Misinformation Effect

The misinformation effect, extensively studied by Elizabeth Loftus and colleagues since the 1970s, demonstrates that memory for an event can be altered by information encountered after the event. In the classic paradigm, participants view an event (e.g., a car accident), then receive misleading post-event information (e.g., a question mentioning a "stop sign" when the actual sign was a yield sign), and subsequently misremember the misleading information as part of the original event. The effect is robust, replicable, and has profound implications for the reliability of eyewitness testimony.

Key Structures

• Eyewitness Memory — The study of how well people remember witnessed events, including the factors that produce accurate testimony and the conditions that lead to memory errors and wrongful identification.
• Elizabeth Loftus — The world's leading researcher on the malleability of human memory, whose work on the misinformation effect and false memories has transformed the legal system.
• Eyewitness Testimony — The cognitive psychology of eyewitness evidence — how encoding, storage, and retrieval processes shape the accuracy and reliability of legal testimony.
• Recognition — A form of memory retrieval in which a previously encountered item is identified as familiar when presented again, typically easier than recall because the target item itself serves as a retrieval cue.

Classic Demonstrations

Loftus and Palmer (1974) showed that the verb used in a question about a car accident influenced speed estimates: participants asked how fast cars were going when they "smashed" gave higher estimates than those asked about "contacted." A week later, those in the "smashed" condition were more likely to falsely remember seeing broken glass. Loftus et al. (1978) demonstrated the stop sign/yield sign paradigm, showing that post-event questions containing false presuppositions led participants to adopt the misinformation. These studies established that memory is not a fixed recording — it is reconstructive and susceptible to contamination.

Mechanisms and Debates

Three main accounts explain the misinformation effect. The memory impairment hypothesis proposes that misinformation overwrites or degrades the original memory trace. The source monitoring failure account suggests that people remember the misinformation but confuse its source, attributing post-event information to the original event. The retrieval blocking account proposes that misinformation competes with and blocks access to the original memory. Current evidence supports source monitoring failure as the primary mechanism in most cases, though genuine memory alteration may also occur under some conditions.