Photographer:Fotograaf: Joey Roberts/ Simone Golob
It is a familiar pattern in crime series: the police investigation into a murder, disappearance or whatever, leads nowhere and detectives are at a loss. And just when they are about to give up, a witness turns up, the case gains momentum and is rapidly solved.
Reality is often less compliant, argues forensic psychologist Melanie Sauerland. “I think that one important interpretation is that we have a lot of faith in our memory. We even overestimate it. Our memory is not static, recollections can change with time and start to lead a life of their own, as it were.” She refers to the 108-year-old work On the Witness Stand by Hugo Münsterberg, a pioneer in applied psychology and then a Harvard lecturer. “To demonstrate the fallibility of memory, he carried out a few experiments in a lecture hall full of students. For example, he had them look at a sheet of paper containing fifty randomly placed black squares for five seconds. Afterwards they had to say how many squares they had seen. The students gave widely varying answers (from 25 to 200, ed.). ”
In short, a witness statement is not necessarily true, but according to Sauerland the cause of that lies initially in the way in which witness statements are taken and not with the witnesses themselves. “Memories can change greatly as a result of external influences. As far as that is concerned, it is the practices and procedures that make a ‘bad witness’. In the murder case of Olof Palme (Swedish Prime Minister, shot dead in 1986, a case that was never solved), his widow had initially given a very vague description. Strangely enough this became more and more specific during the two years that followed. A suspect was also presented. Eventually it was obvious that the development of the description was clearly influenced by photographs shown to the widow by the police.”
During her time as a student, Sauerland was also a witness once. She was a passenger in a bus that collided with a car. “Weeks later my friend and I, after we came forward as witnesses, received a form with all kinds of questions that we could no longer answer properly. For example, whether the road surface was wet or dry. There was nothing on the form stating ‘if you are not sure, don’t guess’. This motivates people to tell as much as they can possibly remember. Even things they don’t remember very well. ”
Many judicial errors are the result of faulty identification in a line-up, an identification test in which witnesses have to recognise the assailant from a line of people. “So much can go wrong in the implementation. There was a case in Spain in 2009, in which an offender was described by two victims as being ‘black’. One black suspect was then put in a line-up with Latino suspects. Everyone who knew the culprit’s description would be able to pick out the black suspect. Even though that man had been nowhere near the crime scene.”
How can we ensure that witnesses and their statements become more reliable? “The Dutch police have a three-hundred-page Handleiding confrontatie (confrontation manual) for line-ups, but this is not legally binding. Although this manual contains useful instructions, not everything in it is correct, Sauerland says. What is important, is that any biases that detectives may have, are corrected. The urge to confirm existing evidence (the investigator bias), for example, can be corrected by organising a double-blind line-up. In that case, the person setting up the line-up on behalf of the police doesn’t know who the suspect is. The witness should also be made aware of this. In general, it is especially important that witnesses aren’t given any extra information and that the questions and instructions are open.” Often, however, Sauerland also hears that eyewitness statements can never be trusted. She feels that this is taking things too far. “As long as the statements are taken under the right conditions and in a responsible way, without suggestion, then they should be reliable.”
This is a series in which academics shoot down popular myths