On the Psychology of the Psychology Subject Pool: An Exploratory Test of the Good Student Effect

Many psychology researches are performed through "psychology subject pools" which give participants considerable flexibility when they participate. This "participant degree-of-freedom" has led to concern that the characteristics of subject pool participants may change with time, with the most engaged students signing up at the start of the semester and the least engaged students leaving it all to the end. In this paper, we performed an exploratory analysis to look for evidence of this "good student effect." Consistent with previous work, we find support for the good student effect with earlier participants scoring higher on the Big-Five subscales of Achievement-Striving and Cooperation, as well as Grit and Empathic-Concern. In addition, we found a non-linear effect of time-of-semester on Sensation-Seeking, with this measure peaking in the middle of the semester as well as the end. However, the vast majority of the measures we tested, including measures of personality, cognition, decision-making, and social interaction, did not correlate with time-of-semester or time-of-day at all. Thus, we conclude that, while some studies directly related to measures of Grit and Sensation-Seeking would do well to recruit throughout the semester, in most cases any bias introduced by the good student effect is likely to be small.