When does the inner-face advantage in familiar face recognition arise and why?

Known faces are recognized better from their inner than outer parts (Ellis, Shepherd, & Davies, 1979). This has previously been demonstrated with cropped images. Using a blurring technique to defocus different parts of the face image systematically, we confirmed the effect for adults viewing famous faces (Experiment 1). Children aged 5-13 years showed an outer-face advantage (Experiments 2 and 3). The inner-face advantage was found only at 15 years (Experiment 3). Experiment 4 showed an outer-face advantage in familiar face recognition when the viewers were adolescents with a mental age of under 10 years. The emergence of the inner-face advantage is a developmental rather than a maturational phenomenon. We discuss the implications of the failure to show a qualitatively adult-like pattern of face recognition before adolescence in relation to theories and models of face recognition.