Effects of Mug Book Size and Computerized Pruning on the Usefulness of Dynamic Mug Book Procedures

Abstract

The usefulness of dynamic mug books with larger sets of mug shots was explored in experiment 1. Participants viewed a videotaped crime and attempted an identification from either a dynamic mug book (computerized video clips could be chosen) or a static mug book. The perpetrator appeared in one of three positions - 70, 140, or 210. When the perpetrator and the 69 preceding foils appeared in positions 1-70, correct identifications and false positives were higher than for later positions. Dynamic information usage decreased so dramatically for the later positions that it was argued that dynamic mug books should be used only when the number of pictures could be pruned. Experiment 2 explored the usefulness of pruning dynamic mug books. Identifications were attempted in mug books that contained either 69 pictures pruned by a computer facial-recognition algorithm for their similarity to the perpetrator, or a random selection of 69 pictures. As in past research, the dynamic mug book reduced false positives; however, in contrast to past research, similarity of mug book pictures as defined by the algorithm did not affect mug book performance. Experiment 3 tested the relationship between the computer facial-recognition algorithm similarity ratings used in experiment 2 with human similarity judgments. No relationship was found between human and computer ratings of similarity.