En base a la prueba de hipótesis general

explanation, is called in question by scientific scrutiny of these phenomena.

The important issue about dreaming is not whetlier tliere are some, or even quite a few, particular cases in which there is good evidence that a person remembers what happened during sleep. Hie important issue is about a general account of our apparent memories upon awakening which are not memories of waking life. Hie Received Opinion, as commonly understood, makes tlie assumption that both (a) sleep and (b) our apparent memories upon awakening which are not

memories of waking life, are homogeneous phenomena. On tliis assumption, the Received Opinion attempts to link 'sleep' and 'dream reports' witliln a single explanation, claiming that our awakening apparent memories which are not memories of waking life are commonly memories of our mental life when asleep. So long as the Received Opinion is shackled to this assumption, it seems to me, the weight of obvious and familiar evidence lies heavily against it. The appeal to 'special cases', either reported anecdotally or systematically recorded by scientists, cannot upset tlie balance of probabilities. At best, it could show that there are some, perhaps numerous, exceptions to tlie general truth that, in 'telling dream s', we do not remember thoughts, images, sensations, desires, feelings and such like from sleep.

However, if there is one lesson which the systematic scrutiny of nature teaches before all others, it is that what we originally supposed to be a distinctive phenomenon inviting a homogeneous explanation, turns out to be no such tiling. The history of science is very largely the story of how, in one case, a syndrome of associated observables was analysed into various factors each the product of a different underlying process and, in another case, two superficially unrelated observables were found to have a common aetiology. The systematic study of 'sleep' and of 'dream reports' recapitulates this very theme. Electrographic techniques have analysed sleep into a cyclical pattern of physiologically discrete periods, completely upsetting the traditional supposition that sleep is a fairly uniform state of bodily rest, varying only in proximity to waking life along a continum of 'depth'. The attempt to correlate physiological distinctive features within sleep to psychologically significant kinds of 'sleep mentation report' has lead scientists to distinguish dreaming from other types of mental phenomenon associated with sleep. This is especially evident in the once heated, but never satisfactorily resolved, debate

about tlie frequency and character of 'dream reports' consequent upon awakening from NREM sleep.

Aserinsky & Kleitman's (1953) hypothesis that there is a unique correlation between Stage REM sleep and 'dream reports' is still widely publicised but has long-since been discredited. Herman, Ellman and Roffwarg (1979) provide a fascinating review of the strikingly divergent experimental results which provoked the debate about the proper definition of 'dream reports', together with the results of a study designed to assess tlie scope and extent of experimenter-induced bias in early studies once supposed to have established that dreaming is uniquely associated witli Stage REM. Perhaps it is not surprising tliat tlie identification of Stage REM sleep with dreaming still enjoys wide popular credence. It remains easily the best shot ever had at establishing a type-type psycho-physiological correlation generally applicable to a familiar mental phenomenon. And, it would seem, many people, though not so many psychologists or philosophers now, still suppose that progress in psychology must result in the discovery of such correlations.

The ability to predict the likelihood that a person will have a story to tell if awoken retains its place as the securest result in psycho-physiology. It is an important result, despite the failure of earlier ambitions to demonstrate content-relative correlations. Some such ambitions were for a time rekindled by LaBerge's (1985) work on 'lucid dreams'. But Hobson's (1988) program of establishing formal' rather than content-specific correlation is probably tlie mainstream of what survives of psycho-physiological dream research. That reseach program is nowadays an altogether more modest giffair than it was in its hey-day of the fifties and sixties, when it flourished largely as a beneficiary of the U.S. defence budget reseach boom, and researchers could

wealth of type-type identities. Rechstaffen's earlier (1967) paper which attem pted to justify the assum ption that 'subjective reports' could be 'validated' by correlations w ith physiological phenomena (such as the supposed correlation of movements within a dream narrative to eye-movements during sleep which was offered in support of the notorious 'scanning hypothesis') was some time ago superseded by an equally influential (1978) essay in which he argued, in effect, that the phenomenological distinctiveness of dream narratives among reports of mental phenomena (features he characterised as the 'single-mindedness' and 'isolation' of dreams) is reflected in the failure of researcher's like himself to establish significant psycho- pysiological correlations. Foulkes, anotlier veteran, once in the cold-war vanguard of correlative research, has long since abandoned any ambition to answer the persistent questions about dreaming in 'hard' neurobiological terms. Foulkes (1978) (1985) has attempted, almost single handedly one might suppose from a glance at the literature, to integrate dream theory w ithin the framework of cognitive psychology, attempting to show both that Freudian psyclio-dynamics is not the only alternative to Hobson's (1988) neurobiology, and that cognitive psychology can embrace the problems about motive and creativity raised by dreaming without compromising its hard-won scientific credentials.

