Thinking Critically With Psychological Science

The Limits of Intuition and Common Sense After 9/11, it seemed obvious that the U.S. intelligence analysts should have taken advance warnings more seriously. The Limits of Intuition and Common Sense Hindsight Bias- the tendency to believe after learning an outcome, that one would have foreseen it. (I-knew-it-all-along phenomenon) After 9/11, it seemed obvious that the U.S. intelligence analysts should have taken advance warnings more seriously. Overconfidence- the tendency to be more confident than correct Experts in predictions of political, economic, & military situations followed for 5 years learned that those who felt more than 80% confident were right less than 40% of the time.

HINDSIGHT BIAS AND OVERCONFIDENCE OFTEN LEAD US TO OVERESTIMATE OUR INTUITION. BUT SCIENTIFIC INQUIRY, FED BY CURIOUS SKEPTICISM AND BY HUMILITY, CAN HELP US SIFT REALITY FROM ILLUSIONS  

The Scientific Attitude Psychologists persistently ask two questions: What do you mean? How do you know? (Show me the evidence) Critical Thinking – examines assumptions, discerns hidden values, evaluates evidence, and assesses conclusions

The Scientific Method Psychologist create theories Theories produce testable predictions- Hypothesis Hypothesis leads to research and observations Validate theory or refine it

Research Process Figure 1.2 The scientific method Myers: Exploring Psychology, Eighth Edition Copyright © 2011 by Worth Publishers

Theories - Psychologists report their research with precise operational definitions of concepts that allow anyone to replicate their observations. Good theories explain by: Organizing and linking observed facts Implying hypothesis that offer testable predictions and, sometimes, practical applications

Global warming will greatly impact our climate in my lifetime. Indicate the degree to which you agree or disagree with the statement. 5 strongly agree -------------------1 Strongly disagree 2. Indicate the percentage of your classmates that you feel with agree with you.

Correlation Correlation Coefficient - a statistical measure of the extent to which two factors vary together and thus how well either one predicts the other. Positive correlation: indicates a direct relationship, two things increase or decrease together. Negative correlation: indicates an inverse relationship, one thing increases the other decrease.

(positive or negative) Correlation When one trait or behavior accompanies another, we say the two correlate. Indicates strength of relationship (0.00 to 1.00) Correlation coefficient r = + 0.37 OBJECTIVE 8| Describe positive and negative correlations and explain how correlational measures can aid the process of prediction. Correlation Coefficient is a statistical measure of the relationship between two variables. Indicates direction of relationship (positive or negative) Psychology 7e in Modules

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 showing height and temperament in people.

The scatterplot below shows the relationship between height and temperament in people. There is a moderate positive correlation of +0.63.

Positive Correlation- Both variables move in the same direction (up or down) Examples: The more we study, the better our grades (both go up). The less we study, the lower our grades (both go down) Both of these examples are positive correlations  Negative Correlation- One variable moves up and one variable goes down. Example: The more I brush my teeth, the few number of cavities. One goes up the other goes down, this is a negative correlation.

Correlation and Causation Correlation indicates the possibility of a cause-effect relationship, but it does not prove causation. or OBJECTIVE 9| Explain why correlational research fails to provide evidence of cause-effect relationships. Psychology 7e in Modules

Illusory Correlations- the perception of a relationship where none exists. Example: Infertile couples become pregnant after adopting or more babies born on full moons. We easily deceive ourselves by seeing what is not there and may forget they are random instead see them as correlated. Illusory correlations arise from our natural eagerness to make sense of our world

Given random data, we look for order and meaningful patterns. 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. Psychology 7e in Modules

Order in Random Events Given large numbers of random outcomes, a few are likely to express order. Jerry Telfer/ San Francisco Chronicle OBJECTIVE 11| Explain the human tendency to perceive order in random events. Angelo and Maria Gallina won two California lottery games on the same day. Psychology 7e in Modules

Experimentation- Exploring Cause and Effect Like other sciences, experimentation is the backbone of psychology research. Experiments isolate causes and their effects. Experiments enable a researcher to focus on the possible effects of one or more factors by: Manipulating the factors of interest Holding constant (“controlling”) the other factors Unlike correlational studies, an experiment manipulates a factor to determine its effect. OBJECTIVE 12| Explain how experiments help researchers isolate cause and effect. Psychology 7e in Modules

Evaluating Therapies Blind - The subject does not know which treatment group they are in. Double-blind - Neither the researcher nor the participants know whether they receive treatment or a placebo. This allows the placebo effect and creates an experimental condition. Double-blind procedure and random assignment build confidence in research findings. Random Assignment reduces preexisting differences between groups by selecting participants by chance for both experimental & control groups (used for comparison)

Independent Variable An Independent Variable is a factor manipulated by the experimenter. The effect of the independent variable is the focus of the study. For example, when examining the effects of breast feeding upon intelligence, breast feeding is the independent variable. OBJECTIVE 14| Explain the difference between an independent variable and a dependent variable. Psychology 7e in Modules

Dependent Variable A Dependent Variable is a factor that may change in response to an independent variable. In psychology, it is usually a behavior or a mental process. For example, in our study on the effect of breast feeding upon intelligence, intelligence is the dependent variable.

A summary of steps during experimentation.

Comparison Below is a comparison of different research methods.

Describing Data A meaningful description of data is important in research. Misrepresentation may lead to incorrect conclusions. OBJECTIVE 16| Explain how graphs can misrepresent data. Psychology 7e in Modules

Measures of Central Tendency A Skewed Distribution POINT TO REMEMBER: Always note which measure of central tendency is reported. If it’s the MEAN, consider whether a few typical scores could be distorting it.  

Measure of Variation – 2 ways to measure variation Range - The gap between the lowest & highest scores (subtract the smallest value from the largest) Weakness of the range is that you are only computing two data points. Standard Deviation – A computed measure of how much scores vary around the mean score Statistical statement of how likely it is that an obtained result occurred by chance. If we really want to know how students are doing in a class, we need to look at the standard deviation rather than the mean.  

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. OBJECTIVE 18| Explain two measures of variation. Psychology 7e in Modules

Standard Deviation

When is an Observed Difference Reliable? Making Inferences When is an Observed Difference Reliable? Representative samples are better than biased samples. Less variable observations are more reliable than more variable ones. More cases are better than fewer cases. OBJECTIVE 19| Identify three principles for making generalizations from samples. Psychology 7e in Modules

When is a Difference Significant? 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. OBJECTIVE 20| Explain how psychologists decide whether differences are meaningful. Psychology 7e in Modules

APA (American Psychological Association) ETHICAL GUIDELINES Any type of academic research must first propose the study to the ethics board or institutional review board (IRB) at the institution for approval.  Animal Research They must have a clear scientific purpose The research must answer a specific important scientific question Animals chosen must be best-suited to answer the question at hand They must care for and house animals in a humane way They must acquire animal subject legally from accredited companies They must design experimental procedures that employ the least amount of suffering feasible

APA (American Psychological Association) ETHICAL GUIDELINES Human Research No coercion Informed consent Anonymity or confidentiality Cannot be placed at significant mental or physical risk Debriefing