also called scattergram or scatter diagram (+1, +3) C1:23 - Coefficient Statistical measure of extent to which two factors vary together and thus how well either factor predicts other Varies from 1 to +1, with 0 indicating no relationship (+1) C1:24 Indicates strength of relationship (0.00 to 1.00) coefficient r = Scatterplot of Height and Temperament Indicates direction of relationship (positive or negative) 4

5 C1:25 C1:26 and Causation - does not imply cause-effect relation Three Possible Cause- Relationships Perfect positive correlation (+1.00) No relationship (0.00) Perfect negative correlation (-1.00) and Causation - Records for city of Copenhagen for 12 years following WW II show strong positive correlation between number of babies born in city and number of storks nesting in city - Are more storks needed to deliver more babies? C1:27 and Causation C1:28 - Does negative correlation (see graph) prove that computer and video game sales decrease violence? and Causation - Li (1975): use of contraception in Taiwan strongly correlated with number of electrical appliances (toasters, fans, ) in home - Would giving people free toasters reduce pregnancy rate? C1:29 and Causation C1:30 - Pellegra: disease that once killed many poor southerners; 10,000 people died in USA in 1915 alone - in South between pellegra and presence of indoor sanitation - Dominant explanation became germ theory - Would improved sanitary conditions / practices reduce incidence of pellegra? - More on pellegra shortly! 5

6 - Illusory Perception of relationship where none exists Adopt Do not adopt Conceive Confirming evidence Disconfirming evidence C1:31 Do not conceive Disconfirming evidence Confirming evidence C1:32 Perceiving Order in Random Looking for Order in Random Sequences If someone flipped coin six times, which of following sequences of heads (H) and tails (T) is most likely? 1. HHHTTT 2. HTTHTH 3. HHHHHH Chance of being dealt hands above is exactly the same (1/ 2,598,160) Outline of Chapter 1 - The Need for Psychological The Scientific Attitude Naturalistic Observation - and Causation Illusory s C1:33 Independent and - Frequently Asked Questions About Psychology Experimentation C1:34 - Exploring Cause and Experiment: Investigator manipulates one or more factors (independent variables) to observe effect (dependent variable) Independent Variable - Experimental factor that is manipulated - Variable whose effect is being studied Dependent Variable - Experimental factor that may change in response to manipulations of independent variable - In psychology it is usually a behavior or mental process Ideally, other factors controlled (constant, equal) Evaluating Therapies - Experimental Design Experimental Condition: Condition of experiment that exposes participants to treatment, that is, to one version of independent variable Control Condition: Condition of experiment that contrasts with experimental treatment. Serves as comparison for evaluating effect of treatment. C1:35 - Placebo Inert substance or condition that may be administered instead of presumed active agent, such as drug, to see if it triggers effects believed caused by active agent - Double-blind Procedure Both subject and research staff ignorant (blind) about whether subject received treatment or placebo Commonly used in drug-evaluation studies - Placebo effects robust in many psychological domains (+1) C1:36 6

7 C1:37 - Random Assignment Assign participants to experimental and control conditions by chance Minimizes chance of pre-existing C1:38 differences between those assigned to different groups Controls other relevant factors - Lanarkshire milk experiment in 1930s England Initial random assignment, BUT teachers then allowed to switch some children. Led to bias. Independent and Dependent Variables C1:39 Experimentation C1:40 Tape label Self-esteem Subliminal tape content Self-esteem Memory - Design of a subliminal tapes experiment Memory Experiments and Pellegra C1:41 - Goldberger Did not think that germ theory was correct or that sanitation was causal factor In institutions he observed that inmates got pellegra, but not staff Pellegra dietary rather than infectious disease? - Series of simple but compelling experiments Better diet cured and prevented disease 11 inmates volunteered for corn diet; 6 became ill Filth parties : Goldberger, wife, and assistants injected with blood from affected people and later ate scrapings from scabs, urine, and runny feces of ill; did not get ill Experiments in Psychology - Harlow: which is more important in motherinfant bond, nutrition or physical comfort? C1:42 7

8 Experiments in Psychology - Bandura: Does viewing violence increase later acts of violence by children? C1:43 Experiments in Psychology - Loftus: Do leading questions influence eyewitness memory for events? C1:44 Experiments in Psychology C1:45 Research Strategies C1:46 - Asch: will people conform to group opinion, even if clearly wrong? Outline of Chapter 1 - The Need for Psychological The Scientific Attitude Naturalistic Observation - and Causation Illusory s C1:47 Independent and - Frequently Asked Questions About Psychology Describing Data: Graphs C1:48 8

9 Frequency Distribution C1:49 - Frequency with which each possible score occurs e.g., below 5 families have income of $30,000 This is example of a Skewed (non-symmetrical) distribution C1:52 Properties of Distributions - Statistics are numbers that describe properties of distributions of scores - Two primary properties Central Tendency: where along horizontal axis set of scores tends to fall (low, medium, high Variability: how spread out scores are from center - Central Tendency Mode: Most frequently occurring score ($20,000) Median: Middle score in distribution ($30,000) - Half scores above median and half below Mean: Arithmetic average ($70,000) - Add scores and divide by number of scores - Variation (or Variability) Range: difference between highest and lowest scores Standard Deviation: measures how much scores vary around mean - Calculation illustrated in Table 1.4 (+1): two classes with identical means but different SDs C1:53 C1:54 C1:55 Making Inferences - Statistics calculated on Samples, but infer conclusions about Populations - Statistical Significance Statistical statement of how likely (probable) it is that obtained result occurred by chance If significant, result is more likely to be true of entire population (not just sample) than if not significant e.g., was improvement in treatment group sufficiently greater than control group that it would be unlikely to have occurred by chance (p less than.05 or 5/100)? C1:56 - Factors that influence significance or reliability of findings (other things being equal) Representative samples better than Biased samples Less variable observations more reliable than More variable observations More cases in sample are better than Fewer cases - Be very cautious about inferences based on small, biased, and variable sets of scores 9

10 Outline of Chapter 1 - The Need for Psychological The Scientific Attitude Naturalistic Observation - and Causation Illusory s Independent and - Frequently Asked Questions About Psychology C1:57 Frequently Asked Questions 1. Can laboratory experiments illuminate everyday life? 2. Does behavior depend on one s culture? C1:58 Culture: enduring behaviors, ideas, attitudes, and traditions shared by large group of people and transmitted from one generation to next Frequently Asked Questions C1:59 Frequently Asked Questions C1:60 3. Does behavior vary with gender? 5. Is it ethical to experiment on animals? 4. Why do psychologists study animals? 6. Is it ethical to experiment on people? C1:61 Frequently Asked Questions 7. Is psychology free of value judgments? Frequently Asked Questions 8. Is psychology potentially dangerous? C1:62 - Much controversy currently around possible participation of psychologists in questioning of imprisoned terrorists, especially possibility that they might use psychological knowledge for harm, rather than benefit of people 10