It comes in three flavours, and may betray your trust.
As we saw in the previous section, learning turns experience into knowledge. But our ability to remember and recall this information at a later date is what makes this knowledge useful. And that’s all down to our memory.
Our brains are very selective about what they memorise. Most experiences pass us by and fade into oblivion because there’s no need to stuff our heads with memories which are unlikely to be useful.
When we do remember things, the system we use can be one of three types, each of which uses a different brain process. ‘Working memory’ uses fast-firing neurons to hold new information temporarily in mind for immediate use, short-term memory is a separate system that involves temporary changes to neural firing patterns in the brain, while long-term memory involves permanent changes in the brain’s tissue which are unlikely to disappear until the tissue itself dies or is damaged.
As we age, it gets more difficult to hold things in mind because the neurons which suppress distractions are less efficient. Meanwhile, laying down new long-term memories is more difficult because our brains are less plastic. We also find it harder to access information, even when it is well-learned. This may be because we no longer have direct pathways to it. Memory is ‘state-dependent’ in that it needs to be prompted by something associated with it. A retired lawyer, for example, may retain complete knowledge of their area of law but be unable to come up with it until they revisit their old office or courtroom.
Forgetting things we want to hold on to is one type of memory failure. Another is inaccurate or fabricated recall. Remembering something that happened to you is to re-experience it – up to a point. Recalling a rainy day on holiday, for example, involves activity in the sensory neurons that originally produced the feel of the water droplets and the sight of the cloudy landscape, together with those that produced an emotion (disappointment, maybe, at not being able to enjoy the beach). Neurons that registered the faces of the people you were with might fire again, together with those triggered by the food you were eating.
While this brain activity is similar to the patterns that occurred at the time, it is never identical. Even when we’re thinking about the past, our brain is keeping tabs on the present, so our neurons are being stimulated not only by the memory, but also by the sounds, sights and smells around us. The patterns are fused together, so every time we recall a memory, we add something of the present moment. Eating a pizza while recalling that rainy day, for instance, might cause the pizza to enter the memory, so that next time you might remember eating a quattro formaggio as that holiday rain fell.
Memory distortions like this are inevitable, and sometimes dangerous. Several decades ago, psychologist Elizabeth Loftus demonstrated that false memories can be planted in people’s minds with astonishing ease. Now, researchers have discovered a new twist: ‘choice blindness’. This refers to people’s failure to notice when their own statements are falsified. It has huge implications for criminal law, which depends on witness reports. In a 2016 study at the University of California, volunteers identified the culprit of a staged crime from a line-up. Two days later they were invited to confirm their choice but, unknown to them, were presented with a photo of a different person. Two-thirds of the volunteers agreed this was the culprit they had first identified.
So it’s clear that memory is a fickle creature, and that we should take our recollections with a pinch of salt.
Tune up your memory
- Consuming lots of B vitamins (found in whole grains, seeds, nuts and beans) may help. These aid many brain functions, including neurotransmitter production. One study found that high doses of B vitamins halved the rate of brain shrinkage in people with mild memory problems. But the jury is still out on vitamin B.
- Use mnemonics such as rhymes (‘30 days has September’) and acronyms (‘Richard Of York Gave Battle In Vain’) – both tried-and-tested ways of making information more memorable.
- Construct a mental picture of a familiar location, such as your home, and place things that you want to recall in its rooms so that you can mentally stroll through the image and spot the unfamiliar items you’ve stored there – a bit like Sherlock’s ‘mind palace’.
- Write a to-do list each morning and consult it at regularly throughout the day, to keep it fresh in your mind..
- Establish habits such as putting your keys on a particular hook every time you come in. This establishes a link in your brain between the objects (e.g. the hook and the keys), so that when you need your keys you automatically remember the hook, rather than trying to recall, each time, where you put them last.
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