Chapter 1: Research Methods

Psychological Research

• Scientific Observation: A systematic empirical investigation that is structured to answer questions about the world

• Research Method: Systematic approach to answering scientific questions

Correlations

• Existence of a consistent, systematic relationship between two events, measures, or variables

Correlation

Perfect positivecorrelation (+1.00)

No relationship (0.00) Perfect negativecorrelation (-1.00)

Scatterplots, showing patterns of correlations

Correlation

Scatterplot of Height and Temperament

55 60 65 70 75 80 85

959085807570656055504540353025

Temperamentscores

Height in inches

Positive Correlation

• Increases in one measure are matched by increases in the other measure

Negative Correlation

• Increases in one measure are matched by decreases in the other measure

Coefficient of Correlation

• Statistical index ranging from -1.00 to +1.00 that indicates direction and degree of correlation– Closer the statistic is to –1.00 or to +1.00,

the stronger the relationship– Correlation of 0.00 demonstrates no

relationship between the variables

Correlation and Causation

• Correlation does not demonstrate causation: Just because two variables are related does NOT mean that one variable causes the other to occur

Naturalistic Observation

• Observing a person or an animal in the environment in which the person or animal lives

Limitations

• Observer Effect: Changes in a subject’s behavior caused by an awareness of being observed

• Observer Bias: Occurs when observers see what they expect to see or record only selected details

• Anthropomorphic Error: Attributing human thoughts, feelings, or motives to animals, especially as a way of explaining their behavior (e.g., “Anya my cat is acting like that because she’s feeling depressed today.”)

The Survey Method

• Using public polling techniques to answer psychological questions

• Representative Sample: Small group that accurately reflects a larger population– Population: Entire group of animals or

people belonging to a particular category (e.g., all married women)

• Courtesy Bias: Problem in research; a tendency to give “polite” or socially desirable answers

The Clinical Method

• Case Study: In-depth focus of all aspects of a single subject

• Natural Clinical Tests: Natural events, such as accidents, that provide psychological data

Experiments

• A formal trial to confirm/disconfirm a hypothesis and to identify cause and effect relationships

The Scientific Method

• Six Basic Elements– Observing– Defining a problem– Proposing a hypothesis (an educated

guess that can be tested)– Gathering evidence/testing the hypothesis– Publishing results– Building a theory

Hypothesis

• Predictable outcome of an experiment or an educated guess about the relationship between variables

• Operational Definition: States exact procedures used to represent a concept. Allows abstract ideas to be tested in real-world terms

Performing an Experiment

• Directly vary a condition you might think affects behavior

• Create two or more groups of subjects, alike in all ways except the condition you are varying

• Record whether varying the condition has any effect on behavior

Variables

• Any condition that can change and that might affect the outcome of an experiment

Independent Variable

• Condition(s) altered by the experimenter; experimenter sets their size, amount, or value. These are suspected causes for behavioral differences

Dependent Variable

• Measures the results of the experiment; Condition is affected by independent variable

Extraneous Variables

• Conditions that a researcher wants to prevent from affecting the outcomes of the experiment (e.g., number of hours slept before the experiment)

Groups

• Experimental Group: The group of subjects that gets the independent variable

• Control Group: The group of subjects that does NOT get the independent variable

• Random Assignment: Subject has an equal chance of being in either the experimental or control group

Placebo

• A fake pill (sugar) or injection (saline)• Placebo Effect: Changes in behavior that

result from expectations that a drug or other treatment will have some effect; the belief that one has taken an active drug

Experiment Types

• Single Blind: Only the subjects have no idea whether they are in the experimental or control group

• Double Blind: The subjects AND the experimenters have no idea whether the subjects are in the control or experimental group– Best type of experiment if properly set up

Experimenter Effects

• Changes in subjects’ behavior caused by the unintended influence of the experimenter’s actions

• Self-Fulfilling Prophecy: A prediction that leads people to act in ways to make the prediction come true

Assessing Experiments

Reliability the extent to which a test yields consistent

results assessed by consistency of scores on:

two halves of the test alternate forms of the test retesting

Validity the extent to which a test measures or

predicts what it is supposed to

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 90 475 710

70

Mode Median Mean

One Family Income per family in thousands of dollars

Assessing Intelligence

Standardization defining meaningful scores by comparison

with the performance of a pretested “standardization group”

Normal Curve the symmetrical bell-shaped curve that

describes the distribution of many physical and psychological attributes

most scores fall near the average, and fewer and fewer scores lie near the extremes

Normal Distribution

The Normal Curve

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

Variance and Standard Deviation

• SD= √variance

• What does this mean?

Critical Thinking

• Ability to analyze, evaluate, compare, critique, and synthesize information

Ethics in Psychology

• Informed consent• Debrief• Protection of Participants• Deception• Confidentiality• Withdrawal from Experiment