Experimental Research

If researchers intend to make cause‐and‐effect statements, they typically use experimental research, which is usually, but not always, conducted in a laboratory. The laboratory environment allows the experimenter to make controlled observations using the steps of the scientific method.

Formulation of the problem. In formulating the problem in a psychological study, the researcher raises a question about behavior or mental processes. Perhaps the investigator wonders whether certain environmental conditions improve or adversely affect motor performance. The investigator might operationally define the environmental condition of interest as “background music” and the motor performance as “typing speed.” Next, the investigator proposes an answer to the research question (“What is the relationship between typing speed and background noise?), an answer called a hypothesis. A hypothesis postulates a relationship between two variables, an independent variable (that which the experimenter manipulates—in this case, the background music) and a dependent variable (that which changes as a consequence of manipulation of the independent variable—in this case, the typing speed). The experimenter hypothesizes that “an increase in loudness of background music will produce a decrease in typing speed.”

Design of the study. Once the problem to be investigated has been selected, the experimenter must decide how to conduct the study. Much of the information used in psychology and other sciences has been collected in laboratory situations because they facilitate the use of many controls during data collection. In the background music/typing speed study, for example, all subjects would be taken to a laboratory for testing and would use the same typewriters to take the typing tests. The experimenter would have to decide whether to use two groups of subjects with comparable typing skills and expose one group to a music loudness level different from that used with the other (a between‐subjects design) or sequentially expose the same subjects to music of two loudness levels (a within‐subjects design). Each procedure has advantages and disadvantages. (Decisions concerning the procedure to use depend on many factors, which are studied in experimental design courses.)

Collection of data. The experimenter collects data (typing speed at different loudness levels) to test the hypothesis according to the selected experimental design.

Analysis of data. The data are analyzed by appropriate statistical methods. In this case, mean scores of the two sets of typing speed/loudness level data would be compared to see if differences are significant or could be due to chance.

Conclusions drawn from the data. Based on analysis of data, conclusions may be drawn about the hypothesized relationship between the independent and dependent variables. The hypothesis, that “an increase in loudness of background music will produce a decrease in typing speed,” may be supported by the data (the increase in loudness of background music—manipulation of the independent variable— did produce a decrease in typing speed—the dependent variable) or may not be supported by the data (the increase in loudness did not produce a decrease in typing speed).

Reporting results. The process used in and the results obtained from the study are gathered and written. If the study results are of sufficient significance, they may be published in a scientific journal (as mentioned above, allowing the study to be replicated or refuted by another researcher) and may eventually be used quite pragmatically. For example, if a study determines that background music (or perhaps background music of a certain loudness level) improves typing performance, certain employers would be likely to make use of the findings in their businesses. Scientific knowledge in all sciences grows as a result of information collected through the scientific method.

Basic and applied research. The goal of basic research in psychology is primarily to describe and understand behavior and mental processes without immediate concern for a practical use. Such research, usually conducted in university settings, is essential to the expansion of scientific knowledge and the development of theories. Applied research uses scientific studies to solve problems of everyday life.

In reality, there is crossover between the two types of research. For example, after conducting basic science experiments to delineate the neural mechanisms associated with Parkinson's disease, the same researcher might then undertake an applied project by continuing the study to find a therapeutic drug that alters the functioning of identified neural mechanisms of the disorder and thereby relieves the symptoms.