NOT all memories are sweet. Some people spend all their lives trying to forget badexperiences. Violence and traffic accidents can leave people with terrible physical and emotionalscars. Often they relive experiences in nightmares. 

Now American researchers are developing a pill which will help people forget bad memories.The pill is designed to be taken immediately after a frightening experience. They hope it mightreduce, or possibly erase the effect of painful memories. 

In November, experts tested a drug on people in the US and France. The drug stops the bodyreleasing chemicals that fix memories in the brain. So far the research has suggested that only theemotional effects of memories may be reduced, not that the memories are erased. 

The research has caused a great deal of argument. Some think it is a bad idea, while otherssupport it. Supporters say it could lead to pills that prevent or treat soldiers' troubling memoriesafter war. They say that there are many people who suffer from terrible memories. 

“Some memories can ruin people's lives. They come back to you when you don't want tohave them in a daydream or nightmare. They usually come with very painful emotions,”saidRoger Pitman, a professor of psychiatry at Harvard Medical School. “This could relieve a lot ofthat suffering.” 

But those who are against the research say that changing memories is very dangerous becausememories give us our identity. They also help us avoid the mistakes of the past. 

“All of us can think of bad events in our lives that were horrible at the time but they canmake us who we are. I'm not sure we want to wipe those memories out,”said Rebecca Dresser ,amedical ethicist.

 The drug tested on people can ______.