Wisdom of the inner crowd benefits both face and voice matching

Identification often involves determining whether two face photographs or voice samples originated from the same person. Here, we investigated the wisdom of the (outer) crowd (averaging two individuals' responses to the same trial) and inner crowd (averaging the same individual's responses to the same trial after completing the test twice) as routes to increased performance. Participants completed the same face (Experiment 1) or voice matching test (Experiment 2) twice with no delay. In addition, we reanalysed previously collected data where these tests were completed with a one-week interval between sessions. For both tests, whether with or without a delay, inner crowds outperformed participants' individual test responses and were equivalent to outer crowds of two participants. Taken together, we demonstrate the use of inner crowds as a robust method of improvement during identification. In contexts where outer crowds are not feasible, agencies should consider inner crowds as a promising alternative.