When can a photo be trusted?

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Photographic Memories

Over the past year and a half Kevin and I have been writing on a variety of issues related to image manipulation and authentication. Beyond the ethical, legal, and economic implications of image tampering, recent studies suggest that doctored images can have an impact on our memories of past events, and our perceptions of future events.

[Photo credit: Sacchi, Agnoli, Loftus. Appl. Cognit. Psychol. 21: 1005–1022 (2007)]In a very nice 2007 study, Dario Sacchi, Franca Agnoli, and Elizabeth Loftus investigated how doctored images can affect people’s memories. Observers viewed either original or doctored images of major and emotional world events: the 1989 Tiananmen Square protest in Beijing and the 2003 protests in Rome against the war in Iraq. The original and doctored images were the same except for the addition of larger crowds.

The observers in this study were Italian students, meaning that they had first-hand memories of the protests in Rome, but not of the Tiananmen Square protests.

After viewing the images, observers answered questions about the events. Most strikingly, those who viewed the doctored image of the Rome event rated the event as more violent and more negative, recalled more physical confrontation, damage to property, and injuries to demonstrators, and were less inclined to participate in future protests.

The authors performed a series of experiments and controls to verify that it was the doctored photos themselves that were impacting observers’ memories.

Perhaps these results should not be entirely surprising given what we understand about the malleability of memory. For example, in her influential work, Loftus showed how everything from repressed memories to eye witness memory can be incredibly faulty and influenced by external factors. If you are interested in ths topic, the full study is worth reading. Here is the original published article: 

Changing History: Doctored Photographs Affect Memory for Past Public Events

and a Slate article describing Loftus’ research on the nature of memory:

The Memory Doctor


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Reader Comments (1)

There are plenty of studies that say eye witnesses are unreliable because memories can change over time. Moreover, how questions are asked can be used to introduce false memories. A good write-up is found at: http://agora.stanford.edu/sjls/Issue%20One/fisher&tversky.htm
And their reference #5:
Krist v. Eli Lilly and Co., 897 F.2d 293, 297 (7th Cir. 1990), (listing the findings of various psychological studies):
Accuracy of recollection decreases at a geometric rather than arithmetic rate (so passage of time has a highly distorting effect on recollection); accuracy of recollection is not highly correlated with the recollector's confidence; and memory is highly suggestible – people are easily ‘reminded’ of events that never happened, and having been ‘reminded’ may thereafter hold the false recollection as tenaciously as they would a true one.

In effect, showing someone a picture can alter their memory just as readily as recalling events and verbally altering events with suggestive questioning.

December 19, 2012 | Unregistered CommenterDr. Neal Krawetz

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