Myers’ PSYCHOLOGY (7th Ed) Chapter 1 Thinking Critically with Psychological Science James A. McCubbin, PhD Clemson University Worth Publishers The Need for Psychological Science Psychologists, like all scientists, use the scientific method to construct theories that organize observations and imply testable hypotheses The Need for Psychological Science Hindsight Bias we tend to believe, after learning an outcome, that we would have foreseen it the “I-knew-it-all-along” phenomenon Overconfidence we tend to think we know more than we do The Need for Psychological Science Critical Thinking thinking that does not blindly accept arguments and conclusions examines assumptions discerns hidden values evaluates evidence The Amazing Randi--Skeptic The Need for Psychological Science Theory an explanation using an integrated set of principles that organizes and predicts observations Hypothesis a testable prediction often implied by a theory The Need for Psychological Science The Need for Psychological Science Operational Definition a statement of procedures (operations) used to define research variables Example intelligence may be operationally defined as what an intelligence test measures The Need for Psychological Science Replication repeating the essence of a research study to see whether the basic finding generalizes to other participants and circumstances usually with different participants in different situations Description Psychologists describe behavior using case studies, surveys, and naturalistic observation Description Case Study Psychologists study one or more individuals in great depth in the hope of revealing things true of us all Is language uniquely human? Description Survey technique for ascertaining the self-reported attitudes or behaviors of people usually by questioning a representative, random sample of people Random Sample a sample that fairly represents a population because each member has an equal chance of inclusion Description False Consensus Effect tendency to overestimate the extent to which others share our beliefs and behaviors Population all the cases in a group, from which samples may be drawn for a study Description Description If marbles of two colors are mixed well in the large jar, the fastest way to know their ratio is to blindly transfer a few into a smaller one and count them Description Naturalistic Observation observing and recording behavior in naturally occurring situations without trying to manipulate and control the situation Correlation Correlation Coefficient a statistical measure of the extent to which two factors vary together, and thus how well either factor predicts the other Indicates direction of relationship (positive or negative) Correlation coefficient r = +.37 Indicates strength of relationship (0.00 to 1.00) Correlation Scatterplot a graphed cluster of dots, each of which represents the values of two variables the slope of the points suggests the direction of the relationship the amount of scatter suggests the strength of the correlation little scatter indicates high correlation also called a scattergram or scatter diagram Correlation Perfect positive correlation (+1.00) No relationship (0.00) Perfect negative correlation (-1.00) Scatterplots, showing patterns of correlations Correlation Height and Temperament of 20 Men Height in Subject Inches Temperament Height in Subject Inches Temperament 1 2 3 4 5 6 7 8 9 10 80 63 61 79 74 69 62 75 77 60 75 66 60 90 60 42 42 60 81 39 11 12 13 14 15 16 17 18 19 20 64 76 71 66 73 70 63 71 68 70 48 69 72 57 63 75 30 57 84 39 Correlation 95 Temperament 90 scores 85 80 75 70 65 60 55 50 45 40 35 30 25 55 60 65 70 Height in inches 75 80 85 Scatterplot of Height and Temperament Correlation Three Possible Cause-Effect Relationships (1) Low self-esteem could cause Depression or (2) Depression could cause Low self-esteem or Low self-esteem (3) Distressing events or biological predisposition could cause and Depression Illusory Correlation Illusory Correlation the perception of a relationship where none exists Adopt Conceive confirming evidence Do not conceive disconfirming evidence Do not adopt disconfirming evidence confirming evidence Two Random Sequences Your chances of being dealt either of these hands is precisely the same: 1 in 2,598,960. Experimentation Experiment an investigator manipulates one or more factors (independent variables) to observe their effect on some behavior or mental process (the dependent variable) by random assignment of participants the experiment controls other relevant factors Experimentation Placebo an inert substance or condition that may be administered instead of a presumed active agent, such as a drug, to see if it triggers the effects believed to characterize the active agent Double-blind Procedure both the research participants and the research staff are ignorant (blind) about whether the research participants have received the treatment or a placebo commonly used in drug-evaluation studies Experimentation Experimental Condition the condition of an experiment that exposes participants to the treatment, that is, to one version of the independent variable Control Condition the condition of an experiment that contrasts with the experimental treatment serves as a comparison for evaluating the effect of the treatment Experimentation Random Assignment assigning participants to experimental and control conditions by chance minimizes pre-existing differences between those assigned to the different groups Experimentation Independent Variable the experimental factor that is manipulated the variable whose effect is being studied Dependent Variable the experimental factor that may change in response to manipulations of the independent variable in psychology it is usually a behavior or mental process Experimentation Research Strategies Subliminal tape content Self-esteem Memory Tape label Self-esteem Design of the subliminal tapes experiment Memory Statistical Reasoning Percentage still functioning after 10 years 100% 99 98 97 96 95 Our Brand Brand Brand Brand X Y Z Brand of truck Statistical Reasoning Percentage still functioning after 10 years 100% 90 80 70 60 50 40 30 20 10 0 Our Brand Brand X Brand Brand Y Z Brand of truck Statistical Reasoning Mode the most frequently occurring score in a distribution Mean the arithmetic average of a distribution obtained by adding the scores and then dividing by the number of scores Median the middle score in a distribution half the scores are above it and half are below it Statistical Reasoning A Skewed Distribution 15 20 25 30 35 40 45 50 70 Mode Median Mean 90 475 710 One Family Income per family in thousands of dollars Statistical Reasoning 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 Statistical Significance a statistical statement of how likely it is that an obtained result occurred by chance Frequently Asked Questions about Psychology Can laboratory experiments illuminate everyday life? Frequently Asked Questions about Psychology Does behavior depend on ones culture? Culture--the enduring behaviors, ideas, attitudes, and traditions shared by a large group of people and transmitted from one generation to the next Frequently Asked Questions about Psychology Does behavior vary with gender? Frequently Asked Questions about Psychology Why do psychologists study animals? Is it ethical to experiment on animals? Is it ethical to experiment on people? Frequently Asked Questions about Psychology Is psychology free of value judgments? Frequently Asked Questions about Psychology Is psychology potentially dangerous?