The results are so creepy -- and so easy to make, if you have access even to rudimentary digital image modification software -- that the wall of photographs we display afterwards makes a real impact.
"I'll never believe a photograph is real again," one student said in an awed voice while looking at the collection of ghosts, spacecrafts, and Bigfoots.
Mont St. Michel is beautiful, isn't it? Yes, but the water and the reflection were all added to the image via Photoshop. [image courtesy of photographer Andrés Nieto Porras and the Wikimedia Commons]
In "Can People Identify Original and Manipulated Photos of Real-World Scenes?", authors Sophie J. Nightingale, Kimberley A. Wade, and Derrick G. Watson set up a series of tests in which subjects were asked if they could detect digitally-altered photographs that had impossibilities -- shadows pointing the wrong way, geometrical inconsistencies, features missing (such as removing the crosswise structural supports from a suspension bridge) or added (such as tables with extra legs). They were given ten photographs, some altered and some not, and as much time as they wanted to study them, and then were asked to identify which (if any) had been manipulated, and if so, how.
And people, in general, were terrible at it. The authors write:
In two separate experiments we have shown, for the first time, that people’s ability to detect manipulated photos of real-world scenes is extremely limited. Considering the prevalence of manipulated images in the media, on social networking sites, and in other domains, our findings warrant concern about the extent to which people may be frequently fooled in their daily lives. Furthermore, we did not find any strong evidence to suggest that individual factors, such as having an interest in photography or beliefs about the extent of image manipulation in society, are associated with improved ability to detect or locate manipulations.
Recall that we looked at two categories of manipulations—implausible and plausible—and we predicted that people would perform better on implausible manipulations because these scenes provide additional evidence that people can use to determine if a photo has been manipulated. Yet the story was not so simple... [E]ven when subjects correctly identified the implausible photo manipulations, they did not necessarily go on to accurately locate the manipulation. It is clear that people find it difficult to detect and locate manipulations in real-world photos, regardless of whether those manipulations lead to physically plausible or implausible scenes.Which, of course, should be enough to give anyone pause. Our capacity for recognizing when we've been fooled is far poorer than we tend to believe.
And the more sophisticated the digital manipulation software gets, the worse this problem will become. Early digital photography programs were nothing short of crude, and attempts to mess around with the image always left traces that a discerning eye could see. But now? It's telling that a bunch of inexperienced high school students could, in short order, produce images that were absolutely convincing.
Think of how much could be done by people who were experts in digital image modification.
There's even an iPhone app that adds six-pack abs and broader shoulders to your photo. Wouldn't it be nice if it were this easy in real life?