The brain's fusiform face area (FFA) responds to images of faces, leading some neuroscientists to theorize that the region is hardwired for facial recognition. Others support the expertise hypothesis, which holds that humans use those same brain circuits to distinguish between all objects with which they have developed considerable familiarity. According to them, humans excel at recognizing faces because most have been doing so all their lives not because of any specialized brain structures. This theory explains why the FFA of a birdwatcher. for example, will activate for both faces and birds. And while FFA responses for other objects are considerably weaker than those for faces, even dedicated birdwatchers have probably spent considerably less time studying birds than looking at faces.