Who comes when: personality differences in early and later participation in a university subject pool

This study used a comprehensive measure of personality, the NEO PI-R to assess the broad traits and narrower facets of personality that predict time of participation in a University subject pool across one semester. A variety of additional demographic and academic variables (e.g. grade point average, semesters completed, current number of semester credits being taken, total degree credits earned) were investigated as they related to both time of participation and enjoyment of participation. Significant associations were found that replicated previous research (e.g. extraverts participate later; compliant persons participate earlier) and previously unreported associations were identified (e.g. openness and its facets correlate significantly with time of participation). Suggestions as to how to avoid these potential experimental confounds and increase truer random assignment of subject pool participants to experimental research are made. (C) 2002 Published by Elsevier Science Ltd.