Even true pictures can lie. Nonetheless, we love to add pictures to our stories. Newspapers are bland without accompanying photos. A TV news show without video just doesn't happen. Even when we tell friends about a trip, the story is better with photographic evidence. Photos enhance the story, but photos can also lead to false beliefs and memories.
In several experiments, Maryanne Garry and her colleagues have studied the misleading effects of photographs. They started by demonstrating the power of photoshop. Garry and her colleagues asked people about childhood events - including the time they took a hot air balloon ride. Although the people had never been in a hot air balloon, the researchers provided photographic evidence. They photoshopped childhood pictures of the individuals into the basket of a balloon (see the sample photo from the study at the side). When people saw themselves in a balloon, they developed memories of riding in that hot air balloon.
But Dr. Garry didn't need to doctor the photos to get the effect. Next Garry used real photos to create false memories. They asked college students about the time they had put ‘Slime' (trademarked, I'm sure) in their 2nd grade teacher's desk. Sometimes the researchers showed people a photo of their second grade class - a real photo. No slime in the photo, no one putting slime in a desk, no angry teacher. The only picture that participants saw was their old school photo (with funny haircuts and bad clothes). But seeing that unrelated photo made people more likely to create memories of pulling that prank on their teacher. (By the way, those of us who know Maryanne Garry try to keep her from obtaining photos of us - we don't particularly trust her photographic evidence. If she ever shows you a photo of anything I've done, I want to deny it right now!)
Garry began to wonder more broadly about the power of photographic evidence. For example, photos and pictures can aid the comprehension of and memory for academic and news material. But Garry wondered if photos could be used to create false beliefs. Thus Garry, Strange, Bernstein, and Kinzett asked people to read a news story about a hurricane. Then they showed people either a photo from before the hurricane hit or a shot of the devastation caused by the hurricane. No information was given about personal injuries or death caused by the hurricane in either the news story or in the photos. But people who saw the photo with physical destruction were more likely to claim that the news story included information on injury and death. The destruction photo led people to draw related inferences concerning injuries to people.
Recently, Garry and her colleagues have presented people with facts accompanied by pictures that do not actually show the fact (for example, turtles don't have ears accompanied by a picture of a sea turtle). In another study, they asked whether somewhat famous people were dead or alive - again sometimes accompanied by a photo of the person. When the knowledge was relatively obscure, the photos increased people's belief in the knowledge. If you tell people something and show them a photo, then they are more likely to believe what you are saying - even if what you say isn't true.
Pictures, even true ones, can be used to create false beliefs, false memories, and lies. If you want to convince someone of something, show them a picture. The photo will help even if it doesn't depict the statement. Want to convince people that Iraq had weapons of mass destruction? Then show them a picture of Saddam Hussein. Want to convince people that Sarah Palin was responsible for the Arizona shooting? Then show a picture of her hunting. No the photos aren't really related to the claims, no they don't provide any real evidence, but yes they will strengthen your argument.
Since our memories are not photographic and our knowledge is not perfect, we rely on various sources when making truth judgments. Pictures make ideas feel more real. You know that you can't believe everything you see. But even when you can believe the photo, you shouldn't necessarily believe what it leads you to think and remember.