Exploring the Role of Memory in Recognition and Emotion

Some people seem to enjoy a state of mind which is a bit like this – detached, spacey – and they get it from commonly used drugs such as cannabis. Psychedelic drugs also do this as well as produce more dramatic distortions in perception.

Clearly memory cannot consist of a static record archive against which new perceptions are matched so that we can say, yes, I recognize that – it’s my house, my street; no that’s new, never seen that before. If it did, memory would keep failing as soon as the lighting was different or we were approaching the object from a different angle; or in the context of people, they had aged, changed their hair style, grown a beard and so forth. You would need an infinite number of versions for each memory record, and that would be so inefficient as to be impractical.

Of course, we do sometimes fail to recognise people if they change their look, at least initially and especially if we see them out of their usual context. Similarly, we do sometimes mistake a stranger for someone we know. That’s because an efficient memory system must ‘cheat to some extent by building up expectations based on prior experience. An efficient memory system stores an abstract blueprint of the object that takes into account the ways it might change in time and context.

Crucially, an efficient memory system must also be able to tolerate a margin of error: perhaps it’s not quite what you were expecting, but it’s close enough. Only recently have computers become able to recognise faces and voices, despite huge invest-ment, and that’s because software engineers have learned to copy the way our minds work.

This is the balancing act of our memory system: if my margin of error is too lax, then everything looks familiar even if I’ve never seen it before, and I will have constant déjà vu. If I am too strict, everything looks new, nothing looks familiar, I don’t remember any of it, and I will be lost. What we have with Patrick is not quite that. Things do look familiar, but only up to a point. It looks like Vicky, but something is missing.

Recognition produces an emotional charge. In fact, we experience a physical response at the moment of recognition, especially when the thing or person is salient or emotionally resonant (like a loved one), and this can be detected in a laboratory as a skin conductance response (SCR). It is simply a tiny burst of sweat that increases the electrical conductivity of the skin, which is the basis of a lie detector test.

Sigmund Freud put this together in an article entitled ‘Mourning and Melancholia’ published in 1917, in which the experience of bereavement was compared with that of depression and the overlap pointed out. People with depression, it is assumed, must have suffered more than their share of losses – including the loss of work, health or more symbolic and abstract losses such as those of status and esteem.

If you are depressed, your mind is flooded with all the bad, unpleas-ant, boring, frustrating, annoying things that happened, and this crowds out all the happy, pleasant, even banal and neutral things that happened. If you weren’t depressed before, you certainly would be afterwards. It is easy to see why this becomes a vicious cycle. Starting off from a position of feeling low, further negative thoughts seem to be normal, the status quo, and low mood becomes self-sustaining.

Is suicide common? It’s all relative. Compared with road traffic accidents, the answer is yes. For a man in his late thir-ties, like Thomas, it is the commonest cause of death. But compared with depression, the answer is no; relative to that, suicide is exceedingly rare. Hence, there is difficulty in predic-tion. When looking back over cases of suicide, the vast majority belong to low- or only moderate-risk groups. This seems like a paradox but is a familiar pitfall of risk prediction.

Because individual risk factors are not overwhelmingly strong, and because some of the risk factors themselves, such as depression, are common, it is a statistical inevitability that most people who die by suicide will come from a relatively large group of low-risk people. A greater but still minor proportion of people from a high-risk group (let’s say men of a certain age with severe depression, alcohol dependence, who are chronically ill, widowed and unemployed) will take their own lives, but that subgroup will be numerically small in the wider scheme of things. The other problem is that the most reliable risk factors don’t change: for example, being male. If you are a man, your risk is the same today as it was last year, and as it will be tomorrow.

Source : Into the Abyss: A Neuropsychiatrist’s Notes on Troubled Minds by Anthony David

Goodreads : https://www.goodreads.com/book/show/52386552-into-the-abyss

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