Doctored photos of past public events can influence what people think they remember of the incident, as well as altering their attitudes and any subsequent responses, according to research published today in the journal 'Applied Cognitive Psychology'.
Three researchers (two in Italy and one in the USA) came to this conclusion after showing either original or digitally doctored images to 299 people aged 19-84. The images were of two different protests, one in 1989 in Tiananmen Square, the other 2003 in Rome. After seeing the images, participants were asked questions about the events, without telling them that the research project was interested in the effect that the photo would have on their responses.
They were asked questions about the numbers of people they thought had been involved, the response of law enforcement authorities and the level of violence.
Clear differences in responses came from people who had seen the original and doctored photos.
"One major result was that viewing modified images affected not only the way people remember past public events, but also their attitudes and behavioural intentions," says Franca Agnoli, from the University of Padova, who supervised the experiments.
For example, people who were influenced to think that the event had been more violent than was the actual case, reported that they were less likely to take part in similar demonstrations in the future.
"Any media that employ digitally doctored photographs will have a stronger effect than merely influencing our opinion - by tampering with our malleable memory, they may ultimately change the way we recall history," says lead author Dario Sacchi.
This research builds on work originally conducted by co-author Elizabeth Loftus, an American researcher at the University of California Irvine.