I'm trying to find out to what extent mere detection of faces (i.e. determining that something is a face, as opposed to recognition of specific individuals) is favored in the central vision vs peripheral vision.
Ideally the answer should be in terms of areas of brain activation, but I realize this might be too ambitious (given the review I've looked at), so merely in terms of experimentally determined perception would an acceptable answer.
To reiterate, I'm talking about mere detection that something is a face, not identifying/recognizing that a certain face is someone in particular (or even deriving less specific attributes like inferring their affect). Whether face detection and recognition are really separate processes I'm not sure, but some neuroscientists have proposed that they are, e.g. Tsao and Livingstone:
The most basic aspect of face perception is simply detecting the presence of a face, which requires the extraction of features that it has in common with other faces. The effectiveness and ubiquity of the simple T-shaped schematic face (eye, eye, nose, mouth) suggest that face detection may be accomplished by a simple template-like process. Face detection and identification have opposing demands: The identification of individuals requires a fine-grained analysis to extract the ways in which each face differs from the others despite the fact that all faces share the same basic T-shaped configuration, whereas detection requires extracting what is common to all faces. A good detector should be poor at individual recognition, and vice versa.
Another reason why detection and identification should be separate processes is that detection can act as a domain-specific filter, ensuring that precious resources for face recognition (e.g., privileged access to eye movement centers (Johnson et al 1991)) are used only if the stimulus passes the threshold of being a face. Such domain-specific gating may be one reason for the anatomical segregation of face processing in primates (it is easier to gate cells that are grouped together). A further important benefit of preceding identification by detection is that detection automatically accomplishes face segmentation, i.e., isolates the face from the background clutter, and can aid in aligning the face to a standard template.
However, whether it is really the case that detection is independent of recognition doesn't matter much to me for in this question: I want to know if mere detection is favored in central vision and to what extent the detection changes as the stimulus moves towards the periphery of vision.
Unfortunately, it looks like not much is known about where face detection happens in human brains because the best known area that activates when looking at faces is the FFA (fusiform face area)... but this region is also overlapping the one for central vision. Quoting from the same source as above:
Although face-specific fMRI activation can also be seen in the superior temporal sulcus (fSTS) and in part of the occipital lobe (the “occipital face area”, OFA), the most robust face-selective activation is consistently found on the lateral side of the right mid-fusiform gyrus, the “fusiform face area” or FFA (Kanwisher et al 1997) (Figure 6). The fact that this part of the brain is activated selectively in response to faces indicates that activity in this region must arise at or subsequent to a detection stage.
On the other hand, the FFA is fairly closely associated with central vision. This idea is derived from where the fusiform face area (FFA) is located. Quoting a review of Kanwisher (2006):
Although it is not clear what is so special about this region of the fusiform gyrus that the FFA apparently has to live here, one intriguing clue comes from reports that face-selective cortex also responds more strongly to central than peripheral visual stimuli (even non-faces; Levy et al. 2001). This fact may suggest that face-selective regions reside in centre-biased cortex either because it has computational properties necessary for face processing, or because we tend to foveate faces during development.
But it's not too clear from this how much face detection actually happens in the peripheral vision. There's gotta be some level of detection that causes us to foveate faces (even just during development). So, to [re]state my question once again, to what extent is peripheral vision worse (than the central vision) at merely detecting faces?