Watch this video about 9-11 flashbulb memories on HowStuffWorks. Brain researchers have found that closeness counts when it comes to how strong our memories are. While everyone remembers where they were on 9-11 when they heard the news of attacks on the World Trade Center, those who were close to the scene formed memories that still provoke the brain's response to danger. See how the human memory works in this video from ScienCentral.