You answer a knock on the door and find yourself confronted by two police detectives. The officers probe you for your whereabouts the day before. A girl was sexually assaulted, and you are the prime suspect. Eye-witnesses place you at the scene. Later, the victim picks you out in a line-up as the thug who viciously assaulted her. "I will never forget that man," she cries. "His face is burned into my memory forever."
You are convicted at trial and condemned to jail. Your life is ruined because memory is fallible, and jurors, like most people, paradoxically labor under many mistaken notions about memory. Anthony Powell spent 12 years in jail on the basis of eye-witness testimony, including the victim who recognized him as her attacker in a line-up of suspects, until DNA evidence exonerated him. The same forensic evidence pinpointed the true attacker who was also a rapist in two other attacks.
A recent survey of the U.S. population by psychologists Daniel Simons and Christopher Chabris at the Beckman Institute in Chicago reveals that most people harbor many mistaken beliefs about memory. The scientists surveyed 1500 people and compared their responses to questions about memory with answers provided by a consensus of scientific experts, who were professors with more than 10 years of memory research.
Fallacy number 1, Amnesia: People suffering from amnesia typically cannot recall their own name or identity. 83% of the respondents agreed; all 16 experts disagreed. This fallacy can be excused because most respondents do not have first-hand knowledge of amnesia. What most people know about this subject likely originated from The Bourne Identity and other movies.
Fallacy number 2, Eye-witness testimony: 63% of people agree that human memory works like a video camera, accurately recording the events we see and hear so that we can review them later. None of the experts agree. Memory is a fabrication-a reconstruction, not a recording. Our minds are very selective about what we remember, and they have to be. Most of what we experience will be useless in the future and is best forgotten. Memory can be distorted by subsequent events, as experiences are replayed and memories become reconsolidated and integrated with existing information in the brain. If jurors believe that memory works like a video camera, they may rely too heavily on eyewitness testimony.
Fallacy number 3, Hypnosis: About half (55.4%) of respondents believe that hypnosis is useful in helping witnesses accurately recall details of a crime. None of the experts agreed, but two experts indicated that they did not know the answer. Here the courts are ahead of the general public, because courts already treat hypnosis-based recollections as untrustworthy. Here's a clue: "When you open your eyes you will forget everything..."
Fallacy number 4, Memory is permanent: 48% of the general public believe this to be true, something the experts know is false. How can this false belief be so common? Clearly, everyone has forgotten all sorts of facts, lost their house key, and misplaced their cell phone; how could almost half of the public believe memory is permanent? After a lost fact is provided or a misplaced item is found, we are rarely astounded by the discovery, but gently reminded of the latent memory. This suggests that memories are permanently stored in the brain, but that recalling them can sometimes be a problem.
The experts would view this differently. This common experience shows that memories are reconstructed, because fragments of experiences are not memories at all. Bits of information, even if permanently stored in the brain, would be as incoherent as a movie filmstrip sliced to bits. Memories must be placed in context and in sequence to make any sense.
The gluing and pasting of stored experiences into a memory is precisely where memory can go awry.