Posts tagged ‘memory’

It’s not just that we don’t know how anaesthetics work – we don’t even know for sure that they work. Joshua Rothman’s review of a new book on the subject by Kate Cole-Adams quotes poignant stories of people on the operating table who may have been aware of what was going on. In some cases the chance remarks of medical staff seem to have worked almost like post-hypnotic suggestions: so perhaps all surgeons should loudly say that the patient is going to recover and feel better than ever, with new energy and confidence.

How is it that after all this time, we don’t know how anaesthetics work? As the piece aptly remarks, it’s about losing consciousness, and since we don’t know clearly what that is or how we come to have it, it’s no surprise that its suspension is also hard to understand. To add to the confusion, it seems that common anaesthetics paralyse plants, too. Surely it’s our nervous system anaesthetics mainly affect – but plants don’t even have a nervous system!

But come on, don’t we at least know that it really does work? Most of us have been through it, after all, and few have weird experiences; we just don’t feel the pain – or anything. The problem, as we’ve discussed before, is telling whether we don’t feel the pain, or whether we feel it but don’t remember it. This is an example of a philosophical problem that is far from being a purely academic matter.

It seems anaesthetics really do (at least) three different things. They paralyse the patient, making it easier to cut into them without adverse reactions, they remove conscious awareness or modulate it (it seems some drugs don’t stop you being aware of the pain, they just stop you caring about it somehow), and they stop the recording of memories, so you don’t recall the pain afterwards. Anaesthetists have a range of drugs to produce each of these effects. In many cases there is little doubt about their effectiveness. If a drug leaves you awake but feeling no pain, or if it simply leaves you with no memory, there’s not that much scope for argument. The problem arises when it comes to anaesthetics that are supposed to ‘knock you out’. The received wisdom is that they just blank out your awareness for a period, but as the review points out, there are some indications that instead they merely paralyse you and wipe your memory. The medical profession doesn’t have a good record of taking these issues very seriously; I’ve read that for years children were operated on after being given drugs that were known to do little more than paralyse them (hey, kids don’t feel pain, not really; next thing you’ll be telling me plants do…).

Actually, views about this are split; a considerable proportion of people take the view that if their memory is wiped, they don’t really care about having been in pain. It’s not a view I share (I’m an unashamed coward when it comes to pain), but it has some interesting implications. If we can make a painful operation OK by giving mnestics to remove all recollection, perhaps we should routinely do the same for victims of accidents. Or do doctors sometimes do that already…?

The new Blade Runner film has generated fresh interest in the original film; over on IAI Helen Beebee considers how it nicely illustrates the concept of ‘q-memories’.

This relates to the long-established philosophical issue of personal identity; what makes me me, and what makes me the same person as the one who posted last week, or the same person as that child in Bedford years ago? One answer which has been a leading contender at least since Locke is memory; my memories together constitute my identity.

Memories are certainly used as a practical way of establishing identity, whether it be in probing the claims of a supposed long-lost relative or just testing your recall of the hundreds of passwords modern life requires. It is sort of plausible that if all you memories were erased you would become new person with a fresh start; there have been cases of people who lost decades of memory and underwent personality change, identifying with their own children more readily than their now wrinkly-seeming spouses.

There are various problems with memory as a criterion of identity, though. One is the point that it seems to be circular. We can’t use your memories to validate your identity because in accepting them as your memories we are already implicitly taking you to be the earlier person they come from. If they didn’t come from that person they aren’t validly memories. To get round this objection Shoemaker and Parfit adopted the concept of quasi- or q-memories. Q-memories are like memories but need not relate to any experience you ever had. That, of course, is too loose, allowing delusions to be used as criteria of identity, so it is further specified that q-memories must relate to an experience someone had, and must have been acquired by you in an appropriate way. The appropriate ways are ones that causally relate to the original experience in a suitable fashion, so that it’s no good having q-memories that just happen to match some of King Charles’s. You don’t have to be King Charles, but the q-memories must somehow have got out of his head and into yours through a proper causal sequence.

This is where Blade Runner comes in, because the replicant Rachael appears to be a pretty pure case of q-memory identity. All of her memories, except the most recent ones, are someone else’s; and we presume they were duly copied and implanted in a way that provides the sort of causal connection we need.

