Why is Edward Snowden a villain to some people while the same people regard Bradley Manning as a hero? Why do so many people say they never thought it could happen if someone they know commits a crime? When is an atrocity not remembered that way at all? An in-group portrayal may make the difference.

A group of scholars focus on recent events to discuss their hypothesis about psychology - what they call atrocities in Iraq, Afghanistan,  Abu-Ghraib and Guantanamo and how people recall them. Those are all very safe things to posture about from the comforts of a western nation - good luck flying to talk to the Taliban about their atrocities and surviving the trip - but it makes the point they want to make; "out-groups", like remote academics or war protesters, will call lots of things atrocities and can recite them easily, while people who are actually there often don't remember them as atrocities at all.

Alin Coman, psychologist at Princeton University, was motivated by media coverage. "We wanted to scientifically investigate the effect of hearing about these incidents at the level of the American public. How will people remember these atrocities? Will they tend to suppress the memory to preserve the positive view of their in-group? Will they conjure potential pieces of information to justify the atrocities?" 

Will they even agree they were atrocities? Or will using the word 'atrocity' over and over again create different memories of the events depending on social group membership? How do you scientifically investigate a subjective area like moral psychology?

You can't, but you can at least catalog how people remember things and document if they change over time. And then see if omissions can lead people to have different memories for the event depending on social group membership. 

Coman and colleagues at the John Jay College of Criminal Justice and New School for Social Research
hypothesized that listeners would more easily forget unrepeated justifications for atrocities that are supposedly perpetrated by someone from an outside group, but would be motivated to remember the unrepeated justifications when the perpetrators are members of their own group – possibly as a way of shielding in-group members from moral responsibility.

To test their hypothesis, the researchers asked 72 Americans to read stories about perpetrators of war atrocities who were either American soldiers (in-group) or Afghan soldiers (out-group). The stories were constructed to resemble actual media reports, and the atrocities in the stories were accompanied by a justifying action – for example, the perpetrator submerged an insurgent's head in cold water because he had withheld information about an upcoming attack.

Participants studied the stories and, after a 10-minute distractor task, they watched a video of another person recounting the atrocities – but not repeating the justifications – from two of the four stories that had been presented. After another distractor task, participants were asked to recall as much as they could about each of the four stories they had studied.

The results showed that participants were more likely to forget justifications for the atrocities committed by Afghan soldiers that had been recounted in the videos compared to justifications for the atrocities that hadn't been recounted. The results indicate that hearing the stories repeated without the original justifications led participants to forget those justifications, just as the researchers expected.

But participants showed no memory impairment for unrepeated justifications when the perpetrator was American. That is, in-group membership made participants more likely to remember the reasons why the soldier committed the act, even though they had not been reminded of those reasons in the video.

"What we learn from this research is that moral disengagement strategies are fundamentally altering our memories," explains Coman. "More specifically, these strategies affect the degree to which our memories are influenced by the conversations we have with one another."

The findings may be important, the researchers argue, because the ways in which people recall justifications could "influence attitudes and beliefs, the willingness to pay reparations, and the level of aggression toward out-groups."