The goals of research are to describe behaviour, to explain its causes, to predict the circumstances under which certain behaviours may occur again, and to control certain behaviours. Psychologists use various methods or research to accomplish each of these goals.
Naturalistic observation. Researchers need to know how people and animals behave naturally. To obtain such information, a psychologist uses naturalistic observation. The cardinal rule of naturalistic observation is to avoid disturbing the people or animals you are studying by concealing yourself.
Case studies. A case study is an intensive study of a person or group. Most case studies combine long-term observations with diaries, tests, and interviews. Case studies provide a wealth of descriptive material that may generate new hypotheses that researchers can later test.
Surveys. One of the most practical ways to gather data on the attitudes, beliefs, and experiences of large numbers of people is through surveys. A survey may consist of interviews, questionnaires, or a combination of the two.
Longitudinal studies. When conducting longitudinal studies, a psychologist studies the same group of people at regular intervals over a period of years to determine whether their behaviour and/or feelings have changed and if so, how.
Cross-sectional studies. An alternative approach to gathering data is cross-sectional studies. In a cross-sectional study, psychologists organize individuals into groups on the basis of age. Then, these groups are randomly sampled, and the members of each group surveyed, tested, or observed simultaneously.
Correlations and explanations. Sometimes researchers want to examine the relationship between two sets of observations – say, between students’ grades and the number of hours they sleep. Scientists use the word correlation to describe how two sets of data relate to each other. It is important to keep in mind that a correlation describes a relationship between two things. It does not mean that one thing causes the other.
Experiments. Experimentation enables the investigator to control the situation and to decrease the possibility that unnoticed, outside variables will influence the results. Every experiment has a hypothesis, or an educated guess, about the expected outcome. In designing and reporting experiments, psychologists think in terms of variables, conditions and behaviours that are subject to change.
Sometimes an experimenter’s behaviour may unwittingly influence the results. The experimenter may unintentionally raise an eyebrow or nod when posing a question, thus influencing the person being studied. One way to avoid this self-fulfilling prophecy is to use a double-blind technique. Suppose a psychologist wants to study the effects of a particular tranquilizer. She might give the drug to an experimental group and a placebo (a substitute for the drug that has no medical benefits) to a control group. The next step would be to compare their performances on a series of tests. This is a single-blind experiment. The participants are “blind” in the sense that they do not know whether they have received the tranquilizer or the placebo. If neither the participant nor the experimenter knows which participants received the tranquilizer, this is a double-blind experiment.