Why has research in face recognition progressed so slowly? The importance of variability

Despite many years of research, there has been surprisingly little progress in our understanding of how faces are identified. Here I argue that there are two contributory factors: (a) Our methods have obscured a critical aspect of the problem, within-person variability; and (b) research has tended to conflate familiar and unfamiliar face processing. Examples of procedures for studying variability are given, and a case is made for studying real faces, of the type people recognize every day. I argue that face recognition (specifically identification) may only be understood by adopting new techniques that acknowledge statistical patterns in the visual environment. As a consequence, some of our current methods will need to be abandoned

A perceptual learning theory of the information in faces

this paper. What has been gained by using a configural/feature-based dichotomy is the understanding that for a human observer, the face is clearly more that the sum of its parts. This has provided insight into the nature of the perceptual unit comprised by a face and has been useful for linking face studies to the larger literature on processing visual features.