Abstract
Searching for unfamiliar faces in crowds is an important task in modern society. In surveillance and security settings, it is sometimes critical to locate a target individual quickly and accurately. In this study, we examine whether we can improve search efficiency in these visual search tasks by changing the face information that is provided to participants. In Experiment 1, we compare speed and accuracy of visual search when searching for unfamiliar and familiar faces after being exposed to either a single exemplar image or a face average created from multiple images of the target face. In Experiment 2, we compare search efficiency when single exemplars and multiple exemplars are provided. Consistent with studies of unfamiliar face matching tasks, we find that, relative to a single image, having multiple images of the target improves the accuracy of visual search. In Experiment 3, we compared search performance for face averages and multiple exemplars while also varying crowd size. Multiple exemplars conferred an additional advantage over face averages, suggesting that exposure to within-face variability results in the best search performance. We discuss the implications of these findings for face-in-a-crowd search and visual search tasks more generally.
Highlights
The identification of people in crowds has emerged as an important task in both crime prevention and law enforcement
We test whether exposure to variability in appearance improves search accuracy relative to exposure to modal appearance, by comparing search performance when face averages and multiple images are provided as search templates
These results extend the findings of studies of unfamiliar face matching (White et al, 2014), where multiple images have been shown to lead to more accurate matching performance than face averages
Summary
The identification of people in crowds has emerged as an important task in both crime prevention and law enforcement. Police can review footage captured on closed-circuit television (CCTV) to locate and identify suspects at large-scale public events after an incident has occurred (BBC, 2011). In both scenarios, success can rely on the identification of suspects from their faces when they are present within the crowd as it is an important cue for person identification (Burton, Wilson, Cowan, & Bruce, 1999).
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