Many researchers still suppose that NREM reports, whilst more frequent than originally believed, tend to differ in character from Stage REM reports, and classify NREM reports as 'tliinking reports' in contrast to the typical Stage REM 'dream report'. This maintains the appealing idea that there is at least some psychological distinction corresponding to tlie dramatic physiological contrast between Stage REM and NREM sleep. There is, however, no consensus about what exactly are the distinctive features according to which 'sleep

mentation reports' should be classified. Some have despairingly questioned whether reports elicited from NREM sleep differ clearly in character from tliose of Stage REM sleep in any particular respect otlier tlian the average length of narrative.

It is, perhaps, unsurprising that there is little agreement about the significant differences and similarities among 'sleep mentation reports', given that leading theorists like Foulkes (1985) and Hobson (1988) take such radically variant views about what an explanation of mental phenomena in sleep should look like. (Foulkes, the cognitive psychologist, evidently regards Chomsky, Fodor and other m odular Representational Realists as his philosophical brethren, whereas Hobson is clearly of a mind-brain with the identity theorist or, rather, w ith elim inative m aterialists like the Churchlands.) Dement (1975), once the most active researcher in the field, suggested a furtlier source of indecision about the classification of waking narratives when he expressed doubts about whetlier to attribute distinctions between 'sleep mentation reports' taken from REM and NREM sleep to discrete kinds of mental life within sleep or to variations in the ability to remember witli uniform clarity and vividness what is in fact a homogeneous mental life more or less continuous throughout 'sleep'. More recently, LaBerge (1985) has further m uddied the classification issue by attempting to meet head-on tlie requirement stipulated by psycho-physiologists like Dement, Rechtstaffen and Hobson that kinds of reports be 'validated' by association with physiological variables in sleep. The fact that 'lucid dream' reports vary so strikingly from typical Stage REM reports presents a serious problem for theorists like Foulkes, Rechtstaffen and Hobson who regard dreaming as a form of credulous hallucination or of thinking and imagining marked by its lack of reflective awareness. According to LaBerge, many established dream researchers take

common comfort in alternatively denying the existence of lucid dreams, attempting to marginalise their importance, or simply yet ignoring them. LaBerge (1986) gives evidence of a sort tliat it is hard, for Hobson at least, to ignore, that narratives of lucid dreams are 'objectively valid' reports and are associated with Stage REM sleep.

If scientific scrutiny of sleep and dreaming has shown any one thing, it is that our pre-scientific concepts tend to disintegrate in tlie face of the amazing complexity of phenomena and tlieir inter-relationships which is discovered. Given this complexity, it cannot be expected that we come away from Nature with neat answers to questions initially posed. More likely, we will come away asking different questions. Sometimes with an answer, sometimes not. But almost certainly we will cease to attach the same importance to the same questions as we did when we started out.

This is not automatically bad news for the defender of tlie Received Opinion and good news for me. The claim that scientific discoveries not so much disprove the Received Opinion as render it obsolete, tells equally against the philosophical interest of my claim that familiar facts show the Received Opinion to be irredeemably false. The contention that scientific discoveries could not justify tlie Received Opinion, needs to be backed up with a plausible account of just what scientific discoveries could show. It is open for tlie traditional defender of the Received Opinion to revise his thesis and argue as follows; Granted that there is no general account of 'telling a dream' as the memory of what a person seemed to see and tried to do during sleep; this does not entail tliat there are merely odd cases where something is remembered from sleep following no regular pattern; there may well be distinctive kinds of cases (i.e. kinds of 'sleep' or kinds of 'sleep mentation report') for which it is a general truth that our awakening narratives are genuine memories of what we

thought, im agined, intended, felt, etc. during sleep; Sleeptalking, Sleepwalking, Night Terrors and Lucid Dreaming might turn out to be distinctive kinds of phenomenon within 'sleep', each associated w ith a particular kind of what scientists (having abandoned using 'dream report' as a catch-all term) now inelegantly call 'sleep mentation reports'.

I stand by tlie claim of Chapter One that, from what we already know, tlie Received Opinion is patently false. But, in tliis cliapter I wish also to examine the evidence for and against 'specialised versions' of the Received Opinion, concerning Sleeptalking, Sleepwalking, Night Terrors and Lucid Dreaming, In cases where a person says or does something during sleep, is there a significant correlation between what he says and does during sleep and what he appears to remember upon awakening? In cases of Lucid Dreaming, where a person appears to remember, not events seen and deeds done, but visual, auditory and tactile impressions w hidi he entertained as vivid representations, sometimes subject to his will, whilst believing himself to be lying asleep in bed, is there any reason to doubt a person's word? And, supposing evidence to be required, is not this provided by the association of Lucid Dream reports witli pre-arranged 'signals' made during sleep?

