DIFFERENCES BETWEEN EXPERIMENTS IN THE LAB AND IN NATURAL SETTINGS

Experiments that are conducted outside the labo- ratory are likely to differ in a number of significant ways from those done in the laboratory. Not every experiment in a natural setting differs from labora- tory experiments in all of these ways, of course. But if you are thinking of doing research in a natu- ral setting, we urge you to consider the following critical issues.
Control

More than anything else, the scientist is con- cerned with control. Only by controlling those fac- tors that are assumed to influence a phenomenon can we make a decision about what caused it. For instance, random assignment of participants to conditions of an experiment is a method of con- trol used to balance individual differences across conditions. Or, researchers can hold other factors constant that are likely to influence a phenom- enon. In a natural setting, a researcher may not always have the same degree of control over as- signment of participants or over the conditions of an experiment that she or he would have in a labo- ratory. A researcher may even be asked to evalu- ate whether an intervention was effective without having been involved in the planning or conduct of the “experiment.” This kind of “after-the-fact” evaluation is especially difficult because those conducting the study may not have considered important factors in the planning and execution of the intervention.
External validity
The high degree of control in the “artificial” environ- ment of the laboratory that increases the internal validity of research often decreases the external validity of the findings. Experiments in natural set- tings may therefore need to be done in order to establish the external validity of a laboratory find- ing. When an experiment is done primarily to test a specific psychological theory, however, the ex- ternal validity of a laboratory finding may not be all that important (e.g., Mook, 1983). In contrast, the external validity of research done in natural set- tings is often very important. This is especially true
when social experimentation serves as the basis for large-scale social changes, such as trying out new ways to curb drunk driving or new procedures for registering voters. Will the results of a program that is judged to be beneficial for curbing drunk driving in a midwestern state generalize to states in other areas of the country? These are, of course, questions about the external validity of research findings.
Goals
Experimentation in natural settings often has dif- ferent goals from those of laboratory research (see Chapter 2). Laboratory research frequently represents basic research with the single goal of understanding a phenomenon—of determin- ing how “nature” works. It may be done to gain knowledge merely for knowledge’s sake. Applied research is also directed toward discovering the reasons for a phenomenon, but it is likely to be done only when knowing the reasons for an event will lead to changes that will improve the pres- ent situation. Experimentation in natural settings, therefore, is more likely than laboratory research to have practical goals.

Consequences
Sometimes experiments are conducted that have far-reaching impact on communities and society, affecting large numbers of people. The Head Start program for disadvantaged children and the Sesame Street television show were so- cial experiments designed to improve the educa- tion of hundreds of thousands of children across the nation (see Figure 10.1). Social experiments are also carried out on a smaller scale in natural settings such as in local schools or businesses. Clearly, society’s “experiments” are likely to have consequences of greater immediate impact than those of laboratory research. By contrast, the im- mediate consequences of a laboratory experiment can be substantial, but they are much more likely to be minimal. They may directly affect only the lives of a few researchers and of those relatively few partici- pants recruited to participate.