A psychologist has said the terrorist atrocities in America will be a moment that people will remember for the rest of their lives.

Dr Daniel Wright, a psychologist at the University of Sussex, said people will recall where they were when they heard the news in the same way they recall where they were on hearing Princess Diana had died or President Kennedy had been shot.

Dr Wright, who specialises in the authenticity of eyewitness testimonies, certainly remembers where he was when he heard of the terrorist attacks.

The former native of Los Angeles was in his office when he was received a series of frantic emails from his family naming numerous friends and neighbours of his who were on the two planes that crashed into the World Trade Centre.

He said: "Being here in this country is difficult and I just have to send my best wishes to all the family and friends who have lost loved ones.

"A number of my parents' friends and my old neighbours were on both planes that went down in New York. Everybody is stunned by what has happened. It doesn't seem real. I just keep hoping we will wake up and discover it was all a bad dream but we're soon realising it's not."

Now the search is on for the people responsible, eyewitness accounts could play a big part in piecing together their identity. The terrorists must have hired cars, stopped at service stations, walked through Customs and passed through the lives of hundreds of Americans.

However, Dr Wright believes that mistaken identity is commonplace as embellishments are unwittingly added to memories based on stories heard after the event.

Dr Wright was one of a team of scientists who discredited the theory of an accomplice to the Oklahoma bomber, Timothy McVeigh.

The FBI launched a manhunt to find the suspect after an eyewitness thought he had seen McVeigh with a second man hiring a vehicle before the bombing.

Dr Wright said: "A lot of people reported seeing McVeigh with someone who wasn't there after they heard key witnesses speculating on an accomplice.

"We'll never know for sure now but the FBI agrees that there wasn't an accomplice with McVeigh at the garage.

"The main evidence was from an eyewitness who gave a good description of somebody he thought he had seen with McVeigh but who actually turned out to be somebody who had gone to the garage on his own the next day.

"He identified a person but misidentified where he saw him. People's memories for very important events tend to be fairly good because of people talking about it straight afterwards. But some people suffer post-traumatic stress disorder and have flashbacks months later."