|Our memories are effected by what others think|
Why is eye witness testimony notoriously unreliable? Why is advertising and propaganda so effective? Researchers have shown (.pdf) that our memories can be strongly effected by what we believe others perceive, and these memories can persist even when the manipulation has been disclosed.
Thirty adults watched a documentary style video in small groups. After three days, they were brought back individually and given a memory test to check their accuracy and confidence in what they had seen.
Four days later, they returned to take another memory test, but this time, first they were 'allowed' to see others' answers to the test questions. They were hooked up to a functional magnetic resonance imaging (fMRI) machine and shown false responses, supposedly by the other members of their small group.
The participants were tested again one week later and the results were striking. Over 68% of them had altered their memory of the event to conform with what they thought was the majority. Tests on control groups tested without social manipulation showed only 15% gave wrong answers.
Even after the full scope of the deception was revealed, more than 40% persisted in believing their falsified memory.
This shows how susceptible we are to group-think and peer pressure. It illustrates how easy it can be to manipulate someones' memories by convincing them that the majority saw it differently.
What causes this memory-shift? The MRI performed during the test on day seven provided some clues.
The MRI showed activity in the amygdala region of the brain, which effects how we remember social and emotional events. It seems to act as sort of a gatekeeper and influences the long and short term memories of the hippocampus.
This social and emotional influence over memory may have a survival component, allowing us to accept the guidance of the larger group, even when it conflicts with our own feelings.
Our tendency for 'herd mentality' may have contributed to the survival of our species, but we must guard against social memory-manipulation which could influence our opinions through advertising, propaganda or tolerance for social injustice.