"Infectious" Memory

We all know that people tend to conform their thinking and beliefs to those of their social group. We call this  peer pressure or “group think.” What many do not realize is that similar effects occur with what we remember. The conformity effect of group think and “infectious” memory is the reason it is so frustrating trying to argue over polarized positions, like politics or religion. In politics for example, conservatives, believing in lower taxes, recall that Regan  lowered taxes, while apparently forgetting that the rate then was an outrageous 90%, counting all taxes. I have heard liberals, believing in higher taxes, say that lowering taxes does not raise federal revenues and that Regan actually raised taxes. In other words, people tend to remember what supports their belief system and forget what does not It’s more comfortable intellectually not to be confused by the facts.

When people reminisce in groups, like family reunions, political rallies, or other social groups, they tend to remember many of the same things, even when some of those things are factually wrong.  Think about how people tell stories. Most of us embellish the story to make it more interesting. With repeated telling, the embellishments gradually get incorporated into the story teller’s memory, even to the point where it becomes a different story. This is an example where the storyteller has infected his own memory. But the group of listeners add their own small embellishments, some of which may even be wrong, to the recollection, and these provide memory infection from the group.

Group contamination of remembered fact can have serious consequences, ranging, for example, from political and religious intolerance, prejudices of all sorts, and wrongful criminal convictions resulting from false eyewitness testimony.

Not surprisingly, infectious memory is not only caused by faulty memory processes in brain but also help create the faulty brain processes. Researchers in Israel and Great Britain teamed up to use brain imaging to study infectious memory. They tested how subjects remembered from recollection of others.

The strategy was to show a movie to groups of five and then test for individual recall.  The first memory test revealed how much the person initially remembered and how confident the person was about the recall accuracy.  Then, a second test of recall occurred after attempts to socially manipulate the memory. Finally, a third memory test occurred after the  social manipulation was removed. The social manipulation,  given four days after Test 1, involved presentation of fabricated recollections of the movie from the other four group members.

A given subject tended to conform his own memory to that of the group, even when the group’s memory was fabricated by the experimenter. With Test 2, after social manipulation with false information, subjects conformed their memory to that of the group’s recall in 68.3%  of the test trials, versus only 15.5% in the non-manipulated condition. Test 3, performed 11 days later, revealed that memory error still persisted but at a lower rate. Even so, errors were significantly greater in the socially manipulated group than in the non-manipulated group.

Brain imaging (functional MRI) revealed that infectious memory modified the brain activity representation of memory. That is, whether a person would form a long-lasting memory that conformed to erroneous memories of the group could be predicted by a particular imaging signature of increased activity in the two major areas known to form memories, the amygdala and the hippocampus. Such increased activity was only seen when the infected memory became long-lasting, not for memories that did not survive.

One might question why humans have this tendency for group think and group memory. Presumably, it has value because “two minds are better than one,” that is, most individuals can benefit from the thinking of others.  Learning should be more efficient and accurate. However, serious problems can arise when the group is wrong, as in religious cults, authoritarian governments, and social prejudices.

All of this makes a strong case that you should not spend all your time with people who think like you do. Likewise, what you read and watch on TV should be diverse. If you are religious, maybe you should read both the Bible and the Koran (a little Buddhism might help too).  If you are a news junkie, maybe you should watch both Fox News and the mainstream networks. If all your friends are in the same ethnic or socio-economic group, maybe you need some new friends..I am not arguing that you should be all things to all people, just that your opinions and the remembered basis for them be more completely informed and accurate.

Source: Roediger, H. L. III and McDermott, K. B. 2011. Remember when? Science. 333, 108-111.