How Psychologists Do Research

1. How Psychologists Do Research Chapter 2

2. How Psychologists Do Research • What makes psychological research scientific? • Research Methods • Descriptive studies • Correlational Studies • Experiments • Evaluating the findings • Keeping the enterprise ethical

3. Making Psychological Research Scientific • Precision • Scepticism • Reliance on empirical evidence • Willingness to make risky predictions • Openness

4. 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.

5. Scepticism • Scientists do not accept ideas on faith or authority. • Scepticism means treating conclusions, both old and new, with caution.

6. 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.

7. Reliance on empirical evidence • A scientist relies on empirical evidence to determine whether a hypothesis is true.

8. Openness • Scientists must be willing to tell others where they got their 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.

9. Descriptive Methods • Methods that yield descriptions of behaviour but not necessarily causal explanations. • Include: • Case studies. • Observational studies. • Psychological tests. • Surveys.

10. 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.

11. Observational Studies • Researchers carefully and systematically observe and record behaviour without interfering with behaviour. • 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.

12. 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.

13. 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 individual’s outcome or score is compared to norms. • To establish norms, the test is 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.

14. 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.

15. Validity • Content validity • The test broadly represents the trait in question. • Criterion validity • The test predicts other measures of same trait in question. • The ability of a test to measure what it was designed to measure.

16. 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.

17. Correlational Studies • Defining a correlational study • Understanding directions of correlations • Reading Scatterplots • Evaluating Correlations

18. 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 - 1.0 to 1.0. • Variables • Characteristics of behaviour or experiences that can be measured or described by a numeric scale; • variables are manipulated and assessed in scientific studies.

19. 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.

20. Scatterplots • Correlations can be represented by scatterplots.

21. 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

22. 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.

23. 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.

24. Control Conditions • In an experiment, a comparison condition in which subjects are 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.

25. 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.

26. Experimenter Effects • Unintended changes in subject’s behaviour due to cues inadvertently given by the experimenter. • Strategies for preventing experimenter effects include single and double-blind studies.

27. Descriptive Statistics • Statistical procedures that organize and summarize research data. • Examples include: • Arithmetic mean • Standard deviation

28. 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 a study’s results occurred merely by chance.

29. 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 a period of time.

30. 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 procedure 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.

31. Ethical Dilemmas • Ethics Considerations in Human Research • Ethics Considerations in Animal Research

32. The Ethics of Studying Humans • Informed consent • Prospective participants should receive enough information to let them decide freely whether to participate. • Freedom to withdraw at any time • Minimize discomfort • Keep data confidential • If deception is necessary, debriefing must occur

33. 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 studied. experimentally with human beings. • To clarify theoretical questions. • To improve human welfare.