Excerpts from: External Validity is More Than Skin Deep: Some Answers to Criticisms of Laboratory Experiments Leonard Berkowitz and Edward Donnerstein March 1982, American Psychologist, 245-257

This mini-lecture is intended to expand our understanding of the philosophical issues surrounding internal and external validity.

"Most criticisms of laboratory experiments in psychology fault them for their 'artificiality' or, in more sophisticated terms, for their lack of external validity. As everyone knows, the great majority of psychology's experiments employ a very limited sample of participants (typically, college students) placed in fairly unique settings (a university laboratory) and usually working on tasks bearing little resemblance to their everyday activities. Given the unrepresentativeness of these subjects and situations, the critics ask, how can the findings be generalized to the 'real world' of ordinary people engaged in their daily lives? In one form or another, this question has been raised by professionals and outsiders, by trained social scientists, and by persons having only slight acquaintance with the field. There can be no easy answer. Anyone familiar with the longstanding debate that has swirled about the topic of experimental validity is well aware of the complex issues bound up in this matter. . . ."

"We will argue, first, that the logic of an experiment does not require that the settings and subjects represent real-world conditions and, second, that the external validity of a study (in the sense of the generalizability of its results) is not necessarily governed by physical representativeness."

"Harré and Secord (1972) have provided an excellent illustration of the attacks on laboratory experimentation in their discussion of what they term the 'information-processing model" in experimental social psychology. In this paradigm, they contended, researchers neglect the social contexts within which people are embedded in their usual lives and ask their subjects to react to some stimulus object on the basis of extremely limited information. Byrne's (1969) well-known studies of interpersonal attraction are held up as particularly horrible examples of this isolation of subjects from their social surroundings. The experimenter in these investigations told the subjects about the attitudes supposedly held by a (fictitious) stranger and then required the participants to rate their liking for that individual . . ."

Some of the replies to this criticism follows: Does methodology determine content? ". . . most influential analyses of human behavior in experimental social psychology today emphasize the role of the individual's thought processes and assume that he or she is an active seeker after meaning and often tries to control what is happening. One can even go further and argue that experiments give us a truer image of human complexity than do uncontrolled, naturalistic investigations. Where the later can only hint at the richness of human nature, the relative precision of laboratory studies shows us much more clearly how people can be deliberate and thoughtful on some occasions and impulsive, non-thougthful, and even irrational at other times. "

The main purpose of an experiment. Kruglanski (1975) offered a view similar to others when he explained why experiments are conducted. "He maintained that many objections to laboratory experiments actually confuse two very different types of psychological research (a) particularistic inquiries in which attention is focused mainly on the the accuracy of statements about specific instances and the intended generalizations are restricted in scope and (b) universalistic (or theoretically oriented) investigations in which the researcher tentatively claims a universal scope of generality for the findings 'across all sorts and varieties of theoretically irrelevant conditions."

Empirical evidence regarding the generalizability of unrepresentative research. "Even though laboratory experiments need not be preoccupied with attempts to mirror naturalistic conditions, many of their findings can be generalized to other settings. As critics should know, many laboratory results have been duplicated by investigations carried out in a more representative manner. Take the Byrne research attacked by Harré and Secord as being unduly 'artificial.' These experiments have shown that attitude similarity affects the degree of liking that people have for each other. Other studies have also found that attitude similarity predicts the development of liking among university men residing in a student rooming house (Newcomb, 1961) and people kept together for 10 days in a small room (Griffitt & Veitch, 1974), as well as the interpersonal preferences expressed by white and black job applicants who did not know they were participating in an experiment (Rokeach, 1968, pp. 68-75). The same processes that influenced the extent to which Bryne's subjects said they liked a fictitious stranger evidently also operate, to a considerable degree at least, in a wide variety of more realistic situations involving face-to-face interaction. "

The meaning of a situation as a determinant of the generalizability of the behavior. "We have now come to our central thesis: "The meaning the subjects assign to the situation they are in and the behavior they are carrying out plays a greater part in determining the generalizability of an experiment's outcome than does the sample's demographic representativeness or the settings surface realism."

"Social scientists have long recognized that consistent interpretations can led to behavioral consistency. If an individual interprets two objectively different situations in much the same manner, he or she will tend to act in the same way on both occasions. . ."

"This is not to say, of course, that laboratory experiments are necessarily as externally valid as field studies conducted in naturalistic settings. Rather, with Dipboye and Flanagan (1979), we argue only that the generalizability of laboratory findings in comparison with the results of naturalistic investigations is an empirical matter. . ."