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Subject: Why do photographs seem so real?
Category: Science
Asked by: viz_think-ga List Price: $5.00
Posted: 24 Nov 2004 13:34 PST Expires: 24 Dec 2004 13:34 PST
Question ID: 433596
Why do photographs seem so real? In particular, if you take a picture of yourself and put a push pin through one of your eyes in the picture, you will feel a definite twinge in your stomach. This doesn't seem to happen at all or not nearly, to the same extent with a drawing. Both photos and drawings have many distortions from "reality" or what one would see, say, looking into a mirror. What perceptual cues cause photos to have more "reality" impact than other forms of visual representation?
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Subject: Re: Why do photographs seem so real?
From: steve_palmer-ga on 01 Dec 2004 10:30 PST
Interesting question. My guess is that the answer has several parts, both perceptual and cognitive. Probably the most important perceptual component is the accuracy of the photo in capturing the structure one sees in viewing real objects. A good photograph viewed under the proper circumstances (with just one eye, from far enough away that lens accommodation isn't an effective cue to depth, and with the edges of the photo occluded by viewing it through an aperture), people cannot actually tell the difference between the real 3-D scene and the photograph. This sort of thing has been studied by MH Pirenne (1970: Optics, painting and photography; Cambridge U. Press).
Yes, there can be distortions in photographs, but most of them are highly constrained, systematic, and the sort of transformations to which the visual system is relatively insensitive. People have elastic enough color constancy, for example, to compensate for poor lighting conditions, and enough of various spatial constancies to compensate for perspective distortions. And even when there are distortions of these sorts (which most picture-takers try to avoid), the accurate rendering of detail is usually still there. Drawings have much less constrained distortions in which the geometry of the images can be arbitrarily different from what would actually be seen when viewing a real face.
Anyone with a digital camera, Photoshop, and an interest in this issue could conceivably study it. Photoshop provides lots of ways of introducing systematic changes into photographs of faces so that one could find out which ones produce changes in the effect you are referring to. Start with a good photographs of some faces (e.g., your own, someone you know well, and a stranger) and then use Photoshop to alter the photo. Inverting the color would very likely make the effect go away, but just increasing the redness or greenness probably wouldn't. You can also introduce textural transformation using the various "artistic" filters to make the photos look more like paintings and less "real." You can also alter the overall geometry by introducing perspective distortions of various sorts using the "distortion" filters.
I suspect that there are some cognitive components as well. Most people know how photography works and that there is a real object corresponding to the image it produces. A painting -- even a very realistic representationalist one -- could be an imagined face of an imagined person, which doesn't have the same impact as if the viewer KNOWS it's a real person, particularly him/herself.
Yet another component to the answer is adaptation: the effect will probably get weaker and go away with repeated exposure to it. That will make doing the study suggested above more difficult just on yourself; you'd have to get some other volunteers.
Finally, there has to be a physiological component to the answer beyond whatever neural firings underlie the perceptual and cognitive components mentioned above. Something (activation of some branch of the vagus nerve?) produces the twinge in the stomach, which I also notice whenever I see someone get hurt. One of the best examples is the razor slicing through a woman's eye in the Luis Bunuel movie, "Un Chien Andalou," which give me a big dose of the same twinge.