# The role of facial distinctiveness in the prioritisation of targets in disjunctive dual-target face search

## TL;DR

This study shows that searching for multiple unfamiliar faces at once is challenging, especially when the faces are typical and the searcher has lower face-processing ability.

## Contribution

The study reveals how facial typicality and individual differences in face processing affect dual-target face search performance.

## Key findings

- Searching for two typical faces leads to prioritization of one target over the other.
- Performance with non-prioritized typical faces correlates with face memory test scores.
- Prior learning of faces reduces the prioritization effect.

## Abstract

Two experiments explored the search for pairs of faces in a disjunctive dual-target face search (DDTFS) task for unfamiliar face targets. The distinctiveness of the target was manipulated such that both faces were typical or distinctive or contained one typical and one distinctive target. Targets were searched for in arrays of eight faces. In Experiment 1, participants completed a DDTFS block with targets learnt over the block of trials. In Experiment 2, the dual-target block was preceded by two training blocks of single-target trials. Participants also completed the upright and inverted long-form Cambridge Face Memory Test (CFMT+). The results showed that searching for two typical faces leads to one target being prioritised at the expense of the other. The ability to search for non-prioritised typical faces was associated with scores on the CFMT+. This association disappeared when faces were learnt before completing DDTFS. We interpret the findings in terms of the impact of typicality on face learning, individual differences in the ability to learn faces, and the involvement of capacity-limited working memory in the search for unfamiliar faces. The findings have implications for security-related situations where agents must search for multiple unfamiliar faces having been shown their images.

Security officers (e.g. police officers) are often required to be on the lookout for specific individuals or suspects. The present study shows that there is a profound challenge in finding unfamiliar targets when searching for more than one face at the same time. Importantly, the nature of this challenge depends on two factors: first, the relative typicality of the faces that are being sought at the same time, and second, the face processing ability of the searchers. The findings have implications for the design of the job roles and the recruitment of security officers tasked with searching for specific individuals.