Smiles in face matching: idiosyncratic information revealed through a smile improves unfamiliar face matching performance

Research output: Contribution to journalArticlepeer-review


Unfamiliar face matching is a surprisingly difficult task, yet we often rely on people’s matching decisions in applied settings (e.g., border control). Most attempts to improve accuracy (including training and image manipulation) have had very limited success. In a series of studies, we demonstrate that using smiling rather than neutral pairs of images brings about significant improvements in face matching accuracy. This is true for both match and mismatch trials, implying that the information provided through a smile helps us detect images of the same identity as well as distinguishing between images of different identities. Study 1 compares matching performance when images in the face pair display either an open-mouth smile or a neutral expression. In Study 2, we add an intermediate level, closed-mouth smile, to identify the effect of teeth being exposed, and Study 3 explores face matching accuracy when only information about the lower part of the face is available. Results demonstrate that an open-mouth smile changes the face in an idiosyncratic way which aids face matching decisions. Such findings have practical implications for matching in the applied context where we typically use neutral images to represent ourselves in official documents.
Original languageEnglish
Pages (from-to)799-811
Number of pages13
JournalBritish journal of psychology
Issue number4
Early online date19 Jun 2018
Publication statusPublished - 4 Oct 2018

Bibliographical note

© 2018, The British Psychological Society. This is an author-produced version of the published paper. Uploaded in accordance with the publisher’s self-archiving policy. Further copying may not be permitted; contact the publisher for details.


  • Face recognition
  • Face matching
  • Emotional expressions

Cite this