Memory impairment in the weapon focus effect.

Two experiments are reported in which postevent source of misinformation was manipulated within weapon-present and weapon-absent scenarios. Participants viewed slides depicting either a weapon or a newspaper event and then received either incomplete questioning or a narrative. Both postevent sources contained misleading information about a central and peripheral detail concerning either the weapon or the newspaper scenario. With a modified test in Experiment 1, questioning was found to increase misinformation effects concerning the central item, as compared with a narrative, and more misinformation effects were found for the weapon-peripheral than for the newspaper-peripheral item. In Experiment 2, the participants were more likely to claim to have seen contradictory and additive misinformation about the central item in the slides following questioning, and more contradictory and additive misinformation effects occurred for the weapon-peripheral than for the newspaper-peripheral item. The findings are considered in terms of the effects of both postevent and encoding factors on memory.