1. How Psychologists Do Research
Introducing Psychology
12/5/2018
How Psychologists Do Research
Prepared by Krista Forrest, Ph.D
These slides © 2002 Prentice Hall Psychology Publishing.
Chapter 2
©1999 Prentice Hall
©1999 Prentice Hall

2. How Psychologists Do Research
Introducing Psychology
12/5/2018
How Psychologists Do Research
What makes psychological research scientific?
Research Methods.
Descriptive studies.
Correlational Studies.
Experiments.
Evaluating the findings.
Keeping the enterprise ethical.
©1999 Prentice Hall
©1999 Prentice Hall

3. Making Psychological Research Scientific
Introducing Psychology
12/5/2018
Making Psychological Research Scientific
Precision.
Skepticism.
Reliance on empirical evidence.
Willingness to make risky predictions.
Openness.
©1999 Prentice Hall
©1999 Prentice Hall

4. Introducing Psychology
12/5/2018
Precision
Theories
organized systems of assumptions that purport to explain phenomena and their interrelationships.
Hypotheses
attempt to predict or account for a set of phenomena; specify relationships among variables, and are empirically tested.
Operational definitions
define terms in hypotheses by specifying the operations for observing and measuring the process or phenomenon.
©1999 Prentice Hall
©1999 Prentice Hall

5. Introducing Psychology
12/5/2018
Skepticism
Scientists do not accept ideas on faith or authority.
Skepticism means treating conclusions, both old and new with caution.
©1999 Prentice Hall
©1999 Prentice Hall

6. Willingness to make “risky predictions”
Introducing Psychology
12/5/2018
Willingness to make “risky predictions”
Confirmation bias.
Tendency to look for or pay attention only to information that confirms one’s own belief.
Principle of Falsifiability.
A scientific theory must make predictions that are specific enough to expose the theory to the possibility of disconfirmation; that is, the theory must predict not only what will happen, but also what will not happen.
©1999 Prentice Hall
©1999 Prentice Hall

7. Reliance on empirical evidence
Introducing Psychology
12/5/2018
Reliance on empirical evidence
A scientist relies on empirical evidence to determine whether a hypothesis is true.
©1999 Prentice Hall
©1999 Prentice Hall

8. Introducing Psychology
12/5/2018
Openness
Scientists must be willing to tell others where they got there ideas, how they tested them and what the results were.
Peer review, publishing and replicating research gives science a built in system of checks and balances.
©1999 Prentice Hall
©1999 Prentice Hall

9. Introducing Psychology
12/5/2018
Descriptive Methods
Methods that yield descriptions of behavior but not necessarily causal explanations.
Include:
Case studies.
Observational studies.
Psychological tests.
Surveys.
©1999 Prentice Hall
©1999 Prentice Hall

10. Introducing Psychology
12/5/2018
Case Studies
A detailed description of a particular individual being studied or treated which may be used to formulate broader research hypotheses.
More commonly used by clinicians; occasionally used by researchers.
©1999 Prentice Hall
©1999 Prentice Hall

11. Observational studies
Introducing Psychology
12/5/2018
Observational studies
Researchers carefully and systematically observe and record behavior without interfering with behavior.
Naturalistic observation.
Purpose is to observe how people or animals behave in their natural environment.
Laboratory observation.
Purpose is to observe people or animals in a more controlled setting.
©1999 Prentice Hall
©1999 Prentice Hall

12. Introducing Psychology
12/5/2018
Psychological Tests
Procedures used to measure and evaluate personality traits, emotional states, aptitudes, interests, abilities and values.
Psychological tests can be objective or projective.
Characteristics of a good test include:
Standardization.
Reliability.
Validity.
©1999 Prentice Hall
©1999 Prentice Hall

13. Introducing Psychology
12/5/2018
Standardization
The test is constructed to include uniform procedures for giving and scoring the test.
In order to score tests in a standardized way, an individuals outcome or score is compared to norms.
To establish norms, the test in given to a large group of people who are similar to those for whom the test is intended.
By having norms or established standards of performance, we know who scores low, average or high.
©1999 Prentice Hall
©1999 Prentice Hall

14. Introducing Psychology
12/5/2018
Reliability
When constructing a test, the scores achieved on the test at one time and place should be consistent with the scores achieved at another time and place.
©1999 Prentice Hall
©1999 Prentice Hall

15. Introducing Psychology
12/5/2018
Validity.
The ability of a test to measure what it was designed to measure.
Content validity.
The test broadly represents the trait in question.
Criterion validity.
The test predicts other measures of same trait in question.
©1999 Prentice Hall
©1999 Prentice Hall

16. Introducing Psychology
12/5/2018
Surveys
Questionnaires and interviews that ask people directly about their experiences, attitudes, or opinions.
Should have a representative sample.
A group of subjects, selected from the population for study, which matches the population on important characteristics such as age and sex.
Popular polls and surveys use volunteers rather than representative samples.
Leads to volunteer bias or the belief that volunteers may differ from those who did not volunteer.
©1999 Prentice Hall
©1999 Prentice Hall

17. Correlational Studies
Introducing Psychology
12/5/2018
Correlational Studies
Defining a correlational study.
Understanding directions of correlations.
Reading Scatterplots.
Evaluating Correlations.
©1999 Prentice Hall
©1999 Prentice Hall

