Some implications for psychological research of early versus late term participation by college subjects

Several surveys of recent psychological literature have indicated that a large percentage of human subjects are introductory psychology students who are given the option of selecting when to participate in research which is either implicitly or explicitly required of them. The present study was conducted to investigate the possibility that those subjects who choose to participate early in the term differ in personality and in attitudes toward research from later term participants. Results indicated that early term males and females, as expected, were more academically oriented and more internally controlled than late term subjects; and early term males were more achievement oriented than their late term counterparts. Additionally, females were found to feel more positive toward research participation than males; while a large percentage of all subjects reported both suspiciousness of experimenter intent and a general and unexpected willingness to voluntarily participate as subjects. Possible effects of these findings on research results and conclusions were discussed, and suggestions for improvements aimed at reducing self-selection bias in college subject pools were made.