If a person witnesses an event, but later receives information that contradicts what they witnessed, their memory can be impaired. An experiment was conducted to determine whether memory impairment due to misleading post-event information can be eliminated or reduced by making it easier to discriminate between the witnessed event and the post event. In addition, the study determines whether a long versus a short delay between the introduction of post-event misinformation and the test of event memory will reduce the effect of misleading post-event information. Finally, the impact of both discrimination and delay on one particular theoretical mechanism proposed to explain memory impairment, retrieval blocking, was examined. Results indicated that, at test, retrieval blocking was alleviated both when participants could discriminate between the event and post event, and after a 48-hour delay. Two competing hypotheses are reviewed and discussed as to theoretical explanations for the misinformation effect and retrieval blocking.

Exposure to misleading post-event information can result in impaired memory for the original event. Two theoretical mechanisms (i.e., retrieval blocking and source misattribution) have been proposed as explanantions for the occurrence of the misinformation effect. The impact of context on the occurrence of these errors has been examined to determine if changing the context between events reduces the misinformation effect. Previous findings indicate that context plays a different role in each of these mechanisms; however, experimental differences in the paradgms used to examine retrieval blocking and source misattribution have made comparisons between these mechanisms difficult. The present study examined the role of context in eyewitness memory using the same materials, manipulations, and procedures to determine if context does, in fact, have a different impact on these mechanisms. Results indicate that changing the context between events reduces the occurrence of source misattribution but does not ameliorate the impact of retrieval blocking.

According to the misinformation effect, exposure to misleading post-event information typically impairs memory for the original event. Such findings are generally obtained in the laboratory using the misinformation paradigm. One component of the typical misinformation paradigm is that most of the post-event information corresponds with the event information, implying that the context surrounding the misinformation is the same as that of the original event. The present experiments investigated the role of such implication by presenting the experimental conditions with misleading items in a narrative that differed from the original event (a slide show) to varying degrees; both the location of the event and the persons described were varied. A significant misinformation effect was obtained regardless of implication condition. Even when a relationship between the witnessed event and post-event narrative was not implied, memory was impaired by the presence of misleading information. The findings are discussed in terms of retrieval blocking.