Suppressing Unwanted Autobiographical Memories Reduces Their Automatic Influences: Evidence From Electrophysiology and an Implicit Autobiographical Memory Test

The present study investigated the extent to which people can suppress unwanted autobiographical memories in a memory-detection context involving a mock crime. Participants encoded sensorimotor-rich memories by enacting a lab-based crime (stealing a ring) and received instructions to suppress memory of the crime in order to evade guilt detection in a brain-wave-based concealed-information test. Aftereffects of suppression on automatic memory processes were measured in an autobiographical Implicit Association Test. Results showed that suppression attenuated brain-wave activity (the P300) associated with crime-relevant memory retrieval, which rendered waveforms from innocent and guilty participants indistinguishable. However, the two groups could nevertheless be discriminated via the late-posterior-negative slow wave, which may reflect the need to monitor response conflict arising between voluntary suppression and automatic recognition processes. Finally, extending recent findings that suppression can impair implicit memory processes, we provide novel evidence that suppression reduces automatic cognitive biases often associated with actual autobiographical memories.