Each semester, approximately 600 students in Introduction to Psychology will participate in research projects, ranging from experiments about coping with stress to improving body image.
The course requirement does more than help students understand how psychology is studied - it provides graduate students and professors with a convenient pool of subjects for their work.
Penn isn't alone - across the country, psychologists rely heavily on undergraduates as an integral part of experiments.
Psychology professor Paul Rozin said the primary appeal of college students is accessibility.
"Researchers will use what is easiest and most readily available," Rozin said. "Biologists have fruit-flies. Psychologists have undergraduates."
But many in the field say this dependence hinders research, particularly in social psychology, because the behaviors and perspectives of American undergraduates do not reflect those of all human beings.
Psychologists are making generalizations based on narrow samplings of background and experience, Rozin said.
"Social psychology is an area where personal experience and maturity affect responding," he said.
Attitudes about relationships and morality, for instance, tend to change with age and may be particularly fluid for ages 18 to 21.
Rozin added that most experiments are conducted at large research universities, where student populations tend to be relatively homogenous and affluent.
The resulting conclusions "disproportionately represent elite American college students," he said.
People of different ages and cultural groups often respond differently to experiments, said Psychology graduate student and head TA of Psychology 001 Nuwan Jayawickreme, who studies the effect of culture on psychological processes.
For instance, American students will respond differently from students in other countries.
If experiments do not include a variety of subjects, he said, there's no way for researchers to know whether differences exist between groups.
When studying neurological phenomena such as perception and memory, a heavily-undergraduate subject pool is less of a concern.
Psychology professor Jason Dana said this type of research is less influenced by its subjects because cognitive processes are basically the same in all people.
"For some things that are true of all human beings, subjects aren't going to matter as much," he said. "The more social and the more complex the behavior, you need to put the findings into context."
But change won't be easy, Dana added. Reliance on undergraduate subjects is so ingrained in the discipline that research practices would be very difficult to overhaul.
