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...).
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...).