In this study it was rather surprising that group work increased student confidence so universally, especially considering that for about half of the cases in which student confident did not change after group work it was because such students were already fully confident prior to group work. While the group effect may be partially due to students simply having more time to consider problems, and/or partly biased by occasional instructor feedback during small group work, it is unlikely that such potentially confounding factors entirely account for the effect demonstrated here. Collective intelligence that arises in groups is at least one plausible explanation for why student confidence increased after group work, since it may bring additional information to light which reduces students' uncertainty in their solutions. This collective intelligence factor is largely dependent on the proportion of females, extent of cooperativity and social perceptiveness at play within groups . Additionally, group members can provide validating feedback to one another, which may also increase their confidence in solutions. Remarkably, it was recently shown that scientific experts consistently make twenty-nine specific types of decisions in the process of solving authentic problems, irrespective of their discipline . While this number of decisions is tractable, it is not few. Groups may also simply raise the likelihood that more of the decisions required to solve problems will be made.