False Memories on Trial – Embed, Manipulate, Delete
Recent successful efforts by neuroscientists to falsify, change, delete, and improve memories highlight how highly manipulable memories are. This growing awareness is behind the call by memory experts for a protocol to regulate memory manipulation of witnesses by therapists, lawyers, and law enforcement officials.
A popular topic in neuroscience, recent research on memory manipulation is showing how easy it is to tamper with recovered memories. Even brief confirmatory feedback by a law enforcement officer to an eyewitness such as “good job, your description matches a suspect” can change a jury verdict. By increasing the confidence of the witness, confirmatory feedback creates over-belief in what he or she is reporting.
When confirmatory feedback was provided to witnesses in a recent study, those listening to the testimony judged the testimony of accurate and mistaken eyewitness accounts at the same level of credibility. Without the feedback, jurors are two times more likely to believe the true versus the false testimony.
A closer look into recent advances in the neuroscience of memory reactivation may shed light on why interference such as confirmatory feedback creates false testimonies that eyewitnesses often retract at a later date. When study participants were asked to perform repetitive tasks, scientists at the National Institute of Neurological Disorders and Stroke demonstrated that interference with memory reactivation can decrease functional connectivity between the cerebellum and cerebral cortex — two brain areas that communicate through polysnynaptic circuits. An example of such interference is the pressuring of a witness by police to wrongly identify Larry Henderson in a photo as a suspect in a New Year’s day shooting in New Jersey.
In the study, when subjects began to perform the memorized tasks again, the cerebellar-cortical connectivity appeared to be reset. In the case of Henderson, who was later exonerated by DNA, the defense asking the witness over and over if he was too high on cocaine to identify the shooter could be a example of memory reset mechanism. The demonstration of the ambiguity of memory by these studies helps explain the conclusions of a report by the Innocence Project that 75% of the 270 people exonerated by DNA in the United States were wrongfully convicted by mistaken eyewitness testimony.
Regional brain connectivity deficits have also been shown to affect working memory in schizophrenics and psychopaths. These memory deficits may explain why psychopaths are more likely to lie in court. While studies have shown that we have memory bias towards emotional versus neutral events and their contexts, psychopaths’ memories are disassociated from the context, which would lead to less accurate memories.
Following a 2012 ruling of the New Jersey Supreme Court involving the Henderson case, more jurors are being educated on the scientific evidence for how memory works. We are learning that memory is more like real-time streaming than a video recording, and is continuously edited by our perceptions, imagination, experiences and a myriad of other interfering factors. Naturally, jurors are beginning to question the authenticity of memories.
Neuroscientists are getting closer to the day when, as expert witnesses, they will be able to independently and definitively identify if a memory is authentic. Acting as neural detective to identify if a memory has indeed existed, brain imaging can compare subjective versus objective memories and whether they are new or old memories. The idea is to track brain patterns to determine if a memory is mnemonically perceived as having been previously experienced. Indeed, a groundbreaking 2010 study by Stanford neuroscientists showed that brain imaging can be used to determine whether a witness’ recognition of a face is old or new.
Of equal concern to court cases is the manipulation of memories post-trauma, especially during therapy. Carol Felstead, for example, received “thought stopping” treatment to dampen her memories of satanic abuse. Scientists have employed numerous techniques to manipulate memories. Those involving the hippocampus, where memory traces may be replayed and reinforced or blocked and impaired, include brain stimulation to alter memories, the reactivation of memories through cues during sleep, and medication. These same techniques have also been used to treat post-traumatic stress disorder and depression after traumatic events.
Longer term, neuroscience is striving to retrieve perfectly intact memories. Mental time travel, a fascinating area formerly in the realm of science fiction, offers the greatest potential among the latest developments in memory research. When neuroscience can retrieve a memory intact in the context in which it was recorded, the credibility of eyewitness testimony will be restored.
Some of this new research is expected to surface in false memory cases slated for 2014 as neuroscience-based evidence takes center stage in trials involving eyewitness testimony. Current advances in brain imaging allowing us to ascertain the veracity of recovered memories (whether they are new or old) could soon vindicate many victims and falsely accused, as well as illuminate and regulate the practices of mental health and law enforcement officials.
Until then, the growing awareness of how easily our memories can be manipulated by ourselves and others is hastening the need for the strengthening of eyewitness questioning protocols to prevent distortion and ensure the contextual preservation of memories.
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