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Existing research shows that the postevent misinformation effect on eyewitness memory can be successfully reduced by retrospective warnings. Exploring potential costs of such warnings, we investigated whether warned eyewitnesses might overcorrect for misinformation influence from the postevent source. Across three experiments, warned participants recognized relatively fewer event items that were truthfully described in a postevent narrative ("tainted" event items) than did unwarned participants. This tainted truth effect was obtained for peripheral but not for central event items (Experiments 1-3); it persisted when the warning took the form of an explicit source-monitoring instruction (Experiment 2) and when the accessibility of the postevent information was increased (Experiment 3). Overall, the effect was stronger with a socially framed warning than with more direct, explicitly phrased warnings. The findings suggest that the tainted truth effect is due to more careful monitoring for information from a suspicious postevent source rather than mere memory impairment.
The susceptibility of human memory to external influences has stirred considerable, sometimes heated, debate among researchers, clinicians, and practitioners, partly because it can have profound implications for real-life issues, such as the reliability of eyewitness testimony, or the possibility of recovering long-forgotten memories of distressing past experiences (e.g., Roediger & McDermott, 2000). Responding to the potentially disconcerting consequences of memory's fallibility, researchers have investigated ways of reducing their impact, especially the distorting effects of postevent misinformation (e.g., a postevent narrative containing false details) on eyewitness memory (e.g., Chambers & Zaragoza, 2001; Christiaansen & Ochalek, 1983; Eakin, Schreiber, & Sergent-Marshall, 2003; Echterhoff, Hirst, & Hussy, 2005; Greene, Flynn, & Loftus, 1982; Wright, 1993; also see Dodson, Koutstaal, & Schacter, 2000; Loftus, 2005). There is now sufficient evidence that the postevent misinformation effect can be successfully mitigated by warnings presented either before or, perhaps more interesting, after exposure to misinformation (e.g., Chambers & Zaragoza, 2001; Eakin et al., 2003; Echterhoff et al., 2005; Lindsay, 1990; Wright, 1993). For instance, when eyewitnesses are warned retrospectively that a co-witness embellished her postevent account with false misleading details, they can resist reporting these details (Echterhoff et al., 2005).
Existing research has primarily focused on the beneficial consequences of warnings on memory performance (i.e., the resistance to misleading influence and the reduction of false memories). We are interested here in the...