The misinformation effect occurs when misleading information presented after an event is incorporated into a person’s memory of that event. The original memory is altered or supplemented by the later material.

Elizabeth Loftus and colleagues demonstrated the phenomenon in a series of experiments. Participants who watched a film of a traffic accident and were later asked questions containing false details—such as a yield sign instead of a stop sign—often incorporated those details into their subsequent reports. The effect is stronger when the misleading information is subtle, when it comes from a credible source, or when time has passed since the original event.

The findings have major implications for eyewitness testimony. Memory is not a fixed recording; it is reconstructive and open to influence. Interview techniques that avoid leading questions and that separate the witness’s own recollection from external suggestions help reduce contamination. The misinformation effect also appears in everyday settings whenever conversations or media reports reshape what people later believe they experienced.

What we remember is partly what happened and partly what we were told afterward.