Variability in photos of the same face
Psychological studies of face recognition have typically ignored within-person variation in appearance, instead emphasising differences between individuals. Studies typically assume that a photograph adequately captures a person’s appearance, and for that reason most studies use just one, or a small number of photos per person. I will describe a number of studies to highlight that photographs are not consistent indicators of facial appearance because they are blind to within-person variability. Crucially, this within-person variability is often very large compared to the differences between people. This observation is critical to our understanding of face processing, because it suggests that a key component of face processing has been ignored. As well as its theoretical significance, this scale of variability has important practical implications. For example, our findings suggest that face photographs are unsuitable as proof of identity.