The psychology of face construction: giving evolution a helping hand

Face construction by selecting individual facial features rarely produces recognisable images. We have been developing a system called EvoFIT that works by the repeated selection and breeding of complete faces. Here, we explored two techniques. The first blurred the external parts of the face, to help users focus on the important central facial region. The second, manipulated an evolved face using psychologically-useful ‘holistic’ scales: age, masculinity, honesty, etc. Using face construction procedures that mirrored police work, a large benefit emerged for the holistic scales; the benefit of blurring accumulated over the construction process. Performance was best using both techniques: EvoFITs were correctly named 24.5% on average compared to 4.2% for faces constructed using a typical ‘feature’ system. It is now possible, therefore, to evolve a fairly recognisable composite from a 2 day memory of a face, the norm for real witnesses. A plausible model to account for the findings is introduced.