Along with the wide increase in psychological research in the past few decades, an important “detail” is often overlooked by many researchers and hidden from many people. As you may already know, a lot of psychology research on human behaviour is primarily done with undergraduate university students, especially those enrolled in psychology courses. A study by Henrich et al. from University of British Columbia has revealed that “68 percent of research subjects in a sample of hundreds of studies in leading psychology journals came from the United States, and 96 percent from Western industrialized nations. Of the American subjects, 67 percent were undergraduates studying psychology — making a randomly selected American undergraduate 4,000 times likelier to be a subject than a random non-Westerner”(Giridhardas, 2010).

Although we always learn about the importance of random sampling in research, these samples are far from being random and they don’t represent the population they often claim to represent. As a result, a lot of these studies lack external validity. These studies use what is called “convenience sampling”, which means using a sample that is readily available and close to hand. Convenience sampling has many advantages for researchers. For example, it takes less time and effort to recruit university students who might need some extra money or want extra credits in their psychology classes. Also, if these subjects weren’t available, researchers would need to advertise a lot more than they do now and it would cost them more money.

However, relying on undergraduate students creates many problems and issues. As mentioned previously, university students do not represent the general population. Most of them are young adults who have a very different psychological profile than the general population and also they are educated and studying at a university, which represent a really small proportion of the world. Plus, most of them are from North America and Europe and therefore, a lot of the findings lack cross-cultural comparisons. Yet, when research is compiled in books or talks and made available to the general public, this reality is rarely mentioned. Also, people who are being exposed to these findings and who are unaware of this fact often use these findings as reference points and when comparing themselves to these “standards,” they can often feel that they are deviant cases, while in reality, they might just be different cases.

In addition, undergrads in psychology courses which are predominantly majoring or minoring in psychology are familiar with a lot of the concepts and tests used in research. Therefore, when a construct is being assessed using self-reports, some subjects might have already taken the test, or learned about it in a class, and these influence how participants would respond to questionnaires. These issues ultimately question the validity of findings based on these samples.

References

Giridharas, A. (2010). A Weird Way of Thinking Has Prevailed Worldwide. The New York Times. Retrieved from

http://www.nytimes.com/2010/08/26/world/americas/26ihtcurrents.html?_r=3&pagewanted=all&