18. Introducing Psychology
12/5/2018
Correlational Study
A descriptive study that looks for a consistent relationship between two phenomena.
Correlation.
A statistical measure of how strongly two variables are related to one another.
Correlational coefficients can range from to 1.0.
Variables.
Characteristics of behavior or experiences that can be measured or described by a numeric scale;
variables are manipulated and assessed in scientific studies
©1999 Prentice Hall
©1999 Prentice Hall

19. Direction of Correlations
Introducing Psychology
12/5/2018
Direction of Correlations
Positive correlations
An association between increases in one variable and increases in another, or decreases in one variable and decreases in another.
Negative correlations
An association between increases in one variable and decreases in another.
©1999 Prentice Hall
©1999 Prentice Hall

20. Introducing Psychology
12/5/2018
Scatterplots
Correlations can be represented by scatterplots.
Figure 1.2 from:
Kassin, S. (1998). Psychology, second edition. Upper Saddle River, NJ: Prentice Hall.
©1999 Prentice Hall
©1999 Prentice Hall

21. Explaining Correlations
Introducing Psychology
12/5/2018
Explaining Correlations
Start with 3 variables, (X, Y, & Z) where X and Y are correlated:
X might cause Y
Y might cause X
X might be correlated with Y, which causes Z
Correlations show patterns, not causes
Figure 1.3 from:
Kassin, S. (1998). Psychology, second edition. Upper Saddle River, NJ: Prentice Hall.
©1999 Prentice Hall
©1999 Prentice Hall

22. Introducing Psychology
12/5/2018
An Experiment
A controlled test of a hypothesis in which the researcher manipulates one variable to discover its effect on another.
An experiment includes:
Variables of interest.
Control conditions.
Random assignment.
©1999 Prentice Hall
©1999 Prentice Hall

23. Introducing Psychology
12/5/2018
Variables of Interest
Independent variables are variables the experimenter manipulates.
Dependent variables are variables that the experimenter predicts will be effected by manipulations of the independent variable or variables.
©1999 Prentice Hall
©1999 Prentice Hall

24. Introducing Psychology
12/5/2018
Control Conditions
In an experiment, a comparison condition in which subjects are no exposed to the same treatment as in the experimental condition.
In some experiments, the control group is given a placebo which is an inactive substance or fake treatment.
©1999 Prentice Hall
©1999 Prentice Hall

25. Introducing Psychology
12/5/2018
Random assignment
In order for experiments to have experimental and control groups composed of subjects similar in characteristics that may effect their results, random assignment should be used.
Each individual participating in the study has the same probability as any other of being assigned to a given group.
©1999 Prentice Hall
©1999 Prentice Hall

26. Introducing Psychology
12/5/2018
Experimenter Effects
Unintended changes in subjects behavior due to cues inadvertently given by the experimenter.
Strategies for preventing experimenter effects include single and double-blind studies.
©1999 Prentice Hall
©1999 Prentice Hall

27. Descriptive Statistics
Introducing Psychology
12/5/2018
Descriptive Statistics
Statistical procedures that organize and summarize research data.
Examples include:
Arithmetic mean.
Standard deviation.
©1999 Prentice Hall
©1999 Prentice Hall

28. Inferential Statistics
Introducing Psychology
12/5/2018
Inferential Statistics
Statistical procedures that allow researchers to draw inferences about how statistically meaningful a study’s results are.
The most commonly used inferential statistics are significance tests.
Statistical tests that show how likely that a study’s results occurred merely by chance.
©1999 Prentice Hall
©1999 Prentice Hall

29. Choosing the Best Explanation
Introducing Psychology
12/5/2018
Choosing the Best Explanation
Interpretation of results may depend on how the research was conducted.
Cross-sectional studies involve subjects of different ages being compared at a given time.
Longitudinal studies involve subjects who are periodically reassessed over period of time.
©1999 Prentice Hall
©1999 Prentice Hall

30. Judging the Result’s Importance
Introducing Psychology
12/5/2018
Judging the Result’s Importance
Statistical techniques such as effect size and meta-analysis can help us determine if results are really important.
Effect size is the amount of variance among scores in the study accounted for by the independent variable.
Meta-analysis is a procedures for combining and analyzing data from many studies. It determines how much of the variance in scores across all studies can be explained by a particular variable.
©1999 Prentice Hall
©1999 Prentice Hall

31. Introducing Psychology
12/5/2018
Ethical Dilemmas
Ethics Considerations in Human Research
Ethics Considerations in Animal Research
©1999 Prentice Hall
©1999 Prentice Hall

32. The Ethics of Studying Humans
Introducing Psychology
12/5/2018
The Ethics of Studying Humans
Informed consent.
Prospective participants should receive enough information to let them desice freely whether to participate.
Freedom to withdraw at any time.
Minimize discomfort.
Keep data confidential.
If deception is necessary, debriefing must occur.
©1999 Prentice Hall
©1999 Prentice Hall

33. The Ethics of Studying Animals
Introducing Psychology
12/5/2018
The Ethics of Studying Animals
Animals have always been used in a small percentage of psychological studies.
To conduct basic research.
To discover practical applications.
To study issues that cannot be studies. experimentally with human beings.
To clarify theoretical questions.
To improve human welfare.
©1999 Prentice Hall
©1999 Prentice Hall