This opens up a lot of questions, some of which are flagged up by Beebee. But  what about q-memories? Do they work? We might suspect that the part about an appropriate causal connection is a weak spot. What’s appropriate? Don’t Shoemaker and Parfit have to steer a tricky course here between the Scylla of weird results if their rules are too loose, and the Charybdis of bringing back the circularity if they are too tight? Perhaps, but I think we have to remember that they don’t really want to do anything very radical with q-memories; really you could argue it’s no more than a terminological specification, giving them license to talk of memories without some of the normal implications.

In a different way the case of Rachael actually exposes a weak part of many arguments about memory and identity; the easy assumption that memories are distinct items that can be copied from one mind to another. Philosophers, used to being able to specify whatever mad conditions they want for their thought-experiments, have been helping themselves to this assumption for a long time, and the advent of the computational metaphor for the mind has done nothing to discourage them. It is, however, almost certainly a false assumption.

At the back of our minds when we think like this is a model of memory as a list of well-formed propositions in some regular encoding. In fact, though, much of what we remember is implicit; you recall that zebras don’t wear waistcoats though it’s completely implausible that that fact was recorded anywhere in your brain explicitly. There need be nothing magic about this. Suppose we remember a picture; how many facts does the picture contain? We can instantly come up with an endless list of facts about the relations of items in the picture, but none were encoded as propositions. Does the Mona Lisa have her right hand over her left, or vice versa? You may never have thought about it, but be easily able to recall which way it is. In a computer the picture might be encoded as a bitmap; in our brain we don’t really know, but plausibly it might be encoded as a capacity to replay certain neural firing sequences, namely those that were caused by the original experience. If we replay the experience neurally, we can sort of have the experience again and draw new facts from it the way we could from summoning up a picture; indeed that might be exactly what we are doing.

But my neurons are not wired up like yours, and it is vanishingly unlikely that we could identify direct equivalents of specific neurons between brains, let alone whole firing sequences. My memories are recorded in a way that is specific to my brain, and they cannot be read directly across into yours.

Of course, replicants may be quite different. It’s likely enough that their brains, however they work, are standardised and perhaps use a regular encoding which engineers can easily read off. But if they work differently from human brains, then it seems to follow that they can’t have the same memories; to have the same memories they would have to be an unbelievably perfect copy of the ‘donor’ brain.

That actually means that memories are in a way a brilliant criterion of personal identity, but only in a fairly useless sense.

However, let me briefly put a completely different argument in a radically different direction. We cannot upload memories, but we know that we can generate false ones by talking to subjects or presenting fake evidence. What does that tell us about memories? I submit it suggests that memories are in essence beliefs, beliefs about what happened in the past. Now we might object that there is typically some accompanying phenomenology. We don’t just remember that we went to the mall, we remember a bit of what it looked like, and other experiential details. But I claim that our minds readily furnish that accompanying phenomenology through confabulation, given the belief, and in fact that a great deal of the phenomenological dressing of all memories, even true ones, is actually confected.

But I would further argue that the malleability of beliefs means that they are completely unsuitable as criteria of identity; it follows that memories are similarly unsuitable, so we have been on the wrong track throughout. (Regular readers may know that in fact I subscribe to a view regarded by most as intolerably crude; that human beings are physical objects like any other and have essentially the same criteria of identity.)


LorenzoConsciousness, as we’ve noted before, is a most interdisciplinary topic, and besides the neurologists, the philosophers, the AI people, the psychologists and so on, the novelists have also, in their rigourless way, delved deep into the matter. Ever since the James boys (William and Henry) started their twin-track investigation there has been an intermittent interchange between the arts and the sciences. Academics like Dan Lloyd have written novels, novelists like our friend Scott Bakker have turned their hand to serious theory.

Recently we seem to have had a new genre of invented brain science. We could include Ian McEwan’s fake paper on De Clerambault syndrome, appended to Enduring Love; recently Sebastian Faulks gave us Glockner’s Isthmus; now, in his new novel A Box of Birds Charles Fernyhough gives us the Lorenzo Circuit.

The Lorenzo Circuit is a supposed structure which pulls together items from various parts of the brain and uses them to constitute memories. It’s sort of assumed that the same function thereby provides consciousness and the sense of self. Since it seems unlikely that a distinct brain structure could have escaped notice this long, we must take it that the Lorenzo is a relatively subtle feature of the connectome, only identifiable through advanced scanning techniques. The Lycée, which despite its name seems to be an English university, has succeeded in mapping the circuit in detail, while Sansom, one of those large malevolent corporate entities that crop up in thrillers, has developed new electrode technology which allows safe and detailed long-term interference with neurons. It’s obvious to everyone that if brought together these two discoveries would provide a potent new technology; a cure for Alzheimer’s is what seems to be at the forefront of everyone’s minds, though I would have thought there were far wilder and more exciting possibilities. The story revolves around the narrator, Dr Yvonne Churcher, an academic at the Lycée, and two of her undergraduate students, Gareth and James.

