Is There a Specific ‘Face Detection’ Mechanism, and Does It Matter?
A 2012 study in Cognitive Neuropsychology which examines deficits in facial recognition ability was recently brought to my attention. The article provides persuasive evidence that human beings have evolved a specific neural mechanism for the recognition of faces. On the one hand, I did not need to be persuaded, because I (and other members of my family) have prosopagnosia (literally, the inability to know faces). But it is always good to have research evidence to back up the claim of a cognitive disability and also to begin to determine the limits of that disability.
When in our early twenties, both my daughter Kerith and I discovered that we had a deficit that most others did not lack. We would go to some kind of conference, meet people in the evening, and appear to insult them when we did not recognize them the next day. And that is because, as prospagnosics, we cannot pick out face-specific features; instead, we rely on props like color and style of hair, presence and type of moustache, style of dress, gait of walking, etc. As with other deficits, we could not completely compensate; all we could do is develop strategies, ranging from writing detailed notes for ourselves about the appearance of people to telling new acquaintances that we would not recognize them on a subsequent encounter.
In earlier times, prosopagnosia did not, in effect, exist. And that is because, as a species, we have evolved to know 100-150 persons, no more, and those persons can be identified in numerous ways. (That is why Kerith and I were unaware of our deficits when we were younger.) Only in a modern ‘weak tie’ society, where one meets hundreds of individuals superficially, does prosopagnosia become a significant deficit.
Is there such a thing as facial intelligence? I answer this question negatively. Inability to recognize faces, at least until this point in time, is a specific kind of visual disorder, akin to color blindness or monocular vision, both of which I also have (my daughter is more fortunate). It is also akin to a sense of absolute pitch—something that is easily acquired by some (I was one) and with great difficulty for others. I would call these modality-specific disorders.
In contrast, an intelligence refers to the way that information is processed, once it has been picked up by one or more sensory organs. Linguistic intelligence is mobilized whether we encounter language through the ears, through the eyes, or (if we are blind) through a sense of touch. We can speak of interpersonal intelligence, because we infer how other persons are feeling, using input from several sensory modalities. And, interestingly, I know of no evidence that prosopagnosics are worse (or better) than others in reading mood off of faces.