**Fingerprint images:**
The fingerprints used in this experiment were collected as part of a large, standardised set of biometric material to allow for scientific testing of forensic identification ability (see Tear, Thompson, & Tangen, 2010). To attain latent print images, researchers, in consultation with local fingerprint examiners, chose five surfaces on which latent prints are commonly found. Almost all of these surfaces are found near points of entry to a building, and include gloss-painted timber (doors, window frames), smooth metal (door handles, knife blades), glass (windows), paper, and smooth plastic. Undergraduates, whose fingerprints were collected, were asked to interact with the surfaces, by asking them, for example, to 'push the gloss-painted timber to open the door.' By interacting with objects in this way, participants left realistic latents, controlling for real world variability in latent quality, size and amount of useful information. Standardised tenprint cards and palm prints were also collected. The tenprint cards use ink to capture each fingerprint, rolled fully from nail-edge to nail-edge, as well as ‘slap impressions’ (pressing, not rolling, the fingers on the card). We separately capture fully rolled palm prints.
For the present study, 50 of the latent prints and 50 of the tenprints were collected from the database, including ten of each finger type. A range of surfaces were also represented when collecting the latent images (timber, glass, knife, bottle). All of the images were cropped to a square in (i.e., equal height and width) where each square was filled with ridge detail. The contrast of the image was then increased to enhance image clarity. Each of the cropped images was presented on a single A4 sheet of paper in a larger booklet, 16cm x 16cm.
**References**
Tear, M. J., Thompson, M. B., & Tangen, J. M. (2010, September). The importance of ground truth: An open-source biometric repository. In Proceedings of the Human Factors and Ergonomics Society Annual Meeting (Vol. 54, No. 19, pp. 1464-1467). Sage CA: Los Angeles, CA: SAGE Publications.