3. Where an association between a person’s dispositions to behaviour and what he subsequently appears to remember upon awakening is good evidence that he remembers something tliat happened, it is also good evidence that he was awake at the time it happened.

Hie liypotliesis that someone remembers what he said or did during sleep is a curious one. Wlien Flashback claims to remember filling out tlie pools coupon in time for the five o'clock post, he wants all the independent evidence tliat he can conceivably muster to convince his wife that he conscientiously went

through the motions, that he paid attention to what he was doing, that, in short, he'd filled in the coupon just as she'd told him. But later, in the pub, when Flashback boasts to his mates that he'd really filled in the pools coupon whilst asleep, his enthusiasm for independent evidence about what he'd done and said suddenly takes on a note of caution. For, if tlie independent evidence that he remembers is 'too good', it will also show tliat he was not asleep at tlie time he filled out the coupon. It is a curious feature of the hypothesis that someone remembers what went tlirougli his mind whilst walking, talking or 'signalling' during sleep, that the evidence that he was aware of what he was doing, and hence remembers something, is necessarily pretty thin and tenuous.

Ayer (1974) tells an amusing story which plays upon die close connection between evidence for tlie conclusion tliat a person's behaviour is tlie product of intentions and beliefs and evidence for the conclusion tliat he is awake:

" . . . it is related of one of the Dukes of Devonshire tliat he dreamed that he was speaking in tlie House of Lords and awoke to find tliat he really was speaking in the House of Lords. Even if this story is untrue, it does not appeal- to be self-contradictory." [p.239]

The humour of the story, as I understand it, rests upon tlie tacit implication that the Duke talked without meaning. He talked without meaning either because he was asleep and unaware of liis utterances or (the satirical point) because he was a stupid windbag, whose waking speech resembled the incoherent ramblings of a sleeptalker. The imaginary picture we are given of the Duke is one in which the evidence is indecisive as to whetlier he remembers what happened whilst he was asleep or whether he was awake but speaking, as it were, on 'automatic pilot', perhaps to delay the passage of a Bill, apparently unaware of the words he uttered.

We can imagine the Duke’s behaviour. (Those who have witnessed the member for Perth & Kinross 'in action' won't need to image.) His eyes are closed, his head nods, he dribbles. His faltering, rambling monologue is irrelevant and incoherent. Suddenly his head jerks, he looks around, dumbfounded and confused. A momentary brightness comes to his eyes. "All, yes! As I was saying to my honourable friend, the member for Sidcup, in tlie eventuality of an infringement of clause four, subsection twelve of the present measure ..." And he's off again. The evidence that the Duke was asleep is exactly evidence that, even if not asleep, he was yet unaware of what he was saying, that his words were uttered without any intentional purpose. Tlie evidence that the Duke remembered what he said (i.e. the evidence that his subsequent narrative relates to thoughts and intentions which give his previous behaviour more coherence than was previously obvious) tends to show tliat he was aware of what he said, that his words expressed thoughts and intentions going through his mind at the time, that he was not on 'automatic pilot'. But this evidence of 'memory' equally tends to show tliat the Duke was not in fact asleep when he made his speech, that he was in fact awake.

It is tempting to argue that a person could only be deemed to have beliefs and intentions about an hallucinated environment where he showed sufficient awareness of his actual environment to be deemed awake or, if not fully awake, then at least in some peculiar state distinguishable from normal sleep. A person asleep might utter various words and go through various motions as if he were engaged with illusory people and objects. But if tliere is sufficient reason to suppose that he was unaware of these words and motions, and hence asleep, there is insufficient reason to infer from these words and motions that he is aware of a train of thoughts, sensations, intentions. What can be said to repel the argument that a person's utterances and behaviour reveal his beliefs and

intentions only where tliey show that he was awake rather tlian asleep? It m ight be said that this argum ent rests upon an inadequate behavioural definition of sleep; that if we had physiological evidence that the 'sleeptalker' or 'sleepwalker' was indeed asleep, it need not bother us that he showed an unusual degree of awareness of his environment and behaviour for one who is asleep.

Unfortunately, the scientific study of sleep does not give reason to be confident that the judgement that a 'sleeptalker' or someone in the grip of a 'night terror' is asleep rather than momentarily awake. Both these phenomena are characterised by a marked interruption of the normal physiological patterns within sleep. Hie supposition that the proper criterion of sleep should be physiological only exacerbates the problem of establishing that the subject was asleep during the episode of talking or terror. In these cases, scientists cannot make the judgement that he was asleep independently of a psychological interpretation of tlie subject's dispositions to concurrent behaviour.

4. Scientists can rely upon a physiological criterion of sleep in cases of