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Post No.: 0275eyewitness


Furrywisepuppy says:


What we each perceive as reality is a subjective yet elaborate reconstruction of reality – of minds interpreting information from senses, coloured by personal expectation and open to influence. ‘Naïve realism’ is the tendency to believe that we personally perceive the world objectively and if anyone disagrees with us then they must be the ones who are uninformed, irrational or biased.


We tend to think we always see the entire picture in front of us in all of its detail, but we actually only see small narrow patches of it where we directly focus on, and fill the rest of the picture in with our minds (hence effects like change blindness). Memory, as well as sight (the fovea only covers a very small area at a time), is fragmentary but the brain naturally fills in the gaps using assumptions to create a perceptually coherent picture and story.


There is indeed a correspondence between what we experience and the true objective reality, and it’s totally convincing, but it’s far from perfect, hence how we can fall for visual illusions – even when we know they are visual illusions (e.g. the sensation of 3D space in virtual reality games)! Two people can legitimately experience the exact same event quite differently. The ‘Rashomon effect’ is when different people give different, often contradictory, interpretations of the exact same event. Woof.


This means that our own personal experience of the world shouldn’t always be trusted. People don’t have to deliberately lie in order to get memories wrong. We make memory errors all of the time, but most of the time the stakes aren’t high so we quickly ignore them and are therefore blind to how frequently they actually occur – which leads us to become more disbelieving that we can make fundamental memory errors when the stakes are high. Memories are fallible even regarding salient or shocking ‘unforgettable’ events. People can even temporarily forget being involved in some minor car accidents altogether when they judge other people’s driving! Or they may even ‘remember’ entire false, planted memories.


So eyewitness reports can sometimes be incomplete, unreliable and partially constructed, and can be manipulated by others. Eyewitness accounts are important in criminal cases and often match other evidence, but eyewitness memories are not as accurate as most people expect them to be. Memory is an active, creative and (re)constructive process and not a passive process like pressing ‘record’ then ‘play’ on a video player.


We can be quite confident in what we (mis)remember too, thus confidence and vividness of memory are not reliable indicators of a good memory. Memories are more fragile and vulnerable to distortion than most people expect. We often lack insight into the (in)accuracy of our own memories. Factors such as viewing conditions, duress, elevated emotions and unconscious biases all influence the visual perception experience. Perceptual experiences are stored by a system of memory that is highly malleable and continuously evolving – neither retaining nor divulging content in an informational vacuum. Unknown to the individual, memories are forgotten, reconstructed, updated and distorted.


The ‘wrong time-slice error’ occurs when – asked to recall a memory about a particular event – people respond with a description of an event from a completely different time. People can relatively easily remember if they saw something but can easily misremember when they saw it. This means that people may have indeed seen a fluffy face before but misremember when they saw that face – and leading questions may make matters worse by suggesting to an eyewitness that this face was present at the scene of a crime. We can also misremember where we saw something. Remembering or processing what something is/was (recognition) and where you encountered it (spatial) uses different brain pathways.


‘Narrative construction’ is when people reconstruct the gaps in the recall of an event based on a script (a general idea of what usually happens or is expected to happen in a particular situation), such as incorporating a presumed cause to an effect, to create a reasonable and more coherent account of the entire event. But these are based on assumptions, and we are often poor at differentiating between induction, abduction and deduction.


Hesitations, tentativeness, backtracks and revisions of recall may give the impression that a person is trying to fabricate a logical sequence of events; perhaps even constructing the memory or story as they’re going along – but these things don’t necessarily mean that the person is consciously trying to lie. An eyewitness may instinctively try to make their recall seem more reasonable and coherent because it would sound more like an accurate memory to most observers. But this can lead to errors. Real unembellished recall is often genuinely choppy.


Encoding (whether one acquired the memory in the first place), storage (whether one can keep that memory intact over time) and retrieval (whether one can access that memory at a particular future time) – errors can occur at any of these three stages…


The ‘weapon focus effect’ is, when a weapon is involved (or other great threat or focal point), the encoding of other peripheral cues by an eyewitness (e.g. the physical appearance of the criminal) is sometimes impaired because attention is fixated upon that weapon. Magicians routinely use this kind of principle to divert attention and create surprises too! Factors that must be taken into account also include the duration of the original event, the amount of time that passes between the original event and retrieval, the level of threat, and how accustomed the eyewitness is to seeing such weapons and situations.


