Understanding Familiar Face Recognition for 3D Scanned Images: The Importance of Internal and External Facial Features

Clay or computerised facial reconstructions are often presented to the public for recognition without information about the external features of a head (hair, ears and neck) as these are thought to be potentially distracting or even misleading. In this context, the mechanisms of face recognition are poorly understood, but existing research using photographs of familiar faces suggests that external features play an important role for recognition, and external features may even be necessary for recognition to occur at all. The current research aimed to determine the contribution that external features make to the recognition of a familiar face rendered in 3D. It will also determine whether the inclusion or exclusion of external features from a reconstruction is likely to be beneficial. Volunteers were asked to name images of 3D faces of people known to them, presented as either full face 3D surface scans, or where the internal or external features had been removed. As was expected, a clear correlation was found between information presented in the scans and the recognition rate, with participants correctly naming full face images most often and images of external features least often. Logistic regression analysis demonstrated a significant linear trend in recognition rate in the order of external features, internal features and full face. Incorrect naming also increased linearly, indicating that participants were more likely to offer a name (correct or otherwise) when more useful facial information was provided.

1. Introduction

Clay or computerised forensic facial reconstructions are often used as a way of identifying an unknown individual. A reconstruction is made from the skull of an unknown individual using standard anthropological techniques [1], [2], and an image of this is presented in the media. It is hoped that the reconstruction will resemble the deceased individual sufficiently in vivo to allow recognition of him or her by a familiar person [2], which may in turn lead to a positive identification through other methods such as DNA or odontology matching.