Face recognition: Are viewpoint and identity processed after face detection?

Previous research has suggested that an object's category is retrieved as soon as it is detected (Grill-Spector & Kanwisher, 2005). Here we examined whether face views and identities are likewise treated as categories. We measured behavioural performance on three tasks: face detection, recognition of face view within identity, and within-view face identification, by using the method of constant stimuli combined with a two-alternative forced-choice (2AFC) paradigm. Stimulus duration was varied between 13 ms and 133 ms in order to estimate the time required for 75%-correct discrimination in each task. The results showed, respectively, 24- and 31-ms shorter threshold durations for face detection than for viewpoint recognition and face identification, while similar threshold durations for viewpoint recognition and face identification. We demonstrated that face view and identity are retrieved after face detection, and importantly, the view-based categorical analysis takes almost as long as the face identification process. Thus, additional processing is essential for viewpoint and identity extraction as opposed to face detection.