Unfortunately I didn’t rate the book all that highly as a novel. The plot is put together out of slightly corny thrillerish elements and seems a bit loosely managed. I didn’t like the characters much either. Yvonne seems to be putty in the hands of her students, letting Gareth steal the Lycée’s crucial research without seeming to hold the betrayal of her trust against him at all, and being readily seduced by the negligent James, a nonsense-talking cult member who calls her ‘babe’ (ack!). I’ve seen Gareth described as a “brilliant” character in reviews elsewhere, but sadly not much brilliance seems to be on offer. In fact to be brutal he seemed to me quite a convincing depiction of the kind of student who sits at the back of lectures chuckling to himself for no obvious reason and ultimately requires pastoral intervention. Apart from nicking other people’s theories and data, his ideas seem to consist of a metaphor from Plato, which he interprets with dismal literalism.

This metaphor is the birds thing that provides the title and up to a point, the theme of the book. In the Theaetetus, Plato makes a point about how we can possess knowledge without having it actually in our consciousness by comparing it to owning an aviary of birds without having them actually in your hand. In Plato’s version there’s no doubt that there’s a man in the aviary who chooses the birds to catch; here I think the idea is more that he flocking and movement of the birds itself produces higher-level organisation analogous to conscious memory.

Yvonne is a pretty resolute sceptic about her own selfhood; she can’t see that she is anything beyond the chance neurochemical events which sweep through her brain. This might indeed explain her apparent passivity and the way she seems to drift through even the most alarming and hare-brained adventures, though if so it’s a salutary warning about the damaging potential of overdosing on materialism. Overall the book alludes to more issues than it really discusses, and gives us little side treats like a person whose existence turns out to be no more than a kind of narrative convention; perhaps it’s best approached as a potential thought provoker rather than the adumbration of a single settled theory; not necessarily a bad thing for a book to be.

Yvonne’s scepticism did cause me to realise that I was actually rather hazy on the subject; what is it that people who deny the self are actually denying, and are they all denying the same thing? There are actually quite a few options.

  • I think all self-sceptics want to deny the existence of the traditional immaterial soul, and for some that may really be about all. (To digress a bit, there are actually caverns below us at this point which have not been explored for thousands of years, if ever: if we were ancient Egyptians, with their complex ontology of multiple souls, we should have a large range of sceptical permutations available; denying the ba while affirming the khaibit, say. Our simpler culture, perhaps mercifully, does not offer us such a range of refinedly esoteric entities in which to disbelieve, but those of a philosophical temperament may be inclined to cast a regretful glance towards those profoundly obscure imaginary galleries.)
  • Some may want to deny any sense, or feeling, of self; like Hume they see only a bundle of sensations when they look inside themselves. I think there is arguably a quale of the self; but these people would not accept it.
  • Others, by contrast, would affirm that the sense of self is vivid, just not veridical. We think there’s a self, but there’s nothing actually there. There’s scope for an interesting discussion about what would have to be there in order to prove them wrong – or whether having the sense of self itself constitutes the self.
  • Some would say that there is indeed ‘something’ there; it just isn’t what we think it is. For example, there might indeed be a centre of experience, but an epiphenomenal one; a self who has no influence on events but is in reality just along for the ride.
  • Logically I suppose we could invert that to have a self that really did make the decisions, but was deluded about having any experiences. I don’t think that would be a popular option, though.
  • Some would make the self a purely social construct, a matter of legal and moral rights and privileges, a conception simply grafted on to an animal which in itself, or by itself, would lack it.
  • Some would deny only that the self provides a break in the natural chain of cause and effect. We are not really the origin of anything, they would say, and our impression of being a freely willing being is mistaken.
  • Some radical sceptics would deny that even the body has any particular selfhood; over time every part of it changes and to assert that I am the same self as the person of twenty years ago makes no sense.

As someone who, on the whole, prefers to look for a tenable account of the reality of the self, the richness of the sceptical repertoire makes me feel rather unimaginative.

