2 Objects of Expertise

Why is face recognition so interesting? Within the realm of visual cognition, faces have been afforded a degree of analysis that surpasses most other object categories. There are several reasons for this intense scrutiny. First, faces are critical to us as social beings. Thus, we are inherently interested the mental and neural processes responsible for our ability to recognize, interpret, and remember faces. Second, face recognition is one of the most difficult visual discrimination tasks we routinely (and almost universally) perform. As such, vision researchers often view face recognition as the most extreme task our visual systems can support. Third, in part motivated by the first two reasons, face recognition is often considered a likely candidate for cognitive and neural specialization. Consequently, face processing makes an interesting litmus test with regard to the nature versus nurture debate. Although these factors do make faces an interesting subject, here we argue that the study of face recognition in and of itself is not nearly as informative as face recognition studied in the context of the recognition of nonface objects. Reviewing the literature, one would not get this impression. Faces have often been specifically studied for two independent reasons. First, they constitute a convenient, complex stimulus category that can be used to probe questions about object processing and recognition. For example, important questions of viewpoint and illumination invariance have been studied using faces (Braje, Kersten, Tarr, & Troje, 1998; Hill, Schyns, & Akamatsu, 1997), not because these problems are unique to faces, but because face stimuli satisfy the need for objects that are not trivially discriminable and because they are convenient to researchers in terms of availability (e.g., http:// www.face-rec.org/databases/). To be clear, we are not suggesting that this is necessarily a bad thing. As we have already acknowledged, faces are highly relevant objects and present a challenging recognition problem worthy of study in its own right. However, research motivated by such logic should not be construed as an attempt to ‘‘prove’’ that faces are ‘‘special.’’ In contrast, the second reason that faces have been targeted as objects of study is intrinsically