Elizabeth Loftus, answered from the texts and cited to the page.
Postevent information is simply any information presented to a witness after the to-be-remembered event is completely over.1 That sounds straightforward, but the consequences are not. What the research shows, repeatedly, is that people take this later information and integrate it into their memories — supplementing what they actually saw, altering it, or adding details they were never present to witness — until it becomes, in a genuine sense, part of their recollection.2
A witness can end up highly confident that they saw something they only heard about afterward.3 The channels through which it enters are various: a question asked during police interrogation, a conversation overheard in the street, a newspaper account read the next morning.4 Bird's classroom study is an early illustration — students who read an error-riddled newspaper account of a lecture later reproduced those errors on an exam, apparently convinced they had learned the material from the instructor directly.5
The postevent source had quietly displaced the original one. Beyond merely filling gaps, this kind of information can cause entirely nonexistent details to become incorporated into a previously acquired memory.6 And it is not a minor effect confined to peripheral details. The false-memory work that followed showed people could be led to believe they had been lost in a mall, attacked by animals, or hospitalized — events that never happened at all.7
The practical implication for any identification case is direct. When a witness views a photograph of a suspect and then later sees that same person in a lineup, the familiarity they feel may owe more to the photograph than to the original crime.8 That enhanced familiarity is invisible to the witness — and to the jury.
Postevent information simply refers to information that is presented in some way to a witness after a to-be-remembered event is completely over.Eyewitness Testimony, pp. 247–248
They will take this information and integrate it into their memories, either supplementing their memory or altering or adding to their memories, and it now becomes, in a sense, a part of their recollection.Eyewitness Testimony, pp. 247–248
a witness can be very confident — that the witness actually saw what the witness has only heard about.Eyewitness Testimony, pp. 247–248
It can also come in in the course of overhearing a conversation or engaging in a conversation or reading a newspaper article.Eyewitness Testimony, pp. 247–248
Those who had read the article made many more errors on the exam; they remembered the erroneous information that was in the newspaper, assuming that they had learned it from the instructor's original lecture.Eyewitness Testimony, pp. 71–72
Postevent information can not only enhance existing memories but also change a witness's memory and even cause nonexistent details to become incorporated into a previously acquired memory.Eyewitness Testimony, pp. 71–72
Researchers devised procedures that could make people believe and remember that earlier in life they had been hospitalized when they had not, that they had been lost and frightened in a mall when they had not, that they had been victims of vicious animal attacks as children even though they had not been.Eyewitness memory for people and events (A M Goldstein (Ed.) Handbook of Psychology Vol 11 Forensic Psychology (I.B Weiner, Editor-in-Chief) New York- John Wiley & Sons, pp 149-160, 2003), pp. 4–5
postevent viewings of a suspect's likeness, either by photograph or in person, can help to make someone look familiar later. That enhanced familiarity can lead to a false identification of the suspect as the person who committed the crime.Eyewitness memory for people and events (A M Goldstein (Ed.) Handbook of Psychology Vol 11 Forensic Psychology (I.B Weiner, Editor-in-Chief) New York- John Wiley & Sons, pp 149-160, 2003), pp. 4–5