Deciding whether two images show the same person sounds easy, but the average individual achieves accuracy of 60-90% on many unfamiliar face matching tasks. However, overall task performance can be improved by combining the identification decisions made by different individuals, through the "wisdom of the crowd" effect. We investigated whether similar gains occur when combining multiple decisions made by the same individual, via a "wisdom of the crowd within" effect. Participants completed the same unfamiliar face matching task three times: in one session (Experiment 1), or over three weeks (Experiment 2). We found a wisdom of the crowd within effect in both experiments, which was significant after two responses and larger with three. Surprisingly, the delay did not offer additional benefit. Though the crowd within improved performance, crowds of different individuals produced larger gains. Our results add to a growing literature showing combined decision-making can improve unfamiliar face matching performance.
Carragher et al. (Wed,) studied this question.