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This is a classic problem of averaging. The average of multiple data sets doesn't retain the average of all the properties of the originals. A simple case of

This is a classic problem of averaging. The average of multiple data sets doesn't retain the average of all the properties of the originals. A simple case of this is averaging two similar images: the local variance will go down because you've blurred out detail and noise that varied between the two images. Thus, as you average large numbers of images together, the composite you get is not necessarily representative of any of those that went in, and for that matter is not necessarily useful for any purpose at all, given that it didn't retain a lot of the properties of the input images.

roundsquare 17y ago
Thats a great point. Two things come to mind: 1) Even if your wrong, and this does make a statement about how we perceive real faces, then contrast would only be a really useful indicator in the case of a very average face. Generally speaking it would probably be a very weak variable in our analysis. 2) It seems like they needed to find a way to separate out just the experimental variable in a way to make its amplitude higher than other variables. The only other way I can think of is to find someone who looks pretty much like the image. When looking at it, I don't see anything that makes me think its a composite (or strange, etc...).