Can eyewitness testimony be trusted?


Losing memory occupies everyone's mind at some stage but perhaps a greater concern is relying on our own or someone else's memory when justice hangs in the balance. This issue boils down to five words: can eyewitness testimony be trusted? What we will see here is quite shocking: accurate memory may be good for a one-time recall only.


All memories have context, although we are not fully aware of it at times. Thinking of someone’s name – an example of declarative memory – replays contextual information, such as a face, a situation and a feeling. Explicit memory deals with concepts such as what a chair means or the difference between hot and cold. Procedural memory enables us use a toaster in a kitchen without having to figure out how it operates each time we encounter it. Basically, memories are sensory images networked with concepts.


Can eyewitness testimony be trusted?

Mood, or state of mind, has a great deal of influence on the construction and retention of such a network. Way back in 1908 two psychologists, Robert Yerkes and John Dillingham Dodson, concluded that arousal helps performance. The study used mice and demonstrated a link between stronger stimuli and better learning (memory). It applies for us as well: we all run faster on hot sand; and perhaps bring flip-flops next time around.


Stress plays a role in performance, learning and memory recall too. The more anxiety that is felt, the poorer the memory recall. A traumatic event can even result in complete amnesia. A lady once told me about her experience with this. She had been abused terribly, as a young child, and only believed it when shown a newspaper article from that time, detailing the men involved and the subsequent investigation.


Fear and stress can also corrupt memories when they are made, with ingrained biases taking over. Details are missed or even manufactured. This has been demonstrated through the predisposition for Caucasians to see weapons in the hands of those of colour, mistaking, for instance, a cell phone. It is a matter of seeing what is expected rather than what is actually there.


For memories that can be recalled accurately, it feels comfortable to think that these are hard-wired. Scientific observation tells us that new connections grow in the brain. These physical traces remain for life, unless dementia gets in the way to block retrieval via plaques or tissue is destroyed, taking part of the physical platform away, like the burning of the Library of Alexandria, but is this the whole story?


Biology is squishy and prone to change. Every time an experience is recalled it becomes plastic or malleable again. The book of the past in our minds is more like play dough than a printed page.


Once triggered as a recall, it seems that memory can be adjusted fairly easily. Back in 2015 this was shown in spectacular fashion when mice had new memories implanted within existing old ones. The researchers waited until a certain pattern of brain activity appeared during sleep. This indicated that a place-based memory was replaying. They then introduced some new information through small electrical pulses about the benefit of visiting a new place. The process had the mice running to this new location the next day, expecting to find food there since this 'image' now existed as part of their original memory.


If it were possible to rewrite a memory only by using electrodes, perhaps there would be no cause for alarm. However, there are plenty of studies in humans that show suggestion has a similar effect. When we recall a memory, it becomes plastic and open to manipulation. Discussion can then result in the memory being laid down again in a changed form. This is the basis of the false-memory debate that has undermined court-based eyewitness accounts. Elizabeth Loftus is the matriarch of this 'misinformation effect', effectively representing accused clients, for the win in court.


The effect of manipulation appears clear from studies carried out by Loftus and her contemporaries. This even involves successfully manipulating memories about committing crimes which never occurred; a modification that can be effective in about 70% of the population!


Since memories created in a mood of stress and fear, or adjusted later during discussion can be suspect, what might be done to make better memories and keep them accurate and safe? There is the option of keeping a diary for everyday memories, to protect their detail. As for unexpected incidents, using a phone app such as iWitnessed can capture the moment before it becomes corrupted by discussion. Such protected material may then be admissible as a statement for court. At any rate, it seems important to avoid discussing an incident before recording or writing it down in our own words.


Can eyewitness testimony be trusted? Well, like keeping a good wine cellar, it appears to depend on how the memory is produced, handled and stored. And for more on the topic of memory see my new book, Design Your Mind: Everyday tools to make every day better.


Till next time – B.W. Cribb

#Memory #Eyewitness #DesignYourMood

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