Why do people think the way they do?

[apparentparadox]

A while back, someone recommended that I read a Scienterrific American article on photo-tampering (see this, and this, and this. I finally did, and it kind of blew me away - not the article itself (which was good), but the realization that people -- including me -- treat photographs as trustworthy.

There is evidence of photo-tampering since basically the beginning of photography. This isn't just since the advent of digital processing; it's been going on since the first days of photography. But people still react very strongly emotionally to a photo, treating it as "evidence", where they wouldn't react as strongly to an oil painting. And the oil painting may have just as much basis in reality as the photograph.

Sure, I've trained myself to never trust photos shown me by individuals, knowing how easy it is to doctor them. But, I still treat photos in newspapers or journals as being "real", even though there is evidence that faked photos have gotten into the print media. [For what it's worth, I don't trust any photos shown on TV news; it's the print media that somehow I "trust" more.]

How much more will it take before I view all photographs as equivalent of a drawing?