✒ Experiments suggest that when witnesses to a simulated crime are confident of having identified the suspect in a later photo line-up, they are almost always correct. Similarly, if they are sure the suspect is not present, that is likely to be right too.
However, just as one of the unavoidable frustrations of quantum mechanics is that measuring a particle’s position or energy irretrievably alters it, something similar happens to memories.
Assessing people’s faces for a possible match, lodges them in a witness’s memory. Once that has happened, anything from police encouragement to the high-pressure environment of a courtroom can twist subsequent attempts at recollection.
The conclusion:
Eyewitness evidence is more reliable than has been thought. But only the first time you ask.