Picture: writing. Carl Zimmer described some interesting research in a recent blog entry . It seems that people who are unable to recall any of the events of their past lives are still able to identify which of a list of words best describes them as people: although their explicit knowledge of their own autobiographies has disappeared, they still have self-knowledge in a different form. It is suggested that two different brain systems are involved. This research might possibly shed a chink of light on the debate about whether, and in what sense, we actually have selves, but it also raises the thorny question of different ways of knowing things. We often talk about knowing things as though knowledge was a straightforward phenomenon, but it actually covers a range of different abilities – look at the following examples.

  1. I know what the capital of Ecuador is.
  2. I know where the keys are.
  3. I know how to sign my name.
  4. I know that zebras don’t wear waistcoats

The first example is the case in which an explicit fact has been memorised – possibly even a fixed formula (“The capital of Ecuador is Quito.”). This is perhaps the easiest form of knowledge to deal with in a computational way – we just have to ensure that the relevant string of characters (“Quito”) or the appropriate digits are stored in a suitable location. There’s relatively little mystery about how you can articulate this kind of knowledge, since it has probably been saved in an articulated form already: it was words on the way in, so it’s no surprise that we can provide words when it’s on the way out.

In the second case, things are slightly less clear. It’s unlikely, unless you have a really bad key-losing problem, that you have memorised an explicit description of the place where they are: however, if you need to produce such a description, you would normally have no particular difficulty in doing so. A reasonable assumption here might be that the relevant data on the position of the keys are still stored somewhere explicitly, (on some sort of map, as co-ordinates, or perhaps more likely, as a set of instructions like those on pirate’s treasure maps, telling you how to get to the treasure/keys). The question of how you are able to translate this inner data into a verbal description when you need one is less easily answered, but then, the process of coming up with a description of anything is not exactly well understood, either.

The third case is a bit different. The importance of ‘knowing how’ as a form of knowledge was emphasised by Gilbert Ryle as part of his efforts to debunk the ‘Ghost in the Machine’. It could legitimately be argued that the difference between ‘knowing how’ and ‘knowing that’ is so great that it makes no sense to consider them together – but both do allow some stored knowledge to influence current behaviour, so there is at least that broad similarity. You sign your name without hesitation, but describing how to do it (unless you happen to be called ‘O’) is challenging. To describe the required series of upstrokes and downstrokes would require careful thought – you might even have to watch yourself signing and take notes. The relevant data must be in your brain or your hand somewhere, but you are hardly any better off when it comes to putting them into words than anyone else who happens to be watching. Presumably the relevant data are still stored somewhere in your brain. Perhaps they are just in a different part of it, or otherwise less accessible: but it seems likely that at least some of them are held in a form which just doesn’t translate into explicit terms. There may be a sequence of impulses recorded somewhere which, when sent down the nerves in your arm, results in a signature: but there need be no standard pattern in the sequence which symbolises ‘downstroke’ or anything else.

The fourth case is the most difficult of all. Most of the things we know, we never think about or use. We never asked ourselves whether zebras wore waistcoats until Dennett proposed the example, but as soon as we heard the question, we knew the answer. This vast stock of common-sense knowledge (Searle refers to it, or something very like it, as ‘the Background’) is crucial to the way we deal with real life and work out what people are talking about: it’s the reason human beings don’t generally get floored by the ‘frame problem’ – unanticipated implications of every action – the way robots do. It surely cannot be that all this kind of knowledge is saved explicitly somewhere in the brain, however vast its storage capacity. In fact, there are good arguments to suggest that the amount of information involved is strictly infinite: we know zebras are normally less than twenty feet tall, normally less than twenty-one feet tall, and so on.

That last argument suggests a better explanation – perhaps key pieces of information are stored in a central encyclopaedia, and the more recondite conclusions worked out as necessary. After all, if we know that zebras are less than twenty feet, simple arithmetic will tell us that they are less than fifty, without the need to store that conclusion separately. The trouble then is that there simply is no general method of working out relevant conclusions from other facts: formal logic certainly isn’t up to the job. I’ve discussed this further elsewhere , but it seems likely to me that part of the problem is that, as with the third case, the information is probably not recorded in the brain in any explicit form. To look for an old-fashioned algorithm is probably, therefore, to set off up a blind alley.

What about the two forms of self-knowledge we started with? It looks as if we are dealing with a loss of the kind of knowledge covered by example 1 above, while type 2 is retained. If so, the loss of memory might be less disabling than it seems. The patients in question would not be able to tell you their address, but perhaps they might still be able to walk to the correct house “without thinking about it”? They might not be able to tell you their own name, even – but perhaps they could sign it and then read it.