Intentional retrieval suppression can conceal guilty knowledge in ERP memory detection tests

Brain-activity markers of guilty knowledge have been promoted as accurate and reliable measures for

establishing criminal culpability. Tests based on these markers interpret the presence or absence of

memory-related neural activity as diagnostic of whether or not incriminating information is stored in

a suspect’s brain. This conclusion critically relies on the untested assumption that reminders of a crime

uncontrollably elicit memory-related brain activity. However, recent research indicates that, in some

circumstances, humans can control whether they remember a previous experience by intentionally

suppressing retrieval. We examined whether people could use retrieval suppression to conceal neural

evidence of incriminating memories as indexed by Event-Related Potentials (ERPs). When people were

motivated to suppress crime retrieval, their memory-related ERP effects were significantly decreased,

allowing guilty individuals to evade detection. Our findings indicate that brain measures of guilty knowledge

may be under criminals’ intentional control and place limits on their use in legal settings.