It’s also startlingly easy to modify, interfere or tamper with memories in storage, either inadvertently or deliberately by introducing misinformation, such as accidentally listening to an inaccurate report of a crime in the media, chatting with another eyewitness who misremembered the original event, or false information heard during gossip. Most people conform to the crowd in order to not risk standing out for possibly being wrong (for most people, it feels safer to be wrong within a crowd than wrong alone, or alone at all), especially if the source that is giving the misinformation sounds more confident that they’re right. People also want their accounts to sound more complete too so they may incorporate that (mis)information into their own subsequent accounts.


Even when told that the other source may be incorrect, if a lot of time has passed since the misinformation was planted, it can still be difficult to ignore it and un-contaminate one’s memory when the original information has been supplanted. This ‘misinformation effect’ can happen even if the situation was very personal and stressful to the eyewitness.


TV footage can interfere with memories because of the strength and dominance of visual information. Visual images can bring about memory errors because they are easy to generate, modify and remember. And most of us think ‘seeing is believing’.


As briefly alluded to in Post No.: 0257, memories can also be influenced during retrieval by a careful use of question wording. For example, if we ask at what speed the car smashed into the other vehicle, it might result in different responses compared to if we ask at what speed the car bumped into the other vehicle. It’ll also suggest that glass must’ve been strewn across the scene. So even without factually incorrect information being planted, a memory can be influenced through leading questions. And therefore we need to try to consciously ignore such planted words and other subjective adjectives or adverbs like ‘that savage man’ or ‘he brutally struck’, to focus solely on the ascertainable facts.


Forensic hypnosis doesn’t hold up in formal experiments. There are lots of anecdotes for it working but that might be down to the increased suggestibility when people are under hypnosis, which means people’s fuzzy threshold for what they consider is a genuine memory lowers i.e. it may increase the number of correct memories recalled but also increase the number of false memories (false positives) ‘recalled’ too. Anecdotal evidence also tends to fall foul of confirmation bias and cherry-picking i.e. the times hypnosis seems to work (by chance) are always reported but the (more frequent) times it doesn’t are ignored or dismissed.


You can get a similar effect to hypnosis by simply asking people to guess an answer when they’re uncertain about a memory judgement i.e. by being told to err on the side of assuming that a memory is correct when they’re actually unsure! People then become more confident of the correctness of their false memories in a later test of their memory, even though they were initially unsure. It’s like planting a seed of doubt but in reverse – we’re planting a seed of certainty when something was actually uncertain. The very act of guessing (and therefore visualising a picture of the guess in your mind) can have the effect of cementing a false memory as being true too. Real and imagined visual memories can be difficult to differentiate without supporting information (e.g. knowing that it happened when one was in bed thus one can work out that it was just a dream). Hypnosis may be useful in generating leads in investigations when no other leads are forthcoming though, as long as we understand that there’s a high chance of some or most of it being inaccurate – the information gathered from hypnosis is not reliable as evidence in themselves.


One practical way to improve recall is to reinstate the context of the event. For example, if you come up with a great idea when on the toilet but forget it once you leave the bathroom – try going back to the bathroom and maybe even go through the sequence of events you can remember around when the thought was generated to ‘jog the memory’ or ‘relive’ it again (well you probably don’t need to force out a pee or poo again if you don’t need one – just sit on the toilet seat… or maybe you do(?!)) It often happens – we leave a room then forget what we’re about to do – so we need to physically retrace our steps to retrace our thoughts.


Recall the surrounding circumstances associated with a detail and you’ll more likely remember that detail. So try going through the motions again in careful detail with the same props and in the location it occurred, as if re-enacting the event. It’s like it’s far easier to remember the sequence of actions to take before riding off when on an actual motorcycle than when behind a desk. If going to the exact scene is impossible as an eyewitness then try recalling all of the periphery sights, sounds, smells and goings-on of the situation and location in detail.


A memory tied to a unique or unusual object (or sight, sound, smell or event) will likewise increase the probability of recalling that memory when re-presented with that object. Memories are about associations so make use of these associations with each of your physical senses.


Eyewitness testimonies are crucial in the catching and convicting of criminals as a part of the suite of evidence that can be used during a trial. But there are ideal protocols such as avoiding talking with other eyewitnesses about what they apparently saw or heard to prevent cross-contamination, and avoiding listening to pre-trial publicity where often the media has already made up its own mind about the wider conclusions of the event.


If you find yourself in the midst of witnessing a criminal act – try not to panic or fixate on weapons, stay out of harm’s way if possible (don’t block the criminal’s exits), defending yourself is allowed but the force must be reasonable and proportional, and try to note features such as the builds, heights, ethnicities, hair colours, eye colours, tattoos and any unusual physical features of the aggressors or thieves, the number plates of any vehicles involved and the exact time of the incident. Your eyewitness account could make the difference in a case.




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