TED視聴：人の記憶は都合よく書き換えられる不確かな主観であって、客観的事実ではないようだ。

A memory that is set with an emotion. For example, we may have a bias to rewrite a memory of an old trip that was not fun because of the emotion that it was fun or to assume that a person who broke up a fight behaved badly.

The memory of dating with someone we loved is sweet and sour and organized as a pleasant memory. But the droll feelings would be forgotten.

Memory is an uncertain thing.  We should understand and remember this fundamental aspect of memory and forgotten mechanism.

In a study in the 1990s, participants recalled getting lost in a  shopping mall as children. Some shared these memories in vivid detail – one even remembered that the old man who rescued him was wearing a flannel shirt. But none of these people had actually gotten lost in a mall. They produced these false memories when the psychologists conducting the study told them they had gotten lost, and although they might not remember the incident, their parents had confirmed it. And it wasn’t just one or two people who thought they remembered getting lost – a quarter of the participants did. These findings may sound unbelievable, but they actually reflect a very common experience. Our memories are sometimes unreliable. And though we still don’t know precisely what causes this fallibility on a neurological level, research has highlighted some of the most common ways our memories diverge from what actually happened. 

The mall study highlights how we can incorporate information from outside sources, like other people or the news, into our personal recollections without realizing it. This kind of suggestibility is just one influence on our memories. Take another study, in which researchers briefly showed a random collection of photographs to a group of participants, including images of a university campus none of them had ever visited. When shown the images three weeks later, a majority of participants said that they had probably or definitely visited the campus in the past. The participants misattributed information from one context – an image they had seen – onto another – a memory of something they believed they actually experienced. In another experiment, people were shown an image of a magnifying glass and then told to imagine a lollipop.  They frequently recalled that they saw the magnifying glass and the lollipop. They struggled to link the objects to the correct context – whether they actually saw them, or simply imagined them.

Another study, where a psychologist questioned over 2,0000 people on their views about the legalization of marijuana, highlights yet another kind of influence on memory. Participants answered questions in 1973 and 1982. Those who said they had supported marijuana legalization in 1973, but reported they were against it in 1982, were more likely to recall that they were actually against legalization in 1973 – bringing their old views in line with their current ones. Our current opinions, feelings, and experiences can bias our memories of how we felt in the past. 

In another study, researchers gave two groups of participants background information on a historical war and asked them to rate the likelihood that each side would win. They gave each group the same information, except that they only told one group who had actually won the war – the other group did not know the real-world outcome. In theory, both groups’ answers should be similar, because the likelihood of each side winning is not affected by who actually won – if there is a 20% chance of thunderstorms, and a thunderstorm happens, the chance of thunderstorms does not retroactively go p to 100%. Still, the group that knew how the war ended rated the winning side as more likely to win than the group that did not. All of these fallibilities of memory can have real-world impacts. If police interrogations use leading questions with eyewitnesses or suspects, suggestibility could result in incorrect identifications or unreliable confessions. Even in the absence of leading questions, misattribution can lead to inaccurate eyewitness testimony. 

in a courtroom, Even if the jury is ordered to disregard the evidence, it can be difficult to comply with the order. In the medical world, if a patient seeks a second opinion and the doctor giving the second diagnosis knows what the first diagnosis was, that knowledge can become a bias in making the diagnosis. Human memory is not a perfect representation of reality, but subjective knowledge. That is not necessarily a bad thing, but problems arise when we treat memories as truth and do not accept the fundamental truth about the nature of memory.