Point-of-Time Effects Across the Semester: Is There a Sampling Bias?

Abstract

Prior research has yielded inconsistent findings regarding differences between university participant-pool students who volunteer early or late in the semester. This issue is important because external validity may be threatened when researchers take samples from university participant pools. In the present study, point-of-time effects were investigated via measures of procrastination, motivation, locus of control, and cued recall. The findings suggest that slight differences exist between early and late volunteers on some measures of personality and motivation; however, there were no point-of-time effects for cued recall. The data indicate that if performance-based measures (e.g., cued recall) are under investigation, potential differences in personality and motivation may be attenuated because of the demand characteristics of laboratory settings.